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(2) With the results of CFD simulation on WAIM cavity filling process, the coupling relationship between load pressure and flow rate is found approximately linear and a linear model on load characteristic is built.
(3) The system is uncontrollable due to the derivative elements, and through the model-based feedback, the system can be transformed to a type 0 system. Further more, the steady-state error can be reduced and the disturbance resisting capacity can be enhanced by closed-loop control of load pressure with integral compensation. The linearization and large variation of flow rate have negligible effect on the low frequency control. In addition, high melt viscosity leads to large oscillation and instability.
(4) Based on the feed-forward compensation for the water hydraulic proportional pressure relief valve, the experimental results show that the max steady-state error of slope injection pressure and maintaining pressure are separately 5.8% and 0.7%. The developed linear controller meets the requirements of water injection pressure control.
(5) Pressure impact and overshoot occur on switch of on-off directional valve. The pressure oscillation caused by switch of directional valve can be suppressed through increasing the flow resistance at the inlet of the accumulator or replacing by a new directional valve with gentle open process.
References
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