The effect of cross porting on derived displacement volume


  • Taeho Kim Purdue University, Indiana, USA
  • Paul Kalbfleisch Purdue University, Indiana, USA
  • Monika Ivantysynova Purdue University, Indiana, USA



derived displacement volume, derived capacity, cross port, axial piston machine, method by Toet, valve plate design


Derived displacement volume (Vi) is very important for the calculation of volumetric and torque efficiency of positive displacement machines. A method for determining the derived displacement volume of a unit was introduced by Toet. This method is known to be more accurate than the current ISO 8426 standard, yet still has a speed dependent error. This paper reveals the main cause of the speed dependent error found in the method by Toet for the determination of derived displacement volume. An accurate pump model enabled the analysis of complex flow interactions inside a positive displacement machine. The analysis of the flows isolated the variations in derived displacement volumes to be dependent on the design of the valve plate. A case study of two valve plates with and without cross porting verified cross porting’s influence on derived displacement volume. Steady state measurement and the pump model simulations at low pressure differences show that the effective displacement volumes (Ve) at different rotational speeds follow nonlinear curves that all converge at Δp = 0. The main cause of the speed dependent error of derived displacement volume calculated using the method by Toet was discovered as the change in back flow volume due to cross porting.


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Author Biographies

Taeho Kim, Purdue University, Indiana, USA

Taeho Kim Born on March 18, 1981, in Busan (South Korea). He received his BS degree from Ajou University and MS degree from KAIST, South Korea, and University of Florida, in Mechanical Engineering in 2012. He is currently a PhD student at Maha Fluid Power research center. His main research interests are noise and control of displacement machines and quiet fluid power systems.

Paul Kalbfleisch, Purdue University, Indiana, USA

Paul Kalbfleisch Born on November 20, 1988, in Louisville, Kentucky. He received his BS degree in Engineering in Acoustics from Purdue University in 2011. He is currently a master’s student in Mechanical Engineering at Purdue University. His main research interests are modeling and design of hydraulic pumps/motors and transmissions for the purpose of noise reduction.

Monika Ivantysynova, Purdue University, Indiana, USA

Monika Ivantysynova Born on December 11, 1955, in Polenz (Germany). She received her MSc degree in Mechanical Engineering and her PhD degree in Fluid Power from the Slovak Technical University of Bratislava, Czechoslovakia. After 7 years in the fluid power industry, she returned to university. In April 1996, she received a Professorship in fluid power and control at the University of Duisburg (Germany). From 1999 until August 2004, she was Professor of Mechatronic Systems at the Technical University of Hamburg- Harburg. Since August 2004, she has been a Professor at Purdue University. Her main research areas are energy saving actuator technology and model based optimization of displacement machines, as well as modeling, simulation, and testing of fluid power systems. Besides the book Hydrostatic Pumps and Motors published in German and English, she has published more than 80 papers in technical journals and at international conferences.


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