Hitachi Automotive Systems Espelkamp GmbH | Eugen-Gerstenmaier-Str. 8 | 32339 Espelkamp

Air Flow Meters

An important criteria for the development of passenger cars is the requirement to meet legal emissions and optimize overall engine performance and fuel economy. To achieve this task it is necessary to determine the exact relation of air mass to fuel which is accomplished by the “air flow meter”.

The Air Flow Meter is used to measure the mass flow rate of air entering the engine. The air mass information is necessary for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine. Air changes its density as it expands and contracts with temperature, altitude and the use of forced induction, which means Air Flow Meters are more appropriate than volumetric flow sensors for determining the quantity of intake air in each piston stroke.

Structure

The actual sensor is integrated in the flow channel of the plug in sensor. These plug in  sensors are suitable for the installation in air cleaners and in so-called measuring tubes, which are to be found in passenger cars.

An electronic measuring system converts the sensor data into appropriate measuring data for the engine management/fuel injection system.

Function

The system is based on an indirect measurement of the air flow. The sensor element is heated by an electric circuit to a specified value. As air passes over the element the sensor measures the drop in temperature. The measured temperature of the sensor element is reduced as the air flow is increased, and measured temperature increases as the air flow is decreased. The sensors integrated electronic evaluates this data resulting in an exact determination of the air flow.

 

Learn more about our range of air flow meters.
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