Method and apparatus for automatic shift of ignition timing. [timing circuit for reduced exhaust emissions]
A transducer provides a signal in the form of a pulse of steady current on which an alternating current is superimposed over a period corresponding to the range of ignition timing shift. Beginning at the same time, a timing circuit determines the width of a gate in which pulses from a pulse generator will be transmitted. The gate width and the pulse generator frequency are controlled by operating conditions of the engine, such as temperature and intake vacuum. The alternations of the transducer output signal are counted in a first counter and the pulses passed through the gate are counted in a second counter and stored for the next count interval. That stored count and the count of the first counter are compared and a match in these inputs controls a trigger for the ignition circuit. At high speeds, the stored count is zero and a null detector allows the initial part of the transducer signal to trigger the ignition, this being the maximum spark advance. Such circuits allow the timing shift to begin at a moderate threshold speed and to vary rapidly with speed over a relatively narrow speed range, until the maximum timing shift is reached. This critical speed range is shifted by changes of engine temperature or of intake vacuum.
- Assignee:
- Robert Bosch GmbH
- Patent Number(s):
- US 3919987
- OSTI ID:
- 7365530
- Resource Relation:
- Patent Priority Date: Priority date 23 Sep 1973, German, Federal Republic of (F.R. Germany)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AUTOMOBILES
CONTROL SYSTEMS
SPARK IGNITION ENGINES
COMPARATOR CIRCUITS
GAS COMBUSTION PROCESS
IGNITION
PULSE GENERATORS
TIME DEPENDENCE
TIMING CIRCUITS
ELECTRONIC CIRCUITS
ELECTRONIC EQUIPMENT
ENGINES
FUNCTION GENERATORS
INTERNAL COMBUSTION ENGINES
VEHICLES
330603* - Vehicle Design Factors- Engine System