Particulate matter detection apparatus

Patent metadata

Field	Value
Publication number	US-2019293541-A1
Application number	US-201916439983-A
Country	US
Kind code	A1
Filing date	Jun 13, 2019
Priority date	Dec 15, 2016
Publication date	Sep 26, 2019
Grant date	—

Abstract

A particulate matter detection apparatus includes a sensor unit and a sensor control unit. The sensor unit outputs a single based on an amount of particulate matter. The sensor control unit detects a particle count of the particulate matter. The sensor control unit applies a first voltage to a pair of electrodes and electrostatically collects the particulate matter. After changing the applied voltage to a second voltage that differs from the first voltage in a state in which the sensor output at the first voltage has reached a threshold, the sensor control unit detects a resistance value between the pair of electrodes, and calculates the particle count using an average particle diameter of the particulate matter that is estimated from the resistance value and a mass of the particulate matter that is estimated from the sensor output.

First claim

What is claimed is:

1 . A particulate matter detection apparatus that detects particulate matter contained in a gas to be measured, the particulate matter detection apparatus comprising:
a sensor unit that includes a detecting unit in which a pair of electrodes that are separated from each other are arranged on a surface of a substrate that is exposed to the gas to be measured, and outputs a signal based on an amount of particulate matter that is electrostatically collected in the detecting unit; and a sensor control unit that detects a particle count of the particulate matter that is electrostatically collected in the detecting unit, based on a sensor output that is transmitted from the sensor unit, wherein the sensor control unit includes
a collection control unit that applies a first voltage between the pair of electrodes of the detecting unit and electrostatically collects the particulate matter in the detecting unit, and
a particle count calculating unit that, after changing the applied voltage between the pair of electrodes to a second voltage that differs from the first voltage in a state in which the sensor output at the first voltage has reached a threshold, detects a resistance value between the pair of electrodes, and calculates the particle count using an average particle diameter of the particulate matter that is estimated from the resistance value and a mass of the particulate matter that is estimated from the sensor output.

2 . The particulate matter detection apparatus according to claim 1 , wherein:
the particle count calculating unit includes
a voltage control unit that, after changing the applied voltage between the pair of electrodes to the second voltage for changing a collection state of the particulate matter when the sensor output at the first voltage for electrostatic collection reaches the threshold, controls the applied voltage to a detection voltage that is a voltage that is the same as or differs from the second voltage and is for inter-electrode resistance detection; and
an inter-electrode resistance detecting unit that detects the resistance value between the pair of electrodes at the detection voltage.

3 . A particulate matter detection apparatus that detects particulate matter contained in a gas to be measured, the particulate matter detection apparatus comprising:
a sensor unit that includes a detecting unit in which a pair of electrodes that are separated from each other are arranged on a surface of a substrate that is exposed to the gas to be measured, and outputs a signal based on an amount of particulate matter that is electrostatically collected in the detecting unit; and a sensor control unit that detects a particle count of the particulate matter that is electrostatically collected in the detecting unit, based on a sensor output that is transmitted from the sensor unit, wherein the sensor control unit includes
a collection control unit that applies a first voltage between the pair of electrodes of the detecting unit and electrostatically collects the particulate matter in the detecting unit, and
a particle count calculating unit that, after changing the applied voltage between the pair of electrodes to a second voltage that differs from the first voltage in a state in which the sensor output at the first voltage has reached a threshold, detects resistance values between the pair of electrodes at a plurality of voltages of which the magnitude differs, and calculates the particle count using an average particle diameter of the particulate matter that is estimated from the resistance values and a mass of the particulate matter that is estimated from the sensor output.

4 . The particulate matter detection apparatus according to claim 3 , wherein:
the particle count calculating unit includes
a voltage control unit that, after changing the applied voltage between the pair of electrodes to the second voltage for changing a collection state of the particulate matter when the sensor output at the first voltage for electrostatic collection reaches the threshold, successively controls the applied voltage to the plurality of voltages that serve as a detection voltage for inter-electrode resistance detection; and
an inter-electrode resistance detecting unit that detects the respective resistance values between the pair of electrodes at the plurality of voltages.

5 . The particulate matter detection apparatus according to claim 3 , wherein:
the particle count calculating unit performs weighting on the respective resistance values detected at the plurality of voltages and estimates the average particle diameter.

6 . A particulate matter detection apparatus that detects particulate matter contained in a gas to be measured, the particulate matter detection apparatus comprising:
a sensor unit that includes a detecting unit in which a pair of electrodes that are separated from each other are arranged on a surface of a substrate that is exposed to the gas to be measured, and outputs a signal based on an amount of particulate matter that is electrostatically collected in the detecting unit; and a sensor control unit that detects a particle count of the particulate matter that is electrostatically collected in the detecting unit, based on a sensor output that is transmitted from the sensor unit, wherein the sensor control unit includes
a collection control unit that applies a first voltage between the pair of electrodes of the detecting unit and electrostatically collects the particulate matter in the detecting unit, and
a particle count calculating unit that, after changing the applied voltage between the pair of electrodes to a second voltage that differs from the first voltage in a state in which the sensor output at the first voltage has reached a threshold, detects resistance values between the pair of electrodes at a plurality of voltages of which the magnitude differs, and calculates the particle count using an average particle diameter of the particulate matter that is estimated from an inclination in a relationship between the plurality of voltages and the resistance values, and a mass of the particulate matter that is estimated from the sensor output.

7 . The particulate matter detection apparatus according to claim 6 , wherein:
the particle count calculating unit includes:
a voltage control unit that, after changing the applied voltage between the pair of electrodes to the second voltage for changing a collection state of the particulate matter when the sensor output at the first voltage for electrostatic collection reaches the threshold, successively controls the applied voltage to the plurality of voltages that serve as a detection voltage for inter-electrode resistance detection; and
an inter-electrode resistance detecting unit that detects the respective resistance values between the pair of electrodes at the plurality of voltages, and an inclination calculating unit that calculates the inclination in the relationship between the plurality of voltages and the resistance values.

8 . The particulate matter detection apparatus according to claim 3 , wherein:
the plurality of voltages include a voltage of which the magnitude is the same as that of the second voltage.

9 . A particulate matter detection apparatus that detects particulate matter contained in a gas to be measured, the particulate matter detection apparatus comprising:
a sensor unit that includes a detecting unit in which a pair of electrodes that are separated from each other are arranged on a surface of a substrate that is exposed to the gas to be measured, and outputs a signal based on an amount of particulate matter that is electrostatically collected in the detecting unit; and a sensor contr

Assignees

• Denso Corp

Inventors

• Koike Kazuhiko
• Miyagawa Go

Classifications

• G01N15/0266

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