Wide Range Oxygen Sensor

ZFAS®-U2

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. Compared to the previous design the ZFAS®-U2 wide range air-fuel sensor achieves outstanding reliability and activation speed.

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 (5sec) 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)