Exhaust gas sensor control system and control method
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsHiroshi Enomoto, Akio Matsunaga
Life of this patent
Estimating the term…
Abstract
In an exhaust gas sensor control system and control method, the exhaust pipe wall temperature is estimated based on the measured exhaust gas temperature measured, the exhaust gas flowrate, and the measured outside air temperature, with reference to a supplied heat quantity calculation map, wall temperature added value map, and a wall temperature subtracted value map. Then the dew-point of the exhaust pipe is calculated based on the air-fuel ratio of the air flow amount to the weight of fuel, and a condensed water added amount is calculated based on the relative wall temperature and the exhaust gas flow amount. The amount of condensed water is then estimated by summing the calculated condensed water added amounts.
Claims18
An exhaust gas sensor control system that controls energization of a heater that heats an exhaust gas sensor provided in an exhaust pipe of an internal combustion engine, the exhaust gas sensor control system comprising:
- an exhaust gas temperature sensor that detects an exhaust gas temperature of exhaust gas in the exhaust pipe;
- a air flow amount sensor that detects an amount of flow of air that is drawn into the internal combustion engine;
- an outside air temperature sensor that detects an outside air temperature;
- a condensed water amount estimating device that estimates an amount of condensed water that collects in the exhaust pipe by sequentially calculating condensed water added amounts and summing the calculated condensed water added amounts, the condensed water amount estimating device using the exhaust gas temperature detected by the exhaust gas temperature sensing device when the internal combustion engine is started, the amount of air flow measured by the air flow amount sensor, and the outside air temperature detected by the outside air temperature sensor;
- a condensed water presence determining device that determines from the amount of condensed water estimated by the condensed water amount estimating device whether or not condensed water is present in the exhaust pipe;
- and
- a heater control device that supplies electric current to the heater if the condensed water presence determining device determines that there is no condensed water present in the exhaust pipe.
An exhaust gas sensor control method for controlling the energization of a heater that heats an exhaust gas sensor provided in an exhaust pipe of an internal combustion engine, the exhaust gas sensor control method comprising:
- detecting an exhaust gas temperature of exhaust gas in the exhaust pipe;
- detecting an amount of air flow amount that is drawn into the internal combustion engine;
- detecting an outside air temperature;
- estimating an amount of condensed water that collects in the exhaust pipe by sequentially calculating condensed water added amounts and summing the calculated condensed water added amounts, the step of estimating using the exhaust gas temperature detected when the internal combustion engine is started, the detected amount of air flow, and the detected outside air temperature;
- determining from the estimated amount of condensed water whether or not condensed water is present in the exhaust pipe;
- and
- supplying electric current to the heater if it is determined that there is no condensed water present in the exhaust pipe.
Dependencies are inferred from the claim text.