Robert Boschgmbh

Bernd Kraus

Hans Schnurle

Otto Glockler

Cornelius Peter

Harro Herth

Ulrich Drews

Erich Singer

Wolf Wessel

Peter Werner

Gunther Plapp

Michael Horbelt

Alfred Kratt

Dieter Gunther

Wilfried Sautter

Richard Bertsch

Thomas Wilfert

Rudi Mayer

Claus Ruppmann

Jurgen Penschuck

An apparatus is proposed for regulating the idling rpm of internal combustion engines with externally supplied ignition. The apparatus includes a comparison circuit for set-point and actual rpm, and the idling rpm set-point value can be influenced in accordance with the actual rpm, time, operating voltage, temperature, and other variables as needed. The actual regulation is effected by means of a PID-regulator, whose individual characteristics may be established for processing data as desired, preferably in accordance with the rpm deviation. A limitation regulator furthermore serves to establish the respective maximum and/or minimum limitation of the adjustment member in accordance with operating characteristics.

Apparatus for regulating the idling rpm of internal combustion engines

A fuel metering system having a .lambda. regulation device in which the delay periods known per se from the prior art are variable upon the switchover of the integration direction of an integrator included in the .lambda. regulation system. This variation produces a shortening of the delay period, as a result of which it is possible to prevent an excessive enrichment of the mixture. The invention relates to a controllable reduction of the individual delay signal as well as a control of the total duration of control exerted on the delay signals as they appear. The invention is independent of whether it is realized by either analog or digital circuit technology.

Fuel metering system for an internal combustion engine

An apparatus for the temperature control of a resistor used for measurement purposes, in particular, in combination with air flow rate measurement purposes, in particular, in combination with air flow rate measuring devices in internal combustion engines for a vehicle wherein the temperature of the resistor with current flowing through it is regulated during the measurement phase and in particular, operational states of the system provided with the apparatus and/or at particular times, the flow of current through the resistor is increased for the purpose of burning off dirt particles, which would falsify the measurement result, from the surface of the resistor which is formed, for example, as a hot wire. The apparatus includes a memory for picking up a signal such as whether a particular engine temperature is present at the beginning of one operational cycle or not and when this temperature is present, a red-hot heating procedure is omitted when the engine is subsequently turned off. In addition, the increase in current for initiating the red-hot heating procedure may also be controlled in accordance with operational duration and driving distance of the vehicle and in accordance with time.

Apparatus for temperature control of a resistor used for measurement

A flow rate meter for measuring the flow rate of a fluid medium, especially that of the air aspirated by an internal combustion engine. A hot wire or film is placed in the air stream and is made part of an electrical circuit powered by the output of a differential amplifier. The voltage drop across the resistor is monitored at the input of the differential amplifier where it is compared with fixed or compensated values. In order to reduce the effect that airborne particles, which are deposited on the hot wire or film, have on the measuring characteristics of the apparatus, the wire or film are shaped so that their leading edge constitutes an area much smaller than the surfaces which are substantially parallel to the stream lines.

Flow rate meter with temperature dependent resistor

The fuel-air mixture preparation system of an internal combustion engine is engaged by signals from a plurality of oxygen sensors located in the exhaust system of the engine. More than one sensor is provided to improve the quality of the output signals in unfavorable engine operation. The individual sensors are provided with comparators which make a comparison between the sensor output and a set-point signal. The output signals from the comparators are fed to a logically controlled coupling circuit which presents them in cyclic alternation to an integrating control circuit which provides a control signal to the final control element in the fuel mixture preparation system for changing the fuel-air ratio. The coupling circuit may also provide a signal based on the logical states of the individual sensor signals.

Method and apparatus for fuel-air mixture control

A control circuit of a fuel management control system for internal combustion engines monitors the operation of an exhaust line sensor. When the oxygen sensor is perceived to be inoperative, for example, due to low ambient temperature, the previously closed loop control process governing the fuel management control signals is interrupted and a direct forward control process is substituted therefor. The reference voltage is changed during this time for eventual adaptation to the changeover to closed loop feedback control after the oxygen sensor again becomes operational.

Method and apparatus for controlling fuel management for an internal

The fuel mixture preparation system of an internal combustion engine, especially a continuous fuel injection system, is engaged during intended engine accelerations by a pressure sensor in the induction manifold which responds to increasing manifold pressure to close a switch. The switch closure affects a pressure control valve that changes the control pressure in the fuel injection system and thereby causes temporary fuel enrichment until the differential pressure in the pressure sensor has returned to equilibrium. The signal from the pressure sensor may be extended arbitrarily by interposition of an electronic timing circuit which is constructed as an integrating circuit so that its output signal, when processed by a comparator, will produce a proportionally extended actuation signal for the control valve.

Method and apparatus for fuel mixture enrichment during acceleration

A flow rate measuring device, especially for measuring the flow rate of incoming fresh air in the induction tube of an internal combustion engine in which a temperature-dependent sensor, e.g. a resistor, is exposed to the air flow while the current through the sensor is controlled and monitored to obtain a signal related to the air flow rate. In order to prevent damage to the sensor from high-temperature flame fronts due to backfiring and also from inadvertent mechanical contact with tools, etc., there is provided at least one protective element downstream of the sensor and possibly another element upstream. The protective element is a plate-like barrier permitting essentially unimpeded air flow. The pattern of the element may be a grid or sieve, a honeycomb pattern or a plurality of parallel tubes.

Flow rate meter with temperature-dependent resistor

Circuitry is described for use with a fuel mixture control system of an internal combustion engine in which an oxygen sensor is located in the exhaust system and generates a generally bi-valued signal which is compared with a set-point voltage to indicate rich or lean mixtures. In order to permit control loop operation even when the sensor signal changes due to decreasing temperatures, the set point voltage is adjusted to remain between the two values of the sensor signal. This adjustment is effective only when the lower sensor signal exceeds a given limit.

Fuel-air mixture control apparatus

A circuit to be used in association with a fuel mixture control system which includes an oxygen sensor in the exhaust system to determine the relative richness of the combustible mixture. When the engine operates at low speeds, its control response time becomes large due to decreased engine throughput. In order to prevent control oscillations from occcurring under these conditions, the time constant of integration of the oxygen sensor control loop is changed to accommodate to the longer engine response time. For this purpose, the zero crossings of the oxygen sensor signal are compared with the unstable time constant of a multivibrator and a transistor which normally shunts a timing resistor is blocked, thereby increasing the time constant of the control integrator.

Apparatus for preventing control oscillations in a combustion mixture

A fuel injection system for an internal combustion engine includes electromagnetic injection valves controlled by a fuel control unit which receives signals from a camshaft actuated switch, a position-dependent throttle transducer and an oxygen sensor. When the oxygen sensor changes output levels, the transmission of this information is delayed, by the action of a switching transistor controlled by a monostable multivibrator, for a period of time equal to the internal time constant of the multivibrator.

Fuel injection system

The maximum speed of an internal combustion engine is limited by a device which compares the period of rpm-synchronous pulses with the time constant of a reference multivibrator. If the engine rpm is so high that a pulse terminates prior to expiration of the reference time period, a gate is activated and acts through further multivibrator circuits to interrupt the fuel delivery to the engine, e.g., the fuel injection control pulses are suppressed. If the maximum rpm is exceeded only intermittently, the device restores normal fuel injection control pulses after a predetermined number of pulses has been suppressed. If the maximum rpm is exceeded continuously, the device restores normal fuel control somewhat later than the time at which the engine speed drops to below maximum rpm.

Method and apparatus for RPM limitation in internal combustion engines

A fuel supply and metering valve assembly used for fuel injection to an internal combustion engine includes a control pressure circuit which determines the restoring force on the movable valve member of the metering valve. The magnitude of the control pressure, and hence the fuel quantity metered out by the valve assembly, can be altered by intermittent actuation of a pressure relief valve whose duty cycle is controlled by an oxygen sensor located in the exhaust line of the engine. The oxygen sensor voltage is superimposed on a sawtooth voltage at the input of a control circuit which varies the duty cycle of the bypass valve. When the oxygen sensor is too cold to generate an output signal, the control circuit is provided with a temporary control signal supplied by a timing circuit until the oxygen sensor has reached its normal temperature and generates an output signal.

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Gerlingen, Germany

Bernd Kraus