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Diesel Exhaust Temperature Sensors with Improved Accuracy Reduce Emissions

DENSO Corporation has improved the temperature detection accuracy of its newly developed diesel exhaust temperature sensor.

The new sensor, which is located in front of the diesel particulate filter (DPF) and used to control temperature for DPF regeneration, helps reduce harmful diesel emissions and improves fuel efficiency. The product will be installed on heavy duty and medium duty diesel vehicles sold in the U.S. in fall of 2009. It will also be installed to vehicles sold in Japan and Europe in 2010.

"DENSO's improved Exhaust Gas Temperature Sensor is a result of the company's continuous efforts to develop products that enable our customers to reduce emissions and improve fuel economy of diesel systems," said Doug Patton , senior vice president of Engineering at DENSO International America. "The accuracy improvement, due to the extended probe length, will allow customers to more precisely control their diesel aftertreatment systems, helping improve the emissions and fuel economy."

To improve the sensor's temperature accuracy, DENSO increased the probe length to almost twice that of the conventional product and extended the sensing tip into the exhaust pipe. The company achieved this by developing a vibration-resistant structure with an anti-resonance pipe to support the probe, or sheath pin, at its optimal position. Also, while the temperature of DPF regeneration needs to be controlled under 650 degrees Celsius for the DPF to maintain its capability, the sensor is equipped with a newly developed thermistor, or sensing element, which improves detection accuracy to plus or minus 10 degrees Celsius compared to that of the conventional product of plus or minus 30 degrees Celsius. These two developments improved the sensor's temperature detection accuracy of the most intensely heated part of the DPF, its core.

With the improved temperature detection performance, the new sensor helps regenerate DPFs more efficiently, resulting in cleaner emissions, as well as increased fuel efficiency due to less fuel required in the DPF regeneration process. In addition, because less fuel is needed for DPF regeneration, less fuel is mixed in the engine oil, which helps prevent the engine oil from deteriorating.

"With more stringent emissions regulations and increasing environmental awareness, DENSO expects an increase in requirements to improve diesel exhaust aftertreatment technologies, which also will increase the demand for highly precise and extended exhaust gas temperature sensors," said Masahiko Miyaki , managing officer responsible for DENSO's Powertrain Control Systems Business Group.

In addition, DENSO also expects an increase in gasoline-powered vehicles with turbochargers to meet the demand for higher engine power as downsizing progresses. To help control the turbocharging system's temperature more precisely, the company plans to apply the new vibration-resistant technology to a gasoline exhaust temperature sensor that can withstand heavy vibrations when mounted near the turbocharger.

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