Robert Boschgmbh

Peter Schulzke

Klaus Harsch

Albrecht Sieber

Peter Werner

Ulrich Steinbrenner

Dieter Gunther

Klaus Streit

Herbert Arnold

Otto Glockler

Walter Buxmeyer

The maximum speed in an internal combustion engine is limited by circuitry which can be adjusted to conditions requiring a lower-than-normal top speed, for example during initial delivery to the customer and during the break-in period of the engine. The top speed limiter includes a comparator for suppressing or altering the fuel injection pulses. As a feature of the invention, the reference signal applied to the comparator and representing the top engine speed can be changed either manually or on the basis of elapsed time or mileage.

Top speed limiter for an internal combustion engine

An apparatus is proposed for driving electromagnetic devices, in particular electromagnetic injection valves in internal combustion engines. The apparatus includes a signal source for actuating pulses and is characterized in that at least one timing circuit is provided for advanced magnetization, preferably dependent on operating characteristics, of the electromagnetic device. The apparatus achieves the most linear possible relationship between the duration of the actuating pulse and, for example, the opening time of the injection valve. In this manner, the fuel quantity to be supplied to the internal combustion engine can be more precisely dosed and the operational behavior of the engine can be made optimal. Because of the advanced magnetization, the electromagnetic injection valve, for example, attracts more rapidly at the onset of the actuating pulse, because the magnetic coil has already stored a certain amount of energy, which lies somewhat below that amount which is required for attraction on the part of the magnetic core and thus for the ejection of fuel.

Apparatus for driving electromagnetic devices, particularly

An apparatus is proposed for controlling the electric current through inductive consumers, in particular through a fuel metering valve in internal combustion engines, this apparatus representing a two-point closed-loop controller and functioning with a single threshold switch for an upper and a lower threshold. The apparatus includes one current-measuring resistor each in the freerunning circuit and in the main current circuit, both measuring resistors being members of a voltage divider between the two supply voltage lines and whose middle junction is carried to the threshold switch. By means of a resistor-diode network in combination with the threshold switch, a correction can be made in the individual switching thresholds in accordance with supply voltage.

Apparatus for controlling the electric current through an inductive

An apparatus is proposed for controlling the de-excitation time of electromagnetic devices, in particular electromagnetic injection valves in internal combustion engines, wherein a switch (or an actuation circuit in general) is disposed in series with the device, characterized in that a circuit arrangement with a controllable output potential is disposed in series or in parallel with the electromagnetic device. It is the purpose of the apparatus to linearize the current decrease through the electromagnetic device after the end of the actuation pulse and preferably to simultaneously control its rate of decrease. As a result, control of the de-excitation time of the particular electromagnetic device is attained. In terms of function, the circuit arrangement represents a controllable Zener diode.

Apparatus for controlling the de-excitation time of electromagnetic

In order to prevent undesirable abrupt changes in engine torque when the fuel supply to the engine is shut off at the onset of engine braking, the invention provides the gradual decrease of the amount of fuel supplied to the engine beginning with the onset of engine braking and continuing until fuel has decreased to approximately 80 percent of the normal amount at which time the fuel is shut off entirely. When engine braking stops or when the operator indicates a demand for acceleration, the fuel supply is initiated at the level of approximately 80 percent of normal and is increased thereafter up to the normal amount according to a second selectable function of time.

Method and apparatus for controlling the fuel supply of an internal

A signal generator for use with a fuel supply system which incorporates a fuel shut-off mechanism. The output signal from the signal generator is applied to the fuel shut-off mechanism whenever the engine exceeds a maximum speed. In order to detect this condition, rpm-synchronous pulses are applied to at least one, and preferably two cascaded multivibrators which control an input of a gate, the other input of which receives the rpm-dependent pulses. The output of the gate is active only if the period of the rpm-dependent pulses is less than the sum of the unstable time constants of the multivibrators, in which case a final multivibrator is triggered and generates a fuel suppression control signal during a large fraction of two crankshaft rotations.

Signal generator for suppression of fuel supply actuation at top engine

An installation for the operation of electromagnetic loads, especially solenoid valves, in fuel supply systems in internal combustion engines, wherein a measuring resistor as well as a switch are connected in series with the load and the entire arrangement is connected to the two supply voltage terminals. The installation comprises two comparators connected in parallel with the measuring resistor, at least one resistor being connected in front of these comparators, and controllable current source arranged between the junction of the threshold switch and the resistor in the proximity of the load, as well as a supply voltage terminal. The supply voltage of one of the comparators is made dependent on the voltage in the freewheel circuit, to maintain at least one of the comparators in the operating position even during freewheeling operation.

Installation for operating electromagnetic loads in internal combustion

A method is proposed for operating an electromagnetic load device with a movable armature, especially an injection valve of an internal combustion engine. The load device is supplied, at the beginning of trigger pulse, with a high amperage current and, at least toward the end of the pulse, with a reduced current. This method is characterized in that, starting with a certain amperage, at which preferably the armature is set into motion but has not as yet reached its final position, the current rise is at least reduced. The apparatus aspect comprises a measuring element and switching element connected in series with the load device. A threshold switch is associated with the measuring element to control the switching element. The switching thresholds of the threshold switch can be controlled in dependence on current and/or on time. The first current threshold is at a value at which the armature of the load is preferably being moved, but has not yet reached its final position. The method and the apparatus achieve a low power operation of the load device with a coincidence factor between the trigger pulse signal and, for example, the switching characteristic of an injection valve. It is essential that the current flow, after the starting current, no longer continue to rise in the same way but rather, if possible, is already somewhat reduced and, after the armature of the load has been attracted, a holding current is established as a function current and/or time. With a view toward a clear cut-out characteristic, a short term current supply to the load is advantageous at the end of the actual trigger pulse signal.

Method and apparatus for operating an electromagnetic load, especially

To provide for rapid interruption of the combustion process in an internal combustion engine, for example by inhibiting ignition or supply of fuel by a fuel injection system, speed pulses are integrated and the integrated signal evaluated with respect to a reference to determine whether the integrated signal, and hence the speed of the engine, exceeds a predetermined level; a timing circuit is connected to the evaluation circuit to provide a control signal for a predetermined time interval to inhibit fuel combustion of the engine for the predetermined time interval in case the speed is exceeded. If fuel injection pulses are to be inhibited, then the timing of the timing circuit is synchronized with the fuel injection pulses to provide for complete suppression thereof without pulse overlap.

Governor system for internal combustion engines

Electronic control circuitry is provided for controlling the actuating current of electromagnetic devices and in particular of the electromagnetic fuel injection valves of an internal combustion engine. In order to program the magnitude of the actuating current from an initial high level to a lower maintenance level, there is provided a driver circuit which receives fuel injection control pulses from a fuel injection system, not itself part of the invention, and processes these control pulses into valve-actuating current pulses. The valve current is sensed by suitable transducer, for example a resistor, and the resulting signal is fed to a two-point controller which suitably alters the input to the driver circuit to thereby change the valve actuating current. The set-point value on which the two-point controller operates is itself subject to change by means of a suitable circuit. There is further provided a free-running circuit and a quenching circuit for reducing the voltage peaks resulting from the collapse of the magnetic fields stored in the valve actuating coils. Two embodiments are presented.

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Hemmingen, Germany

Peter Schulzke