Particulate detection system

Patent metadata

Field	Value
Publication number	US-10690571-B2
Application number	US-201715814796-A
Country	US
Kind code	B2
Filing date	Nov 16, 2017
Priority date	Nov 18, 2016
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

A particulate detection system ( 10, 1010 ) includes a sensor section ( 100 ) and a sensor drive section ( 300 ). A flow EIF of a measurement target gas EI passes through the sensor section, and an amount M of particulates S is detected. The sensor section ( 100 ) includes an ion applying section ( 100 e ) which generates ions CP, discharges ion-adhering electrified particulates SC, and collects unadhered ions CPF. The sensor drive section includes a sensor current value obtainment section ( 530 ) for obtaining a sensor current value Ss corresponding to the amount QH of flowed out charge, a flow velocity obtainment section ( 510 ) for obtaining, the flow velocity Vg of the external gas flow, and a particulate amount obtainment section ( 550, 1550 ) for obtaining the amount M of particulates S. The influence of flow velocity Vg is mitigated using the sensor current value Ss and the flow velocity Vg.

First claim

What is claimed is:

1. A particulate detection system comprising:
a sensor section; and
a sensor drive section for driving the sensor section,
the particulate detection system being configured to utilize an external gas flow which is a flow of external gas flowing outside the sensor section to thereby produce a measurement target gas flow inside the sensor section, the measurement target gas flow being a flow of a measurement target gas which is a portion of the external gas and passing through the interior of the sensor section, and to detect an amount M of particulates contained in the measurement target gas, wherein
the sensor section includes an ion applying section which generates ions originating from the measurement target gas by means of discharge, causes the ions to adhere to the particulates contained in the measurement target gas to thereby produce electrified particulates, discharges the electrified particulates to the outside of the sensor section together with the measurement target gas, and collects at least a portion of unadhered ions which are some of the ions and have failed to adhere to the particulates to thereby restrain the discharge of the unadhered ions to the outside of the sensor section;
the sensor drive section includes:
a sensor current value obtainment section for obtaining a sensor current value Ss which corresponds to an amount of charge flowed out due to the discharge of the electrified particulates to the outside of the sensor section,
a flow velocity obtainment section for obtaining, from the outside, a flow velocity Vg of the external gas flow, and
a particulate amount obtainment section for obtaining the amount M of the particulates while mitigating an influence of the flow velocity Vg by using the sensor current value Ss and the flow velocity Vg of the external gas flow; and

when obtaining the amount M of the particulates from the sensor current value Ss, the particulate amount obtainment section obtains the amount M of the particulates by using an offset current value Sf(Vg) and a gain G(Vg) which change with the flow velocity Vg.

2. A particulate detection system according to claim 1 , wherein the particulate amount obtainment section obtains the amount M of the particulates by dividing, by the gain G(Vg), a value obtained by subtracting from the sensor current value Ss the offset current value Sf(Vg) which changes with the flow velocity Vg of the external gas flow.

3. A particulate detection system according to claim 1 , wherein
the amount M of particulates is a volumetric particulate amount having units of an amount of particulates per unit volume.

4. A particulate detection system comprising:
a sensor section; and
a sensor drive section for driving the sensor section, the particulate detection system being configured to utilize an external gas flow
which is a flow of external gas flowing outside the sensor section to thereby produce a measurement target gas flow inside the sensor section, the measurement target gas flow being a flow of a measurement target gas which is a portion of the external gas and passing through the interior of the sensor section, and to detect an amount M of particulates contained in the measurement target gas, wherein
the sensor section includes an ion applying section which generates ions originating from the measurement target gas by means of discharge, causes the ions to adhere to the particulates contained in the measurement target gas to thereby produce electrified particulates, discharges the electrified particulates to the outside of the sensor section together with the measurement target gas, and collects at least a portion of unadhered ions which are some of the ions and have failed to adhere to the particulates to thereby restrain the discharge of the unadhered ions to the outside of the sensor section;
the sensor drive section includes:
a sensor current value obtainment section for obtaining a sensor current value Ss which corresponds to an amount of charge flowed out due to the discharge of the electrified particulates to the outside of the sensor section,
a flow velocity obtainment section for obtaining, from the outside, a flow velocity Vg of the external gas flow,
a particulate amount obtainment section for obtaining the amount M of the particulates, and
a gas temperature obtainment section for obtaining, from the outside, a temperature of the external gas as a gas temperature Tg;

the particulate amount obtainment section obtains the amount M of the particulates contained in the measurement target gas while mitigating influences of the flow velocity Vg and the gas temperature Tg by using the gas temperature Tg of the external gas in addition to the sensor current value Ss and the flow velocity Vg of the external gas flow; and
when obtaining the amount M of the particulates from the sensor current value Ss, the particulate amount obtainment section obtains the amount M of the particulates by using an offset current value Sf(Vg, Tg) and a gain G(Vg, Tg) which change with the flow velocity Vg and the gas temperature Tg.

5. A particulate detection system according to claim 4 , wherein the particulate amount obtainment section obtains the amount M of the particulates by dividing, by the gain G(Vg, Tg), a value obtained by subtracting from the sensor current value Ss the offset current value Sf(Vg, Tg) which changes with the flow velocity Vg of the external gas flow and the gas temperature Tg.

6. A particulate detection system according to claim 5 , wherein
the offset current value Sf(Vg, Tg) is determined by the following expression (B), and the gain G(Vg, Tg) is determined by the following expression (C):

Sf
⁡

(

Vg
,
Tg

)

=

Sfv
⁡

(
Vg
)

·

Sft
⁡

(
Tg
)

/

Sft
⁡

(
Tgr
)

(
B
)

G
⁡

(

Vg
,
Tg

)

=

Gr

Assignees

• Ngk Spark Plug Co

Inventors

• Murase Hirokazu
• Sugiyama Takeshi

Classifications

• Y02T10/40

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• Y02T10/12

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• F01N2900/1411

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• G01M15/048

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• F01N11/00

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