Methods for detecting particulates in a honeycomb filter

• US 8,225,684 B2
• Filed: 07/20/2011
• Issued: 07/24/2012
• Est. Priority Date: 03/24/2010
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Iwata, Yuichi, Ejiri, Tetsuya, Kondo, Jungo
• Primary Examiner(s): ROGERS, DAVID A
• Application Number:
  US13/187,068
• Publication Number:
  US 20110271740A1
• Time in Patent Office: 370 Days
• Field of Search: 738/658, 210/85, 210/90
• US Class Current: 73/865.8
• CPC Class Codes: B01D 2273/22 Making use of microwaves, e.g. for measurements
• CPC Class Codes: B01D 2279/30 for treatment of exhaust gases from IC Engines
• CPC Class Codes: B01D 46/0086 Filter condition indicators
• CPC Class Codes: B01D 46/2418 Honeycomb filters used for filtering exhaust gases of an internal combustion engine F01N3/022; ceramic honeycomb structures per se C04B38/0006
• CPC Class Codes: B01D 46/2498 The honeycomb filter being defined by mathematical relationships
• CPC Class Codes: B01D 46/442 by measuring the concentration of particles
• CPC Class Codes: F01N 2560/05 the means being a particulate sensor
• CPC Class Codes: F01N 2900/1606 Particle filter loading or soot amount
• CPC Class Codes: F01N 3/0222 the structure being monolithic, e.g. honeycombs
• CPC Class Codes: F01N 3/028 using microwaves
• CPC Class Codes: F01N 3/2013 using electric or magnetic heating means
• CPC Class Codes: F01N 9/002 of filter regeneration, e.g. detection of clogging
• CPC Class Codes: G01N 15/0618 of the filter type G01N15/0643 takes precedence
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A ceramic honeycomb filter including trapping holes forming lattices is used to detect particulates trapped in the filter. An electromagnetic wave is transmitted to the filter in a plane perpendicular to the longitudinal direction of the trapping hole. The electromagnetic wave after the electromagnetic wave passes through the filter is received and the particulates trapped in the filter are detected on the base of a received intensity of the electromagnetic wave. The electromagnetic wave has a frequency of 0.294 c/a or more and c/a or less (a represents a lattice spacing of said trapping holes and c represents the speed of light). The electromagnetic wave is irradiated to the filter wherein the particulates are not trapped and an inclined angle θ of the electromagnetic wave with respect to the lattices is changed so as to increase a received intensity of the electromagnetic wave.

Claims

1. A method of detecting particulates, the method using a ceramic honeycomb filter comprising trapping holes for trapping said particulates from a gas containing said particulates to detect said particulates trapped in said ceramic honeycomb filter, said trapping holes forming lattices, said method comprising:

transmitting an electromagnetic wave to said ceramic honeycomb filter in a plane perpendicular to the longitudinal direction of said trapping hole;

receiving said electromagnetic wave after said electromagnetic wave passes through said ceramic honeycomb filter;

detecting said particulates trapped in said filter based on a received intensity of said electromagnetic wave, wherein said electromagnetic wave has a frequency of greater than or equal to 0.294 c/a or less than or equal to 1 c/a (a represents a lattice spacing of said trapping holes and c represents the speed of light); and

irradiating said electromagnetic wave to said ceramic honeycomb filter wherein said particulates are not trapped and changing an inclined angle of said electromagnetic wave with respect to said lattices so that a received intensity of said electromagnetic wave is increased.

2. The method of claim 1, wherein said lattice spacing a is 0.5 mm or larger and 5 mm or smaller.

3. The method of claim 1, wherein said ceramic honeycomb filter comprises a material having a specific dielectric constant of 1.5 or higher and 10 or lower.

4. The method of claim 1, wherein said material of said ceramic honeycomb filter comprises cordierite, aluminum titanate or silicon carbide.

5. A method of detecting particulates, the method using a ceramic honeycomb filter comprising trapping holes for trapping said particulates from a gas containing said particulates to detect said particulates trapped in said ceramic honeycomb filter, said trapping holes forming square lattices each partitioned by opposing first and second walls and opposing third and fourth walls, said method comprising:

transmitting an electromagnetic wave to said ceramic honeycomb filter in a plane perpendicular to the longitudinal direction of said trapping hole;

receiving said electromagnetic wave after said electromagnetic wave passes through said filter; and

detecting said particulates trapped in said filter based on a received intensity of said electromagnetic wave,

wherein the following relationships are satisfied;

a/λ

≧

0.294;

a/λ

≦

0.294+4.9×

10<sup>−

3</sup>×

θ

; and

a/λ

≦

0.735−

4.9×

10<sup>−

3</sup>×

θ

(a represents a lattice spacing of said trapping holes, λ

represents a wavelength of said electromagnetic wave, and θ

represents an inclined angle of said electromagnetic wave with respect to an axis perpendicular to said first and second walls).

6. The method of claim 5, wherein said ceramic honeycomb filter comprises a material having a specific dielectric constant of 1.5 or higher and 10 or lower.

7. The method of claim 5, wherein said material of said ceramic honeycomb filter comprises cordierite, aluminum titanate or silicon carbide.

8. A method of detecting particulates, the method using a ceramic honeycomb filter comprising trapping holes for trapping said particulates from a gas containing said particulates to detect said particulates trapped in said ceramic honeycomb filter, said trapping holes forming square lattices each partitioned by opposing first and second walls and opposing third and fourth walls, said method comprising:

transmitting an electromagnetic wave to said ceramic honeycomb filter in a plane perpendicular to the longitudinal direction of said trapping hole;

receiving said electromagnetic wave after said electromagnetic wave passes through said filter; and

detecting said particulates trapped in said filter based on a received intensity of said electromagnetic wave,

wherein the following relationships are satisfied;

0.441+4.9×

10<sup>−

3</sup>×

θ

≦

a/λ

≦

0.735−

4.9×

10<sup>−

3</sup>×

θ

; and

0°

≦

Θ

≦

30°

(a represents a lattice spacing of said trapping holes, λ

represents a wavelength of said electromagnetic wave, and θ

represents an inclined angle of said electromagnetic wave with respect to an axis perpendicular to said first and second walls).

9. The method of claim 8, wherein said ceramic honeycomb filter comprises a material having a specific dielectric constant of 1.5 or higher and 10 or lower.

10. The method of claim 8, wherein said material of said ceramic honeycomb filter comprises cordierite, aluminum titanate or silicon carbide.

11. A method of detecting particulates, the method using a ceramic honeycomb filter comprising trapping holes for trapping said particulates from a gas containing said particulates to detect said particulates trapped in said ceramic honeycomb filter, said trapping holes forming square lattices each partitioned by opposing first and second walls and opposing third and fourth walls, said method comprising:

transmitting an electromagnetic wave to said ceramic honeycomb filter in a plane perpendicular to the longitudinal direction of said trapping hole;

receiving said electromagnetic wave after said electromagnetic wave passes through said ceramic honeycomb filter; and

detecting said particulates trapped in said filter based on a received intensity of said electromagnetic wave,

wherein the following relationships are satisfied;

0.882−

4.9×

10<sup>−

3</sup>×

θ

≦

a/λ

≦

0.294+4.9×

10<sup>−

3</sup>×

θ

; and

60°

≦

Θ

≦

90°

(a represents a lattice spacing of said trapping holes, λ

represents a wavelength of said electromagnetic wave, and θ

represents an inclined angle of said electromagnetic wave with respect to an axis perpendicular to said first and second walls).

12. The method of claim 11, wherein said ceramic honeycomb filter comprises a material having a specific dielectric constant of 1.5 or higher and 10 or lower.

13. The method of claim 11, wherein said material of said ceramic honeycomb filter comprises cordierite, aluminum titanate or silicon carbide.

14. A method of detecting particulates, the method using a ceramic honeycomb filter comprising trapping holes for trapping said particulates from a gas containing said particulates to detect said particulates trapped in said ceramic honeycomb filter, said trapping holes forming square lattices each partitioned by opposing first and second walls and opposing third and fourth walls, said method comprising:

transmitting an electromagnetic wave to said ceramic honeycomb filter in a plane perpendicular to the longitudinal direction of said trapping hole;

receiving said electromagnetic wave after said electromagnetic wave passes through said ceramic honeycomb filter; and

detecting said particulates trapped in said filter based on a received intensity of said electromagnetic wave,

wherein the following relationships are satisfied;

0.782−

4.9×

10<sup>−

3</sup>×

θ

≦

a/λ

≦

0.882−

4.9×

10<sup>−

3</sup>×

θ

; and

10°

≦

θ

≦

30°

(a represents a lattice spacing of said trapping holes, λ

represents a wavelength of said electromagnetic wave, and θ

represents an inclined angle of said electromagnetic wave with respect to an axis perpendicular to said first and second walls).

15. The method of claim 14, wherein said ceramic honeycomb filter comprises a material having a specific dielectric constant of 1.5 or higher and 10 or lower.

16. The method of claim 14, wherein said material of said ceramic honeycomb filter comprises cordierite, aluminum titanate or silicon carbide.

17. A method of detecting particulates, the method using a ceramic honeycomb filter comprising trapping holes for trapping said particulates from a gas containing said particulates to detect said particulates trapped in said ceramic honeycomb filter, said trapping holes forming square lattices each partitioned by opposing first and second walls and opposing third and fourth walls, said method comprising:

transmitting an electromagnetic wave to said ceramic honeycomb filter in a plane perpendicular to the longitudinal direction of said trapping hole;

receiving said electromagnetic wave after said electromagnetic wave passes through said ceramic honeycomb filter; and

detecting said particulates trapped in said filter based on a received intensity of said electromagnetic wave,

wherein the following relationships are satisfied;

0.343+4.9×

10<sup>−

3</sup>×

θ

≦

a/λ

≦

0.441+4.9×

10<sup>−

3</sup>×

θ

; and

60°

≦

θ

≦

80°

(a represents a lattice spacing of said trapping holes, λ

represents a wavelength of said electromagnetic wave, and θ

represents an inclined angle of said electromagnetic wave with respect to an axis perpendicular to said first and second walls).

18. The method of claim 17, wherein said ceramic honeycomb filter comprises a material having a specific dielectric constant of 1.5 or higher and 10 or lower.

19. The method of claim 17, wherein said material of said ceramic honeycomb filter comprises cordierite, aluminum titanate or silicon carbide.

20. A method of detecting particulates, the method using a ceramic honeycomb filter comprising trapping holes for trapping said particulates from a gas containing said particulates to detect said particulates trapped in said ceramic honeycomb filter, said trapping holes forming square lattices each partitioned by opposing first and second walls and opposing third and fourth walls, said method comprising:

transmitting an electromagnetic wave to said ceramic honeycomb filter in a plane perpendicular to the longitudinal direction of said trapping hole;

receiving said electromagnetic wave after said electromagnetic wave passes through said ceramic honeycomb filter; and

detecting said particulates trapped in said filter based on a received intensity of said electromagnetic wave,

wherein the following relationships are satisfied;

0.784≦

a/λ

≦

0.98; and

35°

≦

θ

≦

55°

(a represents a lattice spacing of said trapping holes, λ

represents a wavelength of said electromagnetic wave, and θ

represents an inclined angle of said electromagnetic wave with respect to an axis perpendicular to said first and second walls).

21. The method of claim 20, wherein said ceramic honeycomb filter comprises a material having a specific dielectric constant of 1.5 or higher and 10 or lower.

22. The method of claim 20, wherein said material of said ceramic honeycomb filter comprises cordierite, aluminum titanate or silicon carbide.