Influence of Bingham fluid viscosity on energy performances of a vortex chamber pump

There is no “rigid” kinematic connection between the centers of the rotors of the orbital hydraulic motor, which leads to non-standard changes in its output characteristics. A kinematic diagram of the movement of the rotors of an orbital hydraulic motor was developed, which made it possible to substantiate the kinematics of movement of its rotors and analyze the change in output characteristics. Abnormal changes in the output characteristics of this type of hydraulic motors are changes in the overall efficiency and changes in the angular speed of rotation of its shaft. When the gap between the rotors changes in the range of 0 to 0.4 mm, the overall efficiency of the positive displacement hydraulic machine decreases 3.6 times, which is explained by the increasing pour over between its rotors. The high value (0.92) and constancy of the volumetric efficiency of the orbital hydraulic motor is explained by the property of its rotors “self-sealing” in the process of moving, eliminating overflows. A decrease in the angular speed of rotation of the shaft of an orbital hydraulic motor 35 to 27 rad/s, with an increase in the gap of 0 to 0.4 mm, is explained by additional displacements of its inner rotor.

Kinematics of motion of rotors of an orbital hydraulic machine

There is a powerful influence of undissolved air on the axial piston hydraulic machines parameters, which requires research to detect this effect and reduce it. Considering the working fluid’s variable parameters and the load at the hydraulic motor output make it possible to increase the accuracy of mathematical modeling and improve the motor output characteristics. An energy-efficient device for mixing liquid with air is developed. Its use provides a fine gas-liquid mixture. The efficiency of the device was confirmed experimentally and by CFD calculations. The experimental research results of the working liquid gas content influence of and load on the hydraulic motor’s shaft on rotational speed have resulted. The model of the axial piston hydraulic motor rotational speed depending on the specified factors is received. The adequacy of the obtained mathematical models is checked. It is established that with increasing gas content in the working liquid, there is an increase in the amplitude of pressure fluctuations upstream the axial piston motor, and the oscillation frequency remains virtually unchanged. The hydraulic motor’s speed and the torque on the shaft are practically not affected by the gas content of the working liquid.

The Influence of the Gas Content in the Working Fluid on Parameters of the the Hydraulic Motor’s Axial Piston

As a result of the study, an experimental test bench was developed for testing high-torque hydraulic motors. A methodology for experimental studies of a unified series of planetary hydraulic motors has been developed. It has been established that an increase in the throughput of a hydraulic motor with a modernized distributed system makes it possible to increase the hydromechanical efficiency of the modernized hydraulic motor by 11 to 14%, the volumetric efficiency by 2 to 4%, and the overall efficiency by 7 to 9%. The increase in the values of the hydromechanical, volumetric and overall efficiency of the modernized hydraulic motor explains the increase in the throughput of its distributed system. It has been established that the torque of the developed serial hydraulic motor is 300 to 325 min−1, which is a sign of the rigid characteristics of this hydraulic motor. The stability of the torque (within 1.5%) developed by the modernized hydraulic motor 370 to 375 H.m in the frequency range of 75 to 450 min−1 is confirmed by its rigid characteristic.

https://iopscience.iop.org/article/10.1088/1757-899X/1021/1/012054/pdf

Experimental studies of a throughput of the distribution systems of planetary hydraulic motors

Predicting changes in the operating parameters of a planetary hydraulic motor is an urgent direction for improving its design. The physical and mathematical models of the planetary hydraulic motor have been developed, which make it possible to simulate the processes occurring under operating conditions. A design scheme and a mathematical apparatus have been developed for determining the pressure and leaks of the pressure fluid in the gap formed by the end surfaces of the distributors, which make it possible to study the change in the operating parameters of the hydraulic motor. By studying the features of the distribution system of a serial hydraulic motor, it was found that insignificant fluctuations in the flow area (up to 3%) cause rather large (up to 71%) pressure fluctuations. That causes the loss of fluid passing through the hydraulic motor up to 10% and fluctuations in the angular velocity of the output shaft – up to 11%. The absence of pressure fluctuations in the discharge line of the distribution system of the modernized hydraulic motor ensures the stability of its operating parameters. The results of the studies carried out make it possible to predict changes in the operating parameters of planetary hydraulic motors operating as part of a hydraulic drive at the design stage.

/pdf/influence-of-the-flow-area-of-distribution-systems-on-3on8apdrj9.pdf

Influence of the flow area of distribution systems on changing the operating parameters of planetary hydraulic motors

Current trends in expanding the scope of mechatronic systems with a hydraulic drive of active working bodies of self-propelled vehicles require the development of new approaches to solve the problem of improving the output characteristics of hydraulic drives of mechatronic systems with rotary hydraulic machines. It is established that for the drive of active working bodies and running systems of self-propelled equipment, the orbital and planetary hydraulic machines are mostly used. When designing mechatronic systems, much attention is paid to ensuring the specified output characteristics of the actuators of the designed system. A methodology for designing hydraulic mechatronic systems with the elements of multi-criteria optimization has been developed, which allows designing a mechatronic system with specified output characteristics. The optimization parameters of the controls of the mechatronic system with a hydraulic drive of the active working bodies of self-propelled vehicles have been substantiated. This technique involves five stages: the choice of the mechatronic system parameters; substantiation of optimized control parameters; development of a mechatronic system model; optimization of selected parameters of the mechatronic system; analysis of optimization results. The parameters of optimization of controls of a mechatronic system with a hydraulic drive for active working bodies and running systems of self-propelled vehicles have been substantiated. As a result of the studies, the optimal settings of the safety valve of the mechatronic system have been established, providing deviations of the pressure and angular velocity of the actuators from the set ones with an error of 0.17% and 0.67%, respectively.

Anatoly Caldare

Papers

Design of Hydraulic Mechatronic Systems with Specified Output Characteristics