Bi-directional Measurement of Mass Air Flow

Mass air flow (MAF) sensors are one of the essential components of an electronic fuel injection systems. They measure the amount of air entering the engine, or the air flow. Our reliable and accurate mass air flow (MAF) sensors help detect the mass of air flow in a variety of automotive, medical and industrial gas applications.

The LMM-H03 mass air flow sensor is dedicated for applications with high reliability requirements such as medical or industrial gas flow applications.  Mounted directly within the flowing media the LMMH03 is sensitive against the heat transfer on a micrometer scale. This heat transfer is detected by a micro-machined silicon device which is mounted on ceramic substrate defining the geometry of the sensing element. The functional principle of the LMM-H03 is a hot film anemometer, which is the thin film version of the hot wire anemometer. A thin film heating element (heater) is heated to a defined temperature difference with respect to the air. At zero flow there is heat dissipation due to the thermal conductivity of the air. With applied flow the heat dissipation increases steadily with the flow rate. The sensing element can be operated at Constant Power and Constant Voltage mode. However, it is recommended to operate LMM-H03 in the described Constant Temperature Difference (CTD) mode. In the CTD mode the electronics detects any change of the thermal equilibrium very quickly and compensates it by adjusting the power settings through the heaters. This allows a very reliable mass flow measurement with a very short time constant which is in the order of milliseconds.

Sensor Features:

  • Hot film anemometer component
  • highly reliable and long term stability
  • Bi-directional airflow measurement
  • Fast reaction time
  • Can be adapted to various flow channel geometries
  • Can be used for almost all kinds of gases and volatile substances
  • Manufactured according ISO TS16949

Featured Applications

  • Engine control
  • Industrial gas flow measurement
  • Leak detection in pressurized air systems
  • Spirometers