Research on dynamic characteristics of pressure compensator for deep-sea hydraulic system

Abstract

The pressure compensator is an important equipment of the deep-sea hydraulic system to provide the functions of pressure and volume compensation. In this paper, the structure features and static force analysis of the pressure compensator are studied. The physical model of the pressure compensator is established, and its dynamic characteristics influenced by the ambient pressure, the compensated flow and the temperature change are all analyzed. The entire working process of the pressure compensator is then researched. Therefore, two design criteria for reliability and dynamic characteristics respectively are proposed. A pressure compensator for 6000 m deep in the sea was designed and manufactured. Simulations and high-pressure experiments of the designed pressure compensator were conducted. The results show that the dynamic response of the compensated pressure under each input is all composed of a ramp change, a step change and a damped oscillation. The effective area of the rolling diaphragm, the spring stiffness and the mass of the diaphragm-piston assembly are the key design parameters to ensure the reliability and good dynamic characteristics of the pressure compensator. Simulation and high-pressure experiments verified the volume and pressure compensation function of the pressure compensator in the deep-sea environment.

Working Performance of the Deep-Sea Valve-Controlled Hydraulic Cylinder System under Pressure-Dependent Viscosity Change and Hydrodynamic Effects

“…The pressure compensator provides volume compensation and pressure compensation functions for the deep-sea VCHCS. Ignoring the influence of temperature, the flow continuity equation for the oil tank and pressure compensator [15] is:…”

“…For oil-based hydraulic manipulators, a pressure compensator is mounted on the hydraulic system. With elastic components that are easily deformed or displaced under pressure, the pressure compensator can balance the seawater ambient pressure by transmitting it to the inside of the hydraulic system [14,15]. The first advantage of this treatment is that all hydraulic components can be exempted from special pressure-resistant design, which usually leads to large wall thickness, large size, and large mass.…”

Analysis of Efficiency Characteristics of a Deep-Sea Hydraulic Power Source

“…The deep-sea motor and deep-sea pump, as well as various blocks and sensors, are encapsulated in an oil tank, and the oil tank can avoid the direct exposure of internal devices to seawater, prevent pollutants from entering and cool mineral oil [9]. The pressure compensator can balance seawater pressure and internal pressure, avoiding the direct compression of the system structure by external pressure [10], as shown in Figure 1, showing the power source composed of a DC (direct current) brushless motor and a gear pump. The common problem with deep-sea hydraulic power sources is the relatively low total efficiency, which is due to the special environment of the deep sea: high pressure and low temperature can have a significant impact on the efficiency characteristics of the pump and motor [11,12].…”

Effect of Dynamic Swiveling Torque and Eccentricity on the Design of Compensator Cylinders for a Variable Displacement Axial Piston Pump–Modelling & Simulation

“…Gao et al [19]studied the characteristics of variable displacement pumps and the variable-displacement output was implemented by controlling the swash plate angle with a feedback control unit. The pump can also be made to work under variable loading conditions by integrating it with a pressure compensator unit [20]. The pressure compensator unit provides enhanced efficiency and quicker response than valve-controlled systems [21].…”