PFI:AIR - TT: A Novel Concept for Variable Delivery Flow Units for Fluid Power Applications

Purdue University, West Lafayette IN

Investigators

Abstract

This PFI: AIR Technology Translation project focuses on translating a new design that transforms a standard, fixed displacement external spur gear machine (EGM), used in hydraulic motors and pumps, into a variable delivery flow machine that reduces energy demand and fuel consumption. This Variable Delivery - External Gear Machine (VD-EGM) technology offers energy-efficient, reliable and low-cost pumps and motors in engineering applications such as high pressure fluid power circuits (used in construction, agriculture, transportation, aerospace, manufacturing and entrainment) and low pressure fluid systems (fuel injection, washing systems, food and pharmaceutical industry). The VD-EGM concept preserves all typical advantages of EGMs, such as low cost, compactness, high efficiency, tolerance to both contaminants and cavitation, reliability; and it also permits application in efficient "flow on demand" systems layout configurations, for which traditional EGMs are not suitable. This will enable: 1) the use of more energy efficient system layouts in current applications of EGMs; 2) the use of EGMs in place of more expensive designs of variable displacement machines (such as axial piston pumps and vane pumps). As a consequence, the VD-EGM has the potential to impact almost all fluid power machines, which currently handle about 3% of the total national energy consumption, offering significant fuel consumption reduction (up to 40%) without significant cost increase. Similarities in the design and appearance of the VD-EGM with respect to standard EGMs will allow for an easy acceptance of the novel concept into the fluid power market. This project will result in two functional prototypes (P1, P2): P1 will be a hydraulically operated VD-EGM suitable for power transmission systems involving high operating pressures (up to 250 bar), while P2 will be an electronically operated VD-EGM suitable for low pressure applications (up to 30 bar). To promote commercialization, the project will build a technology demonstrator, a hydraulic fan drive system, based on prototype P1. The intellectual merit of this research is the novel principle for obtaining variable timing in EGMs, which uses asymmetric gear profile. This principle introduces an actuation system to modify the fluid dynamic features of the meshing process in such a way that a variable flow is delivered by the EGM. Although suitable to vary the displacement up to a certain range, this principle is applicable for both high- and low-pressure systems and enables high bandwidth associated with flow regulation. The research approach is based on a multi-objective numerical optimization procedure based on a detailed tribological model for EGM that has been created to assist the VD-EGM design. This procedure will advance knowledge not only about variable timing applications of EGMs, but also about the multiple physical characteristics of the meshing process and the displacing action of EGMs. Personnel involved in this project include, the project PI, two graduate level students and two undergraduate students which will receive innovation and technology translation experiences by overcoming the challenges related to the design of the actuation systems of prototypes P1 and P2 of the VD-EGM. The students will also work with a business entity (Purdue Office of Technology and Commercialization) through the project co-PI, and receive feedback from a gear pump manufacturers that will be instrumental for product commercialization.