Flame detector using saturable core control

Claim 2

In a flame monitoring system having a burner adapted to support a flame a. a saturable magnetic core having a substantially rectangular hysteresis loop characteristic provided with three windings; b. a temperature sensitive device adapted to be heated by the presence of said flame and to supply current to a first of said windings, when so heated, in a direction to saturate said core in a predetermined direction, constituting a first state; c. means to supply periodic pulses of current to a second of said windings in a direction to saturate said core in the opposite direction to that of said predetermined direction constituting a second state; d. the rate of change from one of said states to the other being of a magnitude to generate a substantial output voltage pulse in the third of said windings; e. whereby said output voltage pulses are indicative of the presence of said flames.

Claim 3

The system as in claim 1 in which means are provided which is responsive to said output voltage pulses to control the flow of fuel to said burner.

Claim 4

The system as in claim 1 in which said temperature sensitive device is adapted, when heated, to apply a comparatively low voltage to said first winding and said means is adapted to apply a comparatively high voltage to said second winding; whereby each output voltage pulse is generated only upon a shift from said first state to said second state.

Claim 5

The system as in claim 3 in which said temperature sensitive device is a thermocouple.

Claim 6

The system as in claim 1 in which said means comprises: a. a condenser b. means for charging said condenser through a high-impedance circuit in series with said second winding and for periodically discharging said condenser through said second winding through a low-impedance circuit.

Claim 7

The system as in claim 1 in which are provided: a. an alternating voltage source; b. a condenser; c. means for causing said condenser during successive half cycles of said source of a given polarity; d. means for causing said periodic pulses of current supplied to said second winding to occur during half cycles of said source of opposite polarity; whereby said output voltage pulses occur during said Half cycles of opposite polarity; e. and means responsive to each of said output voltage pulses to discharge said condenser during a half cycle of said opposite polarity; f. and means operative in response to the discharge of second condenser to control the flow of fuel to said burner.

Claim 8

In a flame monitoring system having a plurality of burners, each adapted to support a separate flame: a. a separate saturable magnetic core associated with each of said burners; b. each core having a substantially rectangular hysteresis loop characteristic provided with three windings; c. a separate temperature sensitive device associated with each burner and adapted to be heated by the presence of the flame of said burner and to supply current to a first of the windings of its corresponding core to saturate said core in a predetermined direction constituting a first state; d. means to supply simultaneously periodic pulses of current to a second of said windings in a direction to saturate the associated core in the opposite direction to said predetermined direction constituting a second state; e. the rate of change from one of said states to the other being of a magnitude to generate a substantial output voltage in the third of said windings of the associated core; f. means for selecting the number and combination of said burners to be supplied with fuel; g. means responsive to the operation of said last named means to connect to a fuel control device only those of said third windings which are associated with the selected burners; h. and a common fuel supply for all of said burners under the control of said fuel control device; i. whereby said system is responsive only to the presence or absence of flames at the selected burners.

Claim 9

In a flame monitoring system having a plurality of burners, each adapted to support a separate flame: a. a separate saturable magnetic core associated with each of said burners; b. each core having a substantially rectangular hysteresis loop characteristic provided with three windings; c. a separate temperature sensitive device associated with each burner and adapted to be heated by the presence of the flame of said burner and to supply current to a first of the windings of its corresponding core to saturate said core in a predetermined direction constituting a first state; d. means to supply simultaneously periodic pulses of current to a second of said windings in a direction to saturate the associated core in the opposite direction to said predetermined direction constituting a second state; e. the rate of change from one of said states to the other being of a magnitude to generate a substantial output voltage in the third of said windings of the associated core; f. means for selecting the number and combination of said burners to be supplied with fuel; g. means responsive to the operation of said last named means to connect to a fuel control device only those of said third windings which are associated with the selected burners; h. and a common fuel supply for all of said burners under the control of said fuel control device; i. whereby said system is responsive only to the presence or absence of flames at the selected burners.

Claim 10

A system as in claim 7 in which said last named means also connects the selected third windings in parallel with each other, whereby upon the occurences of an output voltage pulse in less than all of the selected third windings, the absence of a voltage pulse in the rest of the selected third windings prevents any of said output voltage pulses from actuating said fuel control device.

Claim 11

In a flame monitoring system having a burner adopted to support a flame; a. a saturable magnetic core having a substantially rectangular hysteresis loop characteristic provided with three windings; b. a temperature sensitive device adapted to be heated by the presence of said flame and to supply current to a first of said windings, when so heated, in a direction to saturate said core in a predetermined direction constituting a first state; c. means to supply current to a second of said windings in a direction to saturate said core in the opposite direction constituting a second state; d. the current supplied to at least one of said windings being in the form of periodic pulses and the rate of change from one of states to the other being of a magnitude to generate a substantial output voltage pulse in the third of said windings; e. whereby said output voltage pulses are indicative of the presence of said flame.

Claim 12

In a flame monitoring system having a burner adopted to support a flame; a. a saturable magnetic core having a substantially rectangular hysteresis loop characteristic provided with three windings; b. a temperature sensitive device adapted to be heated by the presence of said flame and to supply current to a first of said windings, when so heated, in a direction to saturate said core in a predetermined direction constituting a first state; c. means to supply current to a second of said windings in a direction to saturate said core in the opposite direction constituting a second state; d. the current supplied to at least one of said windings being in the form of periodic pulses and the rate of change from one of states to the other being of a magnitude to generate a substantial output voltage pulse in the third of said windings; e. whereby said output voltage pulses are indicative of the presence of said flame.