PURPOSE: To realize a long service life of the title controller and to execute a temperature control with high reliability and with high accuracy by controlling the heating power supplied to a heater for heating an oxygen sensor by turning on and off a switching element.
CONSTITUTION: A heater temperature (oxygen sensor temperature) of a thermocouple 9 of a temperature controller 60 is detected as thermoelectromotive force, and this thermoelectromotive force is compared with a set temperature of a setting device in a PID controller 41, a PID operation is performed and inputted as a control operation output signal S to a pulse width modulating circuit 50, a control of a pulse duty ratio is executed, and a high frequency pulse signal of this pulse width is outputted to a power transistor (switching element) 15 through a photocoupler 55. An output of a DC current supply circuit 11 receives switching of the TR 15, is provided to a primary winding 16a of a high frequency transformer 16 as high frequency power, and high frequency AC power from a secondary winding 16b is inputted to a heater 7 as DC power by a smoothing circuit 18. By the signal S, a temperature of the heater 7 is maintained at a set temperature.
HATTORI AKINOBU
SASAKI YUICHI
| JPS6048518A | 1985-03-16 |
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