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Design and Simulation of Digital Radial Piston Pumps Using Externally Actuated Cam Systems
Energy conservation is a growing topic of research within various fields. Digital Hydraulics is a division of fluid power that focuses on using on/off technology to improve the performance and efficiency of fluid power systems. One significant benefit of Digital Hydraulics is that it has enabled additional control over fluid power systems, which helps achieve component and system level improvements. Conventional radial and inline piston pumps use positive sealing valves, which mitigate leakage losses, compared to port plates commonly seen in variable displacement pumps. By using digitally controlled positive sealing valves on radial and inline piston pumps, leakage losses can be mitigated to develop a more efficient variable displacement pump. This work focuses on the design, modeling, and simulation of a mechanically actuated valving system developed for a commercially available radial piston pump. The design uses a ball screw actuation method to phase the cam during operation, changing the displacement. Using a modeling and simulation software, GT-SUITE, a simulation model was created for the digital pump that shows close correlation to the manufacturer’s data at high pressure. The parameters simulated, 50 – 200 bar, showed that the system could achieve a peak efficiency drop of approximately 11.0% from 87.0% to 76.0% from 100 – 25% displacement simulated at 200 bar and 500rpm. Compared to a typical variable displacement axial piston pump unit, the digital pump showed increased efficiencies across the bandwidth of 35-83% displacement, with a lower overall drop in efficiency across most of its operating conditions. In the comparison used, the pump is outside of its operating range and has not been optimized; thus, the simulation model created in this thesis will be used in the future to optimize the system and evaluate the system's potential performance and feasibility for future prototyping and testing as a proof of concept.