SOLUTION OF THE PROBLEM OF CALCULATING THE LEAKAGE WORKING FLUID IN ECCENTRIC GAP OF THE BALL PISTON PAIR HYDRAULIC FLUID POWER MACHINE

Основний зміст сторінки статті

Vadym Samorodov
Grigory Avrunin

Анотація

Goal. Conclusion of an analytical expression for calculating leaks in the gap between the ball-pistons and cylindrical holes in the cylinder blocks of radial-piston hydraulic pumps and hydraulic motors of hydraulic fluid power transmission. The object of study was the hydraulic fluid power transmission of the GOP-900 model in a monoblock design, consisting of a pump with an adjustable displacement and an hydraulic motor with a constant displacement. Method. For the laminar flow of the working fluid in the gap between the ball-piston and the cylinder, a calculation scheme is developed and a corresponding mathematical model is proposed for calculating the flow differential in each of the sections along the forming hole in the cylinder block of the hydraulic machine, followed by the integration of the specified differential. The calculation of the working fluid leaks in the MathCAD-15 medium allowed us to determine the average values of leaks with a concentric and eccentric arrangement of the piston balls in the holes of the cylinder blocks for specific set values for the diameters of the piston balls, the viscosity of the working fluid and the pressure drop between the
discharge and discharge cavities. Results. For the first time аnalytical expressions are obtained that allow calculating leaks in the gap between the ball piston and the hole in the cylinder block of a radial-piston hydraulic machine. The adequacy of the mathematical model is confirmed by the results of comparisons with the data of experimental measurements of working fluid leaks. It is shown that the coefficient of eccentricity of the circular gap used in the calculations using the Hagen-Poiseuille formula with a value of 2,5 is significantly overestimated. Conclusion. The method of calculating working fluid leaks in ball-piston hydraulic machines is recommended for use by specialists when developing new hydraulic machines and conducting diagnostics of the technical condition of those in operation in order to determine the volumetric efficiency and, in particular, its effect on the speed of vehicles whose transmissions use hydraulic machines with ball-pistons.

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Посилання

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