Robert Boschgmbh

Adolf R Fritz

Reinhard Leussink

Manfred Mezger

Bernd Bodig

Leo Steinke

Gerd Hohne

Alfred Krappel

Helmut Schmied

Jurgen Zimmermann

Karl-Heinz Adler

Gunter Brand

Johannes Guggenmos

Christian Rein

Eugen Kielbas

Michael Gottschick

Rainer Hellberg

Manfred Metger

The invention is directed to a method for adjusting the idle air actuator in the intake system of an internal combustion engine during idle or overrun operation, the method comprising the steps of: transferring the idle air actuator into a non-driven position in a load area outside the idle or overrun operation; continuously monitoring outside of idle and overrun operation as to whether such a change of operating variables takes place which makes a transfer into idle or overrun operation probable; and, if so, driving the idle air actuator with a value which is determined so that the idle air actuator assumes that position, which, when reaching idle or overrun operation, will presumably by substantially the correct position. The method of the invention affords the advantage that the power loss for driving the idle air actuator is considerably reduced without disturbances (caused by intermittent non-driving of the actuator) occurring in the performance of the engine during transitions from the driven into the non-driven state and vice versa.

Method and arrangement for setting an idle air actuator

Method and arrangement for determining at least one threshold voltage

The period of conduction of an electronic interrupter of an ignition circuit is made shorter increasingly with falling engine speed in comparison to the duration of the period for which the switching path of the engine driven timing generator maintains its condition immediately before the ignition moment. During the time in which that condition is maintained immediately before changing at the ignition moment a capacitor (26) is provided with a first change (b) of its charge in a first direction and thereafter a second change (c) thereof is produced in the other direction. The switching of the electronic interrupter (7) into the conducting condition occurs when the charge of the capacitor reaches a threshold value during the second change of the charge. That threshold value is modifiable by a regulating value that depends at least in part on the engine speed. A monitoring circuit (39) is provided for the capacitor and provides a signal when the charge reaches a reference value which corresponds to the charge that can be reached at an engine speed that lies below the idling of the engine. The signal of the monitoring circuit is used to modify the regulating value that alters the threshold charge value, so that the threshold is reached sooner.

Engine ignition system

In addition to a first storage circuit in which a sawtooth wave is generated for comparing the ramp voltage with a threshold voltage that is caused to vary with engine conditions, particularly engine speed, for determining when the interruptor switch of the primary circuit of an ignition coil is closed to begin buildup of current therein, an auxiliary storage circuit is provided for generating an auxiliary signal within the duration of which the sawtooth wave of the main charging circuit must return to its starting condition, and another pulse signal present during all but an initial portion of the auxiliary signal for rapidly returning that sawtooth wave to its beginning a new beginning, thus making a longer part of the ignition cycle available for variation of the duration of the period during which the interruptor switch is closed to allow buildup of current in the ignition coil.

Engine ignition system with automatic timing shift

The operation of the interrupting switch in the primary circuit of an ignition coil triggers a first timing circuit having a fixed interval or one sometimes modified by engine loading, at the end of which a timing interval signal is generated which lasts for a second interval. The latter is applied to switch a resistor across the timing wave generator to load down its output voltage. In this manner, an engine equipped with a simple ignition shift providing spark advance in the low speed region and then steady or slightly retarding timing thereafter, can be caused to provide a retarding priming shift that sets in at a medium speed, increases and then tapers off with higher speeds so as to cover a speed range in which the engine is particularly sensitive to engine knock and avoiding the inefficiencies which would be necessary if the simple ignition shift system had to be backed off to avoid intersecting the knock boundary. It is also possible to utilize the first timing interval to charge or discharge a capacitor to produce an engine speed signal for biasing the threshold of the interrupter switch for control of the dwell angle with respect to engine speed. Two timing intervals can be determined by a single digital counter reset by each ignition pulse and connected with a decoder set to recognize the ends of successive intervals.

Engine ignition system with anti-knock timing shift

To provide an inherent delayed effect of spark trigger pulses derived from a magnetic transducer in which a salient pole piece of a rotor rotates with respect to a salient pole piece of a stator and, upon juxtaposition, a pulse is induced in a pickup coil magnetically coupled to the rotor-stator circuit, the rotor pole piece is formed to have an arcuate length greater than that of the stator pole piece, with stepped configuration so that, with respect to angle of rotation, the output voltage derived from the coil will have, after passing through zero or null, a half wave which has a portion (C) of decreasing rate of change of absolute value, or differential thereof, and a subsequent and adjacent portion (D) of increasing rate or differential of absolute value with respect to angular change with the sign of the differential remains the same, so that, on slow-speed operation, a trigger circuit set to respond only to the subsequent or adjacent portion will have a voltage induced therein only at a later time, that is, after the rotor has rotated to an angle beyond top dead center (TDC) position, upon high-speed operation, however, the curve portion immediately following the passage through zero or null already providing an output voltage sufficient to trigger the threshold circuit. The rotor can fit into all existing rotor structures, requiring only a modification of the shape of its salient pole piece.

Inductive signal source for internal combustion engine ignition system

In order to control the spark advance of an internal combustion engine in the idling domain, the invention provides circuitry for increasing the spark advance below an upper rpm limit and returning the ignition timing to normal when the engine speed drops below a second lower limit. The continuous temporal shift of an output signal which may be used for engaging the ignition control system of the engine is provided by a very small number of elements, in particular only two timing elements, a flip-flop and a number of logical gates. The two flip-flops are triggered by the respective leading and trailing edges of the engine speed transducer signal. One of the flip-flops defines the upper engine speed limit while the second timing element defines the lower engine speed limit. Two embodiments of the invention are described.

Apparatus for generating an ignition control signal for an internal

In order to increase the closure angle of an interrupter switch connected in series with the primary winding of an ignition coil with increasing engine speeds, a capacitor is connected to the input of a trigger circuit whose output controls this closure angle. The capacitor is charged through a diode while the trigger circuit is switched out. The voltage across the capacitor shifts the threshold of the trigger circuit in a direction increasing the time that the interrupter switch is conductive. The charge on the capacitor is controlled by a signal generator which furnishes an output signal having an amplitude increasing with increasing engine speeds. The closure angle of the interrupter switch therefore also varies as a function of engine speed.

Apparatus for maintaining constant ignition energy with increasing

In order to prevent engine misfires and irregular engine performance when an engine is accelerated from very low speeds, for example starting speeds, due to the engagement of an automatic spark advance feature, the apparatus of the invention provides that the automatic spark advance for low and decreasing engine speeds is operative only when the engine is decelerated from higher engine speeds through an upper threshold level but remains inoperative when the engine is accelerated from low speeds through a lower threshold level. The apparatus includes a number of timing members which define a hysteresis characteristc which shifts the occurrence of an ignition control signal only when the upper speed level is crossed from above. A number of embodiments is presented.

An RC circuit branch determines the duration of the period for which the primary circuit of a spark coil remains interrupted after the main peak of the spark discharge in the secondary circuit that includes a spark plug. Engine speed and engine temperature are used to shorten the period during which the secondary circuit is allowed to entertain a spark discharge. As engine speed increases the spark discharge period is reduced until a certain speed is reached after which the spark discharge period remains constant with further increase of engine speed. Engine temperature is also used to shorten the spark discharge period by the use of a temperature sensitive resistor. The charging and discharging of the storage capacitor of the RC circuit branch are separately controlled by the shunt circuits in which diodes are interposed and in one embodiment an additional capacitor can be switched into parallel into the RC circuit branch when the engine is starting up. The degree of intake manifold vacuum can also be used to modify the operation of the circuit.

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Stuttgart, Germany

Adolf R Fritz