Time shared control arrangement for electrical heaters and method

Claim 2

An arrangement for independently operating at least two electrical heaters while sharing a controller means and comprising: alternating current electrical power controller means for selectively modifying at least oNe characteristic of electrical current flowing therethrough and thereby for controlling the average power delivered, a plurality of electrical heaters, independent temperature sensor means operatively associated with each of said electrical heaters for independently sensing the temperatures of the corresponding ones of said heaters, means operatively interconnected with said controller means, said electrical heaters and said sensor means for sensing the cyclic alternations of the electrical current flowing through said controller means, means for delivering successive cyclic portions of the electrical current through said controller means to successive ones of said electrical heaters and means for effecting response of said controller means independently during each successive cyclic portion to the one of said independent temperature sensor means corresponding to the one electrical heater to which the one cyclic portion is delivered so as to independently control the temperature thereof.

Claim 3

The combination according to claim 1 wherein said electrical heaters comprise resistance means predominantly presenting a resistive load and further wherein said successive cyclic portions are successive half-wave portions of alternating current electrical power.

Claim 4

The combination according to claim 1 wherein said electrical heaters comprise inductive means predominantly presenting an inductive load and further wherein said successive cyclic portions are successive full-wave portions of alternating current electrical power.

Claim 5

The combination according to claim 1 wherein said controller means comprises thyristor means operatively connected to control conduction of electrical current through said controller means and triggering circuit means operatively connected with said thyristor means for varying the interval of each successive cycle portion of electrical current during which said thyristor means is conductive.

Claim 6

The combination according to claim 4 wherein said thyristor means comprises a plurality of thyristors each operatively connected for controlling conduction of electrical current through a corresponding one electrical heater.

Claim 7

An arrangement for independently operating at least two electrical heaters while sharing a controller means and comprising: alternating current electrical power controller means for selectively modifying at least one characteristic of electrical current flowing therethrough and thereby for controlling the average power delivered, a plurality of electrical heaters, independent temperature sensor means operatively associated with each of said electrical heaters, independent set-point means for establishing independently predetermined temperature set-points for each of said electrical heaters, means operatively interconnected with said controller means, said electrical heaters, said sensor means and said set-point means for sensing the cyclic alternations of the electrical current flowing through said controller means, means for successively commutating conduction of electrical power from the controller to successive ones of said electrical heaters in response to the sensed cyclic alternations of the power and means for independently controlling the power delivered to each one heater during such cyclic portion of the alternating electrical power as is conducted thereto in response to any difference between the corresponding set-point and sensed temperature.

Claim 8

An arrangement for independently operating at least two electrical heaters while sharing a controller means and comprising: alternating current electrical power controller means for selectively modifying at least one characteristic of electrical current flowing therethrough and thereby for controlling the average power delivered, a plurality of electrical heaters, independent temperature sensor means operatively associated with each of said electrical heaters, independent set-point means for establishing independently predetermined temperature set-points for each of said electrical heaters, means operatively interconnected with said controller means, said electrical heaters, said sensor means and said set-point means for sensing the cyclic alternations of the electrical current flowing through said controller means, means for successively commutating conduction of electrical power from the controller to successive ones of said electrical heaters in response to the sensed cyclic alternations of the power and means for independently controlling the power delivered to each one heater during such cyclic portion of the alternating electrical power as is conducted thereto in response to any difference between the corresponding set-point and sensed temperature.

Claim 9

The combination according to claim 6 wherein said electrical heaters are connected in parallel and said alternation sensing and commutating means includes half-wave sensor means for responding to successive half-wave portions of alternating electrical current and diode blocking means connected in series with said electrical heaters for blocking successive half-wave portions of alternating electrical current from flowing through alternate ones of said electrical heaters.

Claim 10

The combination according to claim 6 wherein said electricAl heaters are connected in series and said alternation sensing and commutating means includes half-wave sensor means for responding to successive half-wave portions of alternating electrical current and diode shunt means connected in parallel with said electrical heaters for shunting successive half-wave portions of alternating electrical current across alternate ones of said electrical heaters.

Claim 11

The combination according to claim 6 wherein said alternation sensing and commutating means includes full-wave sensor means for responding to successive full-wave portions of alternating electrical current and switching circuit means operatively connected to said electrical heaters for conducting successive full-wave portions of alternating electrical current to alternate ones of said electrical heaters.

Claim 14

A method according to claim 10 wherein successive half-wave cyclic portions of alternating current electrical power are delivered through the controller to successive ones of resistive electrical heaters.

Claim 15

A method according to claim 10 wherein successive full-wave cyclic portions of alternating current electrical power are delivered through the controller to successive ones of inductive electrical heaters.

Claim 16

A method according to claim 10 wherein alternating current electrical power is delivered to electrical heaters through at least one thyristor and further comprising the step of controllably varying the interval of each successive cyclic portion of alternating current electrical power during which power is delivered.

Claim 17

A method according to claim 13 wherein the controlled variation of power delivery intervals comprises successively delivering power through a plurality of thyristors to a corresponding plurality of electrical heaters.

Claim 20

A method according to claim 15 wherein the successive commutation of electrical power comprises responding to successive half-wave portions of alternating electrical current and blocking alternate half-wave portions from flow through alternate ones of the heaters.

Claim 21

A method according to claim 15 wherein the successive commutation of electrical power comprises responding to sUccessive half-wave portions of alternating electrical current and shunting alternate half-wave portions across alternate ones of the heaters.

Claim 22

A method according to claim 15 wherein the successive commutation of electrical power comprises responding to successive full-wave portions of alternating electrical current and switching alternate full-wave portions to alternate ones of the heaters.