Particulate matter detection sensor and particulate matter detection apparatus

Patent metadata

Field	Value
Publication number	US-2020018679-A1
Application number	US-201716340231-A
Country	US
Kind code	A1
Filing date	Oct 5, 2017
Priority date	Oct 12, 2016
Publication date	Jan 16, 2020
Grant date	—

Abstract

A detection conductive section and a monitor conductive section made of a conductive material having a higher electrical resistivity than that of PM are included. A deposition surface on which the PM is deposited is provided to the detection conductive section. A pair of detection electrodes are provided to the deposition surface. A pair of monitor electrodes are provided to the monitor conductive section. The configuration is made such that no PM is deposited on the monitor conductive section between the pair of monitor electrodes.

First claim

1 . A particulate matter detection sensor for detecting an amount of particulate matter contained in exhaust gas, the particulate matter detection sensor comprising:
a particulate matter detection section; and a resistance monitor section, wherein the particulate matter detection section includes a detection conductive section and a pair of detection electrodes, the detection conductive section is made of a conductive material having a higher electrical resistivity than that of the particulate matter and has a surface on which a deposition surface is provided, the particulate matter being deposited on the deposition surface, the pair of detection electrodes are provided to the detection conductive section and face each other across the deposition surface, the particulate matter detection section is configured such that an electrical resistance between the pair of detection electrodes is changed according to the amount of the particulate matter deposited on the deposition surface, the resistance monitor section includes a monitor conductive section and a pair of monitor electrodes, the monitor conductive section is made of the conductive material and is arranged at a position adjacent to the detection conductive section, the pair of monitor electrodes are provided to the monitor conductive section, and the resistance monitor section is configured such that no particulate matter is deposited on the monitor conductive section between the pair of monitor electrodes.

2 . The particulate matter detection sensor according to claim 1 , wherein
the detection conductive section is integrated with the monitor conductive section to constitute a single conductive plate section, the conductive plate section is supported by a substrate section, the monitor conductive section is a portion of the conductive plate section on a side closer to the substrate section in a plate thickness direction of the conductive plate section, the detection conductive section is a portion of the conductive plate section on a side opposite to the monitor conductive section, the monitor electrodes are provided to a principal surface of the conductive plate section, the principal surface being in contact with the substrate section, and the deposition surface is provided to a principal surface of the conductive plate section, the principal surface being opposite to the principal surface.

3 . The particulate matter detection sensor according to claim 2 , wherein
in a state in which the deposition surface is covered with the particulate matter, an interval between the monitor electrode and the detection electrode in the plate thickness direction is determined so that a ratio I b /I S of an electric current I b and an electric current I S is 0.02 or less, the electric current I b flowing between the pair of monitor electrodes, the electric current I S flowing between the pair of detection electrodes.

4 . The particulate matter detection sensor according to claim 1 , wherein
the detection conductive section is separated from the monitor conductive section, the detection conductive section and the monitor conductive section each have a plate shape and are supported by the substrate section, the monitor electrodes are provided to a principal surface of the monitor conductive section, the principal surface being opposite to a principal surface of the monitor conductive section in contact with the substrate section, and surfaces of the monitor conductive section and the monitor electrodes are covered with an insulating film.

5 . The particulate matter detection sensor according to claim 1 , wherein
a surface of the monitor conductive section is covered with a gas permeable insulating film, and the gas permeable insulating film prevents the particulate matter from passing through and allows a gas component contained in the exhaust gas to pass through.

6 . The particulate matter detection sensor according to claim 5 , wherein
the gas permeable insulating film is made of a porous material having a plurality of communication holes through which the gas component passes.

7 . The particulate matter detection sensor according to claim 5 , wherein
the gas permeable insulating film is made of a solid electrolyte that ionizes the gas component and allows the gas component to path through.

8 . The particulate matter detection sensor according to claim 2 , wherein
a heater is provided in the substrate section, and the heater burns the particulate matter deposited on the deposition surface.

9 . The particulate matter detection sensor according to claim 1 , wherein
the detection conductive section is integrated with the monitor conductive section to constitute a single conductive plate section, a heater is provided in the conductive plate section, and the heater burns the particulate matter deposited on the deposition surface.

10 . The particulate matter detection sensor according to claim 1 , wherein
the conductive material is used to form the detection conductive section and the monitor conductive section, and when a sample including a plate-shaped substrate and a pair of measurement electrodes is prepared, and an electrical resistance R between the pair of measurement electrodes is measured to calculate a surface electrical resistivity ρ expressed by the following equation, the surface electrical resistivity ρ is in a range of 1.0×10 7 to 1.0×10 10 Ω·cm at a temperature range of 100 to 500° C., the plate-shaped substrate being made of the conductive material and having a thickness T of 1.4 mm, the pair of measurement electrodes being provided to a main surface of the plate-shaped substrate, the pair of measurement electrodes having a length of L and being provided at an interval of D.
ρ=R×L×T/D

11 . The particulate matter detection sensor according to claim 1 , wherein
the conductive material is ceramic having a molecular formula of ABO 3 and having a perovskite structure, where A is at least one selected from La, Sr, Ca, and Mg, and B is at least one selected from Ti, Al, Zr, and Y.

12 . The particulate matter detection sensor according to claim 11 , wherein
A contains Sr as a main component and La as an accessory component, and B is Ti.

13 . A particulate matter detection apparatus comprising:
the particulate matter detection sensor according to claim 1 ; and a control section connected to the particulate matter detection sensor, wherein the control section includes a main measurement section, a compensation measurement section, and a deposition amount calculation section, the main measurement section measures a particulate matter detection resistance which is an electrical resistance between the pair of detection electrodes, the compensation measurement section measures a compensation resistance which is an electrical resistance between the pair of monitor electrodes, and the deposition amount calculation section compensates for a change, according to a temperature, in electrical resistance of the detection conductive section between the pair of detection electrodes by using a measured value of the compensation resistance, and calculates an amount of the particulate matter deposited on the deposition surface.

14 . The particulate matter detection apparatus according to claim 13 , wherein
an interval W a between the pair of detection electrodes is equal to an interval W b between the pair of monitor electrodes.

15 . The particulate matter detection apparatus according to claim 13 , wherein
an interval W a between the pair of detection electrodes differs from an interval W b bet

Assignees

• Denso Corp

Inventors

• Koike Kazuhiko
• Yamamoto Masahiro
• Moritsugu Michiyasu
• Takizawa Kensuke

Classifications

• G01N1/2252

  in a vehicle exhaust · CPC title

• F01N2560/05

  the means being a particulate sensor · CPC title

• F01N2560/20

  Sensor having heating means · CPC title

• G01N15/0656 Primary

  using electric, e.g. electrostatic methods or magnetic methods (by investigating individual particles G01N15/1031, G01N15/12) · CPC title

• F01N13/008

  Mounting or arrangement of exhaust sensors in or on exhaust apparatus (sensor arrangements for engine control F02D41/1439) · CPC title