Particulate sampling system and method

• US 7,299,690 B2
• Filed: 04/26/2006
• Issued: 11/27/2007
• Est. Priority Date: 04/26/2006
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Graze, Russell Robert Jr.
• Primary Examiner(s): Lefkowitz; Edward
• Assistant Examiner(s): JENKINS, JERMAINE L
• Application Number:
  US11/411,088
• Publication Number:
  US 20070251307A1
• Time in Patent Office: 580 Days
• Field of Search: 73116-1181, 738/630.1, 738/630.3, 73/233.1
• US Class Current: 73/114.69
• CPC Class Codes: G01N 1/2252 in a vehicle exhaust
• CPC Class Codes: G01N 2001/2264 with dilution

Abstract

A method for controlling the flow through an exhaust sampling system includes sensing an operating characteristic of a power source, extracting a sample of an exhaust flow of the power source, combining the sample with an additional flow of fluid, and measuring a particulate level of the combined flow. A flow rate of the extracted sample is controlled to be substantially proportional to a flow rate of the exhaust flow based on a difference between the combined flow and the additional flow.

Claims

1. A method for controlling the flow through an exhaust sampling system, comprising:

sensing an operating characteristic of a power source;

extracting a sample of an exhaust flow of the power source;

combining the sample with an additional flow of fluid; and

measuring a particulate level of the combined flow, wherein a flow rate of the extracted sample is controlled to be substantially proportional to a flow rate of the exhaust flow based on a difference between the combined flow and the additional flow.

2. The method of claim 1, further including calibrating a dilute side of the exhaust sampling system to a total side of the exhaust sampling system.

3. The method of claim 1, wherein the operating characteristic includes at least one of an intake air mass flow of the power source, an exhaust mass flow of the power source, and a fuel mass flow.

4. The method of claim 1, wherein the additional flow includes a flow of treated ambient air.

5. The method of claim 1, wherein a flow rate of the combined flow is equal to the sum of a flow rate of the sample and a flow rate of the additional flow.

6. The method of claim 1, further including sensing a flow rate of the combined flow.

7. The method of claim 6, further including calculating an amount of exhaust to be extracted based on the sensed flow rate of the combined flow and the operating characteristic.

8. A method of controlling fluid flow through an exhaust sampling system connected to a power source, comprising:

controllably extracting a portion of an exhaust flow of the power source;

directing the portion through a dilution device; and

combining the portion with a treated flow of fluid, wherein a mass flow rate of the extracted portion is controlled to be substantially proportional to a mass flow rate of the exhaust flow of the power source based on a difference between a mass flow rate of the combined flow and a mass flow rate of the treated flow.

9. The method of claim 8, further including sensing an operating characteristic of the power source.

10. The method of claim 9, wherein the operating characteristic includes at least one of an intake air mass flow of the power source, an exhaust mass flow of the power source, and a fuel mass flow.

11. The method of claim 9, wherein the flow rate of the extracted portion is controlled based on at least one of the sensed operating characteristics.

12. The method of claim 11, wherein the at least one of the sensed operating characteristics includes the mass flow rate of the exhaust flow of the power source.

13. The method of claim 9, further including controlling the mass flow rate of the extracted portion in response to the sensed operating characteristic.

14. The method of claim 13, wherein the system is configured to modify the mass flow rate of the extracted portion in response to the sensed operating characteristic in 500 milliseconds or less.

15. The method of claim 9, wherein the mass flow rate of the extracted portion is substantially continuously controlled to be substantially proportional to the mass flow rate of the exhaust flow during a transient test cycle.

16. An exhaust sampling system, comprising:

a first flow sensor fluidly connected to a compressed air source and configured to sense a characteristic of a dilute flow;

a flow control valve fluidly connected to the first flow sensor and configured to controllably direct the dilute flow to a dilution device;

a second flow sensor fluidly connected downstream of the dilution device and configured to sense a characteristic of a combined flow; and

a controller configured to control a mass flow rate of a flow of exhaust gas extracted by a component of the dilution device based on a difference between the sensed characteristic of the dilute flow and the sensed characteristic of the combined flow.

17. The exhaust sampling system of claim 16, wherein the flow control valve is configured to substantially continuously control the dilute flow in response to the sensed characteristic of the dilute flow and the sensed characteristic of the combined flow.

18. The exhaust sampling system of claim 16, wherein the flow control valve is configured to respond to changes in the sensed characteristic of the dilute flow and the sensed characteristic of the combined flow in 500 milliseconds or less.

19. The exhaust sampling system of claim 16, further including a second flow control valve fluidly connected to the second flow sensor and configured to controllably direct the combined flow to the second flow sensor.

20. The exhaust sampling system of claim 16, wherein at least one of the first and second flow sensors comprises a laminar flow element.