PARTICULATE MEASUREMENT SYSTEM

摘要

A particulate measurement system (10) includes an auxiliary electrode current measurement circuit (780), which can determine whether or not an auxiliary electrode current In has flowed to a second wiring line (222) as well as its magnitude. When a particulate sensor (100) is operating normally, since a second electrode (132) and a casing CS are electrically insulated from each other, no current flows to the second wiring line (222). However, when the second electrode (132) and the casing CS are electrically shorted by soot or the like, the auxiliary electrode current Iir flows to the second wiring line (222). Therefore, by providing the auxiliary electrode current measurement circuit (780), the particulate measurement system (10) can determine the state of adhesion of particulates, etc., in the particulate sensor (100), and can determine whether or not the particulate measurement system (10) is in an anomalous state.

主权项

1. A particulate measurement system which comprises a particulate sensor for detecting particulates and a sensor drive section for driving the particulate sensor and which measures the amount of particulates contained in a gas under measurement,
wherein the particulate sensor comprises: an ion generation section for generating ions by means of corona discharge; an electrification chamber for electrifying at least a portion of the particulates contained in the gas under measurement using the ions generated in the ion generation section; a trapping section for trapping at least a portion of the ions generated by the ion generation section but not used for electrifying the particulates; and an auxiliary electrode section including an auxiliary electrode maintained at a potential which repulses the unused ions and which assists in the trapping of the unused ions at the trapping section, wherein the sensor drive section comprises: an isolation transformer for corona discharge which has a primary-side coil and a secondary-side coil and which performs voltage conversion for electric power used for generating the corona discharge, the secondary-side coil of the isolation transformer for corona discharge being connected to the ion generation section, a reference potential of the primary-side coil of the isolation transformer for corona discharge being defined as a primary-side reference potential, and a reference potential of the secondary-side coil of the isolation transformer for corona discharge being defined as a secondary-side reference potential; an isolation transformer for the auxiliary electrode which has a primary-side coil and a secondary-side coil and which performs voltage conversion for generating an auxiliary voltage to be applied to the auxiliary electrode, the secondary-side coil of the isolation transformer for the auxiliary electrode being connected to the auxiliary electrode section; and a corona discharge control section which detects current flowing from the trapping section to the secondary-side reference potential and which controls the amount of electric power supplied from the isolation transformer for corona discharge to the ion generation section based on the detected current such that the amount of ions generated by the ion generation section approaches a target value set in advance, wherein the sensor drive section further comprises an auxiliary electrode current detection section which detects auxiliary electrode current flowing to a voltage application path for connecting the secondary-side coil of the isolation transformer for the auxiliary electrode to the auxiliary electrode section.