Detection of particle characteristics

• US 9,470,627 B2
• Filed: 08/24/2015
• Issued: 10/18/2016
• Est. Priority Date: 09/05/2008
• Status: Active Grant

• Current Assignee: Garrett Thermal Systems Ltd. (Honeywell International Inc.)
• Original Assignee: Xtralis Technologies Ltd (Honeywell International Inc.)
• Inventors: Alexander, Brian, Vayeda, Nitin, Ajay, Kemal
• Primary Examiner(s): PHAM, HOA Q
• Application Number:
  US14/833,785
• Publication Number:
  US 20160033400A1
• Time in Patent Office: 421 Days
• Field of Search: 356335-343, 356432-440, 250573-575
• US Class Current: 1/1
• CPC Class Codes: G01F 1/667 Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
• CPC Class Codes: G01N 15/06 Investigating concentration of particle suspensions by weighing G01N5/00; investigating sedimentation of particle suspensions G01N15/04; investigating individual particles G01N15/10
• CPC Class Codes: G01N 15/075 by optical means
• CPC Class Codes: G01N 15/1434 Optical arrangements
• CPC Class Codes: G01N 2021/4733 Discriminating different types of scatterers
• CPC Class Codes: G01N 21/53 within a flowing fluid, e.g. smoke
• CPC Class Codes: G01N 2201/061 Sources
• CPC Class Codes: G01N 2201/062 LED's
• CPC Class Codes: G08B 17/10 Actuation by presence of smoke or gases , e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
• CPC Class Codes: G08B 17/107 for detecting light-scattering due to smoke
• CPC Class Codes: G08B 17/113 Constructional details
• CPC Class Codes: G08B 29/26 by updating and storing reference thresholds

Abstract

A method of detecting particles in an air flow is described. The method includes receiving a signal indicative of light intensity scattered from the air flow at a plurality of wavelengths and processing the signal indicative of the intensity of received light at each of the wavelengths and a corresponding wavelength dependent parameter to generate an output signal indicative of at least one characteristic of particles in the air flow. A particle detection system is also described.

Claims

1. A particle detection system for including:

a detection chamber adapted to receive an air sample;

first particle detection means including a first light source for illuminating a first volume of the air sample at at least a first wavelength, and a first light receiver having a field of view intersecting with the first volume for receiving light scattered from the detection chamber and outputting a first signal indicative of the scattered received light;

second particle detection means including a second light source for illuminating a second volume of the air sample at at least a second wavelength, and a second light receiver having a field of view intersecting with the second volume for receiving light scattered from the detection chamber and outputting a second signal indicative of the scattered received light;

light source activation means adapted to selectively activate the first light source in a first time period and the second light source in a second time period; and

processing means adapted to receive a first signal from the first light receiver and a second signal from the second light receiver corresponding to the first time period and process the received signals to generate a first output corresponding to the first time period corrected for background light; and

to receive a first signal from the first light receiver and a second signal from the second light receiver corresponding to the second time period and process the received signals to generate a second output corresponding to the second time period that is corrected for background light.

2. The particle detection system as claimed in claim 1 wherein the detection chamber includes at least one wall within the field of view of each of the first and second light receivers and wherein the first and second light receivers are positioned such that substantially the same portion of said chamber wall lies within the field of view of each of the first and second light receivers.

3. The particle detection system as claimed in claim 1 wherein the first and second light receivers are positioned with respect to their corresponding first and second light sources such that the field of view of the first light receiver and the second volume do not intersect, and the field of view of the second light receiver and the first volume do not intersect.

4. The particle detection system as claimed in claim 1 wherein the first and second wavelengths are different wavelengths.

5. The particle detection system as claimed in claim 1 wherein the first output corresponding to the first time period is corrected for background light by a process including subtracting the second signal indicative of the scattered received light corresponding to the first time period from the first signal indicative of the scattered received light corresponding to the first time period.

6. The particle detection system as claimed in claim 1 wherein the second output corresponding to the second time period is corrected for background light by a process including subtracting the first signal indicative of the scattered received light corresponding to the second time period from the second signal indicative of the scattered received light corresponding to the second time period.

7. The particle detection system as claimed in claim 1 wherein the first and second wavelengths are the same wavelengths.