Candidate: Paulo Francisco do Carmo
Program: UFSC / POSMEC
Date: May, 2003
Advisor: Victor Juliano De Negri
Abstract: This work has as objective to present a more complete mathematical modeling for directional proportional valves flow rate. The flow rate modeling in a directional proportional valve is essential for the study of hydraulic systems, mainly those related to position, force, and velocity control of hydraulic actuators. These forms of control are also applied to robotics, siderurgy, industry, aircrafts, navy, among others. Presently, linearized models are used which incorporate the effects of internal leakage, but these models do not include the square pressure factor, fact that brings results too far away from the reality when the valve works away from its central point. In the linearized models, the square factor of pressure is present, but this model does not include the valve internal leakage, that leads to significative errors when the hydraulic system is exposed to heavy work. The non-linear model proposed in this work is based on the flow composition in the several valve control orifices, adding the effects of internal leakage and, for definition of the parameters of the model, procedures for testing and correlation with technical catalogues are proposed. Therefore, a complete non-linear mathematical modeling is shown, which allows a better representation of the physical phenomena in hydraulic systems design.
CARMO, P. F. Proposta de modelo para descrição da vazão em válvulas direcionais proporcionais, com efeito de vazamento. 2003. Dissertação (Mestrado em Engenharia Mecânica). Universidade Federal de Santa Catarina, Florianópolis.