Pm sensor, pm amount sensing device for exhaust gas, and abnormality detection apparatus for internal combustion engine

Abstract

Provided is a PM sensor capable of sensing the amount of particulate matter, and a PM amount sensing device for exhaust gas. Also provided is an abnormality detection apparatus for an internal combustion engine, which is capable of sensing abnormality of a particulate filter. The PM sensor and the PM amount sensing device are mounted in an exhaust pipe of an internal combustion engine. In the exhaust pipe, installed are an air-fuel ratio sensor, a filter, and an air-fuel ratio sensor in sequence in the direction of the flow of exhaust gas. The filter is a compact filter for trapping fine particles. The ECU has a function of calculating a difference ΔI L between an output I L1 and an output I L2 . Based on ΔI L , it is possible to calculate the amount of particulate matter in the exhaust gas that is currently flowing into the filter.

1 . A PM sensor, comprising:
 an inlet port through which a portion of gas that is drawn from an exhaust path of an internal combustion engine is allowed to flow in;   a filter for filtering particulate matter (PM) in the gas that has flowed in through the inlet port;   a heater attached to the filter and capable of changing the temperature of the filter;   an outlet port through which the gas that has passed through the filter is allowed to flow out to the exhaust path; and   an oxygen concentration sensor element disposed in the outlet port side and including a heater, wherein the oxygen concentration sensor is heated to a predetermined temperature by the heater upon being activated and is adapted to change its output according to an oxygen concentration of gas that has passed through the filter, and wherein the oxygen concentration sensor is disposed being spaced apart from the filter such that the filter has a level of temperature at which particulate matter in the filter is not removed when temperature of the oxygen concentration sensor itself is at the predetermined temperature.   
     
     
         2 . The PM sensor according to  claim 1 , further comprising
 an oxygen concentration sensor element disposed between the inlet port and the filter and adapted to change its output according to an oxygen concentration of gas that has flowed in through the inlet port.   
     
     
         3 . The PM sensor according to  claim 2 , wherein
 the oxygen concentration sensor element of the outlet port side and the oxygen concentration sensor element of the inlet port side are air-fuel ratio sensor elements.   
     
     
         4 . (canceled) 
     
     
         5 . A PM amount sensing device for exhaust gas, comprising:
 a filter provided in an exhaust path of an internal combustion engine and for filtering particulate matter (PM) in exhaust gas that flows through the exhaust path;   an oxygen concentration sensor element disposed in a downstream of the filter in the exhaust path, and adapted to change its output according to an oxygen concentration of gas that has passed through the filter;   a heater attached to the filter;   heating control means for controlling the heater such that the filter is heated until particulate matter in the filter is removed;   temperature reduction control means for controlling the heater such that a temperature of the filter is not higher than a temperature at which particulate matter in the filter is not removed, after the control of the heating control means;   acquisition means for acquiring an output of the oxygen concentration sensor element when a predetermined time period has elapsed after a temperature of the filter becomes not higher than the temperature;   means for calculating an integrated value of an amount of exhaust gas that flows into the filter before an acquisition timing of the output by the acquisition means; and   calculation means for calculating an amount of particulate matter in the exhaust gas per unit time and per unit volume based on the output acquired by the acquisition means, the predetermined time period, the and the integrated value.   
     
     
         6 . (canceled) 
     
     
         7 . The PM amount sensing device for exhaust gas according to  claim 5 , further comprising
 an oxygen concentration sensor element disposed in an upstream of the filter in the exhaust path, and capable of changing its output according to an oxygen concentration of exhaust gas that flows into the filter, wherein   the calculation means calculates an amount of particulate matter in the exhaust gas based on a difference between an output of the oxygen concentration sensor element of the upstream side of the filter and an output of the oxygen concentration sensor element of the downstream side of the filter.   
     
     
         8 . The PM amount sensing device for exhaust gas according to  claim 7 , wherein
 the oxygen concentration sensor element of the downstream side of the filter and the oxygen concentration sensor element of the upstream side of the filter are air-fuel ratio sensor elements.   
     
     
         9 . The PM amount sensing device for exhaust gas according to  claim 8 , further comprising
 calibration means for calibrating an output deviation between the air-fuel ratio sensor of the downstream side of the filter and the air-fuel ratio sensor of the upstream side of the filter.   
     
     
         10 . A PM amount sensing device for exhaust gas, comprising:
 a filter provided in an exhaust path of an internal combustion engine and for filtering particulate matter (PM) in exhaust gas that flows through the exhaust path;   a heater attached to the filter;   an upstream side oxygen concentration sensor disposed in an upstream of the filter in the exhaust path, and adapted to change its output according to an oxygen concentration of gas that flows into the filter;   a downstream side oxygen concentration sensor disposed in a downstream of the filter in the exhaust path, and adapted to change its output according to an oxygen concentration of gas that flows out from the filter;   temperature reduction control means for controlling the heater such that a temperature of the filter is not higher than a temperature at which particulate matter in the filter is not removed;   heating control means for controlling the heater such that a temperature of the filter becomes not lower than a temperature at which particulate matter in the filter is removed, after a predetermined period has elapsed since a temperature of the filter becomes not higher than the temperature through the control by the temperature reduction control means;   electric energy sensing means including:   determination means for determining whether or not particulate matter in the filter is removed based on a difference between an output of the upstream side oxygen concentration sensor and an output of the downstream side oxygen concentration sensor after a start of the control by the heating control means,   electric energy calculation means for calculating electric energy consumption of the heater during a period from a start of the control by the heating control means until it is determined that particulate matter in the filter is removed; and   means for calculating electric energy consumption consumed by the heater for removing particulate matter in the filter based on the electric energy consumption calculated by the electric energy calculation means; and   calculation means for calculating an amount of particulate matter of the exhaust gas based on the electric energy consumption sensed by the electric energy sensing means.   
     
     
         11 - 15 . (canceled) 
     
     
         16 . A PM amount sensing device for exhaust gas, comprising:
 a filter provided in an exhaust path of an internal combustion engine and for filtering particulate matter (PM) in exhaust gas that flows through the exhaust path;   an oxygen concentration sensor element disposed in a downstream of the filter in the exhaust path, and adapted to change its output according to an oxygen concentration of gas that has passed through the filter;   a heater attached to the filter;   a heating control unit for controlling the heater such that the filter is heated until particulate matter in the filter is removed;   a temperature reduction control unit for controlling the heater such that a temperature of the filter is not higher than a temperature at which particulate matter in the filter is not removed, after the control of the heating control unit;   an acquisition unit for acquiring an output of the oxygen concentration sensor element when a predetermined time period has elapsed after a temperature of the filter becomes not higher than the temperature;   an unit for calculating an integrated value of an amount of exhaust gas that flows into the filter before an acquisition timing of the output by the acquisition unit; and   a calculation unit for calculating an amount of particulate matter in the exhaust gas per unit time and per unit volume based on the output acquired by the acquisition unit, the predetermined time period, the and the integrated value.   
     
     
         17 . A PM amount sensing device for exhaust gas, comprising:
 a filter provided in an exhaust path of an internal combustion engine and for filtering particulate matter (PM) in exhaust gas that flows through the exhaust path;   a heater attached to the filter;   an upstream side oxygen concentration sensor disposed in an upstream of the filter in the exhaust path, and adapted to change its output according to an oxygen concentration of gas that flows into the filter;   a downstream side oxygen concentration sensor disposed in a downstream of the filter in the exhaust path, and adapted to change its output according to an oxygen concentration of gas that flows out from the filter;   a temperature reduction control unit for controlling the heater such that a temperature of the filter is not higher than a temperature at which particulate matter in the filter is not removed;   a heating control unit for controlling the heater such that a temperature of the filter becomes not lower than a temperature at which particulate matter in the filter is removed, after a predetermined period has elapsed since a temperature of the filter becomes not higher than the temperature through the control by the temperature reduction control unit;   an electric energy sensing unit including:   a determination unit for determining whether or not particulate matter in the filter is removed based on a difference between an output of the upstream side oxygen concentration sensor and an output of the downstream side oxygen concentration sensor after a start of the control by the heating control unit,   an electric energy calculation unit for calculating electric energy consumption of the heater during a period from a start of the control by the heating control unit until it is determined that particulate matter in the filter is removed; and   an unit for calculating electric energy consumption consumed by the heater for removing particulate matter in the filter based on the electric energy consumption calculated by the electric energy calculation unit; and   a calculation unit for calculating an amount of particulate matter of the exhaust gas based on the electric energy consumption sensed by the electric energy sensing unit.