Maha Fluid Power (Part 3) – Design and Optimization Software

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In Part 3, iEditor will summarize some information about the softwares developed by Maha Fluid Power Center which are used to optimize the pump and system design to improve efficiency and performance. Some of these softwares are being used in some companies to help product design and optimization.

1CASPARCASPAR (Calculation of Swash-Plate Type Axial Piston Pump/Motor) is designed to calculate the losses due to viscous friction and gap flow in swash plate type axial piston machines. Based on given design parameters of the rotating group the individual gap heights between cylinder block and valve plate, between piston and cylinder, and between slipper and swash plate can be calculated in a wide range of operating parameters.

CASPAR consists of two main program modules: Gap Flow Module and Cylinder Pressure Module. The first module realizes the calculation of the gap flow of three main lubricating pairs. The second module performs the calculation of the instaneous pressure in the displacement chamber.

Based on a non-isothermal gap flow model considering the change of gap heights due to micro motion of parts and due to surface deformations for the connected gaps of a swash plate axial piston machines. The program allows the calculation of real flow ripples at both ports, further the calculation of the instantaneous cylinder pressure, the internal and external volumetric losses, viscous friction forces, gap heights, oscillating forces and moments exerted on the swash plate. The updated release of CASPAR includes the consideration of elasto-hydrodynamic effects due to surface deformation of parts forming the gaps.

2AVASThe change of pressure in the displacement chamber of a displacement machine is greatly influenced by the smallest cross-section of the fluid flow which is formed by the valve plate and the rotating cylinder block. For simulation calculations, it is important to know the exact size of the flow passage opening to the high and low pressure side, depending on the angle of rotation. Because of the complex geometric sectioning, an analytical description of the cross-section is not possible. In the past the cross-section was measured and interpolated manually to obtain the area profile. Using a 3D-model of the valve plate AVAS is able to compute the smallest cross-section of the fluid for a complete revolution of the cylinder block automatically. In the single step mode every calculated passage area can be visualized. AVAS uses Unigraphics based routines to determine the smallest cross-section into the estimated flow direction. The program is written in C++ and uses the UG/Open++ interface to start as an internal application in Unigraphics. The 3D-model of the valve plate can be imported from any other CAD-System by the STEP interface.

3VpOptimVpOptim receives its name from optimizing the valve plate of a pump. The approach of VpOptim aims to optimize valve plate design to reduce the noise generated from the pressure changes in the displacement chambers.

4TransModelSimulation software TransModel which includes a time-domain model of the transmission coupling the pump and the motor using a line is developed to reduce the noise generation at the system level.

TransModel has the capabilities to investigate different factors such as rotating group design and hose dimensions which have an effect on the overall noise of the system.

5PSDD – Power Split Drive Design SimulationPSDD (Power Split Drive Design), which is developed in MATLAB Simulink environment, enables various powertrain configurations to be rapidly constructed and evaluated. This tool enables researchers at the lab to rapidly change system architectures and predict with a high degree of accuracy how a given system will perform.

REFERENCES[1].Maha Fluid Power Research Center. 2011 Annual Report.
[2]. Maha Fluid Power Research Center. 2014 Annual Report.
[3]. MATTEO PELOSI. AN INVESTIGATION ON THE FLUID-STRUCTURE INTERACTION OF PISTON/CYLINDER INTERFACE. Dissertation Purdue, US.
[4]. Maha Fluid Power Research Center Wesite. Https://engineering.purdue.edu/Maha/.

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