Heater controlling apparatus for gas sensor

Abstract

A heater controlling apparatus for controlling a heater that heats a sensing element of a gas sensor provided in an exhaust system of a diesel engine includes a device that changes a reference condition for controlling the heater after a start of the engine in a first operation based on an operational state before a stop of the engine in a second operation, which precedes the first operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:

FIG. 1 is an explanatory view of an exhaust system of a diesel engine according to a first embodiment;

FIG. 2 is an explanatory diagram of a schematic flow of a heater control according to the first embodiment;

FIG. 3 is an explanatory diagram of a first flow for computing a low-temperature integrated time based on an operational state before a stop of the engine in a preceding operation according to the first embodiment;

FIG. 4 is an explanatory diagram of a second flow of the heater control after a start of the engine in a following operation according to the first embodiment;

FIG. 5 is a conceptual diagram of a heater controlling apparatus for a gas sensor according to the first embodiment;

FIG. 6 is a diagram showing a relation between the low-temperature integrated time and a reference temperature according to the first embodiment;

FIG. 7 is a diagram showing a relation between the low-temperature integrated time and a reference time according to the first embodiment;

FIG. 8 is a diagram showing a time period for heater energization according to the first embodiment;

FIG. 9 is a diagram showing time profiles of a vehicle speed and an ignition ON/OFF according to the first embodiment;

FIG. 10 is a diagram showing a relation between the low-temperature integrated time and the reference temperature according to a second embodiment;

FIG. 11 is a diagram showing a relation between the low-temperature integrated time and the reference time according to the second embodiment;

FIG. 12 is an explanatory diagram of a first flow for computing a low-temperature integrated time based on the operational state before the stop of the engine in the preceding operation according to a third embodiment; and

FIG. 13 is an explanatory diagram of a flow for a heater control according to a comparative example.

Claims

1. A heater controlling apparatus for controlling a heater that heats a sensing element of a gas sensor provided in an exhaust system of a diesel engine, the apparatus comprising: a device that changes a reference condition for controlling the heater after a start of the engine in a first operation based on an operational state before a stop of the engine in a second operation, which precedes the first operation.

2. The apparatus according to claim 1, wherein: a high-temperature integrated time is an integrated time, during which a temperature in the exhaust system is equal to or larger than a predetermined reference temperature;the device starts energizing the heater when the high-temperature integrated time is equal to or larger than a predetermined reference time; andthe device changes each value of at least one of the reference temperature and the reference time based on the operational state before the stop of the engine in the second operation.

3. The apparatus according to claim 1, wherein: a low-temperature integrated time is an integrated time, during which a temperature in the exhaust system is equal to or smaller than a predetermined comparative temperature, before the stop of the engine in the second operation; andthe device changes the reference condition for controlling the heater after the start of the engine in the first operation based on whether the low-temperature integrated time is equal to or larger than a predetermined comparative time or not.

4. The apparatus according to claim 2, wherein: a low-temperature integrated time is an integrated time, during which the temperature in the exhaust system is equal to or smaller than a predetermined comparative temperature, before the stop of the engine in the second operation; andthe device changes the reference condition for controlling the heater after the start of the engine in the first operation based on whether the low-temperature integrated time is equal to or larger than a predetermined comparative time or not.

5. The apparatus according to claim 3, wherein: a high-temperature integrated time is an integrated time, during which the temperature in the exhaust system is equal to or larger than a predetermined reference temperature;the device starts energizing the heater when the high-temperature integrated time is equal to or larger than a predetermined reference time; andthe device makes each value of at least one of the reference temperature and the reference time larger when the low-temperature integrated time is equal to or larger than the comparative time, than when the low-temperature integrated time is smaller than the comparative time.

6. The apparatus according to claim 4, wherein: the device makes each value of the at least one of the reference temperature and the reference time larger when the low-temperature integrated time is equal to or larger than the comparative time, than when the low-temperature integrated time is smaller than the comparative time.

7. The apparatus according to claim 5, wherein: the device increases each value of the at least one of the predetermined reference temperature and the predetermined reference time in proportion to a magnitude of the low-temperature integrated time.

8. The apparatus according to claim 6, wherein: the device increases each value of the at least one of the predetermined reference temperature and the predetermined reference time in proportion to a magnitude of the low-temperature integrated time.

9. The apparatus according to claim 5, wherein the device includes: a temperature sensing device that senses the temperature in the exhaust system;a temperature decrease determining device that determines whether the temperature in the exhaust system is equal to or smaller than the comparative temperature;a low-temperature time integrating device that measures the low-temperature integrated time;a low-temperature time storing device that stores the low-temperature integrated time;a reference condition change need determining device that determines whether each value of the at least one of the reference temperature and the reference time needs to be changed based on whether the low-temperature integrated time is equal to or larger than the comparative time;a reference condition changing device that changes each value of the at least one of the reference temperature and the reference time based on a determination result of the reference condition change need determining device;a temperature increase determining device that determines whether the temperature in the exhaust system is equal to or larger than the reference temperature;a high-temperature time integrating device that measures the high-temperature integrated time;a heater energization determining device that determines whether it is possible to energize the heater or not based on whether the high-temperature integrated time is equal to or larger than the reference time; anda heater energization controlling device that energizes the heater based on a determination result of the heater energization determining device.

10. The apparatus according to claim 6, wherein the device includes: a temperature sensing device that senses the temperature in the exhaust system;a temperature decrease determining device that determines whether the temperature in the exhaust system is equal to or smaller than the comparative temperature;a low-temperature time integrating device that measures the low-temperature integrated time;a low-temperature time storing device that stores the low-temperature integrated time;a reference condition change need determining device that determines whether each value of the at least one of the reference temperature and the reference time needs to be changed based on whether the low-temperature integrated time is equal to or larger than the comparative time;a reference condition changing device that changes each value of the at least one of the reference temperature and the reference time based on a determination result of the reference condition change need determining device;a temperature increase determining device that determines whether the temperature in the exhaust system is equal to or larger than the reference temperature;a high-temperature time integrating device that measures the high-temperature integrated time;a heater energization determining device that determines whether it is possible to energize the heater or not based on whether the high-temperature integrated time is equal to or larger than the reference time; anda heater energization controlling device that energizes the heater based on a determination result of the heater energization determining device.