Energy-saving hydraulic system of underwater equipment

Abstract

The invention discloses an energy-saving hydraulic system for underwater equipment, and relates to the technical field of underwater equipment, the internal pressure of the hydraulic system is slightly greater than the external pressure all the time in a mode of compensating the pressure of a compensation oil tank, so that the hydraulic system can be designed according to a conventional hydraulic system and used at any water depth; according to the hydraulic system, a slender pipe is arranged at an outlet of an electric control proportional overflow valve of an overflow loop, a pressure difference type pressure sensor is used for detecting the pressure difference delta p of the two sides of the slender pipe in real time, and a motor control module adjusts the rotating speed of a motor and the working state of each control branch according to the pressure difference and the priority of each execution mechanism. Therefore, the output flow of the oil pump and the oil supply amount for each executing mechanism are adjusted, a large amount of waste heat and energy waste caused by overflow of the hydraulic system are remarkably reduced, the energy efficiency of the system is improved, the energy of underwater equipment is greatly saved, and the underwater service time is prolonged.

Description

Technical Field

[0001] This application relates to the field of underwater equipment technology, and in particular to an energy-saving hydraulic system for underwater equipment. Background Technology

[0002] Hydraulic systems are widely used in various underwater equipment due to their high energy density, simple structure, and high reliability. With the development of deep-sea pressure compensation technology, hydraulic systems have become the preferred choice for power supply and motion control of various actuators in underwater equipment. However, the working environment of underwater equipment is complex, and multiple actuators often need to work together when performing complex underwater tasks. The simultaneous and non-linear operation of multiple actuators leads to drastic changes in the demand for hydraulic oil flow. This results in traditional hydraulic systems generating a large amount of overflow heat and energy waste, affecting the duration of underwater operation. Therefore, improving system energy efficiency has become a design challenge for hydraulic systems in underwater equipment. Summary of the Invention

[0003] This application addresses the aforementioned problems and technical needs by proposing an energy-saving hydraulic system for underwater equipment. The technical solution of this application is as follows:

[0004] An energy-saving hydraulic system for underwater equipment, comprising: The valve box contains several solenoid directional valves. Each solenoid directional valve is connected to the high-pressure flow channel P and the return oil flow channel T of the valve box, and each solenoid directional valve is connected to an actuator of the underwater equipment to form a control branch. The compensation oil tank adopts a spring-loaded bladder design with the spring providing pre-pressure. The compensation oil tank is connected to the oil pump's suction port, and the oil pump's outlet is connected to the high-pressure flow channel P in the valve box via a check valve and a high-pressure filter. The compensation oil tank is also connected to the return flow channel T in the valve box and the valve box body. The high-pressure oil output from the oil pump to the high-pressure flow channel P also flows back to the compensation oil tank via the electronically controlled proportional relief valve and the slender pipe. The motor is connected to both the battery and the oil pump. The motor control module is electrically connected to the motor, the electronically controlled proportional relief valve and each control branch. It also uses a pressure sensor to detect the system pressure p of the high-pressure oil output from the oil pump to the high-pressure flow channel P in real time, and uses a differential pressure sensor to detect the pressure difference Δp on both sides of the slender tube in real time. When the motor control module controls the motor to work in electric motor mode and drives the oil pump to output high-pressure oil to the high-pressure flow channel P, when the actuator is detected to be in motion, the motor is controlled to switch to full speed. When the system pressure p reaches the pressure target pset of the electronically controlled proportional relief valve, the electronically controlled proportional relief valve is controlled to open. The motor speed and the working status of each control branch are dynamically adjusted according to the pressure difference Δp on both sides of the slender tube and the priority of each actuator.

[0005] A further technical solution involves the motor control module dynamically adjusting the motor speed and the operating status of each control branch based on the pressure difference Δp across the slender tube and the priority of each actuator in the valve box. When the motor control module determines that only one actuator is in operation, it uses a PID controller to adjust the motor speed with Δp=0 as the target. When the motor control module determines that multiple actuators are in operation, it dynamically calculates the total flow rate Qtotal and the flow rate allocation setting value for each actuator based on the priority of each actuator. The motor speed is adjusted according to the total flow rate Qtotal, and the working status of each control branch is adjusted according to the flow rate allocation setting value for each actuator.

[0006] A further technical solution involves the motor control module calculating the total required flow rate Qtotal and the flow allocation settings for each actuator, including: The total demand flow (Total_Demand) is obtained by summing the demand flow of all actuators in the control branches. The demand flow of actuators in the active state is greater than 0, and the demand flow of actuators not in the active state is equal to 0. When the total demand flow rate Total_Demand ≤ Q_pump_max, the total flow rate Qtotal = Total_Demand is determined, and the flow allocation setting value Qset_i = Demand_i for the actuator in any i-th control branch is determined. Demand_i is the demand flow rate of the actuator in the i-th control branch, and Q_pump_max is the maximum available flow rate of the oil pump. When the total demand flow Total_Demand > Q_pump_max, initialize the flow allocation setting value Qset_i = 0 for any i-th control branch actuator, and initialize the remaining flow Remaining_F = Qpump_max; in each iteration, calculate the sum of priorities Priority_S for all actuators whose flow allocation setting value is less than the demand flow and whose flow demand is not met, calculate the theoretical allocation amount Qgrant_j = (Priority_j / Priority_S) × Remaining_F for any j-th control branch actuator whose flow demand is not met, and obtain the actual allocation amount Qgrant_j' = min(Qgrant_j, Demand_j) for the j-th control branch actuator in the current iteration; update the flow allocation setting value Qset_j = Qset_j + Qgrant_j' for the j-th control branch actuator, and update Remaining_F. =Remaining_F-∑Qgrant_j and enter the next iteration round until all actuators in the control branches meet the flow requirements, or until the updated remaining flow Remaining_F≤0, then obtain the flow allocation setting value of the actuators in each control branch, and obtain the total flow Qtotal=Qpump_max-Remaining_F.

[0007] A further technical solution is that the inlet of the solenoid directional valve in each control branch is connected to the high-pressure flow channel P of the valve box, and the return port is connected to the return flow channel T of the valve box. The working port of the solenoid directional valve is connected to an actuator in the underwater equipment via a hydraulic speed control valve group. The motor control module is electrically connected to the solenoid directional valve and the hydraulic speed control valve group in each control branch. The motor control module adjusts the motor speed according to the total flow rate Qtotal and adjusts the working state of each control branch according to the flow distribution setting value of each actuator, including: The motor control module adjusts the motor to the target speed: Ndemand = Qtotal / (Vp) ηv), where Vp is the displacement of the oil pump and ηv is the volumetric efficiency; The motor control module controls the hydraulic speed control valve group of the branch in the i-th control to output the flow distribution setting value Qset_i of the actuator in the i-th control.

[0008] The further technical solution is that, in the process of controlling the motor to work in electric motor mode and driving the oil pump to output high-pressure oil to the high-pressure flow channel P, the motor control module also determines the load characteristics according to the system pressure p, and dynamically adjusts the pressure target pset of the electronically controlled proportional relief valve according to the load characteristics; wherein, the load characteristics are stable, periodic and impact.

[0009] A further technical solution involves the motor control module dynamically determining the pressure target pset of the electronically controlled proportional relief valve based on load characteristics, including: When the motor control module determines that the load characteristics are stable based on the system pressure p, it determines the pressure target pset of the electronically controlled proportional relief valve to be the value of the maximum pressure required by the current actuator plus a low safety margin. When the motor control module determines that the load characteristic is periodic based on the system pressure p, it periodically adjusts the pressure target pset of the electronically controlled proportional relief valve according to the periodic characteristics of the load characteristic. When the motor control module determines that the load characteristic is impact type based on the system pressure p, it determines the pressure target pset of the electronically controlled proportional relief valve to be the maximum allowable safe pressure of the system.

[0010] A further technical solution involves the motor control module determining the load characteristics based on the system pressure p, including: Calculate the rate of change, fluctuation amplitude, and dominant frequency of the system pressure p; When the main frequency of the system pressure p is in a stable state, the load type is determined to be periodic. When the main frequency of system pressure p is not in a stable state, and the rate of change and fluctuation amplitude of system pressure p are both less than the corresponding threshold, the load characteristic is determined to be stable. When the main frequency of the system pressure p is not in a stable state, and the rate of change or fluctuation of the system pressure p reaches the corresponding threshold, the load type is determined to be impact type.

[0011] A further technical solution is that the underwater equipment energy-saving hydraulic system includes an accumulator and an electrically controlled recovery valve. An accumulator is also connected in parallel on the pipeline from the oil pump to the high-pressure flow channel P. The oil outlet of the accumulator also flows back to the compensation oil tank through the electrically controlled recovery valve. The motor control module is also electrically connected to the accumulator and the electrically controlled recovery valve. When the motor control module detects that the actuator is not in braking or gravity descent mode, it controls the electronic recovery valve to close and controls the motor to work in motor mode, and stores high-pressure oil in the accumulator. When the motor control module detects that the actuator is in braking or gravity descent mode, it controls the electronic recovery valve to open and controls the motor to work in generator mode. The high-pressure oil stored in the accumulator drives the oil pump to reverse and drives the motor to generate electricity, which is then fed back to the battery to complete energy recovery.

[0012] A further technical solution is that the motor control module adjusts the generator torque of the motor in generator mode when it is in braking or gravity descent mode. When the motor control module is not in braking or gravity descent mode, it controls the accumulator to release the stored high-pressure oil to assist in driving the actuator.

[0013] A further technical solution is that the valve box also includes a loading valve, the oil inlet of which is connected to the high-pressure flow channel P of the valve box and the oil return port is connected to the oil return flow channel T of the valve box. The loading valve is H-shaped in the middle position, and the oil inlet, oil return port and two working oil ports of the loading valve are all connected. During the startup phase of the underwater equipment's energy-saving hydraulic system, the loading valve is de-energized, and the motor control module controls the motor to operate in electric motor mode and drive the oil pump to output hydraulic oil at full speed. The hydraulic oil output by the oil pump returns directly to the compensation oil tank through the loading valve, and the underwater equipment's energy-saving hydraulic system starts in a low-pressure, high-flow mode. After startup, the loading valve switches to the energized state, and the motor control module uses a PID controller to reduce the motor speed with a pressure difference Δp=0 as the target and operates in a high-pressure, low-flow mode.

[0014] The beneficial technical effects of this application are: This application discloses an energy-saving hydraulic system for underwater equipment. This system compensates for the pressure in the oil tank, ensuring that the internal pressure is always slightly higher than the external pressure. This allows the system to be designed like a conventional hydraulic system and used at any water depth. Furthermore, the system incorporates a slender tube at the outlet of the electrically controlled proportional relief valve in the overflow circuit. A differential pressure sensor continuously monitors the pressure difference Δp across this tube, which represents the overflow flow rate. The motor control module adjusts the motor speed and the operating status of each control branch based on the pressure difference and the priority of each actuator, thereby adjusting the oil pump output flow and the oil supply to each actuator. This achieves precise and dynamic matching of the oil pump output flow, significantly reducing the inherent overflow loss of a constant flow system. It also significantly reduces the large amount of waste heat and energy wasted due to overflow, improving system energy efficiency and greatly saving energy for underwater equipment, thus extending its underwater operating time.

[0015] The motor control module optimizes flow distribution through multi-actuator collaborative control, ensuring that the system flow can be optimally distributed according to priority under various working conditions such as compound actions and limited pump supply capacity. This greatly reduces overflow at the system level, resulting in significant energy savings. Furthermore, the hydraulic system has a simple structure and sophisticated control, making it suitable for use and widespread adoption in the most common and mature DC motor fixed displacement pump systems.

[0016] The motor control module also introduces adaptive dynamic pressure setting control based on load characteristic identification. By identifying load characteristics online and dynamically adjusting the pressure target pset of the electronically controlled proportional relief valve, that is, adjusting the system's maximum pressure, a perfect balance between energy saving and safety is achieved, significantly reducing system energy consumption and component wear under off-peak loads.

[0017] The motor control module uses a motor with generator and motor modes, and is equipped with an energy storage device and an electronically controlled recovery valve. Combined with an energy recovery and reuse mechanism, it can convert braking energy and gravitational potential energy into electrical energy for storage, and use the energy storage device to provide peak power assistance, further improving the system's energy efficiency and dynamic performance. Attached Figure Description

[0018] Figure 1 This is a system result diagram of an underwater equipment energy-saving hydraulic system according to an embodiment of this application.

[0019] Figure 2 This is a schematic diagram of a control method for an energy-saving hydraulic system for underwater equipment in one embodiment of this application.

[0020] Figure 3 This is a schematic diagram illustrating a method for determining the total flow rate and the flow rate allocation setting value for each actuator when multiple actuators operate simultaneously, according to one embodiment of this application.

[0021] Figure 4 This is a schematic diagram of a method for determining complex characteristics based on system pressure and dynamically adjusting the pressure target pset of an electronically controlled proportional relief valve in one embodiment of this application. Detailed Implementation

[0022] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0023] This application discloses an energy-saving hydraulic system for underwater equipment. Please refer to [link / reference]. Figure 1 The diagram shows the system structure of an energy-saving hydraulic system for underwater equipment. This system includes a valve box 1 and a compensation tank 6, as well as a pipeline structure and an electrical control structure connecting the valve box 1 and the compensation tank 6.

[0024] The valve box 1 contains several solenoid directional valves 3. Each solenoid directional valve 3 is connected to the high-pressure flow channel P and the return flow channel T of the valve box 1, and each solenoid directional valve 3 is connected to an actuator 2 of the underwater equipment to form a control branch. Actuators in underwater equipment commonly include cylinders and motors. Specifically, each control branch includes a solenoid directional valve 3, a hydraulic speed control valve group 4, and an actuator 2. The inlet of the solenoid directional valve is connected to the high-pressure flow channel P of the valve box 1, and the return port is connected to the return flow channel T of the valve box 1. The working port of the solenoid directional valve is connected to the actuator 2 via the hydraulic speed control valve group 4. Figure 1 Taking valve box 1 as an example, which includes three solenoid directional valves forming three control branches.

[0025] The compensating oil tank 6 contains hydraulic oil and is connected to the suction port of the oil pump 7. It is also connected to the return flow channel T in the valve box 1 and to the valve box 1's housing. The compensating oil tank 6 uses a spring-loaded bladder design, which transmits external environmental pressure to the hydraulic oil within it. Simultaneously, the spring provides preload, ensuring that the compensating oil tank 17 consistently supplies hydraulic oil at a pressure slightly higher than the external environmental pressure to the oil pump 1's suction port, the valve box 8's return flow channel T, and the valve box 8's housing. This design allows the hydraulic system to be designed as a conventional hydraulic system that does not withstand external pressure.

[0026] The oil pump 7's outlet is connected to the high-pressure flow channel P in the valve box 1 via a check valve 8 and a high-pressure filter 9. The high-pressure filter 9 also has a bypass valve, ensuring the cleanliness of the hydraulic oil. Additionally, as... Figure 1 As shown, a filter with a bypass valve can also be installed in the pipeline between the compensation oil tank 17 and the return oil channel T to further ensure the cleanliness of the hydraulic oil.

[0027] Oil pump 7 is connected to motor 12, and motor 12 is also connected to a storage battery. Figure 1 The battery is not shown in the image. The motor 12 in this application includes both motor mode and generator mode.

[0028] The electronically controlled proportional relief valve 10 and the slender tube 11 form an overflow circuit. The high-pressure oil output from the oil pump 7 to the high-pressure flow channel P also flows back to the compensation oil tank 6 via the electronically controlled proportional relief valve 10 and the slender tube 11. The slender tube 11 refers to a straight tube whose length reaches the length threshold and whose diameter is smaller than the diameter threshold.

[0029] The pipeline from the oil pump 7 to the high-pressure flow channel P is also equipped with a pressure sensor 14, and the two ends of the slender tube 11 are also connected to differential pressure sensors 15.

[0030] The motor control module 13 is the core control module of this hydraulic system. It is electrically connected to the motor 12, the electrically controlled proportional relief valve 10, the pressure sensor 14, and the differential pressure sensor 15. The motor control module 13 also connects to various control branches, specifically the solenoid directional valve 3 and the hydraulic speed control valve group 4 in each control branch, such as... Figure 1 The electrical control circuit is shown in red. The motor control module 13 can detect the system pressure p of the high-pressure oil output from the oil pump 7 to the high-pressure flow channel P in real time via the pressure sensor 14. The motor control module 13 can also detect the pressure difference Δp across the slender tube 11 in real time via the differential pressure sensor 15. The working process of this underwater equipment's energy-saving hydraulic system is as follows: I. Energy-saving hydraulic system for underwater equipment starts with low pressure and high flow. like Figure 1As shown, the valve box 1 also includes a loading valve 5. The oil inlet of the loading valve 5 is connected to the high-pressure flow channel P of the valve box 1, and the oil return port is connected to the oil return flow channel T of the valve box 1. The loading valve 5 is H-shaped in the middle position, and the oil inlet, oil return port and two working oil ports of the loading valve 5 are all connected.

[0031] During the startup phase of the underwater equipment's energy-saving hydraulic system, the loading valve 5 is de-energized. The motor control module 13 controls the motor 12 to operate in electric motor mode and drive the oil pump 7 at full speed to output hydraulic oil. The hydraulic oil output by the oil pump 7 returns directly to the compensation oil tank 6 through the loading valve 5, enabling the underwater equipment's energy-saving hydraulic system to start in a low-pressure, high-flow manner. At this time, the oil pump 7 only outputs hydraulic oil at the pressure required to meet the losses of pipelines, valves, etc.

[0032] II. The underwater equipment's energy-saving hydraulic system operates in a high-pressure, low-flow mode after startup. After startup is complete, the loading valve 5 switches to the energized state. At this time, the hydraulic oil output by the oil pump 7 returns to the compensation oil tank 6 through the overflow circuit formed by the electronically controlled proportional relief valve 10 and the slender tube 11. The motor control module 13 detects the pressure difference Δp across the slender tube 11 in real time via the differential pressure sensor 15. This pressure difference Δp is directly related to the overflow flow rate, and the conversion relationship between the two can be pre-calibrated. The motor control module 13 uses a PID controller to reduce the speed of the motor 12 with the pressure difference Δp=0 as the target. At this time, the actuator has not yet moved, and the motor 12 operates at a very low speed, so that the energy-saving hydraulic system of the underwater equipment operates in a high-pressure, low-flow mode.

[0033] 3. When the actuator of the underwater equipment is activated, the energy-saving hydraulic system of the underwater equipment operates according to the flow requirements of the actuator. When the underwater equipment's energy-saving hydraulic system is started, the motor control module 13 controls the motor 12 to work in electric motor mode and drives the oil pump 7 to output high-pressure oil to the high-pressure flow channel P. After operating in high-pressure low-flow mode according to the above process, the system is activated.

[0034] When actuator 2 in the underwater equipment needs to operate, motor control module 13 controls the solenoid directional valve 3 in the control branch where the actuator is located to be energized and opened. The flow rate required by actuator 2 is controlled by hydraulic speed control valve group 4 in the control branch where it is located. When actuator 2 operates, motor control module 13 will monitor the system pressure p of the high-pressure oil output from oil pump 7 to high-pressure flow channel P in real time through pressure sensor 14. The system pressure p will drop instantaneously, and then motor control module 13 will control motor 12 to resume full speed operation, causing system pressure p to rise.

[0035] To maintain system energy efficiency, the motor control module 13, after controlling the motor 12 to switch to full speed, will also monitor the system pressure p and the pressure difference Δp across the slender tube 11 in real time. For example... Figure 2As shown, when the system pressure p is less than the pressure target pset of the electronically controlled proportional relief valve 10, the motor control module 13 controls the electronically controlled proportional relief valve 10 to remain closed, and all the high-pressure oil output by the oil pump 7 is supplied to the actuator. When the system pressure p is detected to reach the pressure target pset of the electronically controlled proportional relief valve 10, the electronically controlled proportional relief valve 10 is opened to achieve overflow. The excess hydraulic oil output by the oil pump 7 at full speed flows back to the compensation oil tank 6 from the electronically controlled proportional relief valve 10 and the slender pipe 11. As mentioned above, the pressure difference Δp on both sides of the slender pipe 11 is related to the overflow flow rate. The motor control module 13 will further dynamically adjust the speed of the motor 12 and the working state of each control branch according to the pressure difference Δp on both sides of the slender pipe 11 and the priority of each actuator in the valve box 1, thereby eliminating overflow at the system level. This ensures that the output flow of the oil pump 7 is used entirely to drive the actuator, avoiding the heat generated by the hydraulic system due to overflow, greatly saving the energy of the underwater equipment, extending the underwater operating time, and improving the system energy efficiency. Specifically, there are two cases; please refer to [the relevant documentation]. Figure 3 The flowchart shown below: 1. Single actuator, 2 actions When the motor control module 13 determines that only one actuator is currently in operation, it uses a PID controller to adjust the speed of the motor 12 with Δp=0 as the target. In this case, the motor 12 operates at the speed required by the actuator, and the hydraulic system does not generate waste heat due to overflow, effectively saving electrical energy and improving the motor's utilization rate of electrical energy.

[0036] 2. Multi-actuator coordinated action When the motor control module 13 determines that multiple actuators are currently in operation, it dynamically calculates the total flow rate Qtotal and the flow distribution setting value for each actuator based on their priority. It then adjusts the speed of the motor 12 according to the total flow rate Qtotal and the operating status of each control branch according to the flow distribution setting value for each actuator. Specifically: First, the control signal of the solenoid directional valve 3 and the feedback signal of the hydraulic speed control valve group 4 in each control branch are collected. The demand flow of the actuator in the control branch is calculated in real time. The demand flow of the actuator in the i-th control branch is denoted as Demand_i. When the control signal of the solenoid directional valve 3 in the control branch is enabled, the actuator in the control branch is in the operating state; otherwise, the actuator in the control branch is not in the operating state. The demand flow of the actuator in the operating state is greater than 0, and the demand flow of the actuator in the non-operating state is equal to 0.

[0037] Then, the total demand flow rate (Total_Demand) is calculated by summing the demand flow rates of the actuators in all control branches, and compared with the maximum available flow rate (Q_pump_max) of oil pump 7. In one embodiment, the maximum available flow rate (Q_pump_max) of oil pump 7 is the maximum flow rate of oil pump 7. Alternatively, in another embodiment, the maximum available flow rate (Q_pump_max) of oil pump 7 is related to the battery charge in the underwater equipment. When the battery charge is sufficient, the maximum available flow rate (Q_pump_max) is equal to the maximum flow rate of oil pump 7; when the battery charge is insufficient, the maximum available flow rate (Q_pump_max) is less than the maximum flow rate of oil pump 7, and the lower the battery charge, the smaller the maximum available flow rate (Q_pump_max).

[0038] When the total demand flow Total_Demand≤Q_pump_max, it indicates that the supply is sufficient. In this case, the total flow Qtotal=Total_Demand is directly determined, and the flow allocation setting value Qset_i=Demand_i for the actuator in any i-th control branch is determined.

[0039] When the total demand (Total_Demand) exceeds Q_pump_max, it indicates a supply shortage, requiring appropriate allocation of flow. Specifically: (a) First, initialize the flow allocation setting value Qset_i=0 for the actuator in any i-th control branch, and initialize the remaining flow Remaining_F = Qpump_max. Then, in each iteration, start from (b) below.

[0040] (b) Filter out all executors whose traffic demand has not been met in the current iteration round. Executors whose traffic allocation setting value Qset_i is less than the required traffic Demand_i. In the first iteration round, since the Demand_i of inactive executors is 0, all inactive executors have met their traffic demand. However, the Demand_i of active executors is >0, so their traffic demand has not yet been met.

[0041] Then, the total priority_S of all executors that have not met the traffic demand in the current iteration round is calculated. The priority of each executor is pre-configured and determined.

[0042] (c) Allocate proportionally according to priority, and calculate the theoretical allocation Qgrant_j for the actuators in any j-th control branch where the flow demand is not met in the current iteration: Qgrant_j = (Priority_j / Priority_S) × Remaining_F (d) Obtain the actual allocation of the actuator in the j-th control branch in the current iteration round, Qgrant_j': Qgrant_j'= min(Qgrant_j, Demand_j) Wherein, min(Qgrant_j, Demand_j) represents taking the minimum value of the theoretical allocation amount Qgrant_j and the demand flow Demand_j.

[0043] (e) Update the actuator flow allocation setting value Qset_j=Qset_j+Qgrant_j' in the j-th control branch, and update Remaining_F =Remaining_F-∑Qgrant_j.

[0044] (f) If there are still actuators that have not met the flow requirements, and the updated remaining flow Remaining_F > 0, continue to the next iteration round to execute (b)-(e). When all actuators in the control branches meet the flow requirements, or the updated remaining flow Remaining_F ≤ 0, obtain the flow allocation setting value of the actuators in each control branch, and obtain the total flow Qtotal = Qpump_max - Remaining_F.

[0045] Ideally, this method will precisely allocate all traffic, meaning that Remaining_F = 0 after the final iteration, then Qtotal = Qpump_max. In some special cases, such as when the priority of all actuators is 0, there may still be a small surplus.

[0046] After determining the total flow rate Qtotal and the flow distribution setting value Qset_i of the actuator in any i-th control branch, the motor control module 13 adjusts the motor 12 to the target speed Ndemand = Qtotal / (Vp ηv), and the flow distribution setpoint Qset_i of the actuator in the i-th control branch hydraulic speed control valve group 4. Where Vp is the displacement of oil pump 7, and ηv is the volumetric efficiency. This enables precise closed-loop control of the flow in each control branch. This mode ensures that when multiple actuators operate, the total system output flow precisely matches the total demand flow, eliminating overflow at the system level and achieving maximum energy saving.

[0047] IV. Adaptive Dynamic Pressure Setting Control As described above, the motor control module 13 will open the electronically controlled proportional relief valve 10 when the system pressure p reaches the pressure target pset of the electronically controlled proportional relief valve 10. Therefore, the pressure target pset of the electronically controlled proportional relief valve 10 will also affect the system control effect. This pressure target pset can be taken as an empirical value, but in order to further achieve a perfect balance between energy saving and safety, this embodiment introduces an adaptive dynamic setting strategy for the pressure target pset: In the process of controlling the motor 12 to work in electric motor mode and driving the oil pump 7 to output high-pressure oil to the high-pressure flow channel P, the motor control module 13 also determines the load characteristics based on the system pressure p, and dynamically determines the pressure target pset of the electronically controlled proportional relief valve 10 based on the load characteristics.

[0048] The load characteristics are stable, periodic, and impulsive. Motor control module 13 determines the load characteristics based on the system pressure p, including (see reference). Figure 4 Calculate the rate of change, fluctuation amplitude, and dominant frequency of system pressure p. When the dominant frequency of system pressure p is stable, the load type is determined to be periodic. When the dominant frequency of system pressure p is not stable, and both the rate of change and fluctuation amplitude of system pressure p are less than the corresponding thresholds, the load characteristic is determined to be steady. When the dominant frequency of system pressure p is not stable, and the rate of change or fluctuation amplitude of system pressure p reaches the corresponding threshold, the load type is determined to be impulsive. These thresholds can be customized.

[0049] When the load characteristic is determined to be stable based on the system pressure p, the motor control module 13 determines the pressure target pset of the electronically controlled proportional relief valve 10 to be the value of the maximum pressure required by the current actuator plus a low safety margin. A lower pressure target pset is adopted to reduce system operating energy consumption and component wear.

[0050] When the load characteristic is determined to be periodic based on the system pressure p, the motor control module 13 periodically adjusts the pressure target pset of the electronically controlled proportional relief valve 10 according to the periodic characteristics of the load characteristic. The set pressure is increased in advance before the load peak arrives and the pressure is quickly reduced during the load trough period to achieve "pressure supply on demand".

[0051] When the load characteristic is determined to be impact type based on the system pressure p, the motor control module 13 determines the pressure target pset of the electronically controlled proportional relief valve 10 to be the maximum allowable safe pressure of the system, thus providing the system with instantaneous safety protection equivalent to that of a traditional safety valve.

[0052] V. Energy Recovery and Reuse Control like Figure 1As shown, the underwater equipment's energy-saving hydraulic system also includes an accumulator 16 and an electrically controlled recovery valve 17. The accumulator 16 is connected in parallel on the pipeline from the oil pump 7 to the high-pressure flow channel P. The oil outlet of the accumulator 16 also flows back to the compensation oil tank 6 via the electrically controlled recovery valve 17. The motor control module 13 is also electrically connected to the accumulator 16 and the electrically controlled recovery valve 17, which is a two-position normally closed solenoid valve.

[0053] Then as described above Figure 2 As shown, the motor control module 13 detects whether the actuator is in braking or gravity descent mode: when the actuator is determined to perform braking operation according to the instruction of the solenoid directional valve 3 in the control branch, and the system pressure p suddenly increases while the current of the motor 12 approaches 0, the actuator is determined to be in braking mode. When the actuator is determined to perform descent operation according to the instruction of the solenoid directional valve 3 in the control branch, and the system pressure p abnormally increases while the current of the motor 12 is low, the actuator is determined to be in gravity descent mode.

[0054] When the motor control module 13 detects that the actuator is not in braking or gravity descent mode, it controls the electronic recovery valve 17 to close and controls the motor 12 to operate in motor mode, storing high-pressure oil in the accumulator 16. Additionally, the motor control module 13 can also control the accumulator 16 to release the stored high-pressure oil to assist in driving the actuator, thereby reducing the instantaneous power demand of the motor and improving the system's dynamic response.

[0055] When the motor control module 13 detects that the actuator is in braking or gravity descent mode, it controls the electronic recovery valve 17 to open and controls the motor 12 to operate in generator mode. The high-pressure oil stored in the accumulator 16 drives the oil pump 7 to reverse and drive the motor 12 to generate electricity, which is then fed back to the battery to complete energy recovery. In addition, the motor control module 13 can also adjust the generating torque of the motor 12 in generator mode to achieve smooth and controllable braking or descent speed control of the actuator.

[0056] The above are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. An energy-saving hydraulic system for underwater equipment, characterized in that, The energy-saving hydraulic system of the underwater equipment includes: Valve box (1), the valve box (1) includes several electromagnetic directional valves (3), each electromagnetic directional valve (3) is connected to the high pressure flow channel P and the return oil flow channel T of the valve box (1) respectively, and each electromagnetic directional valve (3) is connected to an actuator (2) of the underwater equipment to form a control branch. The compensation oil tank (6) is in the form of a spring-loaded bladder with the spring providing pre-pressure. The compensation oil tank (6) is connected to the suction port of the oil pump (7). The outlet of the oil pump (7) is connected to the high-pressure flow channel P in the valve box (1) via a check valve (8) and a high-pressure filter (9). The compensation oil tank (6) is also connected to the return flow channel T in the valve box (1). The compensation oil tank (6) is also connected to the body of the valve box (1). The high-pressure oil output by the oil pump (7) to the high-pressure flow channel P also flows back to the compensation oil tank (6) via the electronically controlled proportional relief valve (10) and the slender pipe (11). Motor (12), which is connected to the storage battery and oil pump (7) respectively; The motor control module (13) is electrically connected to the motor (12), the electronically controlled proportional relief valve (10) and each control branch respectively. It also uses a pressure sensor (14) to detect the system pressure p of the high-pressure oil output by the oil pump (7) to the high-pressure flow channel P in real time, and uses a differential pressure sensor (15) to detect the pressure difference Δp on both sides of the slender tube (11) in real time. When the motor control module (13) controls the motor (12) to work in motor mode and drives the oil pump (7) to output high pressure oil to the high pressure channel P, when the actuator is detected to be in action, the motor (12) is switched to full speed and when the system pressure p is detected to reach the pressure target pset of the electronically controlled proportional relief valve (10), the electronically controlled proportional relief valve (10) is opened. The motor control module (13) dynamically adjusts the speed of the motor (12) and the working status of each control branch according to the pressure difference Δp on both sides of the slender tube (11) and the priority of each actuator.

2. The energy-saving hydraulic system for underwater equipment according to claim 1, characterized in that, The motor control module (13) dynamically adjusts the speed of the motor (12) and the working status of each control branch according to the pressure difference Δp on both sides of the slender tube (11) and the priority of each actuator in the valve box (1): When the motor control module (13) determines that only one actuator is in operation, it uses a PID controller to adjust the speed of the motor (12) with Δp=0 as the target. When the motor control module (13) determines that multiple actuators are in operation, it dynamically calculates the total flow rate Qtotal and the flow distribution setting value of each actuator based on the priority of each actuator. It adjusts the speed of the motor (12) according to the total flow rate Qtotal and adjusts the working state of each control branch according to the flow distribution setting value of each actuator.

3. The energy-saving hydraulic system for underwater equipment according to claim 2, characterized in that, The motor control module (13) calculates the total required flow rate Qtotal and the flow distribution settings for each actuator, including: The total demand flow (Total_Demand) is obtained by summing the demand flow of all actuators in the control branches. The demand flow of actuators in the active state is greater than 0, and the demand flow of actuators not in the active state is equal to 0. When the total demand flow Total_Demand≤Q_pump_max, the total flow Qtotal=Total_Demand is determined, and the flow allocation setting value Qset_i=Demand_i for the actuator in any i-th control branch is determined, where Demand_i is the demand flow of the actuator in the i-th control branch, and Q_pump_max is the maximum available flow of the oil pump (7); When the total demand flow Total_Demand > Q_pump_max, initialize the flow allocation setting value Qset_i = 0 for any i-th control branch actuator, and initialize the remaining flow Remaining_F = Qpump_max; in each iteration, calculate the sum of priorities Priority_S for all actuators whose flow allocation setting value is less than the demand flow and whose flow demand is not met, calculate the theoretical allocation amount Qgrant_j = (Priority_j / Priority_S) × Remaining_F for any j-th control branch actuator whose flow demand is not met, and obtain the actual allocation amount Qgrant_j' = min(Qgrant_j, Demand_j) for the j-th control branch actuator in the current iteration; update the flow allocation setting value Qset_j = Qset_j + Qgrant_j' for the j-th control branch actuator, and update Remaining_F. =Remaining_F-∑Qgrant_j and enter the next iteration round until all actuators in the control branches meet the flow requirements, or until the updated remaining flow Remaining_F≤0, then obtain the flow allocation setting value of the actuators in each control branch, and obtain the total flow Qtotal=Qpump_max-Remaining_F.

4. The energy-saving hydraulic system for underwater equipment according to claim 2, characterized in that, The inlet of the solenoid directional valve (3) in each control branch is connected to the high-pressure flow channel P of the valve box (1), and the return port is connected to the return flow channel T of the valve box (1). The working port of the solenoid directional valve is connected to an actuator (2) in the underwater equipment via a hydraulic speed control valve group (4). The motor control module (13) is electrically connected to the solenoid directional valve (3) and the hydraulic speed control valve group (4) in each control branch. The motor control module (13) adjusts the speed of the motor (12) according to the total flow rate Qtotal and adjusts the working state of each control branch according to the flow distribution setting value of each actuator, including: The motor control module (13) adjusts the motor (12) to the target speed Ndemand = Qtotal / (Vp) ηv), where Vp is the displacement of the oil pump (7) and ηv is the volumetric efficiency; The motor control module (13) controls the branch hydraulic speed control valve group (4) in the i-th control to output the flow distribution setting value Qset_i of the actuator in the i-th control.

5. The energy-saving hydraulic system for underwater equipment according to claim 1, characterized in that, In the process of controlling the motor (12) to work in the electric motor mode and driving the oil pump (7) to output high pressure oil to the high pressure channel P, the motor control module (13) also determines the load characteristics according to the system pressure p, and dynamically adjusts the pressure target pset of the electronically controlled proportional relief valve (10) according to the load characteristics; among which, the load characteristics are stable, periodic and impact.

6. The energy-saving hydraulic system for underwater equipment according to claim 5, characterized in that, The motor control module (13) dynamically determines the pressure target pset of the electronically controlled proportional relief valve (10) based on the load characteristics, including: When the load characteristics are determined to be stable based on the system pressure p, the motor control module (13) determines the pressure target pset of the electronically controlled proportional relief valve (10) to be the value of the maximum pressure required by the current actuator plus the low safety margin. When the load characteristic is determined to be periodic based on the system pressure p, the motor control module (13) periodically adjusts the pressure target pset of the electronically controlled proportional relief valve (10) according to the periodic characteristics of the load characteristic. When the load characteristics are determined to be impact type based on the system pressure p, the motor control module (13) determines the pressure target pset of the electronically controlled proportional relief valve (10) to be the maximum allowable safe pressure of the system.

7. The energy-saving hydraulic system for underwater equipment according to claim 5, characterized in that, The motor control module (13) determines the load characteristics based on the system pressure p, including: Calculate the rate of change, fluctuation amplitude, and dominant frequency of the system pressure p; When the main frequency of the system pressure p is in a stable state, the load type is determined to be periodic. When the main frequency of system pressure p is not in a stable state, and the rate of change and fluctuation amplitude of system pressure p are both less than the corresponding threshold, the load characteristic is determined to be stable. When the main frequency of the system pressure p is not in a stable state, and the rate of change or fluctuation of the system pressure p reaches the corresponding threshold, the load type is determined to be impact type.

8. The energy-saving hydraulic system for underwater equipment according to claim 1, characterized in that, The underwater equipment energy-saving hydraulic system includes an accumulator (16) and an electrically controlled recovery valve (17). The accumulator (16) is also connected in parallel on the pipeline from the oil pump (7) to the high-pressure flow channel P. The oil outlet of the accumulator (16) also flows back to the compensation oil tank (6) via the electrically controlled recovery valve (17). The motor control module (13) is also electrically connected to the accumulator (16) and the electrically controlled recovery valve (17). When the motor control module (13) detects that the actuator is not in braking or gravity descent mode, it controls the electronic recovery valve (17) to close and controls the motor (12) to work in motor mode, and stores high-pressure oil in the accumulator (16). When the motor control module (13) detects that the actuator is in braking or gravity descent mode, it controls the electric recovery valve (17) to open and controls the motor (12) to work in generator mode. The high-pressure oil stored in the accumulator (16) drives the oil pump (7) to reverse and drive the motor (12) to generate electricity and feed it back to the battery to complete energy recovery.

9. The energy-saving hydraulic system for underwater equipment according to claim 8, characterized in that, When the motor control module (13) is in braking condition or gravity descent condition, it adjusts the generating torque of the motor (12) in generator mode; When the motor control module (13) is not in braking or gravity descent mode, it controls the accumulator (16) to release the stored high-pressure oil to assist in driving the actuator.

10. The energy-saving hydraulic system for underwater equipment according to claim 1, characterized in that, The valve box (1) also includes a loading valve (5). The oil inlet of the loading valve (5) is connected to the high pressure flow channel P of the valve box (1), and the oil return port is connected to the oil return flow channel T of the valve box (1). The loading valve (5) is H-type in the middle position. The oil inlet, oil return port and two working oil ports of the loading valve (5) are all connected. During the startup phase of the underwater equipment energy-saving hydraulic system, the loading valve (5) is de-energized, and the motor control module (13) controls the motor (12) to work in motor mode and drive the oil pump (7) to output hydraulic oil at full speed. The hydraulic oil output by the oil pump (7) returns directly to the compensation oil tank (6) through the loading valve (5). The underwater equipment energy-saving hydraulic system starts in a low-pressure, high-flow mode. After startup, the loading valve (5) switches to the energized state, and the motor control module (13) uses the PID controller to reduce the speed of the motor (12) with the pressure difference Δp=0 as the target and operates in a high-pressure, low-flow mode.

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