Gear tooth position and speed sensor with four, bridge circuit connected, magnetic resistance tracks

US4506217A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Manfred Rothley · Gondelsheim, DE
• Erich Zabler · Blankenloch, DE
• Kurt Neuffer · Stuttgart, DE
• Karl-Franz Reinhart · Weinsberg, DE

Key dates

• Filing date: Jul 15, 1982
• Grant date: Mar 19, 1985
• Expiry date: Jul 15, 2002

Classification

• Technology area (CPC G): Physics
• CPC primary: G01P3/488
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

To simplify a field plate effect speed and position sensor, particularly for association with the starter gear of an automotive-type internal combustion engine, four meander-arranged permalloy resistance tracks are located on a substrate at the corners of a rectangle, spaced, in circumferential direction, by about half the pitch distance of the teeth (2) of the starter gear. The resistances can be connected in a voltage divider (FIG. 4) configuration, or in form of a bridge circuit (FIG. 5) supplied from a constant current source (CC) to eliminate temperature variation affects, and providing alternating current output voltages within the wide range of temperature of essentially uniform level as the teeth (2) scan the sensor, a special marker tooth (10) providing an output signal of different level. Preferably, the resistances (5-8) are formed as meander-shaped thin film vapor deposited tracks on a silicon substrate (4), a permanent magnet (9) providing bias magnetization, the direction of which changes with respect to the orientation of the meander tracks--preferably 45.degree. with respect to the direction of rotation (11) to cause the resistance elements to either have high, or l…