The Siemens VDO / NGK Smart NOx Sensor

The innovative sensors are helping customers meet increasing global performance requirements and emissions regulations.

Product applications

The Siemens VDO / NGK Smart NOx-Sensor is a stand-alone, multifunctional sensor, which measures both the NOxconcentration and the air/fuel-ratio lambda (λ) in the exhaust gas. In order to comply with the forthcoming emission legislation, such as Euro IV, V, US2007), the sensor helps to control different kinds of exhaust gas aftertreatment both at gasoline and diesel engines, e.g.:

• 1. Regeneration of NOx storage catalyst at leanburn gasoline and diesel engines

• 2. On-board-diagnosis and closed-loop control of Selective-Catalytic-Reduction (SCR) applications at Light and Heavy Duty Trucks

Concept

The Smart NOx-Sensor consists of the sensing element (material: Zirconia multilayer ceramics in metal housing) and the electronic control unit, combined by an approx. 600mm (24 inches) cable. Similar to a wide-range linear lambda sensor, electro-chemical pumps adjust the oxygen concentration in the cavities of the sensing element.

The NOx concentration in the exhaust gas is proportional to

the electrical current controlling the pumps. Based upon the physical measurement, the electronic control unit generates 3 output signals (NOx, binary, linear). The signals are transmitted to the engine ECU digitally via CAN bus.

Product benefits

• Helps to achieve emission legislation
• Fulfills On-Board-Diagnosis requirements
•  Increase of fuel economy
• Wide range of applications:

        – Gasoline / Diesel

        – Passenger car / Truck

•  Triple signal output: – NOx-concentration

        –  linear lambda (λ)

        – binary lambda (λ)

        – Digital data transmission via CAN-Bus

•  Integrated control Electronics –no further hardware in engine ECU required
•  Independent of catalyst supplier, ECU supplier and engine management System – no adaption necessary

Product technical specifications

• ZrO2-based multilayer sensor with 3 oxygen pumps
• Triple output signal (NOx, linear λ, binary λ)
• Supply voltage: 12V or 24V
• Measuring

        range: NOx: 0 – 500ppm or 0-1500ppm

        lin. λ: 0,75 to air

        bin. λ: >0,75V at λ=0,9; <0,2V at λ=1,1

• Accuracy: NOx: at 100ppm and 500ppm: ± 10%;

      at 0ppm: ± 10ppm

      lin. λ: at λ=1: ±6 (1000/λ ) fresh

      bin. λ: 1,002 ± 0,008

• Response time

      (33-66%): NOx: 750 msec

      lin. λ: 550 msec

     bin. λ: 100 msec

• CAN

      communication: standard (500kbaud, 11bit) or extended (250kbaud, 29bit) Data update rate: 10 msec

The source is from www.siemensvdo.com