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Research on the use of hydro-pneumatic accumulators in order to reduce the flow rate and pressure pulsations of oscillating hydraulic intensifiers

Chirita Aleksandru-Polifron, Popescu Teodor-Costinel, Popescu Ana-Maria Carla, Dinca Radu-Serban, Marinescu Alexandru Daniel

Mining Machines

2021

no. 4

37--46

Oscillating hydraulic pressure intensifiers, of the minibooster type, are supplied at the inlet, in the primary, by low-pressure pumps and provide, at the outlet, in the secondary, high pressure to the hydraulic consumers (linear or rotary hydraulic motors under load). The pressure increase in the secondary, proportional to the amplification factor of the intensifier occurs at a much lower flow rate than the supply flow rate, and thus the two hydraulic parameters (pressure and flow rate) at the outlet of the intensifier are affected by oscillations. Because of this, the miniboosters are designed for static applications, which require low displacements of hydraulic motors. The authors aimed to expand the field of use of miniboosters by reducing the flow rate and pressure pulses with the help of hydro-pneumatic accumulators mounted on the primary and secondary of the intensifiers. If these pulsations can be mitigated, then low-pressure pump units of small dimensions, equipped with miniboosters, can be used in dynamic mining-specific applications, in complete safety, such as, for example, those involving relatively uniform displacement, under load, of some hydraulic jacks. A numerical simulation model developed in Simcenter Amesim highlights the effect of using hydro-pneumatic accumulators on the mitigation of flow rate and pressure pulsations of the oscillating hydraulic intensifiers. Numerical simulations performed with and without hydro-pneumatic accumulators mounted on the primary and secondary of the intensifier highlight the following aspects: • hydro-pneumatic accumulators can be used successfully for the partial damping of flow rate and pressure pulses, but they must be dimensioned for each specific application and work optimally for a relatively narrow pressure range; • using hydro-pneumatic accumulators can sufficiently improve the uniformity of displacement and the velocity of displacement of a hydraulic cylinder, so that it can be used in less demanding dynamic applications, as well.

Studium energetyczne hydrostatycznego napędu akumulatorowego

Grzesikiewicz W., Knap L., Makowski M.

TTS Technika Transportu Szynowego

2012

R. 19, nr 9

1235--1242, CD

W pracy rozpatrujemy procesy termodynamiczne powstające w komorach z gazem akumlatora hydro-pneumatycznego w trakcie napędzania bezwładnika odwzorowującego inercję pojazdu. Bezpośrednim celem tych badań jest energetyczna analiza procesów przemiany energii w czasie napędu. Badania te będą prowadzone przy użyciu modelu w postaci układu termodynamiczno-mechanicznego. W prezentowanej wersji modelu pominięto wszelkie zjawiska dyssypacyjne, które będą rozpatrywane w następnych pracach. Badania symulacyjne będą prowadzone w celu ustalenia parametrów przyjętego modelu. Zasadniczym elementem rozważanego modelu jest akumulator hydro-pneumatyczny, dla którego należy ustalić charakterystykę oraz dopuszczalny zakres pracy obu akumulatorów. Prace wykonano w ramach projektu, który został sfinansowany ze środków Narodowego Centrum nauki przyznanych na podstawie decyzji numer DEC-2011/01/B/ST8/06822.

A hydrostatic drive system with hydro-pneumatic accumulators consists of a bilateral hydrostatic machine with two hydro-pneumatic accumulators attached. This type of a drive system can be a part of the hydrostatic hybrid in which hydro-pneumatic accumulators are employed for breaking the vehicle. In this article an analysis of the flow of energy between hydropneumatic accumulators, hydrostatic machine, inertia element and surrounding environment is presented. In the analysis a model of transmission system with some extent of idealization of energy conversion process is considered. The main part the discussion here is related to thermodynamic changes in the gas chambers of hydro-pneumatic accumulators. These changes take place inside chambers with a constant amount of gas. The energy stored in hydro-pneumatic accumulator is exchanged with an inertia element as the hydrostatic energy and with the environment as heat. By recourse to the hydrostatic machine, the hydrostatic energy can be exchanged with the kinetic energy of the inertia element. For the considered process of energy exchange a mathematical description of inertia element motion and thermodynamic processes in chambers of hydro-pneumatic accumulators was formulated. This aproach resulted in a mathematical formulation leading to a set of algebraic equations.