Pulse amplifier with zero crossing point detection

US4311924A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Werner Breckel · Wissen, DE
• Bert Wurst · Asperg, DE

Key dates

• Filing date: Jun 13, 1979
• Grant date: Jan 19, 1982
• Expiry date: Jun 13, 1999

Classification

• Technology area (CPC H): Electricity
• CPC primary: H03K3/2893
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

In order to generate a signal having a well-defined feature which exactly coincides with the zero-crossing point of an input signal, for example in order to define the top dead center position of the crankshaft of an engine for the purpose of valve and ignition timing, the invention provides a circuit which is prepared by the passage of the first half of an input signal across a predetermined threshold. When the first threshold is exceeded, the circuit opens a switch which connects a source of reference potential, equal to the zero crossing point of the input signal, to the threshold switch, to represent a second threshold. As the input signal crosses that second threshold level, which constitutes the zero crossing point, the threshold switch closes, thereby generating the trailing edge of the output signal which constitutes a signal feature coincident with the zero crossing point and hence with a fixed angular position of the rotating shaft. As the zero crossing point is passed, the first threshold level is reestablished. The occurrence of the trailing feature of the output signal is in a constant phase relationship to the input signal and does not depend on the amplitude, frequen…