UPDATE : 2017-09-07





Hall devices are extensively applied to modern automobiles, including signal sensors on distributors, speed sensors in ABS systems, autometers and odometers, liquid physical quantity detectors, current detection and working status diagnosis sensors for various electric loads, engine speed sensors and crankshaft angle sensors, various switches, etc.

Here, automobile ignition system is taken as an example. The designer uses a Hall sensor to replace the traditional circuit breaker used in the distributor as the ignition impulse generator. The kind of Hall ignition impulse generator will produce impulse voltage inside the electriferous semiconductor along with the magnetic field with varying speed to control primary current of electronic control unit (ECU). Compared with the traditional mechanical circuit breaker, the Hall ignition impulse generator has no wear and is maintenance-free, which can fit harsh working environment. Besides, it can accurately control ignition timing and substantially improve engine mobility, featuring distinct advantages.

Hall power circuit used on the automobile switching circuit is able to restrain electromagnetic interference. It’s known to all that the higher the automation degree of an automobile, the more microcircuits used on it, and the more it is vulnerable to electromagnetic interference. However, many lamps and electric devices used on the automobile, headlamps, A/C motor and wiper motor featuring large power in particular, can produce surge current at the moment they are powered on or off. Mechanical switching contacts will generate arc and produce large electromagnetic interference signals in this case, while use of Hall power switching circuit can reduce the effect.

Hall devices detect changes in the magnetic field and convert the changes to electric signals before output, which can be used to monitor and measure changes in operating parameters of automobile parts, for instance, position, displacement, angle, angular speed and revolving speed. They can make secondary transformation of these variables and measure others like pressure, mass, liquid level, flow velocity and flow as well. Output quantities of Hall devices are directly accessed to ECU to realize automatic detection.

Currently, Hall devices can all bear certain vibration and are able to work in the temperature range from -40 to 150. They are completely sealed to be free from water and oil contamination and can be totally fit for harsh working environment of automobiles.

Recommended Hall sensors: LC2441F, LC2422 and LC2421

Recommended magnets: bonded NdFeB, sintered NdFeB, and samarium cobalt 

Preview:Electric Bicycle