DE102020101552A1 - Method for operating an externally ignited reciprocating internal combustion engine - Google Patents

Abstract

A method for operating an externally ignited reciprocating piston internal combustion engine with an air intake system which opens into a cylinder head and an exhaust system which is arranged on the cylinder head, a charging device being arranged in the air intake system, an exhaust gas cleaning device being arranged in the exhaust system, with a Valve drive is arranged for a gas exchange of the reciprocating internal combustion engine, which is designed for an early closing of the gas exchange inlet valve (Miller cycle), wherein a passive prechamber ignition system is provided in the cylinder head, with a cavity in which an ignition device can be arranged, the cavity is covered with a cover opposite a combustion chamber of the reciprocating internal combustion engine, the cover having at least one opening which connects the cavity and the combustion chamber to one another in a gas-conducting manner, characterized by the following method steps during an Au Heating phase for the exhaust gas cleaning device: - Starting the reciprocating internal combustion engine, - Setting the valve drive for an early closing of the gas exchange inlet valve during a suction phase of the reciprocating internal combustion engine, - Activating the charging device, at least until the exhaust gas cleaning device reaches a light-off temperature (light-off temperature). Due to the method according to the invention, the prechamber ignition system ignites perfectly immediately after the reciprocating internal combustion engine is started, without misfiring.

Description

The invention relates to a method for operating an externally ignited reciprocating piston internal combustion engine with the features from the preamble of claim 1.

For the technical environment, for example, the German Offenlegungsschrift DE 10 2014 111 897 A1 pointed out. From this an ignition device for igniting fuel-air mixtures in a combustion chamber of an internal combustion engine by means of a corona discharge is known, with an ignition electrode, an outer conductor surrounding the ignition electrode, which has a front and a rear end and with one between the ignition electrode and the outer conductor arranged electrical insulator, from which at least one tip of the ignition electrode protrudes. The at least one tip of the ignition electrode lies in a space which is shielded by a cap assigned to the insulator, which has an inside facing the insulator and an outside facing away from the insulator, as well as one or more holes through which the shielded space and one on the outside The space lying on the cap, the combustion chamber, is in communication.

• - eine Zündelektrode,
• - eine elektrische Versorgungsleitung, an welche die Zündelektrode angeschlossen ist,
• - einen Isolatorkörper, durch den die Versorgungsleitung hindurchgeführt ist,
• - ein Gehäusekopf, der dichtend auf dem Isolatorkörper sitzt und ein Außengewinde zum Einschrauben in einen Verbrennungsmotor,
• - ein Rohrgehäuse, das an dem Gehäusekopf befestigt ist, den Isolatorkörper umgibt und einen Sechskant trägt,

wobei das Rohrgehäuse eine Isolatorkörper-Halterung umgibt, die über eine Schweißnaht mit dem Gehäusekopf verschweißt ist und den Isolatorkörper mit einer Vorspannung gegen den Gehäusekopf presst.Next is from the international patent application with the international publication number WO 2008/031482 A2 Known a spark plug for igniting a combustible gas mixture in an internal combustion engine, comprising:

• - an ignition electrode,
• - an electrical supply line to which the ignition electrode is connected,
• - an insulator body through which the supply line is passed,
• - a housing head that sits tightly on the insulator body and an external thread for screwing into an internal combustion engine,
• - a tubular housing which is fastened to the housing head, surrounds the insulator body and carries a hexagon,

wherein the tubular housing surrounds an insulator body holder which is welded to the housing head via a weld seam and presses the insulator body against the housing head with a pretension.

For further technical information, please refer to the German Offenlegungsschrift DE 10 2016 120 984 A1 pointed out. A prechamber spark plug for a gas-operated internal combustion engine and a method for its production are known from this laid-open specification.

Further is from the German Offenlegungsschrift DE 10 2016 206 992 A1 known a spark plug. The spark plug is in particular a prechamber spark plug with a housing, an ignition electrode and a ground electrode, the ignition electrode being able to be subjected to an electrical voltage via a supply line and the supply line running at least partially within an insulator, with at least one discharge area of the housing is made of a material with a thermal conductivity of over 150 W / mK.

The disadvantage of the known pre-chamber ignition systems is the fact that they are error-free either only at high loads and / or speeds or at low loads and / or speeds of the internal combustion engine, i. H. work without misfiring.

The object of the present invention is to show a method of how a passive prechamber ignition system reliably ignites even in the low load and speed range of a reciprocating internal combustion engine, in particular during catalytic converter heating after the reciprocating internal combustion engine has been started.

This object is achieved by the method in the characterizing part of claim 1.

In passive prechamber ignition systems, i. H. in pre-chamber ignition systems in whose pre-chamber no fuel is actively introduced, a large part of the combustion gas from the previous work cycle remains in the pre-chamber and is mixed with the fresh gas flowing in from the air intake system. In particular, in the load point “catalytic converter heating”, after the reciprocating internal combustion engine has started, the residual gas content in the prechamber is so high that ignition of the mixture in the prechamber is not ensured. Via the process control according to the invention “early inlet closes”, a strong negative pressure is generated in the combustion chamber and in the antechamber, so that the antechamber is virtually sucked empty by this negative pressure.

“Early intake closes” means operating the reciprocating internal combustion engine with the Miller cycle (also called Miller cycle). This is named after the inventor Ralph Miller, who patented a gas exchange valve drive in 1957, in which the gas exchange inlet valve closes very early, ie during the intake stroke, before the piston has reached its bottom dead center. The filling of the cylinder with fresh gas and the final compression pressure are thereby reduced, but the compression and thus the expansion ratio remain the same. In Miller operation of a reciprocating internal combustion engine, this causes an increase in the thermodynamic Efficiency through better utilization of the expansion energy in the work cycle.

When the fresh gas subsequently flows over from the main combustion chamber through the openings in the cover of the pre-chamber ignition system into the pre-chamber, a mixture with significantly lower residual gas flows in, which can then be safely ignited. For the "catalytic converter heating", however, a maximum fresh air mass is required in the combustion chamber in order to ensure, on the one hand, a high exhaust gas mass flow with a high exhaust gas temperature to heat the catalytic converter by means of a retarded ignition angle and, on the other hand, to still have enough torque available to operate the reciprocating internal combustion engine litigation via "early admission closes" is not guaranteed. To compensate for this disadvantage, the further process control according to the invention is proposed, in which the required fresh air mass can be introduced into the cylinder by using a charging device that can be electrically driven, for example (e-compressor, e-ATL). The purging of the prechamber ignition system will then take place at a higher pressure level for reliable ignition.

• 1 zeigt einen Schnitt durch ein beispielhaftes Vorkammerzündsystem.

The invention is briefly explained below with reference to a single figure.

• 1 shows a section through an exemplary prechamber ignition system.

1 Figure 11 shows a section through an exemplary passive atrial ignition system 1 . The pre-chamber ignition system 1 is intended for an externally ignited reciprocating internal combustion engine, for example for use in a motor vehicle or a single-track vehicle.

The pre-chamber ignition system 1 has a housing 2 on, in which an ignition device 4th with a center electrode 5 and a ground electrode 6th is introduced. From an ignition end of the ignition device 4th and the case 2 is a cavity 7th locked in. The pre-chamber ignition system 1 is introduced into a cylinder head, not shown in detail, of the reciprocating internal combustion engine until one of the ignition device 4th remote part of the housing 2 protrudes with its non-numbered cover into a combustion chamber of the reciprocating internal combustion engine.

The cover has at least one opening 8th on, in the present embodiment four, of which in 1 only two can be seen that form the cavity 7th and connect the combustion chamber with gas. When the reciprocating internal combustion engine is operating, a fuel / air mixture is produced, which flows from the main combustion chamber through the openings 8th flows through into the prechamber ignition system, in the cavity 7th ignited, subsequently due to the combustion in the cavity 7th "Fire torches" through the breakthroughs 8th shoot through into the combustion chamber and ignite the main fuel / air mixture in the combustion chamber. In the prechamber ignition system 1 no fuel is brought in directly.

In this exemplary embodiment, the cover has a gas line 9 through which a fresh air / fuel mixture up to the area of the center electrode 5 and the ground electrode 6th can be conveyed and thus displaces undesired residual gas, which prevents reliable ignition.

In a further exemplary embodiment, it is also conceivable that the gas line 9 not straight into the cavity 7th protrudes, but coiled, so that a swirl flow in the cavity 7th is generated, for an even better displacement of the residual gas, whereby the ignition is further improved.

Thus, particularly in the case of low load and / or speed ranges, in particular when the reciprocating piston internal combustion engine is “catalyzed”, there is always an ignitable fresh air / fuel mixture in the ignition range of the ignition device 4th in front. Reliable ignition is therefore always guaranteed, especially with "catalytic converter heating".

“Katheizen” is the period of time until an exhaust gas cleaning device in the exhaust system of an internal combustion engine has reached its operating temperature (light-off temperature). This is the temperature at which the exhaust gas cleaning device neutralizes 50% of the pollutants emitted by the reciprocating internal combustion engine.

• - Starten der Hubkolben-Brennkraftmaschine,
• - Einstellen des Ventiltriebs für ein frühes Schließen des Gaswechseleinlassventiles während einer Ansaugphase der Hubkolben-Brennkraftmaschine,
• - Aktivieren der Aufladevorrichtung, zumindest bis zum Erreichen einer light-off Temperatur (Anspringtemperatur) der Abgasreinigungsvorrichtung.

With such a passive prechamber ignition system, an externally ignited reciprocating piston internal combustion engine with an air intake system which opens into a cylinder head and an exhaust system which is arranged on the cylinder head, a charging device being arranged in the air intake system, an exhaust gas cleaning device being arranged in the exhaust system, in the cylinder head is arranged a valve drive for a gas exchange of the reciprocating internal combustion engine, which is designed for an early closing of the gas exchange inlet valve (Miller cycle), are operated according to the invention by the following method steps during a heating phase for the exhaust gas cleaning device:

• - Starting the reciprocating internal combustion engine,
• - Setting the valve drive for an early closing of the gas exchange inlet valve during an intake phase of the reciprocating internal combustion engine,
• - Activation of the charging device, at least until a light-off temperature (light-off temperature) of the exhaust gas cleaning device is reached.

List of reference symbols

1

Pre-chamber ignition system

2

casing

3

Cylinder head

4th

Ignition device

5

Center electrode

6th

Ground electrode

7th

cavity

8th

breakthrough

9

Gas pipe

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102014111897 A1 [0002]
• WO 2008/031482 A2 [0003]
• DE 102016120984 A1 [0004]
• DE 102016206992 A1 [0005]

Claims (1)

Method for operating an externally ignited reciprocating piston internal combustion engine with an air intake system which opens into a cylinder head and an exhaust system which is arranged on the cylinder head, wherein A supercharging device is arranged in the air intake system, an exhaust gas cleaning device being arranged in the exhaust system, a valve drive for a gas exchange of the reciprocating internal combustion engine being arranged in the cylinder head, which is designed for an early closing of the gas exchange inlet valve (Miller cycle), wherein in A passive pre-chamber ignition system is provided for the cylinder head, with a cavity in which an ignition device can be arranged, the cavity being covered with a cover opposite a combustion chamber of the reciprocating internal combustion engine, the cover having at least one opening that contains the cavity and the combustion chamber gas connects with each other in a leading way, characterized by the following process steps during a heating phase for the exhaust gas cleaning device: - Starting the reciprocating internal combustion engine, - Setting the valve drive for an early closing of the gas exchange inlet valve during an intake phase of the reciprocating internal combustion engine, - Activation of the charging device, at least until a light-off temperature (light-off temperature) of the exhaust gas cleaning device is reached.

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