Abstract: Process for the preparation of a compound with enhanced optical purity wherein a mixture of the enantiomers of a chiral compound of formula 1 wherein: R1 represents an alkyl or an aryl group R2 represents H, an alkyl or an aryl group Y represents an alkyl group, an aryl group, (CH2)nCOOH, (CH2)n—COOR, (CH2)n—CONRR?, CH2OH, or C?N wherein R and R? independently represent H, an alkyl or aryl group, and n represents 0 or 1, is brought into contact with an enzyme having peptide deformylase activity with a bivalent metal ion as a cofactor wherein the metal is chosen from the groups 5–11 of the periodic system, or for the preparation of a formylated compound with enhanced optical purity from a mixture of the enantiomers of the corresponding not formulated chiral compound in the presence of a formylation agent. Preferably the peptide deformylase is chosen from the class EC 3.5.2.27 or EC 3.5.1.31, and contains the sequences of (I) HEXXH, (ii) EGCLS and (iii) GXGXAAXQ.

Abstract: 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.

Abstract: In a method for determining at least one threshold voltage in controlling lambda one, this voltage is no longer set to a precisely predetermined value with the aid of a high-precision reference voltage source; instead, a counter voltage, connected in opposition to the probe voltage, is measured and the threshold voltage is referred or the threshold voltages are referred to the measured value and the absolute amount of the measured voltage does not have to be known. This method makes it possible to manage without a high-precision reference voltage source and without high-precision resistors. Instead, an arrangement according to the invention has a means for measuring the counter voltage and a means for referring threshold voltages to the counter voltage.

Abstract: 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, tha

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An internal combustion engine is comprised of at least one engine cylinder, devices for introducing a combustion mixture into the cylinder, and an electrical igniting element operative for igniting the combustion mixture in the cylinder once per ignition cycle. An ignition transformer has a secondary winding connected across the igniting element, and also has a primary winding. A flow of current is established through the primary winding. An electronic switch is connected in the current path of the primary winding to control the flow of current through the primary winding. A triggering unit generates a train of crankshaft-synchronized triggering signals.