Novel Concept for Variable Displacement External Gear Machine
Researchers affiliated with the Center for Compact and Efficient Fluid Power (CCEFP), an NSF-funded Engineering Research Center (ERC) headquartered at the University of Minnesota, have formulated a novel concept for a variable delivery flow unit based on the classic external gear machine design. A fully operational prototype was realized and tested in 2014 at Purdue University's Maha Fluid Power Research Center (see figure).
The new machine encompasses the well-known advantages of traditional external gear machines, such as low cost, compact units, good reliability, and reasonable efficiency. This new concept for low-cost variable displacement units has the potential to substitute for current fixed displacement units in many applications, such as charge pumps in hydrostatic transmissions or hydraulic fan drives, with significant reduction of fuel consumption.
Although unit designs for higher flow variation have been formulated at Purdue, the prototype used for the experiments offers displacement variation in the range of 35%. The proposed design allows for variable delivery flow while maintaining an energy efficiency level comparable to that of other variable displacement machines.
CCEFP is extensively researching new system concepts to minimize energy consumption of fluid power applications. One of CCEFP's partnering institutions is Purdue University, and the prototype in the figure was realized by researchers under the supervision of Purdue’s Dr. Andrea Vacca.