PARTICULATE DETECTION SYSTEM

摘要

A particulate detection system (1) for detecting the quantity of particulates S in a gas under measurement EG includes first heater energization means S2 to S3, current convergence determination means S4 to S5, S7 to S8, second heater energization means S6, and detection start means S10. S2 to S3 performs low-temperature energization of heater (78) for a predetermined period after operation of ion source (11) is started by ion source drive circuit (210) such that gaseous discharge current Id becomes equal to a predetermined target current It. S4 to S5, S7 to S8 determines, after elapse of the predetermined period, whether or not Id has converged to an allowable range IR. When S4 to S5 determines that Id has not yet converged, S6 performs high-temperature energization of the heater (78) until Id converges. Then, S10 starts detection of particulates S using signal Is detected by a detection circuit (230).

主权项

1. A particulate detection system for detecting the quantity of particulates contained in a gas under measurement flowing through a gas flow pipe, comprising:
a detection section attached to the gas flow pipe; a drive circuit for driving the detection section; and a control section for controlling the drive circuit and detecting the quantity of the particulates, wherein the detection section includes an ion source for generating ions by means of gaseous discharge, a particulate electrification section for mixing a portion of the gas under measurement with the ions to thereby produce electrified particulates which originate from the particulates within the gas under measurement and which carry the ions adhering thereto, and a heater for heating the ion source; the drive circuit includes an ion source drive circuit for performing constant current control such that the gaseous discharge current supplied to the ion source becomes equal to a predetermined target current, and a heater energization circuit for energizing the heater; and the control section includes a detection circuit for detecting a signal corresponding to the quantity of the electrified particulates, first heater energization means for causing the heater energization circuit to perform low-temperature energization for a predetermined period after operation of the ion source by the ion source drive circuit has been started, to thereby increase the temperature of the heater to a heater temperature at which water adhering to the ion source is removed, current convergence determination means for determining, after elapse of the predetermined period, whether or not the gaseous discharge current supplied from the ion source drive circuit has converged to a predetermined allowable range including the target current, second heater energization means, operable when the current convergence determination means determines that the gaseous discharge current has not yet converged, for causing the heater energization circuit to perform high-temperature energization until the gaseous discharge current converges to the predetermined allowable range, to thereby increase the temperature of the heater to a heater temperature at which a foreign substance which adheres to the ion source and cannot be removed by the low-temperature energization is removed, and detection start means for starting detection of the quantity of the particulates through use of the signal after the gaseous discharge current has converged to the allowable range.