Abstract. The work is devoted to experimental research of throttles characteristics in hydraulic shock absorber. The throttles in shock absorber are formed by the functional apertures between piston and cylinder and between piston and rod. Also absorber consists of piston "throttle-valve" and bottom "throttle-valve" units
IntroductionThe principle of hydraulic shock absorber based on the processes of fluid throttling [1,2]. In case shock absorber reduces vibration of asymmetric loadings in it is used of two type "throttle-check valve" groups -on the piston (piston throttles) and on the bottom (base valve); and it works in two operating modes -"compressing" and "return" [3,4] (Fig. 1). Each one of the groups provides appropriate work in two modes. Herewith in two-chambered shock absorber, fluid is extruded into reserve chamber through the base valve in the compressing mode. In return mode fluid backs into cylinder chamber. Flow directions and velocities are defined by opening or closing of check valves in throttling lines. Check valves are designed as flat round springs. They work depends on the shock absorber mode. One of them is pressed to the piston and closing appropriate throttle lines. Opposite one is opening and make ring-shaped aperture with value that depends on the current velocity of piston. Theoretically, fluid's velocities in throttle lines are due to shock absorber characteristics and operating modes. In practice, the shock absorber construction has two additional throttling apertures formed by cylindrical contact surfaces of piston, rod and cylinder. In contrast to turbulent flows in the throttles of the piston and in the base valve channels there are laminar flows in additional throttles, as usual. Also shock absorber work accompanied by transforming kinetic energy into heat. It influences on the fluid temperature [5]. The temperature changes can have bad influence on damping characteristics by differ flow modes and throttling in inner channels of shock absorber [6].To ensure the planned characteristics of damping it necessary to take in account these features in design of shock absorbers. Presented researching is due to define the way of accounting these features.
Considered here are the questions of the simplification of the building process of the computer models. Suggested here is the “screwdriver” technology of the model building. The technology is based on the application of the set of the symbols of the typical elements and their models. The models of the object are built by the assembling of the element models in correspondence with the object structure. The application of the technology is illustrated on the example.
The cyclic modular approach is proposed for mechatronic object design. The approach is based on a new conceptual model of the object and a new algorithm of its design. The model consists of invariant and changeable parts. The parts have a hierarchical structure. The proposed algorithm allows for creating the object from the basis principle to the construction step by step. It makes it possible to design an adequate object in all forms of its representations: structure, schematic diagram, mathematical model and construction. Each of these forms has an invariant part, i.e. the structure of the functioning process of the object. Application of the proposed approach reduces the time needed for the object design.
Based on the analysis of known electro-hydraulic positioning actuators, its generalized scheme was given, which includes: control unit, command formation unit for reaching given position, executive mechanism, position sensor, and hydraulic energy supply unit. It was determined that the main difference between the actuators lies in the command formation unit, the structural solutions of which are based on four control methods: analog control of fluid supply to reach preset position; discrete control the time of fluid supply to reach preset position; discrete control of fluid supply to reach preset fixed position; discrete control of portioned fluid supply to reach preset position. For various structural solutions of actuators, the influence of the main parameters on their effectiveness in achieving the basic properties was analysed. A quantitative evaluation was proposed, which made it possible to reveal the relationship between the structure and properties of the actuators. The obtained results can be used to develop new effective positional actuators.
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