WHEEL SPEED CHECKING DEVICE Russian patent published in 1998 - IPC

FIELD: transport engineering; automobile antilocking brake system, for measuring wheel rotation speed and automobile engine microprocessor control system for determining position of crankshaft and forming angular position pulses. SUBSTANCE: device has magnetic field source, transducer made of four thin-film magnetoresistors on dielectric base built around bridge circuit, serrated rotor made of ferromagnetic material, amplification and output signal shaping unit. In proposed device base with thin film magnetoresistors is placed on ferromagnetic plate which, in its turn, is arranged on pole of permanent magnet. Size of plate equals 0.5-1.2 of magnet pole surface area, and thickness is 0.3- 0.5 mm. Amplification and output signal shaping unit is built around Schmitt flip-flop on voltage comparator with divider consisting of two resistors placed between supply voltage terminal and comparator output. Noninverting input of comparator is connected to common point of series- connected diode and resistor. Supply of bridge circuit is effected through circuit consisting of voltage stabilizing diode and resistor. High-pass filters formed by resistors and capacitors are placed between output diagonally opposite pair of junctions of bridge circuit and inputs of amplification and output signal shaping unit. EFFECT: enlarged operating capabilities. 4 cl, 4 dwg