Particulate matter detecting device

A particulate matter detecting device comprising:

• an element unit on which particulate matter contained in exhaust gas from an internal combustion engine is deposited;
• a heater that heats the element unit;
• a detecting unit that detects an amount of the particulate matter on the basis of electrical characteristics of the element unit;
• and
• a control unit that controls operation of the heater, wherein
• for a predetermined period excluding a period in which the particulate matter is deposited on the element unit, the control unit operates the heater using a predetermined amount of control set in advance such that a temperature of the element unit is higher than a temperature of the exhaust gas and lower than 650° C. to exert a thermophoretic force for moving the particulate matter away from the element unit;
• and
• the temperature of the element unit varies according to the temperature of the exhaust gas.

A particulate matter detecting device comprising:

• an element unit on which particulate matter contained in exhaust gas from an internal combustion engine is deposited;
• a heater that heats the element unit;
• a detecting unit that detects an amount of the particulate matter on the basis of electrical characteristics of the element unit;
• and
• a control unit that controls operation of the heater, wherein
• for a predetermined period excluding a period in which the particulate matter is deposited on the element unit, the control unit operates the heater using a predetermined amount of control set in advance such that a temperature of the element unit is higher than a temperature of the exhaust gas and lower than 650° C. to exert a thermophoretic force for moving the particulate matter away from the element unit;
• and
• if the temperature of the element unit is higher than the temperature at which the particulate matter starts to burn, the control unit operates the heater using an amount of control that reduces the temperature of the element unit instead of operating the heater using the predetermined amount of control.

A particulate matter detecting device comprising:

• an element unit on which particulate matter contained in exhaust gas from an internal combustion engine is deposited;
• a heater that heats the element unit;
• a detecting unit that detects an amount of the particulate matter on the basis of electrical characteristics of the element unit;
• and
• a control unit that controls operation of the heater, wherein
• for a predetermined period excluding a period in which the particulate matter is deposited on the element unit, the control unit operates the heater using a predetermined amount of control set in advance such that a temperature of the element unit is higher than a temperature of the exhaust gas and lower than 650° C. to exert a thermophoretic force for moving the particulate matter away from the element unit;
• the particulate matter detecting device further comprises a temperature sensor configured to detect a temperature of the element unit;
• and
• if the temperature detected by the temperature sensor is higher than the temperature at which the particulate matter starts to burn, the control unit operates the heater using the amount of control that reduces the temperature of the element unit instead of operating the heater using the predetermined amount of control.