Wide Range Oxygen Sensor

ZFAS®-U

Application

Paired with a special interface circuit, this sensor can produce an electric current corresponding to the exhaust gas O₂ concentration. This sensor can be used for control over a wide range of air-fuel ratios from precise stoichiometric control, to lean burn, to enrichment for component protection. The capability of lean measurement enables control for lean burn and diesel engines.

Features

• Accurate output over the entire measurement range
• Fully sealed waterproof design does not require external reference air
• Excellent heat resistance for improved durability
• Fast activation due to monolithic heater and element structure

While a standard oxygen sensor essentially outputs only two states-either rich or lean, the wide range air-fuel sensor is able to measure the degree of richness or leanness. Knowing the magnitude of deviation from the stoichiometric point enables more precise control of the air-fuel ratio. The figure bottom of this page (Histogram of controlled A / F during driving mode) shows the air-fuel ratio distribution over a drive cycle. Exhaust gas contains fewer toxins in the region close to the stoichiometric air-fuel ratio. The lighter background in the figure indicates cleaner exhaust, while the darker regions represent more pollutants. Since the wide range sensor produces a narrower distribution around the stoichiometric point, emissions can be lower than with a standard oxygen sensor. This sensor also enables air-fuel control at points other than stoichiometric, which is applicable to lean burn or diesel engines.

• Sensor output characteristics
  Activation time comparison
  Histogram of controlled A/F during driving mode.

  (3.3MB)

XCU®-UA(ASIC for ZFAS®-U)

Application

XCU®-UA is a single-chip interface and control circuit between the ZFAS®-U sensor and the vehicle CPU. For example, this ASIC provides information to the CPU about the sensor element, which can be used to control the heater and maintain a target temperature for stable oxygen readings.

Features

• Basic ZFAS®-U control circuitry
• Element temperature control circuitry
• Equipped with SPI digital communication
• Basic OBD capability such as terminal open & short detection

• Figure

  (1.4MB)