Robert Boschgmbh

Franz Sellmaier

Rainer Bone

Rudolf Nagel

Bernward Boning

Helmut Reum

Bernward B/o/ Ning

To obtain higher current yield from ion current measurable across the electrodes of a spark plug upon application of a biasing potential thereto, occurring immediately after an ignition event due to ionization of burning hydrocarbons within the combustion chamber of an internal combustion engine (ICE), the polarity of the circuit including a spark plug is so selected that the smaller one of the electrodes, typically the center electrode of the spark plug, has a positive measuring voltage and positive ignition voltage applied thereto so that the positively charged ions, which have a substantially greater mass than the electrons, will be caused to flow to the negatively charged substantially greater electrode, thus resulting in an enhanced ion current. A standard automotive ignition circuit can be used, with the battery connected, as customary, with negative-ground (FIG. 3) by reversely connecting the secondary of the ignition coils--with respect to customary connection--to the center electrode of the spark plug. An auxiliary biasing battery can be avoided by charging a capacitor, for example from the ignition system, to provide measuring energy.

Internal combustion engine combustion chamber pressure sensing apparatus

The output of a combustion chamber sensor is analyzed in two succeeding time intervals defined in term of crankshaft position by use of a reference mark. The sensor output is compared with prescribed threshold values in the respective intervals, and a logic circuit recognizes whether normal combustion, slow combustion or a combustion failure is present and an engine control, such as fuel injection or ignition timing, or a combination of both is modified accordingly.

Control of an internal combustion engine with reference to a combustion

A light guide element, secured in a spark plug-like housing and positioned, for example, within a metallic tube forming a spark plug connector, is coated at the end facing the combustion chamber with a light-impervious material viz: graphite, the graphite emitting radiation upon influence of heat arising within the combustion chamber, which radiation is transmitted to the optical pick-up for subsequent photo-electric evaluation thereof. The optical pick-up is, for example, a quartz glass rod coupled to a light guide cable, or directly coupled to an opto-electrical transducer.

Optical combustion event sensor structure particularly knock sensor for

In order to eliminate from an ion current sensor signals which are not derived from knocking of an engine, the ion current sensor signal is evaluated by a high-pass - low-pass filter to filter out signals of frequencies extraneous to knocking frequencies, using, preferably, a digital filter including two timing stages (11, 13) connected to a counter; to inhibit response of the circuit, an interrupter switch (8) is included in the evaluation circuit, which is opened upon sensing of disturbance signals due to ignition events, for example upon occurrence of ignition, by setting a timing stage (20) which maintains the switch open, and thus inhibits evaluation of oscillatory signals from the ion current sensor (1) for the timing duration thereof. To store previously counted oscillatory signals, a further timing stage (21) can be provided, likewise connected to the ignition signal and enabled at the initiation of current flow through the primary of an ignition coil to prevent resetting of the counter for the timing duration thereof.

Growing community of inventors

Schwieberdingen, Germany

Franz Sellmaier