Exhaust particulate matter measuring apparatus

Abstract

A PM sensor for measuring particle matter in exhaust gas is disposed between a three-way catalyst and a muffler in an exhaust pipe, and has an oxidation catalyst and an electrical heater that are stacked together, and a temperature sensor that measures a temperature of the oxidation catalyst interposed between the oxidation catalyst and the electrical heater. The oxidation catalyst carries a ceria as an oxygen-storing agent that occludes oxygen in the exhaust gas, and a ECU calculates a sediment amount of the exhaust particulate matter based on an amount of temperature rise when the electrical heater heats the oxidation catalyst and an accumulated value of an intake air amount.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an exhaust particulate matter measuring apparatus that measures the amount of particulate matter present in exhaust gas.[0003]2. Description of the Related Art[0004]A conventional direct-injection type of internal combustion engine is known in which fuel is injected directly into a combustion chamber, rather than into an intake port. In this direct-injection type internal combustion engine, when the intake valve is open, air is drawn into the combustion chamber from the intake port and compressed by a piston, an injector directly injecting fuel to this high-pressure air. The high-pressure air in the combustion chamber and the fuel mist are mixed, and the resulting air-fuel mixture is ignited by a spark plug to cause an explosion to generate driving power. When the exhaust valve is open, the exhaust gas after combustion is discharged from an exhaust port.[0005]In an internal combustion en...

AI Technical Summary

Benefits of technology

[0008]The present invention provides an exhaust particulate matter measuring apparatus that accurately measures that amount of particulate matter present in exhaust gas.

[0011]According to the exhaust particulate matter measuring apparatus noted above, by carrying an oxygen-storing agent on an oxidation catalyst disposed in the exhaust passage of the internal combustion engine and providing a heating means to heat the oxidation catalyst, a temperature sensor to measure the temperature of the oxidation catalyst, and a sediment amount calculation means for calculating a sediment amount of exhaust particulate matter in response to the degree of temperature rise when the heating means heats the oxidation catalyst, the following effect is achieved. Although the oxygen-storing agent of the oxidation catalyst occludes oxygen that usually exists in the exhaust gas, when the oxidation catalyst is heated by the heating means the exhaust particulate matter captured by the oxidation catalyst is properly combusted, along with the oxygen occluded by the oxygen-storing agent, and the sediment amount calculation means can accurately calculate the sediment amount of exhaust particulate matter, in accordance with the degree of temperature rise at that time.

Problems solved by technology

For this reason, the problem arises that, when there is not a sufficient amount of oxygen in the area surrounding the soot sensor, even if the molded member is heated by the electrical heating member, it is not possible to properly combust the soot particles settled on the molded member, making it impossible to measure the soot amount with high accuracy.

Images