Prediction of Swash Plate Moment Using the Simulation Tool CASPAR

Author(s):  
Monika Ivantysynova ◽  
Jo¨rg Grabbel ◽  
Jean-Claude Ossyra

The paper presents a new method of prediction of the swash plate moment based on a complex simulation model of the rotating group of swash plate axial piston machines. Due to further important demands within the design of the next generation of displacement machines – the reduction of noise and an increase of efficiency – the optimization of pump and motor control becomes really difficult. The application of the computer aided design tool CASPAR, a simulation tool developed at the Technical University of Hamburg-Harburg for the design and optimization of swash plate axial piston machines, allows the calculation of swash plate moments dependent on time, design and operating parameters of the machine. Especially the valve plate design affects the generated swash plate moment. The paper presents results of a simulation study into the influence of swash plate moments on the valve plate design. The dependency on the instantaneous pressure behaviour in the displacement chamber is explained. The simulation results were compared with experimental results obtained by measurements of the instantaneous pressure behaviour in the displacement chamber for various valve plate designs.

Author(s):  
Rene Chacon ◽  
Monika Ivantysynova

This paper explains how a combination of advanced multidomain numerical models can be employed to design an axial piston machine of swash plate type within a virtual prototyping environment. Examples for the design and optimization of the cylinder block/valve plate interface are presented.


Author(s):  
J. H. Shin ◽  
H. E. Kim ◽  
K. W. Kim

This application study of a swash-plate type axial piston pump was concerned about the hydrostatic lubrication characteristics of cylinder barrel and valve plate which are main rotating body and its opposite moving part respectively. A computer simulation was implemented to assess thrust bearing and mechanical sealing functions of the fluid film between cylinder barrel and valve plate. A new algorithm was developed to facilitate simultaneous calculations of dynamic cylinder pressure, 3 degree-of-freedom barrel motions considering inertia effect, and fluid film pressure assuming full fluid film lubrication regime. Using the simulation tool, force and moment balancing of cylinder barrel which is a key issue of piston pump design was analyzed. Time dependent fluid film pressure and thickness distributions for several given balance ratios were calculated. This analysis helps to decide appropriate balance ratio in the valve and cylinder barrel. Oil leakage flow and friction torque in the fluid film between cylinder barrel and valve plate were calculated as well and discussed in the viewpoint of energy loss. The results show that film thickness in plain surface is not high enough to bear the barrel and reduce power loss and that surface waviness which exists in actual sliding surfaces can have a positive effect on it. This simulation tool could also predict time dependent barrel motions due to simultaneous calculation algorithm. It has been known that cylinder barrel rotates with oscillation. Therefore average clearance, tilt angle, and azimuth angle were calculated for each time step and the results were discussed.


Author(s):  
Michael Deeken

A research project at the Institute for Fluid Power Drives and Controls (IFAS) sponsored a simulation tool, which was developed to analyze the tribological contacts in an axial piston machine. This paper describes the comparison between simulation and measurement results. The research project defined several objectives. These included extending the program for the tribological contacts, such as slipper/swash plate and cylinder block/valve plate pairings. Furthermore, the results of the simulations were to be verified by means of measurements conducted on the test rig and these were to be performed on a standard unit, if possible. The values to compare simulation and measurement must first be defined in order to meet these objectives.


Author(s):  
Ganesh Kumar Seeniraj ◽  
Monika Ivantysynova

In designing an axial piston pump, lot of attention is given to the design of the valve plate. A well designed valve plate can reduce both flow pulsations as well as oscillating forces on the swash plate. In the presented study, a computational tool, CASPAR, has been used for investigating the effect of valve plate design on flow ripple (fluid borne noise), oscillating forces (structure borne noise) and volumetric efficiency. The impact of various valve plate design parameters such as precompression grooves, cross port, indexing and additional precompression volume will be presented using simulation results from CASPAR. The study also details how rate of pressurization and decompression inside the displacement chamber directly relate to the flow ripple, forces applied on swash plate and the control effort needed to stroke the swash plate. The effect of noise reduction techniques on volumetric efficiency will also be presented with simulated results.


Author(s):  
А.И. Гайкович ◽  
С.И. Лукин ◽  
О.Я. Тимофеев

Процесс создания проекта судна или корабля рассматривается как преобразование информации, содержащейся в техническом задании на проектирование, нормативных документах и знаниях проектанта, в информацию, объем которой позволяет реализовать проект. Проектирование может быть представлено как поиск решения в пространстве задач. Построение цепочки последовательно решаемых задач составляет методику проектирования. Проектные задачи могут быть разбиты на две группы. Первая группа ‒ это полностью формализуемые задачи, для решения которых есть известные алгоритмы. Например, построение теоретического чертежа по известным главным размерениям и коэффициентам формы. Ко второй группе задач можно отнести трудно формализуемые или неформализуемые задачи. Например, к задачам этого типа можно отнести разработку общего расположения корабля. Важнейшим инструментом проектирования современного корабля или судна является система ав­томатизированного проектирования (САПР). Решение САПР задач первой группы не представляет проблемы. Введение в состав САПР задач второй группы подразумевает разработку специального ма­тематического аппарата, базой для которого, которым является искусственный интеллект, использующий теорию нечетких множеств. Однако, настройка искусственных нейронных сетей, создание шкал для функций принадлежности элементов нечетких множеств и функций предпочтений лица принимающего решения, требует участие человека. Таким образом, указанные элементы искусственного интеллекта фиксируют качества проек­танта как специалиста и создают его виртуальный портрет. The process of design a project of a ship is considered as the transformation of information contained in the design specification, regulatory documents and the designer's knowledge into information, the volume of which allows the project to be implemented. Designing can be represented as a search for a solution in the space of problems. The construction of a chain of sequentially solved tasks constitutes the design methodology. Design problems can be divided into two groups. The first group is completely formalizable tasks, for the solution of which there are known algorithms. For example, the construction of ship's surface by known main dimensions and shape coefficients. Tasks of the second group may in­clude those which are difficult to formalize or non-formalizable. For example, tasks of this type can include develop­ment of general arrangement of a ship. The most important design tool of a modern ship or vessel is a computer-aided design system (CAD). The solu­tion of CAD problems of the first group is not a problem. Introduction of tasks of the second group into CAD implies development of a special mathematical apparatus, the basis for which is artificial intelligence, which uses the theory of fuzzy sets. However, the adjustment of artificial neural networks, the creation of scales for membership functions of fuzzy sets elements and functions of preferences of decision maker, requires human participation. Thus, the above elements of artificial intelligence fix the qualities of the designer as a specialist and create his virtual portrait.


Author(s):  
Gary A. Gabriele ◽  
Agustî Maria I. Serrano

Abstract The need for superior design tools has lead to the development of better and more complex computer aided design programs. Two of the more important new developments in application tools being investigation are Object Oriented Languages, and HyperMedia. Object Oriented Languages allow the development of CAD tools where the parts being designed and the design procedures specified are conceptualized as objects. This allows for the development of design aids that are non-procedural and more readily manipulated by the user trying to accomplish a design task. HyperMedia allows for the easy inclusion of many different types of data, such as design charts and graphs, into the tool that are normally difficult to include in design tools programmed with more conventional programming languages. This paper explores the development of a computer aided design tool for the design of a single stage gear box using the development HyperCard® environment and the HyperTalk® programming language. The resulting program provides a user friendly interface, the ability to handle several kinds of design information including graphic and textual, and a non-procedural design tool to help the user design simple, one stage gear boxes. Help facilities in the program make it suitable for undergraduate instruction in a machine elements design course.


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