Method for measuring starter motor current to determine engine status

US5585717A · kind A · utility

Assignee

• AB Volvo · SE

Inventors

• Robert Eriksson · Kungälv, SE
• Urban Kristiansson · Göteborg, SE
• Christer Lundstrom · Enköping, SE

Key dates

• Filing date: Dec 23, 1992
• Grant date: Dec 17, 1996
• Expiry date: Dec 23, 2012

Classification

• Technology area (CPC G): Physics
• CPC primary: G01P3/48
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A measuring method for vehicles equipped with an internal combustion engine, the engine including a starter battery and a driven staffer motor used when an attempt is made to start the engine, is disclosed. According to the method, a voltage across a measuring shunt inserted in a current circuit between the battery and the starter motor is repeatedly measured, at a sampling rate, during each revolution of a crankshaft of the engine during activation of the starter motor. Corresponding values of a current delivered from the starter battery to the starter motor are derived from voltage measuring results. Values of the current are registered in a memory of a measuring computer. The registered values are used to establish a status of the combustion engine and its starting system. A value of a derivative of a rotational speed of the combustion engine crankshaft is obtained from the registered values. The sampling rate is sufficiently high to permit obtaining the value of the derivative of the rotational speed of the combustion engine crankshaft.