Continental’s Urea Sensor Makes Diesel Engines Cleaner

Exhaust-gas aftertreatment is proven contributory when it comes to the reduction of motor vehicle emission. In addition to reducing CO2 emissions, reducing the level of harmful nitrogen-oxide emissions is one of the biggest challenges for the automotive industry.

Aiming to deal with this challenge, Continental has been driving forward the development of selective catalytic reduction (SCR) technology since 2011. A number of passenger cars and commercial vehicles with diesel engines already feature an SCR system. The reaction of an aqueous urea solution (“AdBlue” or urea solution) with nitrogen oxides in the engine exhaust chemically converts nitrogen oxide to water and nitrogen. The efficacy of this process depends on an accurate metering of the urea amount that is injected, which in turn requires a measurement of the urea concentration.

In order to support this new control function, Continental is launching for the very first time the production of its urea sensor. This sensor, which is designed to further enhance SCR and documents its effectiveness, can measure the level, quality and temperature of the urea solution in the tank. A number of automakers have expressed their interest in using the sensor.

Klaus Hau, Head of the Sensors & Actuators Business Unit in Continental’s Powertrain pision, explains that their sensor technology supports SCR systems. The sensor offers the data basis to adapt the injected amount of urea to the prompt engine load. This data is necessary for the on-board diagnosis of the exhaust-gas aftertreatment function. Hau added that the sensor tracks the urea fill level in the tank to help the driver top-up AdBlue in good time. Given that an effective SCR is a key requirement for the upcoming Euro 6c emission legislation, incorporating a urea sensor into the system will also enhance the driver’s trust in the car’s exhaust-gas aftertreatment function.

The groundbreaking urea sensor includes piezo elements, a negative temperature coefficient (NTC) resistance thermometer, and an application-specific integrated circuit (ASIC), all of which Continental is already utilizing for gauging oil levels. Ultrasonic signals gauge both the urea concentration in the tank’s fill level as well as in the water. For this purpose, the Continental urea sensor can be welded either into the pump unit or into the tank.

Research and development for the urea sensor is located in Nuremberg, Germany and in the newly opened competence center at Ostrava, Czech Republic. Meanwhile, the component is produced at the Frenstat location in Czech Republic.