The hydro-viscous drive (HVD) is an effective device to save energy and reduce consumption. In order to reveal the flow field characteristics and calculate the shear torque, the mathematical model of fluid flow characteristics was built. The characteristics of velocity distribution, pressure distribution and theoretical required flow rate were obtained through the step analytic method. Then cavitation was analyzed based on the Reynolds boundary conditions, and the equivalent radius and shear torque model were achieved. Meanwhile, the equivalent temperature model was introduced by considering temperature field. Finally, the test rig of torque characteristics was set up to testify the trend of fluid field and shear torque. The characteristics of flow field and shear torque during the full film shear stage in HVD can be forecasted much more accurately through both experimental research and theoretical modeling which mainly consisted of equivalent temperature model, equivalent radius model and shear torque model.
A slipper model of axial piston pumps and motors that includes the vibration of a swashplate and constraint by a retainer is developed. The effects of the vibration and constraint upon the dynamic behavior and tribological characteristics are numerically examined. The theoretical model is established in consideration of the vibration of the counter surface of the slipper and the suppression of the slipper by the additional load. The calculation is performed under unsteady mixed lubrication and the motion, flow rate, friction torque, power loss, and stiffness are shown. The effects of the swashplate vibration, the retainer loads, and the operating conditions on the tribological characteristics of the slipper are discussed. The retainer enables to suppress the jumping motion of the slipper and the appropriate loads contribute to reduction in leakage flow rate and power loss and to improvement of tribological characteristics under a wide range of operating conditions.
Water hydraulics is developed toward widening application especially in food processing systems. Water hydraulic pushing cylinder system used in meat slicer is recently paid attention by both academic and industrial researchers in Japan. Due to very fast working cycle (0.5-1 seconds per cycle corresponding to 120-60 meat slices per minute), in conventional systems, methods to make a supply pressure track a load pressure for saving energy cannot be used. Supply pressure is normally set around a constant value by a relief valve. Thus, the energy loss in such system is huge because of much surplus supply pressure. This research introduces a novel energy-saving water hydraulic pushing cylinder system in meat slicer, which uses a 2/2 flow control valve for controlling the pressure in high-pressure chamber of the cylinder and 3 On/Off valves mainly for adjusting working direction of the piston rod. This system made the supply pressure nearly equal to the load pressure. As a result, the energy consumption reduced much, the reduction is approximately 50% based on the simulation result and control performance is acceptable.
The hydraulic quadruped bionic robot has great carrying capacity, moving performance and environmental adaptiveness, making the hydraulic robot become an important branch of the bionic robot systems. The hydraulic drive unit brings about the high performance and also enhances the difficulty in controlling the system at the same time: load disturbance can produce great influence for hydraulic drive control performance. In order to ensure the robot can keep good stability on various complex road environment, establishing a single leg control system to achieve the complex load characteristic test of the robot is needed, and the high performance control method should be studied. A single leg mechanical entity model of the hydraulic robot in ADAMS needs to be established and the hydraulic control system model of the hydraulic drive unit in MATLAB/Simulink, and through the collaborative simulation method to get single leg machine-fluid-electric combined with simulation model.