AIR SAMPLER WITH CLOSED LOOP FLOW CONTROL SYSTEM

摘要

A battery powered, personal air sampler is described which uses a closed loop control circuit to adjust the power that is delivered to an internal pump such that a stable and accurate flow rate is maintained independent of changes in inlet pressure due to filter loading. Furthermore, the described personal air sampler provides improved efficiency to the entire electronic and flow pumping system which, in turn functions to optimize the available battery run time of the device.

主权项

1. A personal air sampler, comprising:
a housing having an air flow passage defined between an air inlet and an air outlet; a pump disposed in the air flow passage for moving air through the air flow passage at an air flow rate; a pressure sensing sub-system for generating a signal indicative of the air flow rate; a coreless DC motor for driving the pump; a battery for providing a voltage to the DC coreless motor; a regulator sub-system, having a switch and an inductor, electrically coupled to and disposed between the battery and the coreless DC motor; a processing device coupled to the regulator sub-system; and a memory associated with the processing device having stored therein a look-up table for use in implementing a proportional-integrated-derivative closed loop air flow control process; wherein the processing device switches on and off the switch of the regulator sub-system as a function of the signal indicative of the air flow rate and data contained within the look-up table to thereby adjust the voltage that is provided from the battery to the coreless DC motor via the inductor in accordance with the proportional-integrated-derivative closed loop air flow control process whereupon a driving of the pump by the coreless DC motor is controlled for the purpose of having the air flow rate attain a target set point level.