FLAME SENSOR CONTROL CIRCUIT

• US 3,727,073 A
• Filed: 08/02/1971
• Issued: 04/10/1973
• Est. Priority Date: 02/27/1970
• Status: Expired due to Term

• Current Assignee: Allen-Bradley Company (Rockwell Automation, Inc.)
• Original Assignee: Philip J. Cade
• Inventors: Cade, Philip J.
• Primary Examiner(s): Schaefer, Robert K.
• Assistant Examiner(s): Smith, William J.
• Application Number:
  US05/168,074
• Time in Patent Office: 617 Days
• Field of Search: 317/132 307/116,117,141 340/227
• US Class Current: 307/117
• CPC Class Codes: F23N 2227/12 Burner simulation or checking
• CPC Class Codes: F23N 2227/22 Pilot burners
• CPC Class Codes: F23N 2227/30 for pilot burners
• CPC Class Codes: F23N 2229/00 Flame sensors
• CPC Class Codes: F23N 2231/20 Warning devices
• CPC Class Codes: F23N 2233/06 at the air intake
• CPC Class Codes: F23N 5/12 using ionisation-sensitive elements, i.e. flame rods
• CPC Class Codes: F23N 5/123 using electronic means
• CPC Class Codes: F23N 5/203 using electronic means

Abstract

Control apparatus featuring a condition sensor, a first relay responsive to a signal from the condition sensor, the first relay being in a first state in the absence of a signal from the condition sensor and being switched to a second state in response to a signal from the condition sensor, a control relay adapted to be switched between first and second states, circuitry responsive to an operation request for switching the control relay from the first state to the second state after a time interval, and clamping circuitry operative in response to the detection of the first relay in its second state during the time interval to clamp the first relay in the second state and the control relay in the first state, overriding the influence of the condition sensor on the first relay.

Claims

1. Control apparatus for a burner comprising a flame sensor, a first relay responsive to a signal from said flame sensor, said first relay being in a first state in the absence of a signal from said flame sensor and being switched to a second state in response to a signal from said flame sensor, a control relay adapted to be switched between first and second states, time interval providing circuitry responsive to an operation request for switching said control relay from said first state to said second state after a time interval, and clamping circuitry responsive to the detection of said first relay in its second state during said time interval to clamp said first relay in said second state and said control relay in said first state, overriding the influence of said flame sensor on said first relay.

2. The control apparatus of claim 1 wherein said control relay includes an operating coil connected in series with a normally open contact of said control relay across a power source, and further including a normally open contact controlled by said first relay connected in series between said control relay coil and the input to said first relay.