GB/T 47539-2026Design specification for the hydraulic equipment of submersibles (English PDF)

4.1 Functions and Components

4.1.1 Functions The core of a submersible's hydraulic system is to provide reliable and precise power execution and support functions for the submersible to perform complex underwater operations. It uses hydraulic oil as the working medium and provides actuators (hydraulic cylinders) for various hydraulic users of submersibles through a power unit, pipelines, and control unit. (or a hydraulic motor) provides the necessary hydraulic energy to drive the actuator to complete a specific action.

4.1.2 Composition The hydraulic system of a submersible mainly consists of a power unit, a control unit, a compensation unit, an execution unit, auxiliary equipment and components, and sensor monitoring elements. Composed of components, etc., including.

a) The power unit is a hydraulic pump source;

b) The control unit is a hydraulic control valve box, including directional control valves, pressure control valves, flow control valves, etc.

c) The compensation unit is a pressure compensator;

d) The actuation unit is a hydraulic actuator such as a hydraulic cylinder or hydraulic motor;

e) Auxiliary equipment and components include compensating oil tanks, filters, pipeline fittings, etc.

f) It is recommended to configure sensor monitoring components, mainly including oil tank level sensor, water leakage alarm sensor, oil temperature monitoring sensor, and pressure sensor. Force sensors, etc. Figure 1 shows a schematic diagram of the composition and principle of a typical submersible hydraulic system.

4.2 Design Conditions The hydraulic system design should include the following requirements for the hydraulic system of the submersible.

a) Working condition requirements, including requirements for working depth, temperature, vibration, noise, corrosion, and leakage;

b) Performance requirements, including operating power/fuel supply pressure and flow rate requirements;

c) Control characteristics requirements, including the timing and coordinated control of actuators;

d) Interface requirements, including electrical interfaces, communication interfaces, hydraulic interfaces, and mechanical installation interface requirements.

7.1 Hydraulic Circuit Design

7.1.1 General Design Requirements The hydraulic circuit design should comply with the requirements of GB/T 3766-2015 to ensure stable operation of the circuit under rated conditions and to have overload protection. It has basic functions such as protection, pressure compensation, and emergency pressure relief.

7.1.2 Pump Control Loop Design The pump control circuit design should select an appropriate control method based on the motion characteristics of the actuator (constant speed, variable speed, reciprocating motion, etc.). The core principle is... The specifications and design requirements are as follows:

a) The variable displacement pump control loop should have continuous displacement adjustment function, with an adjustment range of not less than 10% to 100% of the rated displacement; a constant displacement pump should be used. During power control, the constant power hyperbola should be matched with the load demand to avoid redundant energy consumption in the system.

b) The set pressure of the relief valve in the quantitative pump relief valve circuit should be 10% to 15% higher than the maximum operating pressure of the system, and it should be equipped with anti-relief features. The circuit should be equipped with a pressure buffer device to suppress pressure surges during pump startup, ensuring that the peak surge pressure does not exceed the set value.

1.2 times the pressure.

c) A pressure synchronization control module should be configured for the multi-pump joint control loop, and the difference in set output pressure between each pump should not exceed the system operating pressure. ±5%; when a single pump fails, the circuit should be able to disconnect the failed pump and switch to the standby pump, with system pressure fluctuations not exceeding [a certain value] during the switching process. Exceeding the system's rated working pressure by 10% to 15%.

7.1.3 Valve Control Circuit Design The valve control circuit should select a suitable hydraulic valve (throttle valve, proportional valve, servo valve, etc.) based on control accuracy, response speed, and load characteristics. The body design requirements are as follows:

a) In a throttling speed control circuit, the flow rate adjustment range of the throttling valve should cover 5% to 100% of the rated flow rate of the actuator.

b) For electro-hydraulic proportional/servo control loops, the valve input signal should match the controller output signal, and signal isolation and anti-interference measures should be configured. Device.

c) In the directional control circuit, the diameter of the reversing valve should be selected based on the maximum working flow rate and allowable pressure drop of the circuit. The peak value of the reversing impact pressure should not exceed [the specified value]. The pressure should be

1.2 times the rated pressure. If there is interference during the reversal of multiple actuators, the circuit should be equipped with an interlock device to avoid interference.

d) Safety protection configuration. An independent safety valve should be installed in the valve-controlled circuit. The safety valve's set pressure should be

1.25 times the system design pressure. The full valve should be arranged in parallel with the main oil circuit to ensure rapid pressure relief in case of failure.

7.2 Pressure and Flow Design The design requirements for pressure and flow rate of the hydraulic system are as follows: The maximum working pressure of the hydraulic pump source shall not be less than the calculated value of formula (1), and shall meet the pressure requirements of the maximum external load of the hydraulic user.

7.6 Device Configuration

7.6.1 Selection of Hydraulic Oil The hydraulic oil should be selected according to the following requirements.

a) The hydraulic oil should possess the basic properties of hydraulic system oil, and should also have anti-wear properties, lubrication properties, and compatibility with sealing materials and hydraulic components. Requirements include good compatibility between components, metallic materials, and non-metallic materials;

b) The hydraulic oil selected should meet the temperature requirements for use at sea and underwater, mainly two types. high temperature and normal pressure at sea, and low temperature and high pressure underwater. Operating conditions;

c) The minimum and maximum viscosity of hydraulic oil when operating underwater shall comply with the provisions of Chapter 5, c).

7.6.2 Hydraulic Pump Source The design requirements for the hydraulic pump source are as follows:

a) The selection of pressure and flow rate of the hydraulic pump should meet the requirements of the maximum working pressure and maximum flow rate;

b) The outlet of the hydraulic pump should be equipped with a safety device to prevent overpressure.

c) The operating temperature of the hydraulic pump source should not exceed 60°C.

7.6.3 Hydraulic control valve box The hydraulic control valve box includes directional control valves, pressure control valves, flow control valves, etc., and its design requirements are as follows:

a) The selection of pressure and flow rate for hydraulic control valves should meet the requirements of the corresponding working pressure and flow rate;

b) When the hydraulic directional valve is in the neutral position, the inlet and return oil chambers of the hydraulic actuator should be pressure compensated, and a Y-type neutral position function should be used. Magnetic or electro-hydraulic directional valves;

c) The electromagnet in the solenoid valve should be a wet-type solenoid coil;

d) If a plate valve is used, it should be encapsulated, and the encapsulation housing should be filled with hydraulic oil to compensate for the internal and external pressure balance;

e) The opening pressure of the safety valve should not exceed 110% of the rated working pressure.

9.2 Land-based testing

9.2.1 Hydraulic system operation test The testing content and requirements for the hydraulic system are as follows:

a) Test whether the hydraulic system is working properly;

b) Test whether the pressure and flow rate meet the requirements;

c) Test whether various sensor devices are working properly.

9.2.2 Pipeline strength test and tightness test The requirements for pipeline strength testing and tightness testing shall be in accordance with the provisions of Section 2, Chapter 9 of the "Classification Specification for Diving Systems and Submersibles" (2018).

9.3 Pressure Cylinder Test

9.3.1 Test Requirements To ensure the hydraulic system can withstand the external pressure environment of the submersible, it was operated step-by-step and in stages within a pressure cylinder simulating environmental pressure. The pressure test mainly includes the following inspection items.

a) Pressure resistance and sealing tests of hydraulic devices;

b) Voltage withstand capability of components and sensors;

c) Conduct functional tests of the hydraulic device inside the pressure cylinder.

9.3.2 Test Procedure Before the maximum hydrostatic pressure test and the hydrostatic pressure test, apply appropriate pressure to the pressure-resistant structure and observe for any leakage. Only after passing through... Only after passing the sealing test can the next step, the hydrostatic pressure test, be carried out. The hydrostatic pressure test is shown in Figure 4.

9.3.3 Pressure Cylinder Functional Test During the hydrostatic pressure test, a functional test of the hydraulic device was conducted inside the pressure cylinder at the maximum working pressure to verify the hydraulic device's performance at the maximum pressure. Does it work properly under water pressure?

9.3.4 Evaluation of Test Results After the hydrostatic pressure test is completed, a comprehensive inspection of the hydraulic system should be carried out. The basic requirements are as follows:

a) The external structure is undamaged and has not undergone permanent deformation;

b) No leaks were observed and the seal was intact;

c) The functional test indicators of the hydraulic device meet the design performance requirements.