Method of calculating the fluid power drive of pneumatic motor inlet valve

Abstract

Introduction. Hybrid power plants with a pneumatic motor, which operates at low speeds, are widely used, and an internal combustion engine is used on the rest of the speed range. Due to limitations in the regulation of valve timing in standard mechanical engine valve actuators, the possibility of using a fluid power drive for the pneumatic motor inlet valve is considered. A feature of such a fluid power drive is the use of a directional control valve with electromagnetic proportional control, which, in combination with an electronic unit, provides flexible control of the phases of air distribution in a pneumatic motor. Problem. Based on the analysis of the literature and preliminary developments, the electro-hydraulic drive of the air distribution mechanism was selected at KhNAHU, which allows not only to improve the filling characteristics, but also to carry out 2 or 4-stroke operation of the hybrid power plant.Evaluation of the capabilities of modern hydraulic control systems for speed showed that throttling servo-valve and valve with proportional electromagnets have high-frequency and speed-adjustable ones. When choosing the latter as the intake valve actuator, a static calculation of the parameters of the pumping unit is necessary. Method. The basis for solving static problems in the field of a volume hydraulic drive is the Pascal law for the working fluid in a confined space, the continuity equation of the working fluid and the third law of Newtonian mechanics, as well as the dependences of power losses due to friction forces and leaks in the gaps of precision pairs. The practical results. The diameter and speed of the valve follower movement, the consumed flow rate of the working fluid at a given speed, the pump discharge pressure, the leakage of the working fluid in the slotted seal of the plunger and the friction force are determined. The results obtained are the basis for choosing a pump and hydraulic equipment for a particular fluid power drive and conducting further dynamic calculations in order to identify the amplitudes and nature of the oscillatory processes during opening, steady state and closing the inlet valve of the pneumatic motor.