HEATER CONTROL METHOD AND HEATER CONTROL APPARATUS FOR GAS SENSOR

摘要

A heater control method and apparatus for a gas sensor which can quickly activate a detection element while reducing load due to heating even when a higher power supply voltage is applied. A heater element is connected to a power supply whose voltage is higher than 16 V, and power is supplied under PWM control such that a temperature rise of the heater element follows a temperature rise curve obtained when a voltage of 12 V is applied to the heater element. Even though a higher voltage is applied, the temperature rise per unit time during the ON time of the PWM control is decreased. This is because the ON time per cycle is shortened by increasing the PWM frequency to 30 Hz or higher. Thus, the temperature rise per cycle is kept low, whereby the temperature rise per 0.1 second is rendered less than 25° C.

主权项

1. A heater control method for controlling energization of a heater of a gas sensor the gas sensor comprising:
a gas detection element having at least one cell composed of a solid electrolyte body and a pair of electrodes provided thereon, and a heater which generates heat, when a power supply voltage is applied to the heater from a power supply apparatus, so as to heat and activate the gas detection element, the power supply voltage applied from the power supply apparatus to the heater being higher than 16 V, the heater control method comprising: applying the power supply voltage to the heater and stopping application of the power supply voltage using a switching means; controlling energization of the heater by operating the switching means under PWM control at a PWM frequency of 30 Hz or higher; and operating the switching means at a duty ratio of less than 100% such that the temperature of the heater does not change 25° C. or more per 0.1 second and an effective value of the voltage applied to the heater is equal to a lower applied voltage set for the heater in advance.