Flame detector with UV sensor

• US 7,244,946 B2
• Filed: 05/06/2005
• Issued: 07/17/2007
• Est. Priority Date: 05/07/2004
• Status: Expired due to Fees

• Current Assignee: Walter Kidde Portable Equipment Incorporated (Carrier Global Corporation)
• Original Assignee: Walter Kidde Portable Equipment Incorporated (Carrier Global Corporation)
• Inventors: Buchholz, Matthew J., Burnette, Stanley D., Mott, Kenneth J., Kwor, Richard
• Primary Examiner(s): Porta; David
• Assistant Examiner(s): TANINGCO, MARCUS H
• Application Number:
  US11/123,872
• Publication Number:
  US 20050247883A1
• Time in Patent Office: 802 Days
• Field of Search: 250/372
• US Class Current: 250/372
• CPC Class Codes: G01J 1/429 applied to measurement of ultraviolet light using counting tubes G01T
• CPC Class Codes: G01J 1/46 using a capacitor
• CPC Class Codes: G08B 17/12 Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions

Abstract

A flame detector system includes an ultraviolet sensor to detect ultraviolet radiation, and a microcontroller coupled to the ultraviolet sensor. The microcontroller processes output from the ultraviolet sensor to identify a flame. The system can also include a HV supply circuit to constantly refresh a drive voltage of the sensor. The microcontroller can sense when the sensor discharges and thereupon immediately refresh the sensor. The microcontroller can also monitor a run time for the sensor and adjust a drive voltage for the sensor accordingly. Further, a background count can be monitored to determine the health of the sensor. A memory can also be provided to store data associated with the detector, and a communications module can communicate the data stored in the memory to an external device. The microcontroller calculates a filtered event count and compares the filtered event count to a threshold to determine if a flame is present.

Claims

1. A flame detector system, comprising:

an ultraviolet sensor configured to detect ultraviolet radiation; and

a microcontroller coupled to the ultraviolet sensor, the microcontroller being configured to process output from the ultraviolet sensor to identify a flame;

wherein the microcontroller monitors a discharge event count for the ultraviolet sensor during a fixed window and calculates a filtered event count, and wherein the microcontroller compares the filtered event count to a threshold to determine if a flame is present; and

wherein the filtered event count is calculated according to the following equation;

filtered event count=((1−

Weighting Constant)×

FEC_previous)+(Weighting Constant×

Current Reading)

wherein;

the FEC_previous is a measure of previously accumulated discharge events from previous fixed windows; and

the Current Reading is a number of discharge events measured in a most recent fixed window.

2. The system of claim 1, wherein the Weighting Constant is between 0.1 and 0.3.

3. The system of claim 1, wherein the threshold is between 0.8 and 1.1.

4. The system of claim 1, wherein a duration of the fixed window is between 100 ms and 300 ms.

5. The system of claim 1, wherein the microcontroller initiates an alarm condition if the filtered event count exceeds the threshold.