Recently, the Environmental Protection Agency made changes to the emissions limits for large diesel engine vehicles. In the advent of these new rules, new ceramic filters have been added to the exhaust systems of trucks which catch up to 95% of the debris and waste created by burning diesel fuel. Unfortunately, in commercially operated vehicles, these filters can get clogged up and require cleaning several times a day.
The good news is that the cleaning process for ceramic filters, called filter regeneration, in the diesel engine is internal. The engine itself adjusts to burn hotter, which then burns all of the collected soot off of the filter element. The downside to this system is that there is currently no means of monitoring sensors to determine when they need cleaning, nor when the cleaning is complete. As a result trucks are either driving too long with clogged filters before the cleaning process begins, or they are cleaning too often, which burns more fuel than necessary and causes the engine to run inefficiently during the cleaning process.
A team at MIT has endeavored to change this situation by introducing wireless sensor technologies to determine filter health and trigger filter regeneration more reliably. Filter Sensing Technologies (FST) is placing sensors on or near filters which transmit a signal to the truck’s electronics bank. As the filters fill up with soot and debris, the sensors transmit weaker and weaker signals, which alert the diesel engine emissions control system that it is time for filter regeneration. At this point, the engine begins to heat up and burn the soot until the wireless sensor is able to transmit freely once again.
A two year trial of these sensors among New York’s sanitation trucks has shown a consistent improvement of fuel economy. In fact, the frequency of filter regeneration, and the length of regeneration time was reduced by half. It is expected that these sensors could save one to two percent of fuel consumption, which translates to several hundred gallons of fuel in trucks that are operated commercially year round. The resulting cost savings will be a worthwhile investment, and will keep trucks in compliance with EPA regulations.
FST has recently been acquired by an industry leader in the large vehicle electronics sector, CTS Corporation. CTS intends to move forward with production of sensors for the mass market as an OEM option.