OPTIMIZATION OF PARAMETERS OF THE MOBILE MACHINE ADAPTIVE HYDRAULIC CIRCUIT

Mobile machine hydraulic circuits tend to adopt electrohydraulics. Such hydraulic circuits are based on controlled pumps, modulated hydraulics, sensors and controllers. This allows adapting the hydraulic circuit operating modes to the changes of external conditions of the machine operation. Application of hydraulic circuits with electrohydraulics in mobile machines allows to use mobile machines efficiently with a high number of removable endangers, increases their performance and improves the quality of performed works. The authors propose an adaptive hydraulic circuit for a mobile machine. The operation process in the adaptive hydraulic circuit in static and dynamic modes is determined by the interaction of the pump controller and pressure differential control valves. The hydraulic system operation stability, its fast response and readjustment are determined by the controller parameters. It has been revealed that the main parameters affecting the dynamic characteristics of the hydraulic system are: throttle area and coefficient of amplifying the pump controller orifice, dampener area and coefficient of amplifying the pressure differential control valve orifice. These parameters affect the stability, controlling and readjustment time in the hydraulic circuit differently. A functional including the values of controlling time , σ controlling and losses in the pump controller was used as an optimization criterion. The optimization has been made according to the developed mathematical model applying the method developed by I. Sobol and R. Statnikov. During the optimization each controller parameter changed on 3 levels. 81 tests were made and the best combination of controller parameters for the optimization criterion was determined. The following hydraulic circuit operation values were reached under the optimal values of parameters = 1.0·10-6 m2, = 1.0·10-3 m, = 1.2·10-6 m2, = 10·10-3 m: = 1.1 с, σ = 32 %, = 0.82 kW that comply with the requirements towards hydraulic circuits of mobile machines.

ALGORITHM OF CONTROLLING AN ADAPTIVE HYDRAULIC CIRCUIT FOR MOBILE MACHINES

Hydraulic systems based on adjustable pumps, proportional electrohydraulic equipment and controllers are used in mobile machines. The authors propose a new scheme of the hydraulic system for mobile machines, which provides the auger drilling operation. A number of studies have shown that a certain ratio should be maintained between the frequency of auger rotation and its feed during operation, where the productivity of soil disruption should not exceed the productivity of transporting loose soil from the drilling zone. Ensuring the required ratio between the speed of the auger rotation and its feed is implemented by a controller that works according to a certain algorithm. A nonlinear mathematical model of the hydraulic system was developed to create the algorithm for controller operation and setting. The equations of the mathematical model are solved in the MATLAB-Simulink environment by the Rosenbrock method. As a result of solving the equations for the mathematical model, the dependences of variables describing the state of the hydraulic system on time are obtained. The values of the controller settings are determined at which the hydraulic system works steadily, the error of flow rate stabilization, the time for pressure adjustment and readjustment does not exceed the allowable values. The algorithm for controlling the auger feed value is formed. This algorithm provides the necessary ratio between the auger feed and speed, as well as reducing the feed rate in the case of soil hardness increases. This creates the conditions for uninterrupted pit drilling at full depth and protection of the hydraulic system from overload.

A Closed-loop Control for Swing System and Energy Regeneration Analyses of the Multi-system of Grasp Steel Machine

Facing the environment problems, the improvement on the efficiency of the construction machinery is highly demanded, meanwhile, large energy wasted in hydraulic slewing systems, reaching the desired speed slowly and vibration in braking are widespread. In this paper, a closed-loop control swing system (CCSS) is proposed. In this system, bidirectional variable pump controls the change of oil flow by programmed software algorithm, instead of pilot actuated reversing valve, which significantly improves the efficiency of hydraulic circuit. Based on the model structures, we develop a hydraulic swing prototype and verify the advantages of our design means of theoretical calculation and simulation. It verifies that CCSS and based on accumulator slewing system(BASS) can respectively save 875.5 KJ and 347.2 KJ more than OCSS with operational weight of 100 tons grasp steel machine, which can support theoretical basis for energy conservation and environmental protection to study the new type of engineering machinery.

Experimental study of the flow in the elastic model of the abdominal aortic bifurcation

This paper reflected preliminary results of physical modeling of pulsating flow in a model of abdominal aortic bifurcation with taking into account the physiological elasticity of the vessel walls. Elastic vessel models were made via molding from a silicone mixture based on Lasil-T4 silicone rubber. The auxiliary study was performed to assess the elastic properties of the silicone mixture and select a necessary composition. The experiment on the pulsating flow in the rigid and elastic models of the abdominal aortic bifurcation was carried out using a blood flow simulator with circulation of blood-emulating fluid. It was revealed that interaction between the elastic model and closed rigid circuit of the blood flow simulator resulted in generation of intense parasite flow oscillations and prevented from getting similar flow conditions for rigid and elastic models. A way to solve the problem is to include dampers with liquid in the hydraulic circuit of the blood flow simulator at the inlet and the outlets of the elastic model.

A Needle-Free Jet Injection System for Controlled Release and Repeated Biopharmaceutical Delivery

Swift vaccination is necessary as a response to disease outbreaks and pandemics; otherwise, the species under attack is at risk of a high fatality rate or even mass extinction. Statistics suggest that at least 16 billion injections are administered worldwide every year. Such a high rate of needle/syringe injection administration worldwide is alarming due to the risk of needle-stick injuries, disease spread due to cross-contamination and the reuse of needles, and the misuse of needles. In addition, there are production, handling, and disposal costs. Needle phobia is an additional issue faced by many recipients of injections with needles. In addition to a detailed literature review highlighting the need for needle-free injection systems, a compressed air-driven needle-free jet injection system with a hydro-pneumatic mechanism was designed and developed by employing an axiomatic design approach. The proposed injection system has higher flexibility, uninterrupted force generation, and provides the possibility of delivering repeated injections at different tissue depths from the dermis to the muscle (depending on the drug delivery requirements) by controlling the inlet compressed air pressure. The designed needle-free jet injector consists of two primary circuits: the pneumatic and the hydraulic circuit. The pneumatic circuit is responsible for driving, pressurizing, and repeatability. The hydraulic circuit precisely injects and contains the liquid jet, allowing us to control the volume of the liquid jet at elevated pressure by offering flexibility in the dose volume per injection. Finally, in this paper we report on the successful design and working model of an air-driven needle-free jet injector for 0.2–0.5 mL drug delivery by ex vivo experimental validation.

Development of direct driven servo hydraulic actuator

Direct control of hydraulic cylinders - without use of control valve, represents a newer concept of energy-saving control of cylinders, without damping losses. In order to study this type of drive, it is necessary to design and manufacture a compact model of such device to study the control concepts and to check the operation of the system. We will study the existing implementations of such drives and create our own direct driven servo-hydraulic actuator (hereinafter DD SHA), with which we will move different loads. A servomotor must be attached to a suiTable hydrostatic unit (pump-motor). All the missing components need to be designed and manufactured for completed hydraulic circuit.