SFI SYSTEM


  1. CONSTRUCTION


    1. A planar type air fuel ratio sensor and a cup type oxygen sensor are used. The basic construction of the air fuel ratio sensor and oxygen sensor is the same. However, they are divided into the planar type and the cup type, according to the different types of heater construction that are used.

    2. The planar type air fuel ratio sensor uses alumina, which excels in heat conductivity and electrical insulation, to integrate a sensor element with a heater, thus improving the warm up performance of the sensor.

    3. The cup type oxygen sensor contains a sensor element that surrounds a heater.

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      *1 Air Fuel Ratio Sensor (Planar Type) *2 Oxygen Sensor (Cup Type)
      *3 Solid Electrolyte (Zirconia Element) *4 Atmosphere
      *5 Heater *6 Platinum Electrode
      *7 Sensor Element (Zirconia) - -

    4. The air fuel ratio sensor and oxygen sensor differ in output characteristics.

    5. As illustrated below, the oxygen sensor is characterized by a sudden change in its output voltage at the threshold of the stoichiometric air-fuel ratio (14.7:1). In contrast, the air fuel ratio sensor data is approximately proportionate to the existing air-fuel ratio. The air fuel ratio sensor converts the oxygen density to current and sends it to the ECM. As a result, the detection precision of the air-fuel ratio has been improved. The air fuel ratio sensor data can be viewed using the Global TechStream (GTS).

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