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Energy saving systems of hydrostatic drives for ship deck machines

Skorek G.

New Trends in Production Engineering

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2018

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Vol. 1, Iss. 1

507--514

EN

A control system with a proportional directional throttling control valve or a directional control servo valve, controlling a cylinder (linear hydraulic motor) is used in the ship steering gear drive, in the controllable pitch propeller control, in the variable capacity pump control system for hydraulic deck equipment motors or fixed pitch propellers in small ships (for example ferries). Energy savings in a constant capacity pump operation can be achieved by means of overflow valve controlled by the oil outlet pressure between the directional throttling control valve and the cylinder. Although structural volumetric losses cannot be eliminated in such a system, but it is possible to reduce considerably structural pressure losses, mechanical losses and volumetric losses in the pump, and mechanical losses in the cylinder too. The paper discusses these energy savings using an earlier developed by Paszota mathematical model of losses in elements, the energy efficiency of the system and the operating range of the cylinder. The paper also presents a comparison of the energy behavior of two widespread structures of hydrostatic systems: a standard individual systems with a throttling steering fed by a constant capacity pump. Both system solutions are described and equations of the total efficiency η of the system are presented. Diagrams of energy efficiency of two hydraulic systems working at the same parameters of a speed and a load of hydraulic linear motor, which were different due to structure and ability of energy saving, were presented and compared.

2

Influence the applied control structure on energy efficiency of the hydrostatic system

Skorek G.

Journal of KONES

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2018

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Vol. 25, No. 3

411--418

EN

A control system with a proportional directional throttling control valve or a directional control servo valve, controlling a cylinder (linear hydraulic motor) is used in the ship steering gear drive, in the controllable pitch propeller control, in the variable capacity pump control system for hydraulic deck equipment motors or fixed pitch propellers in small ships (for example ferries). The hydraulic system is designed first of all taking into consideration the nominal parameters of the cylinder load and speed. For such parameters, the energy efficiency of the elements and complete system is described. Meanwhile the exploitation conditions can vary in full range changes of the cylinder load and speed coefficients. The article presents a comparison of the energy behaviour of two widespread structures of hydrostatic systems: a standard individual systems with a throttling steering fed by a constant capacity pump. Both hydraulic solutions are described and equations of the total efficiency η of the system are presented. Diagrams of energy efficiency of two hydraulic systems working at the same parameters of a speed and a load of hydraulic linear motor, which were different due to structure are presented and compared, as well ability of energy saving. This publication also presents analyses and compares the areas of the power fields of energy losses occurring in the elements of two hydraulic systems with different structures of the hydraulic linear motor speed control.

3

Comparison of the structural and total energy efficiency of selected hydraulic systems with proportional control linear motor

Skorek G.

Journal of KONES

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2016

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Vol. 23, No. 2

317--324

EN

In the paper are presented the diagrams of the structural energy efficiency of system with the throttling control assembly and total energy efficiency of the system with constant or variable capacity pump cooperating an overflow valve with the throttling control of the linear hydraulic motor. Diagrams of total energy efficiency of three hydraulic systems working at the same parameters of speed and load of hydraulic linear motor, which were different due to structure and ability of energy saving were presented and compared. This publication also presents analyses and compares the areas of the power fields of energy losses occurring in the elements of three compared hydraulic systems with different structures of the hydraulic linear motor speed control on example on Load Sensing system. The graphical interpretation of the power of losses in the hydrostatic drive and control system elements lets to compare the same power fields of energy losses with other power fields of another structure. This enables to understand what energy losses are the biggest and in which elements of compared hydraulic systems. The best possibility to use in system, as a supply source of the hydraulic cylinder speed series throttling control assembly, is a set consisting of a variable capacity pump cooperating with a Load Sensing (LS) regulator, which totally eliminates the structural volumetric losses in a system. Power ΔPstv of structural volumetric losses is equal to zero, because the current pump capacity QP is adjusted, by the LS regulator, to the current flow intensity QM set by the throttling assembly.

4

Porównanie dwóch układów hydrostatycznych ze sterowaniem dławieniowym - zasada działania, rozkład ciśnień oraz straty mocy

Skorek G.

Zeszyty Naukowe Akademii Morskiej w Gdyni

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2011

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nr 71

115-130

PL

W artykule porównano dwa układy ze sterowaniem dławieniowym, zasilane pompą o stałej wydajności. Przedstawiono również rozkład ciśnień w układach oraz formę graficzną, ilustrującą moce i straty mocy w poszczególnych elementach. Porównano zarówno wielkość mocy poszczególnych strat, wynikających z zastosowanej struktury sterowania prędkości silnika hydraulicznego liniowego, jak i moc pobieraną przez pompę od napędzającego ją silnika elektrycznego, konieczną do zapewnienia wymaganej niezmienionej wielkości użytecznej, napędzanego pompą, silnika hydraulicznego liniowego. Układ hydrauliczny napędu i sterowania proporcjonalnego silnika hydraulicznego liniowego może być zasilany pompą o stałej wydajności, współpracującą z zaworem przelewowym, stabilizującym ciśnienie zasilania rozdzielacza proporcjonalnego na poziomie ciśnienia nominalnego, bądź pompą współpracującą z zaworem przelewowym sterowanym ciśnieniem na dopływie do odbiornika. Układ zmiennociśnieniowy umożliwia obniżenie strat w pompie, w zespole sterowania i w silniku hydraulicznym liniowym.

EN

This publication compares two hydrostatic systems with a throttling steering fed by a constant capacity pump. It also presents a distribution of pressures in hydraulic units as well as a graphic form, which illustrates powers and losses of power in particular elements. The analysis allows to compare the values of power of losses ensuing from the used structure of control of the hydraulic linear motor speed as well as the value of power absorbed by the pump from its driving electric motor, power necessary for providing the required stable value of useful power of the hydraulic linear motor driven by the pump. A system of drive and proportional steering of hydraulic linear motor can be fed by constant capacity pump cooperated with an overflow valve, which stabilizes a supply pressure of proportional valve on a level of nominal pressure, or by pump cooperated with controlled overflow valve a pressure on inlet to receiver. A variable pressure system enables the losses decreasing in the pump, in the control unit and in the hydraulic linear motor.