Heater control method and heater control apparatus for gas sensor

Patent metadata

Field	Value
Publication number	US-9386633-B2
Application number	US-201414189540-A
Country	US
Kind code	B2
Filing date	Feb 25, 2014
Priority date	Feb 26, 2013
Publication date	Jul 5, 2016
Grant date	Jul 5, 2016

Abstract

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.

First claim

What is claimed is:

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:
controlling energization of the heater by operating the switching means under PWM control at a PWM frequency of 30 Hz or higher, wherein the power supply voltage is applied to the heater when the switching means is turned on, and the power supply voltage is not applied to the heater when the switching means is turned off; 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 such that the PWM control acts to reduce power input to the heater as if supplied at an applied voltage set in advance that is lower than the power supply voltage of higher than 16 V.

2. The heater control method as claimed in claim 1 , which comprises operating the switching means at a duty ratio such that an input power to the heater at the applied voltage of higher than 16V is equal to an input power to the heater at the lower applied voltage.

3. The heater control method as claimed in claim 1 , which comprises operating the switching means at a duty ratio such that a temperature rise curve of the gas detection element at the applied voltage of higher than 16V follows a temperature rise curve of the gas detection element at the lower applied voltage.

4. A heater control apparatus 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 header 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 apparatus comprising:
switching means for applying the power supply voltage to the heater when the switching means is turned on and stopping application of the power supply voltage when the switching means is turned off; and
control means for controlling energization of the heater by operating the switching means under PWM control at a PWM frequency of 30 Hz or higher, wherein the control means is configured to turn the switching means off and on,
said control means performing the PWM control such that the switching means is operated at a duty ratio of less than 100% whereby the temperature of the heater does not change 25° C. or more per 0.1 second, and such that the PWM control acts to reduce power input to the heater as if supplied at an applied voltage set in advance that is lower than the power supply voltage of higher than 16 V.

Assignees

• Ngk Spark Plug Co

Inventors

• Igarashi Ai
• Hayashi Hiroyuki
• Terui Tomohisa
• Hisada Kaoru

Classifications

• H05B1/023 Primary

  Industrial applications · CPC title

• H05B1/0247 Primary

  For chemical processes · CPC title