Particulate matter detection strategy in exhaust filter

A method of detecting particulate matter in an exhaust filter for an internal combustion engine comprising the steps of:

• receiving data indicative of a time delay between transmission and reception of electromagnetic energy propagated through particulate matter trapped within a filter medium of the exhaust filter;
• outputting a signal indicative of an amount of the trapped particulate matter responsive to the data;
• transmitting the electromagnetic energy via a probe positioned downstream the filter medium in a flow of filtered exhaust gases passing to an exhaust outlet of the exhaust filter;
• receiving the transmitted electricity via the probe;
• and
• energizing the probe for transmitting the electromagnetic energy via an analog circuit having one of a spark inductor and a thyratron;
• wherein the step of transmitting includes transmitting a pulse of electromagnetic energy having a pulse duration, less than about 1 microsecond;
• and
• wherein the step of transmitting further includes transmitting electromagnetic frequencies from about 700 MHz to about 3000 MHz in the pulse.

An exhaust filter system for an internal combustion engine comprising:

• an exhaust filter including a housing having an exhaust inlet, an exhaust outlet, and a filter medium positioned within the housing and configured to trap particulates in exhaust gases passed from the exhaust inlet to the exhaust outlet;
• and
• a particulate sensing mechanism coupled with the exhaust filter and including at least one probe configured to transmit electromagnetic energy within the housing, and to receive transmitted electromagnetic energy propagated through particulate matter trapped within the filter medium at a speed of propagation dependent upon an amount of the trapped particulate matter;
• the particulate sensing mechanism further including an electronic control unit coupled with the at least one probe, and being configured to determine a value indicative of an amount of the trapped particulate matter responsive to a time delay between transmitting and receiving the electromagnetic energy dependent upon the speed of propagation.

A method of operating an exhaust filter system comprising the steps of:

• transmitting electromagnetic energy through an exhaust filter having a filter medium containing trapped particulate matter;
• receiving transmitted electromagnetic energy propagated through the trapped particulate matter at a speed of propagation dependent upon an amount of the trapped particulate matter;
• and
• commanding regeneration of the exhaust filter via outputting a control command from an electronic control unit, responsive to a time delay between the transmission and the reception of the electromagnetic energy dependent upon the speed of propagation.