Model and examination of flow rate reducing system in positive displacement pump. The possibility of using hydraulic pumps with constant displacement in the combustion engine-powered systems has been presented. Problems associated with the selection of the pump size and cavitation have been discussed. Flow rate reducing system for pumps with high rotational speeds of the drive motor, without the need for use of electronic circuits or additional hydraulic circuit components, has been proposed. The principle of operation and two ways to control flow rate have been presented. A theoretical model of the design has been formulated. The research results of the pump without flow rate reducing system and the pump with the system in various configurations have been compared. Opportunities and limitations of the use of the presented solution have been identified.
Keywords: cavitation, pumps efficiency, flow regulator, theoretical model
Application of indirect tank method to find the static characteristics of pneumatic valves. The article concerns the examination of static flow and pressure characteristics of the 5/3-way proportional control valve. The test stands for determining those characteristics using the indirect tank method have been described. In the proposed method a pressure charge and discharge of two pneumatic tanks has been used to determine the parameters of the proportional valve . In the article the mathematical equations describing the mass and volume flow of air have been formulated. The characteristics of the valve are used as a function of the analog input signal to the proportional solenoid transmitter. Flow characteristics are used for the position control of the pneumatic servo drive, whereas the pressure characteristics are used for the position control of the pneumatic muscular drives system.
Keywords: flow characteristics, pressure characteristics, proportional control valve
Analytical prediction of leakage from a contact area of a valve head and valve seat. Article presents a method of estimation of the leakage from the contact area of valve head and seat in a valve. The causes of leakage have been discussed and a mathematical model of the flow through the gap between the head and the seat has been formulated. The impact of waviness and roughness on the size of the leakage has been included. Theoretical calculations were compared with the experimental research results. Conclusions on the received data have been formulated.
Keywords: surface waviness, roughness, measurements of leakage
