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1

Effect of the working liquid compressibility on the picture of volumetric and mechanical losses in a high pressure displacement pump used in a hydroststic drive. Part I. Energy losses in a drive system, volumetric losses in a pump

100%
Paszota Z.
Polish Maritime Research
|
2012
|
tom 19
|
nr 2
Working liquid compressibility may considerably change the values and proportions of coefficients of volumetric and mechanical energy losses in the displacement pump used in a hydrostatic drive system. This effect can be particularly seen in the operation under high pressure and also in the system, where aeration of the working liquid can occur. In the Part I a diagram is presented, proposed by the author, of power increase in a hydrostatic drive system (hydraulic motor, pump) opposite to the direction of power flow, replacing the Sankey diagram of power decrease in the direction of power flow. Mathematical model is presented of volumetric losses in the pump and its laboratory verification
2

Energy losses in the hydraulic rotational motor definitions and relations for evaluation of the efficiency of motor and hydrostatic drive

100%
Paszota Z.
Polish Maritime Research
|
2010
|
tom 17
|
nr 2
The evaluation methods of energy losses and efficiency of the hydraulic rotational motors for the hydrostatic drives, used so far in the scientific research and in the industrial practice, give wrong results because the parameters that the losses and efficiencies are a function of are themselves dependent on those losses.The aim of the paper is to define the motor operating parameters, developed powers, energy losses and efficiencies and also to show the respective relations. Conclusions are drawn, based on the analyses of presented definitions and relations, on the motor energy investigations
3

Hydrostatic drives as safe and energy saving machines. The drive investigation method cpmpatible with the diagram of power increase opposite to the direction of power flow

100%
Paszota Z.
Polish Maritime Research
|
2011
|
tom 18
|
nr 1
Designers and manufacturers of hydrostatic drives have not a tool for precise determination of their energy efficiency, changing in a wide range in the driven device operating field, i.e. in the full range of the hydraulic motor speed and load and the working medium viscosity. This applies both to determining of losses and energy efficiency of displacement machines (pump and hydraulic motor) used in the drive system, and to losses and energy efficiency of the motor control system structure. A method is proposed compatible with the diagram of power increase opposite to the direction of power flow. That diagram replaces the Sankey diagram of power decrease in the direction of power flow
4

Theoretical and mathematical models of the torque of machanical losses in the pump used in a hydrostatic drive

100%
Paszota Z.
Polish Maritime Research
|
2011
|
tom 18
|
nr 4
The paper presents theoretical and mathematical models of the torque of mechanical losses in the pump with theoretical (constant) capacity qPt per one shaft revolution (with constant theoretical working volume VPt) and geometrical (variable) capacity qPgv per one shaft revolution (with variable volume VPgv). The models may be used in the laboratory and simulation investigations of the pump energy efficiency and the hydrostatic drive efficiency
5

Effect of the working liquid compressibility on the picture of volumetric and mechanical losses in a high pressure displacement pump used in a hydroststic drive. Part II. Mechanical losses in a pump

100%
Paszota Z.
Polish Maritime Research
|
2012
|
tom 19
|
nr 3
Working liquid compressibility may considerably change the values and proportions of coefficients of the volumetric and mechanical energy losses in the displacement pump used in a hydrostatic drive system. This effect can be particularly seen in the operation under high pressure and also in the system, where aeration of the working liquid can occur. In the Part II the mathematical model is presented of the torque of mechanical losses in the pump and its laboratory verification. Conclusions are drawn regarding the effect of working liquid compressibility on the mechanical and volumetric losses in the pump
6

Comparison of the powers of energy losses in a variable capacity displacement pump determined without or with taking into account the power of hydraulic oil compression

100%
Paszota Z.
Polish Maritime Research
|
2015
|
tom 22
|
nr 2
Powers of energy losses in a variable capacity displacement pump are compared with or without taking into account the power of hydraulic oil compression. Evaluation of power of liquid compression in the pump was made possible by the use of method, proposed by the Author, of determining the degree of liquid aeration in the pump . In the method of determining the liquid aeration in the pump and of powers of volumetric losses of liquid compression a simplified formula (qPvc × ∆pPi)/2 was used describing the field of indicated work of volumetric losses qPvc of liquid compression during one shaft revolution at indicated increase ∆pPi of pressure in the chambers. Three methods were used for comparing the sum of powers of volumetric losses ∆PPvl due to leakage and ∆PPvc of compression and also of mechanical losses resulting from increase ∆pPi of indicated pressure in the working chambers
7

The operating field of a hydrostatic drive system parameters of the energy efficiency investigations of pumps and hydraulic motors

100%
Paszota Z.
Polish Maritime Research
|
2009
|
tom 16
|
nr 4
The operating field of hydrostatic drive system is presented. Subdivision of the hydraulic motor and pump work parameters into parameters independent of and dependent on the operation of displacement machines and the system is justified. A research project is proposed aimed at development of methods determining the energy characteristics of pumps and rotational hydraulic motors as well as modified methods of determining the energy characteristics of hydrostatic drive systems with selected structures of hydraulic motor speed control. The paper is an extended version of reference [11]
8

Theoretical and mathematical models of the torque of mechanical losses in a hydraulic rotational motor for hydrostatic drive

100%
Paszota Z.
Polish Maritime Research
|
2010
|
tom 17
|
nr 3
The paper presents theoretical and mathematical models of the torque of mechanical losses in a hydraulic rotational motor with constant capacity qMt per one shaft revolution (with constant theoretical working volume VMt) and with variable capacity qMgv = bM qMt per one shaft revolution (with variable geometrical working volume VMgv). The models are to be used in the laboratory and simulation investigations of motor energy losses aimed at evaluation of the motor energy efficiency and hydrostatic drive efficiency
9

Mathematical model defining volumetric losses of hydraulic oil compression in a variable capacity displacement pump

100%
Paszota Z.
Polish Maritime Research
|
2014
|
tom 21
|
nr 4
The objective of the work is to develop the capability of evaluating the volumetric losses of hydraulic oil compression in the working chambers of high pressure variable capacity displacement pump. Volumetric losses of oil compression must be determined as functions of the same parameters, which the volumetric losses due to leakage, resulting from the quality of design solution of the pump, are evaluated as dependent on and also as function of the oil aeration coefficient ε. A mathematical model has been developed describing the hydraulic oil compressibility coefficient as a relation to the ratio ∆pPi/pn of indicated increase ∆pPi of pressure in the working chambers and the nominal pressure pn, to the pump capacity coefficient bP, to the oil aeration coefficient ε and to the ratio ν/νn of oil viscosity ν and reference viscosity νn. A mathematical model is presented of volumetric losses of hydraulic oil compression in the pump working chambers in the form allowing to use it in the model of power of losses and energy efficiency
10

Graphical presentation of the power of energy losses and power developed in the elements of hydrostatic drive and control system. Part I. Rotational hydraulic motor speed series throttling control systems

100%
Paszota Z.
Polish Maritime Research
|
2008
|
tom 15
|
nr 3
Paper proposes and justifies a diagram of the direction of increase of power stream fromthe shaft or piston rod of a hydraulic motor to the pump shaft, power increasing as an effect of the imposed power of energy losses in the hydrostatic drive and control system elements. Graphical interpretation of the power of energy losses in the hydrostatic drive and control system elements and also of the power developed by those elements is presented. An individual system with the rotational hydraulic motor speed series throttling control fed by a constant capacity pump cooperating with an overflowvalveinaconstantpressuresystemp=cte≈pnis analyzed and also an individual system with the rotational hydraulic motor speed series throttling control fed by a constant capacity pump cooperating with an overflowvalvecontrolledinavariablepressuresystem:p = var, an individual system with the rotational hydraulic motor speed series throttling control fed by a variable capacity pump cooperating with a pressure regulator in a constant pressure system p = cte ≈ pn and an individual system with the rotational hydraulic motor speed series throttling control fed by a variable capacity pump cooperating with the Load Sensing regulator in a variable pressure p = var system
11

On power stream in motor or drive system

100%
Paszota Z.
Polish Maritime Research
|
2016
|
tom 23
|
nr 4
In a motor or a drive system the quantity of power increases in the direction opposite to the direction of power flow. Energy losses and energy efficiency of a motor or drive system must be presented as functions of physical quantities independent of losses. Such quantities are speed and load. But the picture of power stream in a motor or drive system is presented in the literature in the form of traditional Sankey diagram of power decrease in the direction of power flow. The paper refers to Matthew H. Sankey’s diagram in his paper „The Thermal Efficiency of Steam Engines” of 1898. Presented is also a diagram of power increase in the direction opposite to the direction of power flow. The diagram, replacing the Sankey’s diagram, opens a new prospect for research into power of energy losses and efficiency of motors and drive systems
12

Method of determining the degree of liquid aeration in a variable capacity displacement pump

100%
Paszota Z.
Polish Maritime Research
|
2013
|
tom 20
|
nr 3
The Author concludes, that there is a possibility of determining a concrete value of the liquid aeration coefficient ε during the pump operation by finding such value of ε with which the increase ΔMPm|ΔpPi = pn, qPgv of torque of mechanical losses is proportional to the indicated torque MPi|ΔpPi = pn, qPgv determined with a fixed value ∆pPi = cte of increase of pressure in the pump working chambers. The fixed value ∆pPi assumed in searching the liquid aeration coefficient ε equals to the nominal pump operation pressure pn (∆pPi = cte = pn ). The increase ΔMPm|ΔpPi = pn, qPgv of torque of mechanical losses with a fixed value of ∆pPi (∆pPi = cte) is proportional to the pump geometrical working capacity qPgv , therefore: only with taking into account the aeration coefficient ε of liquid displaced by the pump the relation ΔMPm|ΔpPi = pn, qPgv ∼ qPgv can be obtained from tests. The method, proposed by the Author, of determining the working liquid aeration coefficient ε, is presented in this paper and has been practically applied for the first time by Jan Koralewski in his investigations of the influence of viscosity and compressibility of aerated hydraulic oil on volumetric and mechanical losses in a pump of HYDROMATIK A7V.58.1.R.P.F.00 type [8, 9]
13

Graphical presentation of the power of energy losses and power developed in the elements of hydrostatic drive and control system. Part II. Rotational hydraulic motor speed parallel throttling control and volumetric control systems

100%
Paszota Z.
Polish Maritime Research
|
2008
|
tom 15
|
nr 4
Paper presents graphical interpretation of the power of energy losses in the hydrostatic drive and control system elements and also of the power developed by those elements. An individual system fed by a constant capacity pump, where rotational hydraulic motor speed control is effected by a parallel throttling control system, is analyzed and also a system with the rotational hydraulic motor speed volumetric control by a variable capacity pump, an individual system with a rotational hydraulic motor volumetric speed control by means of a simultaneous change of the pump capacity per one revolution and change of the motor capacity per one revolution, the system operating at the constant pressure in the pump discharge conduit equal to the nominal pressure of the system: pP2 = pn and central system (with situated in parallel and simultaneously operating motors) with volumetric speed control of each rotational hydraulic motor by a motor secondary circuit assembly, the system fed by a pump with variable capacity per one shaft revolution fitted with pressure regulator pP2 = pn
14

Losses and energy efficiency of drive motors and systems. Replacement of the Sankey diagram of power decrase in the direction of power flow by a diagram of power increase opposite to the direction of power flow opens a new perspective of research of drive motors and systems

100%
Paszota Z.
Polish Maritime Research
|
2013
|
tom 20
|
nr 1
Losses and energy efficiency of every drive motor must be presented as functions of physical quantities independent of losses in the motor. Such quantities are speed and load required by the machine or device driven by the motor, changing in the drive operating field. Speed and load of the motor decide of the instantaneous useful power of the motor and also in a differentiated way of kinds and values of losses occurring in the motor. However, losses and energy efficiency of the hydrostatic drive motors and systems are evaluated by researchers and manufacturers as functions of parameters depending on the losses. The basic cause of such situation is the traditional, commonly accepted but erroneous, view of the power flow in the drive motors and systems represented by the Sankey diagram of power decrease in the direction of power flow. It is necessary to replace the Sankey diagram by the proposed diagram of increase of power in the motor and in the drive system in the direction opposite to the direction of power flow. The proposed view of losses and energy efficiency should be applied to all types of motor and drive systems. The aim of this paper is showing the resulting problems of the above postulates, exemplified by operation of a rotational displacement motor in a hydrostatic drive system. In order to make possible objective evaluation of the energy behaviour of different motor and system solutions and sizes, the losses and energy efficiency should be described and compared as dependent on the motor speed coefficient ωM and load coefficient changing in the drive system operating field (0 ≤ ωM< ωMmax, 0 ≤ M< Mmax). The presented proposals open a new perspective of unavoidable research of drive motors and systems, making it possible to compare objectively the energy efficiency of different types of motors and drive systems
15

Model of the energy losses in the displacement rotational machines for description of efficiency of the hydrostatic drive. Part I. Model of volumetric losses

100%
Paszota Z.
Polish Maritime Research
|
2000
|
tom 07
|
nr 3
16

Model of the energy losses in the displacement rotational machines for description of efficiency of the hydrostatic drive. Part II. Model of mechanical and pressure losses

100%
Paszota Z.
Polish Maritime Research
|
2000
|
tom 07
|
nr 4
17

Energy-saving structures of hydrostatic drives for ship deck machines

100%
Paszota Z.
Polish Maritime Research
|
2000
|
tom 07
|
nr 1
18

Energy aspects of hydrostatic drives

63%
Paszota Z.
Polish Maritime Research
|
2003
|
tom 10
|
nr 2
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