Robert Boschgmbh

Helmut Moder

Peter Werner

Ulrich Drews

Ulrich Steinbrenner

Hans Schnurle

Klaus Streit

Erwin Gloss

Adolf Kugelmann

Dieter Kirn

To reduce further switching energy arising upon changing-of-state of a semiconductor switch pair, connected to a load (17), particularly an inductive load, switching dissipating networks (6, 7), each including a storage capacitor (9, 12) which receive and accept switching energy in the respective semiconductor switch (4, 5), are interconnected by an additional network (15, 16; 20; 21-26) to place the respective capacitors, effectively, in parallel for additional energy storage and provide a single network for current flow upon changing-of-state of the respective switch to the capacitors, the energy represented by the current flow being retrievable by forming the additional network (FIG. 3), for example, as a voltage converter, e.g. a blocking oscillator, permitting feedback of the recovered switching energy to a supply source (1, 3) which may be a storage battery.

Low-loss semiconductor switching circuit

A fuel injection control circuit includes a monostable multivibrator for generating injection valve control pulses. The circuit includes a trigger sub-circuit which controls the switching characteristics of the monostable multivibrator in a well-defined manner which is immune to electrical noise and to voltage fluctuation in the supply lines of the vehicle.

Electrically controlled fuel injection system

A fuel mixture control apparatus for an electronic fuel injection system for internal combustion engines. In a warm-up controller, the fuel injection control pulses are lengthened for enrichment of the fuel-air mixture during engine warm-up on the basis of signals supplied by a temperature transducer. In order to make the warm-up enrichment dependent on prevailing engine states, for example on the conditions of idling and partial or full load, circuitry is provided to sense these conditions and to suitably alter the enrichment factor. A further circuit suppresses the dependence or enrichment on engine status during engine starting. Various embodiments are presented.

Fuel mixture control system

A sensor which determines an operational variable of a system, for example an oxygen sensor of an internal combustion engine, generates a usable output voltage only at the proper elevated temperature. In order to uncouple the control loop from an improperly operating sensor, i.e., a cold sensor, the internal resistance of the sensor is monitored by passing through it a test current and by comparing the resulting voltage drop to a set-point value. Whenever the internal resistance is too high, indicating non-readiness, the control loop is opened and a substitute average output value is supplied to the fuel injection system or to the system driven by the control loop. During normal operation, the sensor is tested periodically with short test pulses to continuously monitor the operational readiness, but the main test current is normally shut off, thereby preventing falsification of the output signal.

Sensor monitoring apparatus

A fuel injection control apparatus provides electrical pulses whose length determines the amount of fuel supplied to the injection valves of the engine. These pulses can be extended by a circuit including a temperature dependent resistor when the engine has not reached operational temperature. This same mechanism is utilized to lengthen the fuel delivery control pulses even when the engine is warmed up, i.e., under hot-start conditions, by connecting a switching transistor in series with the temperature-dependent resistor that monitors the engine temperature. If, while the engine is hot, the starter motor is being cranked longer than a predetermined length of time, the switching transistor turns off and causes the fuel injection pulse to be lengthened, thereby supplying additional fuel to the engine to overcome a possible fuel vapor lock.

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Stuttgart, Germany

Helmut Moder