Control system for a fuel burner

Claim 2

An electrically energizable control system for a fuel burner comprising: means for actuating a fuel valve to enAble flow of a combustible fuel to the burner; means for igniting the fuel emitted from the burner; a first controlled switching device; means for connecting the actuating means and the first controlled switching device to a source of electrical energy to effect energization of the actuating means when the first controlled switching device becomes conductive; a second controlled switching device coupled to the first controlled switching device for rendering the first controlled switching device nonconducting when the second controlled switching device has been nonconducting for a predetermined length of time; a third controlled switching device responsive to combustion of the fuel emitted from the burner for maintaining the second controlled switching device in its conducting state; and the first controlled switching device including a relay having normally open contacts in series with the actuating means and the source of electrical energy, and an actuating coil in series with the second controlled switching device.

Claim 3

A control system as set forth in claim 1, further comprising means responsive to an initial conducting state of the second switch and nonconducting state of the actuating coil for preventing the actuation of the relay.

Claim 4

In an electrically energizable control system for a fuel burner having a fuel valve opened on thermostatic demand and closed a predetermined time thereafter if fuel ignition fails; a spark igniter supply circuit comprising first and second gate controlled switches, first and second transformers, one winding of the first transformer being connected in series with the first gate controlled switch and another winding of the first transformer being coupled to the gate of the second gate controlled switch, and one winding of the second transformer being connected in series with the second gate controlled switch and another winding of the second transformer providing a spark source for igniting the fuel.

Claim 5

In an electrically energizable control system for a fuel burner having a fuel valve opened on thermostatic demand and closed a predetermined time thereafter if fuel ignition fails; a spark igniter supply circuit comprising first and second gate controlled switches, first and second transformers, one winding of the first transformer being connected in series with the first gate controlled switch and another winding of the first transformer being coupled to the gate of the second gate controlled switch, and one winding of the second transformer being connected in series with the second gate controlled switch and another winding of the second transformer providing a spark source for igniting the fuel.

Claim 6

The circuit as set forth in claim 3, further comprising means for providing a series of enabling signals to the gate of the first gate controlled switch, means for stopping the enabling signals a predetermined time after the enabling signals begin.

Claim 7

The circuit as set forth in claim 4, further comprising a timing circuit coupled to the gate of the first gate controlled switch to render it nonconducting at a time subsequent to the predetermined time after the enabling signals begin.

Claim 8

The circuit as set forth in claim 3, further comprising a relay having normally open contacts closable to open the fuel valve and having an actuating coil in series with the first gate controlled switch.

Claim 9

The circuit as set forth in claim 6, further comprising means responsive to an initial conducting state of the gate controlled switch and nonconducting state of the actuating coil for preventing actuation of the relay.

Claim 10

In an electrically energizable control system for a fuel burner where a fuel valve is opened on thermostatic demand and closed a predetermined time thereafter if fuel ignition fails; a flame detector circuit comprising a Darlington amplifier, means in circuit relation with the Darlington amplifier input for enabling it when impedance between the enabling means and a reference potential is below a predetermined impedance, the enabling means also being operable generally to disable the Darlington amplifier when impedance between the enabling means and the reference potential is above the predetermined impedance, a spark igniter supply circuit including first and second gate controlled switches, and first and second transformer means, one winding of the first transformer means being connected in series with the first gate controlled switch and another winding of the first transformer means being coupled to the gate of the second gate controlled switch, and one winding of the second transformer means being connected in series with the second gate controlled switch and another winding of thE second transformer means providing a spark source for igniting the fuel, the output of the Darlington amplifier being coupled to the gate of the first gate controlled switch to maintain it in a conducting state so long as the thermostat demands and a flame is present.

Claim 11

In an electrically energizable control system for a fuel burner where a fuel valve is opened on thermostatic demand and closed a predetermined time thereafter if fuel ignition fails; a flame detector circuit comprising a Darlington amplifier, means in circuit relation with the Darlington amplifier input for enabling it when impedance between the enabling means and a reference potential is below a predetermined impedance, the enabling means also being operable generally to disable the Darlington amplifier when impedance between the enabling means and the reference potential is above the predetermined impedance, a spark igniter supply circuit including first and second gate controlled switches, and first and second transformer means, one winding of the first transformer means being connected in series with the first gate controlled switch and another winding of the first transformer means being coupled to the gate of the second gate controlled switch, and one winding of the second transformer means being connected in series with the second gate controlled switch and another winding of thE second transformer means providing a spark source for igniting the fuel, the output of the Darlington amplifier being coupled to the gate of the first gate controlled switch to maintain it in a conducting state so long as the thermostat demands and a flame is present.

Claim 12

The circuit as set forth in claim 8, further comprising means for providing a series of enabling signals to the gate of the first gate controlled switch, means for stopping the enabling signals a predetermined time after the enabling signals begin, and a timing circuit coupled to the gate of the first gate controlled switch to render that switch nonconducting at a time subsequent to the predetermined time after the enabling signals begin.

Claim 13

The circuit as set forth in claim 8, further comprising a relay having normally open contacts closable to open the fuel valve and having an actuating coil in series with the first gate controlled switch, and means responsive to an initial conducting state of the gate controlled switch and nonconducting state of the actuating coil for preventing actuation of the relay.

Claim 14

An electrically energizable control system for a fuel burner comprising: means for actuating a fuel valve to enable flow of a combustible fuel to the burner; means for igniting the fuel emitted from the burner; a first controlled switching device; means for connecting the actuating means and the first controlled switching device to a source of electrical energy to effect energization of the actuating means when the controlled switching device becomes conductive; a gate controlled switch coupled to the first controlled switching device for rendering it nonconducting when the gate controlled switch has been nonconducting for a predetermined length of time; and a Darlington amplifier responsive to combustion of the fuel emitted from the burner for enabling the gate of the gate controlled switch to maintain it in a conducting state.

Claim 15

An electrically energizable control system for a fuel burner comprising: means for actuating a fuel valve to enable flow of a combustible fuel to the burner; means for igniting the fuel emitted from the burner; a first controlled switching device; means for connecting the actuating means and the first controlled switching device to a source of electrical energy to effect energization of the actuating means when the controlled switching device becomes conductive; a gate controlled switch coupled to the first controlled switching device for rendering it nonconducting when the gate controlled switch has been nonconducting for a predetermined length of time; and a Darlington amplifier responsive to combustion of the fuel emitted from the burner for enabling the gate of the gate controlled switch to maintain it in a conducting state.

Claim 16

An electrically energizable control system for a fuel burner comprising: means for actuating a fuel valve to enable flow of a combustible fuel to the burner; means for igniting the fuel emitter from the burner; a first controlled switching device; means for connecting the actuating means and the first controlled switching device to a source of electrical energy to effect energization of the actuating means when the controlled switching device becomes conductive; a gate controlled switch coupled to the first controlled switching device for rendering it nonconducting when the gate controlled switch has been nonconducting for a predetermined length of time; and a third controlled switching device responsive to combustion of the fuel emitted from the burner for gating the gate controlled switch to a conducting state.

Claim 17

An electrically energizable control system for a fuel burner comprising: means for actuating a fuel valve to enable flow of a combustible fuel to the burner; means for igniting the fuel emitter from the burner; a first controlled switching device; means for connecting the actuating means and the first controlled switching device to a source of electrical energy to effect energization of the actuating means when the controlled switching device becomes conductive; a gate controlled switch coupled to the first controlled switching device for rendering it nonconducting when the gate controlled switch has been nonconducting for a predetermined length of time; and a third controlled switching device responsive to combustion of the fuel emitted from the burner for gating the gate controlled switch to a conducting state.

Claim 18

A control system as set forth in claim 12, further comprising means coupled to the gate of the gate controlled switch for also supplying enabling signals to the gate.

Claim 19

A control system as set forth in claim 13, further comprising means responsive to the enabling of the gate controlled switch by the supplying means for actuating the igniting means to ignite the fuel.

Claim 20

A control circuit as set forth in claim 13, further comprising a first timing circuit for controlling the supplying means to stop the enabling signals thereof a predetermined time after the enabling signals begin.

Claim 21

A control system as set forth in claim 15, further comprising a second timing circuit coupled to the gate of the gate controlled switch to render it nonconductive at a time subsequent to the predetermined time after the enabling signals begin.

Claim 22

A control system as set forth in claim 12, wherein the actuating means comprises a first transformer, another gate controlled switch, and a second transformer, one winding of the first transformer being connected in series with the first named gate controlled switch and another winding of the first transformer being coupled to the gate of the oTher gate controlled switch, and one winding of the second transformer being connected in series with the other gate controlled switch and another winding of the second transformer being coupled to the igniting means.

Claim 23

In an electrically energizable control system for a fuel burner where a fuel valve is opened on thermostatic demand and closed a predetermined time thereafter if fuel ignition fails; the combination therewith comprising a flame detector circuit including a Darlington amplifier, and means in circuit relation with the Darlington amplifier input for enabling it when impedance between the enabling means and a reference potential is below a predetermined impedance, the enaabling means also being operable generally to disable the Darlington amplifier when impedance between the enabling means and the reference potential is above the predetermined impedance, and a spark ignitor supply circuit including means operable generally for providing a spark to effect ignition of the fuel supplied by the fuel burner, and a gate controlled switch for controlling the spark providing means to effect its operation in the event the enabling means disables the Darlington amplifier.

Claim 24

In an electrically energizable control system for a fuel burner where a fuel valve is opened on thermostatic demand and closed a predetermined time thereafter if fuel ignition fails; the combination therewith comprising a flame detector circuit including a Darlington amplifier, and means in circuit relation with the Darlington amplifier input for enabling it when impedance between the enabling means and a reference potential is below a predetermined impedance, the enaabling means also being operable generally to disable the Darlington amplifier when impedance between the enabling means and the reference potential is above the predetermined impedance, and a spark ignitor supply circuit including means operable generally for providing a spark to effect ignition of the fuel supplied by the fuel burner, and a gate controlled switch for controlling the spark providing means to effect its operation in the event the enabling means disables the Darlington amplifier.