BROADVIEW, Ill. — Bosch announced this week it has produced its 100 millionth hot-film air-mass meter (HFM) at its plant in Eisenach, Germany. Hot-film air mass meters are designed to measure the engine’s air intake, independently of air temperatures and density. The data it provides forms the basis for metering the amount of fuel injected into the engine.
"Achieving the right air-fuel ratio ensures that the engine operates efficiently, which, in turn, reduces emissions," said Warren Suter, director, Engine Management Systems for Bosch’s Automotive Aftermarket Division. "Moreover, in modern diesel engines, hot-film air mass meters serve to control exhaust gas recirculation," Suter said.
The new generation HFM 7 is characterized by its high-precision metering, compact design and sturdiness and is available with either an analog or digital interface to the control unit. And, "as a result of its spontaneous response characteristic," Suter said, "it can quickly deliver reliable data relating to the air flow in the induction tract after starting the engine in a vehicle equipped with a stop-start system."
The success story of the hot-film air-mass meter began in the 1970s with the first air-flow sensor, which worked according to the dynamic-pressure principle. In the 1980s, the hot wire air-mass meter was the first to measure air mass using thermal measurement principles.
The hot wire air-mass meter was first used in Formula1 racing. In 1989, Bosch began manufacturing the first generation of hot wire air-mass meters for production vehicles. They were installed in the Volvo 240. In terms of volume, the HFM5 stands out from the rest. Launched in 1996, it is still being produced today. The HFM5 was the first micromechanical hot-film air-mass meter to be produced on a large scale. In 2006, Bosch launched the HFM6, the first generation to feature a digital interface.
According to Suter, to make engines even more fuel-efficient and eco-friendly in the future, Bosch is working to further improve the air-mass meter’s precision and flexibility. By integrating additional measuring signals into the HFM, such as temperature, pressure or humidity, additional data can be made available for engine management.
Currently Bosch manufactures hot-film air-mass meters at five locations worldwide, including Germany, Russia, Korea and China. The lead plant, however is located in Eisenach, Germany.
