An investigation of the cooling power requirements for displacement-controlled multi-actuator machines
Modern trends in fluid power technologies emphasize the design of efficient fluid power systems. Although improvements to individual hydraulic component efficiencies can increase total system efficiency, the demand for even higher system efficiencies has forced researchers to move away from traditional valve-controlled actuation. Displacement-controlled (DC) actuation is one such alternative under investigation by the Maha Fluid Power Research Center. Research has shown that this technology can achieve up to 50% savings in energy consumption when compared with valve-controlled actuation. These savings are primarily due to the main advantage of DC actuation: the elimination of metering losses. The absence of metering losses is achieved by replacing proportional valves controlling individual actuators with variable-displacement pumps, thus actuator motion is controlled by pump displacement. Another advantage of highly-efficient DC actuation is lower working temperatures. This thesis focuses on this aspect of DC actuation. In order to study the temperature and cooling requirements in DC systems, a simulation model has been developed based on conservation of mass and energy for predicting the localized thermodynamic behavior of a multi-actuator DC machine as part of a project funded by the Center for Compact and Efficient Fluid Power (CCEFP). This model estimated a 50% reduction in necessary cooling capacity. Despite the model was originally created for DC systems exclusively, the posed question was how can the model be used for mixed systems, i.e. systems comprised by both DC and valve controlled actuators. The general modelling approach and a second model validation through measurements taken on a valve-controlled wheel loader during field operation are also presented as part of the model validation study.
Ivantysynova, Purdue University.
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