Robert Boschgmbh

Hermann Vetter

Ernst-Olav Pagel

Winfried Klotzner

Wolfgang Borst

Hubert Schweiggart

A method of determining a measurement value (U.sub.-- M) utilizes a calibrating operation and a measuring operation together with an operational amplifier (OP) having an output voltage (U.sub.-- A). The measurement value (U.sub.-- M) represents a current (I) flowing through a load (L) in a motor vehicle having a battery. The battery has a terminal of high potential and a terminal of low potential with the difference between the potentials being the battery voltage (U.sub.-- BATT). The load (L) is connected into a load current circuit and a measuring resistor (R.sub.-- M) also is connected into the load current circuit conducting a load current (I) which, in turn, causes a voltage (R.sub.-- M.cndot.I) to drop across the measuring resistor (R.sub.-- M). The method includes the steps of: amplifying the voltage R.sub.-- M.cndot.I across the measuring resistor (R.sub.-- M) utilizing the operational amplifier (OP); performing the calibrating operation with a sequence of substeps; and, performing the measuring operation with a further sequence of substeps to obtain the measurement value (U.sub.-- M). In this way, the previously required balancing of resistors in the calibrating operation can be omitted.

Method for determining the current flowing through a load in a motor

The input dc voltage is used to operate an astable multivibrator, the output of which is supplied to an emitter-follower that is coupled to an amplifier through a current-limiting resistor, so that a transistor across the input of the amplifier can controllably reduce the amplification of the amplifier. The amplifier output is supplied to the primary winding of a transformer which has a secondary winding that feeds a rectifier to supply the output dc voltage. The output dc voltage is coupled back to the control transistor through a Zener diode and a resistor in series, so that when the output voltage exceeds the Zener diode voltage, the control transistor will reduce the amplification of the amplifier, reducing the amplitude of the rectified ac voltage and hence regulating the output voltage.

DC Converter

To control the ignition timing in a multicylinder engine, the computer output signal which controls the current flow through the ignition coil for generating the spark in the first cylinder is delayed and then applied to the ignition coil controlling the spark in a subsequent cylinder. The computer output signal is delayed by passing through a shift register whose clock input is derived from a pulse generator generating a pulse for each predetermined incremental angular rotation of the crankshaft. If a single ignition coil and a distributor are used, the computer output signal and the delayed computer output signal are applied to an OR gate whose output controls a switch controlling the current through the ignition coil. When more than one ignition coil is used, the computer output signal is applied to a switch controlling the current through the first coil, the delayed computer output signal to a switch controlling the current to a second coil. Further delays may be furnished for a control of sparking in additional cylinders.

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Hessigheim, Germany

Hermann Vetter