US Patent 10226917 Powder delivery systems and methods for additive manufacturing apparatus

A powder delivery system for use in an additive manufacturing device includes a powder control valve configured to selectively divert at least a portion of an input fluid flow to a return line while a remainder of the input flow is delivered to a delivery nozzle. In some embodiments, the powder delivery valve may be modulated to alter the percentage of input flow diverted to the return line. Alternatively, the powder delivery valve may be either fully open or closed. In each embodiment, the powder delivery valve permits rapid changes in the amount of powder delivered to the nozzle.