Linear heave compensation device based on double-piston double-rod energy accumulator

Abstract

The invention designs a linear heave compensation device based on a double-piston double-rod type energy accumulator, which belongs to the technical field of ocean engineering equipment, adopts the double-piston double-rod type energy accumulator as a coupling device of compensation power, is provided with a plurality of functional cavities, and connects a high-pressure gas cylinder group with a passive compensation gas cavity of the double-piston double-rod type energy accumulator to form a high-pressure gas cylinder group. Therefore, a passive compensation force is provided on the piston rod of the energy accumulator; the two-way variable pump is connected with two active compensation liquid cavities of the energy accumulator, active compensation force capable of controlling the magnitude and the direction is provided on a piston rod of the energy accumulator through a closed variable pump speed control and regulation loop, the passive compensation force and the active compensation force jointly overcome the load of the energy accumulator, and the piston rod of the energy accumulator is driven to move. And finally, the compensation cylinder is indirectly driven to realize a heave compensation function. In addition, the deepwater high-pressure environment pressure acts on the end portions of the energy accumulator load pressure liquid cavity piston rod and the compensation cylinder piston rod at the same time, and the deepwater pressure compensation function is achieved through pressure interaction offset. According to the invention, a plurality of operation modes and functions such as passive compensation, active compensation and water pressure compensation are realized, operation under different working conditions such as overwater, underwater and deepwater areas can be realized, and the device has the characteristics of novel structure, compact system, integration of multiple functions, 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 working at sea, engineering equipment will be affected by wind, waves and currents, which will generate six-degree-of-freedom motion. Heave, roll and pitch will cause the load to move vertically, which may cause the load to collide with the underwater platform, or the lowered load to be suspended again. These emergencies may cause equipment damage and cable breakage, or even safety accidents and casualties. In order to successfully complete offshore operations and increase the operating sea condition window, offshore engineering equipment must be equipped with a heave compensation system.

[0003] Heave compensation systems are divided into fixed and mobile types according to the installation method, winch rotary type and hydraulic cylinder linear type according to the working principle, and passive compensation type, active compensation type and active-passive combined compensation type according to the power supply. The actuator of the linear compensation system is a hydraulic cylinder. Compared with equipment with large rotational inertia such as winches, its system responds more quickly and has more precise control.

[0004] Most of the existing linear compensation systems can only be installed on ships and do not have the ability to be used in a mobile manner or for underwater operations. They have no compensation function for the external environmental water pressure in deep-water high-pressure environments, and it is difficult to solve problems such as splash zone compensation and deep-water resonance. Most of the compensation systems that have the ability to operate underwater only have simple passive compensation functions, and some compensation schemes with active compensation functions also have problems such as complex structure, large equipment volume and size. In the existing active compensation scheme, when an ordinary single-rod hydraulic cylinder is used as a heave compensation hydraulic cylinder, although its compensation system has a simple structure and low cost, it is difficult to realize the active control function of the extension / retraction of the compensation cylinder because there are only two functional chambers inside the ordinary single-rod hydraulic cylinder, which leads to the motor working condition of the hydraulic pump during the reversing and speed regulation process, and the working pressure of the active chamber of the compensation cylinder fluctuates greatly, thereby affecting the compensation accuracy and operation stability of the system; using a composite cylinder as a heave compensation hydraulic cylinder, its compensation system can realize dual power stroke control, with high compensation accuracy, and the flow rate required by the pump during the active compensation process is small, which is convenient for the system to control. However, due to the complex structure and manufacturing process of the composite hydraulic cylinder itself, its manufacturing cost is high, its service life is reduced, and its maintenance cost is high. Summary of the invention

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

[0006] To achieve the above purpose, the overall concept of the present invention is to use a double-piston double-rod accumulator and a common compensating hydraulic cylinder to replace the traditional common compensating hydraulic cylinder or compound compensating cylinder, connect the high-pressure gas cylinder group with the passive compensation air chamber of the double-piston double-rod accumulator, provide a passive compensation force of the load, connect the two-way variable pump to the two active chambers of the double-piston double-rod accumulator, and provide an active compensation force that can change the size and direction by controlling the oil volume in the two active chambers. At the same time, a displacement sensor is installed in the air chamber of the double-piston double-rod accumulator to detect the compensation displacement of the piston, thereby realizing displacement closed-loop control in active compensation.

[0007] The technical solution adopted by the present invention 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 gas cylinder group, an oil storage accumulator, an oil replenishment accumulator, a low-pressure gas cylinder, a passive compensation mode switching valve, an active compensation mode switching valve, an oil replenishment circuit, a throttle valve block, a displacement sensor, a pressure sensor, an MRU motion posture sensor and a PLC control unit are added. The low-pressure gas cylinder is connected to the rodless chamber V1 of the compensation cylinder through the second stop valve. The rod chamber V2 of the compensation cylinder is connected to the load pressure liquid chamber F of the double-piston double-rod accumulator. The gas cylinder group is connected to the passive compensation gas chamber G of the double-piston double-rod accumulator, and the two ports of the two-way variable pump are connected to the two active compensation liquid chambers H and L of the double-piston double-rod accumulator through the active compensation mode switching valve. The oil drain port of the two-way variable pump is connected to the oil replenishment circuit through a one-way valve. The oil replenishment circuit is composed of an oil storage accumulator, an oil replenishment accumulator, an oil replenishment pump, a constant speed motor, a stop valve, a one-way valve, a pressure sensor, a relief valve, a first and second cartridge one-way valves, and a first and second cartridge relief valve. During the oil replenishment process, the replenishment oil enters from the inlet of the first and second cartridge one-way valves and flows out from the side port to the compensation circuit to replenish the system; the replenishment oil can also be replenished 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 chambers H and L of the double-piston double-rod accumulator are connected through a passive compensation mode switching valve. The gas cylinder group is connected to the passive compensation gas chamber G of the double-piston double-rod accumulator through the gas cylinder switch valve and the throttle valve block.

[0008] The present invention is beneficial in that:

[0009] 1. The present invention realizes multiple operation modes and functions such as passive compensation, active compensation, deep water pressure compensation, etc. It can operate in different working conditions such as above water, underwater, and deep water areas. It has the characteristics of compact structure and multi-functional integration. The double-piston double-rod accumulator adopts double piston bearing, and 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 pump-controlled speed regulation is formed by using two volume-coupled active chambers of a bidirectional variable pump and a dual-piston dual-rod accumulator, which realizes active control of the bidirectional motion stroke of the accumulator and the compensation cylinder, and solves the problem of large fluctuations in the working pressure of the active chamber in the existing single active chamber compensation scheme.

[0011] 3. The double-piston double-rod accumulator and compensation cylinder adopt low-friction sealing materials and structures, which reduces the influence of sealing 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 compensation system from resonance and insufficient cylinder movement stroke, and meeting the work needs of conventional wave compensation, splash zone, landing buffer and other non-operating 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 move downward 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 the running stability and reduce the impact.

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

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

[0016] Figure 1 The schematic diagram of a linear heave compensation device based on a double-piston double-rod accumulator of the present invention.

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

[0018] Among them: 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-earring; 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-gas cylinder switch valve;13-gas cylinder group;14-second throttle valve block;15-drain valve;16-fourth stop valve;17-passive compensation mode switching valve;18-active compensation mode switching valve;19-first plug-in one-way valve;20-first plug-in overflow valve;21-first overflow valve;22-oil replenishment accumulator;23-fifth stop valve;24-oil replenishment 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 plug-in overflow valve;32-second plug-in one-way valve;33-seventh stop valve. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementations.

[0020] like Figure 1 , 2 As shown, the low-pressure gas cylinder (7) is connected to the rodless chamber V1 of the compensation cylinder through the second stop valve (5), 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 the first throttle valve block (2) and the first stop valve (3), the passive compensation gas chamber G of the double-piston double-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 two-way 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 port of the bidirectional variable pump (27) is connected to an oil storage accumulator (25) through a one-way valve and a sixth stop valve (26), and is connected to an oil replenishment pump (24) through a one-way valve. The oil replenishment pump (24) is driven by a constant speed motor (29). The oil replenishment pump (15) is connected to an oil replenishment accumulator (22) through a one-way valve and a fifth stop valve (23), and is connected to a load pressure liquid chamber F of a double-piston double-rod accumulator through a one-way valve and a seventh stop valve (33). The one-way valve is connected to the inlet of a first plug-in one-way valve (19) and a second plug-in one-way valve (32). The side port and outlet of the first plug-in one-way valve (19) are connected to the bidirectional variable pump (27) and the inlet of the first plug-in relief valve (20), the outlet of the first plug-in one-way valve (20) is connected to the side port through the first relief valve (21), and the side port is connected to the oil replenishment accumulator (22) through the fifth stop valve (23); the side port and outlet of the second plug-in one-way valve (32) are connected to the bidirectional variable pump (27) and the inlet of the second plug-in relief valve (31), the outlet of the second plug-in relief valve (31) is connected to the side port through the second relief valve (30), and the side port is connected to the oil replenishment accumulator (22) through the fifth stop valve (23).

[0022] In order to realize the functions of oil replenishment and oil discharge, different pressures need to be set for the cartridges, among which the pressure of the first and second cartridge one-way valves must be lower than the pressure of the first and second cartridge overflow valves. When the device needs oil replenishment, the oil replenishment pump drives the replenishing oil to enter from the inlet of the first and second cartridge one-way valves, and flow out from the side port to the compensation circuit to replenish oil for the system; opening the seventh stop valve can also replenish 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 discharge is required, and the high-pressure oil in the circuit enters from the inlet of the first and second cartridge overflow valves, flows out from the side port, and returns to the oil storage accumulator, thereby reducing the pressure in the circuit and realizing the safety protection function.

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

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

[0025] Before the device is put into operation, it is necessary to set the pressure provided by the gas cylinder group (13) and the pressure of the low-pressure gas cylinder (7) according to the sea conditions and the load, first open the fourth stop valve (16), then gradually open the second throttle valve block (14), and slowly fill the gas into the passive compensation gas chamber G, so that the two active compensation liquid chambers H and L of the double-piston double-rod accumulator are at equal volume positions, and the piston of the compensation cylinder (4) is in the middle position.

[0026] Before the device is put into operation, in order to prevent the device from leaking oil and causing the circuit pressure to drop and affect the compensation performance, it is necessary to replenish oil in the circuit. The stop valves (23) and (26) below the oil storage accumulator (25) and the oil replenishment accumulator (22) are opened, and the active compensation mode switching valve (18) and the oil replenishment pump (24) are controlled to open. The oil replenishment pump (24) draws oil from the oil storage accumulator (25) and guides the replenishment oil to enter from the inlet of the first and second plug-in check valves (19) and (32), and flow out from the side port to the compensation circuit to replenish oil for the system. When it is necessary to replenish oil in the circuit between the load pressure liquid chamber F of the double-piston double-rod accumulator in the device and the rod chamber V2 of the compensation cylinder, the seventh stop valve (33) and the first stop valve (2) are opened, and the valve port opening of the first throttle valve block (2) is adjusted to the maximum, so that the circuit can be replenished with oil.

[0027] When the pressure of the passive compensation air chamber G of the double-piston double-rod accumulator in the device is too high, it is necessary to perform a deflation process. When the device is located in the air or in a shallow water area with low water pressure, the excess gas can be directly discharged to the outside through the discharge valve (15). When the device is located in a deep water area with high water pressure, directly using the discharge valve (15) to exhaust gas will cause seawater to flow back into the gas cylinder group. To avoid this phenomenon, the electromagnetic switch valve under the low-pressure gas collecting bottle is opened to release the excess gas 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, the first stop valve (3) is opened, and the active compensation working mode can be performed after the system is stabilized.

[0029] During the active compensation process, the PLC control unit (10) uses the signal of the MRU (9), the displacement signal of the displacement sensor in the compensation cylinder (4) and the pressure signal of the pressure sensor as input signals, processes the displacement sensor signal in the double-piston double-rod accumulator (1) as a feedback signal, transmits the output signal to the bidirectional variable pump (27), and adjusts the oil volume in the two active compensation liquid chambers H and L of the double-piston double-rod accumulator by controlling the inclination angle and direction of the swash plate of the bidirectional variable pump (27), thereby controlling the volume of the load pressure liquid chamber F, providing an active compensation force for the piston, indirectly controlling the movement stroke and position of the compensation cylinder, and working together with the passive compensation force provided by the passive compensation air chamber G to achieve compensation for the load position.

[0030] When the platform rises, the active control unit controls the dual-piston variable pump (27) to absorb oil from the active compensation liquid chamber L of the dual-piston accumulator and supply oil to the active compensation liquid chamber H. The gas in the passive compensation gas chamber G enters the gas cylinder group (13), and the volume of the gas chamber G decreases. The load pressure chamber F absorbs oil from the rod chamber V2 of the compensation cylinder and increases its volume, thereby reducing the volume of the rod chamber V2. The gas in the low-pressure gas cylinder (7) enters the rodless chamber V1, and the volume of the rodless chamber V1 increases, thereby pushing the compensation cylinder piston rod outward to maintain the relative unchanged load position.

[0031] When the platform descends, the active control unit controls the dual-piston variable pump (27) to absorb oil from the active compensation liquid chamber H of the dual-piston accumulator and supply oil to the active compensation liquid chamber L. The gas in the gas cylinder group (13) enters the passive compensation gas chamber G, causing the volume of the passive compensation gas chamber G to increase. The load pressure chamber F discharges oil to the rod chamber V2 of the compensation cylinder, reducing its volume, thereby increasing the volume of the rod chamber V2 of the compensation cylinder. The gas in the rodless chamber V1 enters the low-pressure gas cylinder (7), reducing the volume of the rodless chamber V1, and causing the piston rod of the compensation cylinder to retract, so as to maintain the relative unchanged load position and realize the active heave compensation function.

[0032] When the system performs the 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, the first stop valve (3) is opened, and the passive compensation working mode can be performed after the system is stable.

[0033] When the passive compensation mode switching valve (17) is connected, the two active compensation liquid chambers of the dual-piston dual-rod accumulator are connected. When the platform rises, the load still tends to remain in place under the action of inertia, causing the piston rod of the compensation cylinder to move downward, the volume of the rodless chamber V1 of the compensation cylinder increases, and the volume of the rod chamber V2 of the compensation cylinder decreases. The oil flows into the dual load pressure liquid chamber F, and the pressure of the load pressure liquid chamber F increases, pushing the lower piston upward, reducing the volume of the passive compensation gas chamber G, and the gas enters the gas cylinder group, causing the pressure of the gas cylinder group to increase. When the platform descends, the load still tends to remain in place due to inertia, causing the piston rod of the compensation cylinder to move upward, the volume of the rodless chamber V1 of the compensation cylinder to decrease, the gas in the rodless chamber V1 enters the low-pressure gas cylinder (7), the volume of the rod chamber V2 increases, and the oil flows from the load pressure liquid chamber F into the rod chamber V2. The pressure of the load pressure liquid chamber F decreases, the lower piston moves downward, the volume of the passive compensation gas chamber G increases, the pressure decreases, and the gas in the gas cylinder group enters the passive compensation gas chamber G, thereby realizing passive heave compensation.

[0034] When the device is working in a high sea condition operating environment, due to the high frequency of the sea waves, the impact on the device is large. If the device resonates, it will cause safety problems. A variable damping control strategy is adopted to close the active compensation mode switching valve (18), open the passive compensation mode switching valve (17), and open the first stop valve (3). The PLC control unit receives the displacement sensor signal on the cylinder barrel of the compensation cylinder as an input signal, determines the sea condition size according to the input signal, and applies the output signal to the first throttle valve block (2). By controlling the opening size of the throttle valve block, the damping ratio of the device is adjusted, thereby changing the natural frequency of the device, so that the natural frequency of the device avoids the wave frequency range, and prevents the device from resonating.

[0035] When the device needs to cross the splash zone, the waves in the splash zone will impact the load and the device, which will cause a large stress change in the hoisting wire rope, reduce the service life of the wire rope, and cause breakage. Therefore, a variable damping and variable stiffness control strategy is adopted in the process of the device crossing the splash zone. When the device receives a signal to cross the splash zone, the control unit closes the cylinder switch valve under the working cylinder in the cylinder group, only opens the splash zone cylinder, and controls the damping size of the system by adjusting the opening of the first and second throttle valve blocks (2) and (14). The larger compression stiffness is used to prevent the cylinder movement stroke of the compensation cylinder from being too large when responding to the wave force impact buffer, causing mechanical impact and damage to the cylinder, thereby reducing the impact of the waves on the load and the device, reducing the stress fluctuation on the wire rope, and realizing the function of the device to stably cross the splash zone.

[0036] The deepwater pressure compensation function is integrated inside the double-piston double-rod accumulator. When the water depth pressure acts on the compensation device, the ratio of the force to the effective area on the piston rod of the compensation cylinder is the same as the ratio of the force to the effective area on the outer piston rod of the double-piston double-rod accumulator, thus realizing the deepwater pressure compensation function.

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

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, the lower piston is connected to the outer piston rod, and the double piston / piston rod divides the accumulator into four chambers: a passive compensation air chamber G, active compensation liquid chambers H and L, and a load simulation 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 (4.5) 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 the 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), so as to transmit the load pressure to the lower piston (1.9). 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 connected or disconnected with the two-way variable pump (27) through the active compensation mode switching valve (18); The bidirectional variable pump (27) is driven by a 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), and is connected to the oil replenishment pump (24) through a one-way valve. The oil replenishment pump (24) is driven by a constant speed motor (29). The oil replenishment pump (15) is connected to the oil replenishment accumulator (22) through a one-way valve and a fifth stop valve (23). The oil replenishment pump (15) is connected to the load pressure liquid chamber F of the double-piston double-rod accumulator through a one-way valve and a seventh stop valve (33). The oil replenishment pump (15) is also connected to the first plug-in one-way valve (19) and the second plug-in one-way valve ( The first plug-in check valve (19) is connected to the inlet of the bidirectional variable pump (27) and the inlet of the first plug-in relief valve (20); the side port and the outlet of the first plug-in check valve (20) are connected to the bidirectional variable pump (27) and the inlet of the first plug-in relief valve (20); the outlet of the first plug-in check valve (20) is connected to the side port through the first relief valve (21); the side port is connected to the oil replenishment accumulator (22) through the fifth stop valve (23); the side port and the outlet of the second plug-in check valve (32) are connected to the bidirectional variable pump (27) and the inlet of the second plug-in relief valve (31); the outlet of the second plug-in relief valve (31) is connected to the side port through the second relief valve (30); the side port is connected to the oil replenishment accumulator (22) through the fifth stop valve (23).

2. A linear heave compensation device based on a double-piston double-rod accumulator according to claim 1, characterized in that: The static load and dynamic load of the compensation cylinder (4) during the compensation process 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 two-way variable pump (27) to provide a two-way active compensation force for the device, and indirectly drive 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.

3. A linear heave compensation device based on a double-piston double-rod accumulator according to claim 1, characterized in that: The double-piston double-rod accumulator (1) has two sections of 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 need to satisfy the following relationship 4. A linear heave compensation device based on a double-piston double-rod accumulator according to claim 1, characterized in that: 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 other gas cylinders, and the low-pressure gas collecting cylinder recovers excess gas. The gas cylinder group (6) is connected to the passive compensation air chamber G of the double-piston double-rod accumulator through a second throttle valve block (14), and the discharge valve (15) is used for exhausting gas.

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