EP3464876A1

EP3464876A1 - Ignition device and method for igniting an air/fuel mixture

Info

Publication number: EP3464876A1
Application number: EP17728054.2A
Authority: EP
Inventors: Michael Wollitzer; Gunnar Armbrecht; Martin Fuchs; Peter Awakowicz; Thomas Musch; Sven GRÖGER; Andre Bergner; Gordon NOTZON; Marcel VAN DELDEN
Original assignee: Rosenberger Hochfrequenztechnik GmbH and Co KG
Current assignee: Rosenberger Hochfrequenztechnik GmbH and Co KG
Priority date: 2016-06-02
Filing date: 2017-05-30
Publication date: 2019-04-10
Also published as: DE102016006782A1; CN109312708B; KR20190012140A; CN109312708A; US20190293043A1; US10895241B2; JP2019520512A; WO2017207098A1; TW201809457A

Abstract

The present invention relates to an ignition device for igniting an air/fuel mixture in at least one combustion chamber, in particular an internal combustion engine, having at least one ignition system with electrodes for each combustion chamber, at least one high-voltage source for generating an electrical high-voltage impulse at an output of the high-voltage source, and having at least one high-frequency voltage source for generating an electrical high-frequency alternating voltage at an output of the high-frequency voltage source, wherein m ignition systems (10_i) are provided with the formula (I) (natural numbers without zero) and m ≥ 2, wherein ĸ high-frequency voltage sources are provided with the formula (II), and ĸ < m, wherein at least one power distributor device is provided which is electrically connected, on the one hand, to at least one high-frequency voltage source and, on the other hand, to n ignition systems, wherein formula (III) and 2 ≤ n ≤ m, wherein the power distributor device transmits the high-frequency alternating voltage or voltages from the high-frequency voltage source or sources, electrically connected to this power distributor device, to the ignition systems n which are electrically connected to this power distributor device.

Description

Ignition device and method for igniting an air-fuel like isches

The invention relates to an ignition device for igniting an air-fuel mixture in at least two combustion chambers, in particular an internal combustion engine, with at least one ignition system with electrodes for each combustion chamber, at least one high voltage source for generating a high voltage electrical pulse at an output of the high voltage source and at least one high frequency power source for generating an electrical high-frequency AC voltage at an output of the high-frequency voltage source, wherein m ignition systems with me N (natural numbers without zero) and m> 2, are provided, according to the preamble of patent claim 1. The invention also relates to a method for igniting an air-fuel mixture in m combustion chambers with m ε N (natural numbers without zero) and m> 2, in particular an internal combustion engine, wherein in a predetermined period of time in at least one combustion chamber, an ignitable mixture is generated with an electrical high voltage pulse in the at least one combustion chamber with ignitable mixture, an electrically conductive channel between at least two electrodes of the respective combustion chamber is generated, wherein the at least two electrodes with the conductive channel, an electrical high-frequency AC voltage for generating and maintaining The invention further relates to a method for operating an ignition device for igniting an air-fuel mixture in at least one combustion chamber, in particular an internal combustion engine, with at least one ignition system for each combustion chamber, at least one high voltage source for generating a high voltage electrical pulse at an output of the high voltage source and at least one high frequency voltage source for generating a high frequency electrical AC voltage at an output of the high frequency voltage source, wherein m ignition systems with m EN (natural numbers without zero) and m> 2 The invention also relates to a method for igniting an air-fuel mixture in m combustion chambers with me M (natural numbers without zero) and m> 2, in particular one Internal combustion engine, wherein in a predetermined period of time in at least one combustion chamber, an ignitable mixture is generated, wherein an electrically high voltage pulse in the at least one combustion chamber with ignitable mixture, an electrically conductive channel between at least two electrodes of the respective combustion chamber is generated, wherein the at least two electrodes a high-frequency electrical alternating voltage for generating and maintaining a plasma in the at least one combustion chamber with ignitable mixture is supplied with the conductive channel, according to the preamble of claim 22.

The number set N always denotes the set of natural numbers without zero.

For ignition of an air-fuel mixture in an internal combustion engine atomic (dissociated) oxygen is required, which is generated by means of a plasma between the electrodes of a spark plug. Typically, the plasma is a conductive channel (spark) generated by a momentarily high voltage, the high voltage being generated by a high voltage source such as an ignition coil. Usually, the high electrical voltage is a DC electrical voltage. Novel ignition systems follow the approach after this initial spark the plasma by means of additional excitation of the electrodes from a second energy source on upright to produce more atomic oxygen. Because the demand for the ignition has risen in modern engines due to turbocharging, emaciation, exhaust gas recirculation and stratified charge. The second energy source for additional excitation of the plasma usually generates a high frequency (hereinafter referred to as HF or high-frequency AC voltage) and is thus designed as an RF amplifier (hereinafter also referred to as high-frequency voltage source). Since automotive internal combustion engines have more than one spark plug, each spark plug requires its own RF amplifier. However, this is costly and space intensive.

So-called gasoline combustion methods with direct injection of the fuel have a great potential in terms of fuel consumption reduction due to the possibility of representing a stratified charge in the combustion chamber. The non-homogeneous mixture in the combustion chamber, however, places increased demands on the ignition method used with regard to reliable ignition at the appropriate time. Fluctuations of any kind reduce, for example, the quality of the ignition and thus the efficiency of the entire engine. On the one hand, the position of the ignitable mixture can vary slightly and on the other hand, the hook of the ground electrode of the spark plug, which projects into the combustion chamber, can interfere with the mixture formation. Helpful for a direct injection combustion process is an ignition system with a greater spatial extent into the combustion chamber. For this purpose, it is proposed in DE 10 2004 058 925 A1 to ignite a fuel-air mixture in a combustion chamber of an internal combustion engine by means of a high-frequency plasma. A corresponding high frequency plasma ignition device comprises a series resonant circuit with an inductance and a capacitance and a high frequency source for the resonant excitation of this series resonant circuit. The capacitance is represented by inner and outer conductor electrodes with intervening dielectric. These electrodes extend with their outermost ends at a predetermined mutual distance into the combustion chamber.

From DE 10 2008 051 185 A1 a method for ignition is known in which by means of an electrical DC voltage pulse, a discharge plasma is generated, which is then ionized by means of an RF field. Of the DC pulse and an output signal of an RF generator are supplied together to a spark electrode of a spark plug. A counter electrode of the spark plug is grounded. Modern ignition systems for gasoline engines today have a spark plug and a single ignition coil with electronic control unit. The spark plug is a coaxial structure and consists essentially of a central electrode surrounded by an insulator and an outer electrode connected to the spark plug housing. The ignition coil provides the spark plug with an electrical high voltage pulse. Between the electrodes a spark is created (conductive channel) which initiates combustion. An alternative method in which a high-frequency electrical voltage is applied to the spark plug in addition to the applied high voltage of the ignition coil in order to extend the spark duration is described in DE 10 2013 215 663 A1.

The invention is based on the object, an igniter of o.g. To improve the type of construction and function. This object is achieved by an igniter of o.g. A type having the features characterized in claim 1, by a method for igniting an air-fuel mixture of the above-mentioned type. A type having the features characterized in claim 10 and a method for operating an igniter of the above mentioned type. Art solved with the features characterized in claim 14. Advantageous embodiments of the invention are described in the further claims.

For this purpose, it is provided according to the invention in an ignition device of the type mentioned above that k high-frequency voltage sources with ke N, and k <m are provided, wherein at least one power distribution device is provided, which on the one hand with at least one high-frequency power source and on the other hand with n ignition systems, where ne M and 2 <n <m, the power distribution apparatus applying the high frequency AC voltages from the high frequency power source or sources electrically connected to this power distribution apparatus to the power sources this power distribution device electrically connected n ignition systems transmits.

This has the advantage that a high frequency voltage source can be used for several spark plugs, resulting in a reduction of the required hardware complexity.

A particularly simple and cost-effective power distribution device is achieved by virtue of the fact that at least one power distributor device is designed such that, during operation of the ignition device, the output of at least one high-frequency voltage source which is electrically connected to this power distributor device is permanently in time with all the ignition systems connects electrically. A reduction of the required high-frequency energy is achieved in that at least one power distribution device is designed such that it during operation of the ignition device, the output of at least one high frequency power source, which is electrically connected to this power distribution device, temporarily for a predetermined period of time with all n ignition systems simultaneously electrically connected.

A targeted supply of the high-frequency energy is achieved in that at least one power distribution device is designed such that it during operation of the ignition device, the output of at least one high-frequency power source, which is electrically connected to this power distribution device, temporally successively and temporarily for a predetermined period with each one of the n ignition systems electrically connects.

A further reduction of the hardware effort is achieved by having at least one power distribution device with q

High frequency voltage sources is electrically connected, wherein q is N, and q <k, wherein the power distribution device is designed as a q-to-n-demultiplexer. A targeted supply of the high-frequency energy to respective groups of spark plugs is achieved in that at least one power distribution device is designed such that it during operation of the ignition device, the output of at least one high-frequency power source, which is electrically connected to this power distribution device, separated in time and sequentially temporarily electrically interconnects with each ignition system of the n ignition systems, where 2 3 and n> 3.

An individual and temporally exact supply of a high-voltage pulse to a respective spark plug is achieved in that m high-voltage sources are provided and the output of each of a high voltage source, each with an ignition system is electrically connected.

A further simplification of the switching and control technical effort is achieved in that at least one high-frequency power source, which is electrically connected to n spark plugs, is designed such that it permanently emits the electrical high-frequency AC voltage at its output during operation of the ignition device. The use of existing components for the ignition device according to the invention is made possible in that at least one high voltage source is designed as an ignition coil.

In a method for igniting an air-fuel mixture of the abovementioned type, it is provided according to the invention that the electrical high-frequency AC voltage is applied to the at least two electrodes in the at least one combustion chamber with ignitable mixture in time prior to generating the electrically conductive channel between the at least two electrodes of the respective Combustion chamber is supplied.

This has the advantage that the generation or maintenance of the plasma takes place automatically immediately after the electrically conductive channel has been generated, without the need for an external trigger for the electrical high-frequency channel. AC voltage is necessary. An issue of high frequency before ignition additionally improves the take-over.

A simplification of the ignition system with only one source for the electrical high-frequency AC voltage for a plurality of combustion chambers is achieved in that the electrical high-frequency AC voltage is also supplied to the at least two electrodes of at least one such combustion chamber, in which no ignitable mixture is present. Deletion of the plasma in such a way that a new ignitable mixture can be generated in the respective combustion chamber with plasma for a renewed ignition is achieved in that after a predetermined period of time after the plasma has been generated, the electrical high-frequency AC voltage of at least two electrodes a respective combustion chamber is separated for at least a predetermined dead time over which the plasma was generated.

Optionally, it is provided that the predetermined dead time is 0.5 ms to 2 ms, in particular 1 ms.

In a method for operating an ignition device for igniting an air-fuel mixture of the above-mentioned type, it is provided according to the invention that the electrical high-frequency AC voltage is supplied to n ignition systems at the output of a high-frequency voltage source, where n e N and 2 <n <m.

This has the advantage that a high frequency voltage source can be used for several ignition systems, resulting in a reduction of the required hardware complexity.

A particularly simple and cost-effective power distribution device is achieved in that the output of at least one high-frequency voltage source is permanently electrically connected to all n ignition systems. A reduction of the required high-frequency energy is achieved in that the output of at least one high-frequency voltage source is temporarily electrically connected to all n ignition systems simultaneously. A targeted supply of high-frequency energy is achieved in that the output of at least one high-frequency voltage source is connected in chronological succession and temporarily electrically for a predetermined period of time with one of the n ignition systems. Further reduction of the hardware cost is achieved by electrically connecting at least one RF power source to q power distribution devices, where q is EN, and q <k.

A targeted supply of high-frequency energy to respective groups of spark plugs is achieved by electrically connecting the output of at least one high-frequency voltage source successively and temporarily with each p ignition systems of the n ignition systems, where 2 3 and n 3 is. An individual and temporally exact supply of a high-voltage pulse to a respective spark plug is achieved by providing m high-voltage sources and electrically connecting the output of a high-voltage source to an ignition system. A further simplification of the switching and control technical effort is achieved by permanently output from at least one high-frequency voltage source, the electrical high-frequency AC voltage at the output. In a method for igniting an air-fuel mixture in m combustion chambers, it is provided according to the invention that the electrical high-frequency AC voltage is also supplied to the at least two electrodes of at least one such combustion chamber, in which no ignitable mixture is present. This has the advantage that a simplification of the ignition system with only one source for the electrical high-frequency AC voltage for a plurality of combustion chambers is achieved.

The generation or maintenance of the plasma itself immediately after generating the electrically conductive channel without requiring an external trigger for the electrical high-frequency AC voltage is achieved in that the electrical high-frequency AC voltage to the at least two electrodes in the at least one combustion chamber is supplied with ignitable mixture in time prior to generating the electrically conductive channel between the at least two electrodes of the respective combustion chamber.

Deletion of the plasma, so that a new ignitable mixture can be generated in the respective combustion chamber with plasma for re-ignition, is achieved in that after a predetermined period of time after the plasma has been generated, the electrical high-frequency AC voltage of at least two electrodes a respective combustion chamber is separated for at least a predetermined dead time over which the plasma was generated.

Optionally, it is provided that the predetermined dead time is 0.5 ms to 2 ms, in particular 1 ms. The invention will be explained in more detail below with reference to the drawing. This shows in

Fig. 1 is a schematic block diagram of a first preferred

Embodiment of an ignition system according to the invention;

Fig. 2 is a schematic block diagram of a second preferred

Embodiment of an ignition system according to the invention; 3 shows a schematic block diagram of a third preferred embodiment of an ignition system according to the invention;

4 shows a time profile of high-frequency AC voltage,

Output active power of a high frequency power source and

Active power in a plasma for an ignition system with a high frequency voltage source and four ignition systems and

5 shows a time course of high-frequency AC voltage,

Output active power of high frequency power sources and

Active power in a plasma for an ignition system with two high-frequency voltage sources and four ignition systems.

The three preferred embodiments of an ignition device according to the invention, illustrated in FIGS. 1 to 3, each comprise m ignition systems 10 ,, i = 1,... M, with me N (natural numbers without zero) and k high-frequency voltage sources 12 _j , j = 1, ... k, with k EN, and k <m. Accordingly, in FIGS. 1 to 3, the m ignition systems 10i, 10 ₂ ,... 10 _m (i), 10 _m (i) + i, 10 _m (i) + ₂ ,... 0 _m (2), ... 0 _m (ki) + i, 10 _m ( _k-1 ) +2, ... 10 _m (k) with m (k) = m and the k high-frequency voltage sources 12i, 12 ₂ , ... 12 _k shown. Each high-frequency voltage sources 12 _j outputs at the respective output a high-frequency electrical AC voltage 14. The ignition systems 10, a high voltage pulse 18 is supplied from one or more high voltage sources 16 in each case according to a predetermined timing.

Each ignition system is assigned to a combustion chamber, for example an internal combustion engine, so that in the present example the internal combustion engine has m combustion chambers. Each ignition system has, for example, at least two, three or more electrodes, which are constructed, for example, in the form of a spark plug, wherein the electrodes protrude into the respective combustion chamber.

As is well known, an ignitable mixture is generated in an internal combustion engine at a certain time in one or more combustion chambers and the combustion systems associated with these ignition systems 10, the energy for a Sparks in the form of high voltage pulse 18 supplied. This is to generate a spark in the respective combustion chamber between the electrodes and ignite the ignitable mixture. The spark forms an electrically conductive channel between the electrodes. But with the spark, this electrically conductive channel or the spark breaks down immediately when the energy for the spark is consumed.

By means of the high-frequency AC voltage 14, which is also the ignition system 10) and thus supplied to the electrodes, the electrically conductive channel is now used to maintain this by means of the energy from the high-frequency AC voltage 14 and a plasma between the electrodes and in to produce the respective combustion chamber or to maintain for a period of time that is longer than the actual spark would maintain the conductive channel, so that the spark in the form of the plasma is longer in time for igniting the ignitable mixture available. Furthermore, a spatial expansion of the plasma increases. As a result, a more reliable and homogeneous ignition of the ignitable mixture is achieved. Only with the separation of the high-frequency AC voltage 14 from the respective ignition system 10, which just maintains a plasma in the combustion chamber, the plasma extinguished and the ignition process is completed.

According to the invention, it is provided that fewer high-frequency voltage sources 12j are provided as ignition systems 10. In other words, the number k of the high-frequency voltage sources 12 _{j is} smaller than the number m of the ignition systems 10 j (k <m). In order nevertheless to supply each ignition system 10 with a high-frequency AC voltage 14, according to the invention at least one power distributor device 20 is provided. This is on the one hand electrically connected to at least one high-frequency voltage source 12 _j and on the other hand with n ignition systems 10, where ne M and 2 <n <m, wherein the power distribution device 20, the high-frequency AC voltage or voltage 14 from the or the high-frequency voltage source or sources 12 _j electrically connected to this power distribution device 20 to the n ignition systems 10 electrically connected to this power distribution device 20 transmits. In the exemplary illustration, the ignition systems are 10 _f ... 10 _{m (} D via a power distribution device 20 with the high-frequency voltage source 12i, the ignition systems 10 _{m (} i) ₊ i, 1 0m (i) ₊₂ ,... 10 _{m (2)} via a further power distribution device 20 with the high frequency voltage source 12 ₂ and the ignition systems 10 _m ( _k- i) + i, 10 _m ( _k -i _{) +} 2, ... 1 0 _{m (k} ) (where m (k) = m) via a further power distribution device 20 with the high frequency power source 12 _k electrically connected.

In general, the ignition systems are 10 _m (i) + i, 1 0 _m (ji) +2, ... 0 _m <j) ^w ith the high frequency power source 12j connected, where m (0) = 0, m (k) = m , j = 1, ... k and 2 <[τη ^' ) -m (j-1)] <n <m and 0 <m (J) <m and m (j + 1)> m (/) , In this way, the output or the high-frequency AC voltage 14 of a single high-frequency voltage source 1 2j for several ignition systems 1 0 _m (ji) ₊ i, 10m j_i) +2, ■■■ 10m (j) is used.

In the illustration of FIGS. 1 to 3, for each of the high frequency voltage source 1 2j associated ignition systems 10 _m ai) + i. 10 _m ai) +2, ··· 0 _m o) ^a separate high-voltage source 16 for generating the initial spark is shown. However, this is just an example. Alternatively, a central energy source for generating the spark and the electrically conductive channel may be provided with a distributor, the energy of the energy source to the respective ignition system 0m (ji) + i, 10 _rt1 (ji) +2, ·· - passes 0mO) ,

An exemplary configuration for a 4-cylinder gasoline engine would be k = 1 and m = 4, ie a high-frequency voltage source 1 2i and four cylinders each with a combustion chamber and ignition systems 10ι, 10 ₂ , I O 3, 10 _{4 associated} with each combustion chamber (one ignition system each for a combustion chamber).

Some or all of the ignition systems 10 are, for example, designed as 2-electrode ignition systems, preferably in the form of spark plugs. Here, the high voltage pulse 1 8 and the high frequency AC voltage 1 4 is supplied directly or via a separator of an electrode, wherein the other electrode is at a fixed potential, such as ground. Alternatively, the high voltage pulse 18 is directly or via a separator of an electrode and the High-frequency AC voltage 1 4 supplied directly or via a separator of the other electrode.

Alternatively, some or all of the ignition systems 10 are designed as 3-electrode ignition systems, preferably in the form of spark plugs. The high voltage pulse 18 is fed directly or via a separator of a first electrode. The high-frequency AC voltage 1 4 is fed directly or via a separator of a second electrode. A third electrode is at a fixed potential, such as ground.

A high-frequency plasma is formed only if an initial charge carrier channel is present, which is generated here by the spark. In the first embodiment according to the Fig. 1, the device 20 Leistungsverteiler- is designed as a simple node, all the ignition systems 1 0 _m (ji) + i, 1 0m (ji) +2. ... 1 0 _m (j) permanently electrically connected to the output of the high-frequency voltage source 1 2j, so that one of the high-frequency voltage source 1 2j output at the output high-frequency AC voltage 1 4 directly to all ignition systems , 1 0m (ji) +2, ... 1 0 _m Q) is passed on electrically. In other words, this means that the high-frequency AC voltage 1 4 from the high-frequency voltage source 12 j applied to all ignition systems 1 0 _m (ji) + i, 10 _m (ji) ₊₂ , ... 1 0 _m a>, as long as this of the high-frequency voltage source 1 2j is output at the output.

In the second embodiment according to FIG. 2, the power distribution device 20 is designed as a passive power divider. This achieves an improved matching of the impedance between the output of the high-frequency voltage source 1 2j and the input of the ignition systems 1 0,. The passive power divider is designed, for example, as a Wilkinson divider or directional coupler. As in the first embodiment, in this second embodiment, all the ignition systems 1 0 _m (ji) + i, 1 0 _m (ji) + 2, ... 1 0 _m (j) are electrically continuous with the output of the high-frequency voltage source 1 2j connected such that one output from the high-frequency power source 1 2j at the output High frequency AC voltage 1 4 directly to all ignition systems 1 0 _m (ji) ₊₁ , 10 _m (ji) +2. ■■■ 0m (j) is passed on electrically. In other words, this means that the high-frequency AC voltage 1 4 of the

High frequency power source 1 2j (all ignition systems ^ _rΏ ^ j. ^) ₊ ^, 1 0 _m ji) +2, ... 10mq) is applied, as long as high-frequency AC voltage is output 14 from the high frequency power source 1 2j at its output.

In the third embodiment according to FIG. 3, the power distribution device 20 is designed as a demultiplexer. In contrast to the first and second embodiments, the output of the high frequency voltage source 12j is not temporally permanent with all ignition systems , 1 0 _m (ji) +2, ■■ · 0 _m (j) of which the 1-to-m (j) -m (j-1)! Demultiplexer always connects only one of the ignition systems 10 at a time _m (ji) + i. 0 _m (ji) +2, ... 10 _m ü) ^m 't the output of the high-frequency voltage source 12j, so that the high-frequency AC voltage 14 at a given time to only one ignition system of the plurality of high frequency power source 12, the associated ignition systems 10 _m (ji) + i, 10 _m (ji) +2, ■■■ 1 0m (j) is transmitted. As a result, the demands on the high-frequency voltage source 12j decrease, so that this can be realized more easily. For example, the high-frequency voltage source 12j can be made smaller.

Depending on a control signal, which is provided, for example, by an engine controller, the demultiplexer switches the high-frequency ac voltage 14 exclusively to exactly this ignition system before or during the ignition of an ignition system 10j. The advantage compared to the direct parallel connection of the high-frequency voltage source 12j with all ignition systems 10 ^ -1) + -! , 10 _m (j - i) +2, ■■ x 1 0 _m (j) is that those ignition systems in which no ignition is to take place not be burdensome for the high frequency power source 12j due to the high-impedance disconnection by the demultiplexer. Thus, only one or a few high frequency voltage sources / n 1 2j are required with reduced requirements.

Regardless of the specific embodiment of the power distribution device 20 according to FIGS. 1 to 3, the invention includes an efficient distribution of a high-frequency signal (high-frequency AC voltage 14) in an HF signal. supported ignition system for internal combustion engines to reduce the number of energy sources (k = number of RF amplifiers (high-frequency voltage sources 12 _j ), m = number of ignition systems to be operated 10 ,, k <m, k> 1, m 2, k, m ε N ). An exemplary configuration for a 4-cylinder gasoline engine, as previously mentioned, k = 1 and m = 4, ie a high-frequency power source 12i and four ignition systems 10, (i = 1, 2, 3, 4), each an ignition system for a Combustion chamber of a cylinder of the internal combustion engine. All four ignition systems 10 are electrically connected to the high frequency voltage source 12i via the power distribution device 20. In this case, therefore, n = 4 = m. For this configuration, a time curve of the voltage U _H F 22 at the output of the high-frequency voltage source 12i, the output active power P _H F 24 of the high-frequency voltage source 12 and the active power P _P ii 26, in the plasma for the i-th ignition system 10j with in this example i = 1, 2, 3, 4, shown over a time axis 28 in Fig. 4. The voltage amplitude of the high-frequency AC voltage 14 is not large enough to ignite a plasma itself. Only in conjunction with an ignition pulse (high-voltage pulse 18), an initial spark, so an electrically conductive channel, at which the high-frequency AC voltage 14 (RF signal) attaches and generates a high-frequency plasma, is introduced into the additional energy, whereby the RF Voltage due to the impedance change decreases (marked with arrow 30). Without the ignition pulse (high-voltage pulse 18) in one system or the other systems (ignition system 26-i, 26 ₂ , 26 ₃ and 26 ₄ ), the high-frequency AC voltage 14 in this has no effect and can during the other process steps in one cycle of the internal combustion engine without problems abut the electrodes of this or these systems. Therefore, the high-frequency AC voltage 14 may be applied simultaneously to all ignition systems 26i, 26 ₂ , 26 ₃ , 26 ₄ . Between two successive ignitions in the ignition systems 26 ^ 262, 26 ₃ , 26 ₄ which are electrically connected to the high-frequency voltage source 12i, the high-frequency AC voltage 14 is turned off (dead time), so that the plasma does not continue to burn but extinguished. The high-frequency AC voltage 14 is turned off, for example, for a period of about 1 ms, so that no unwanted plasma generation takes place due to the presence of free charge carriers of the last plasma. As can be seen from FIG. 4, initially a plasma is generated In the first ignition system 26i ignited and this plasma extinguished by switching off the high-frequency AC voltage 14. Thereafter, each time a plasma in the second ignition system 26 ₂ , the third ignition system 26 ₃ and the fourth ignition system 26 _{4 is} ignited and extinguished again.

In the event that, due to the necessary timing of the plasma ignitions, the dead time for extinguishing one plasma in the ignition system 26 would coincide with the ignition of a plasma in the next ignition system 26 _{i +} i or 26 _{i + x} , more than one high frequency voltage source 12j provided and the ignition systems, which would differ in dead time and plasma ignition time are associated with different high-frequency voltage sources 12 _j . This is the case, for example, when the number of cylinders becomes so great that the ignition pulse of an ignition system falls within the dead time of the previous ignition system. Then, a plasma would undesirably be generated at both ignition systems. Therefore, in this case, at least two high-frequency power sources 12i and 122 are provided.

The resulting temporal course of the voltage U _H F 22 at the output of the high-frequency voltage source 12-i, the output active power P _H F 24 of the high-frequency power source 12 _! and the active power P _PU 26, in the plasma for the i-th ignition system 10, with in this example i = 1, 2, 3, 4, over a time axis 28 is shown in Fig. 5. In Fig. 5 functionally identical parts are designated by the same reference numerals, as in Fig. 4, so that reference is made to the explanation of the above description of FIG. 4. In contrast to FIG. 4, two voltages UHF.I 22I and _UHF, 2 22 ₂ applied at the output of each of the high frequency power source 12 i and 12 ₂ and two output active power PHFJ 24I and PRF, 2 24 ₂ of the high frequency power source 12 i and 12 _2. The ignition systems 26i and 26 ₃ are electrically connected to the first RF power source 12i via a first power distribution device 20, and the ignition systems 26 ₂ and 26 _{4 of the} second power distribution device 20 are electrically connected to the second RF power source 12 ₂ . At 32, a necessary dead time for an ignition system 26, characterized. This embodiment with k = 2 and m = 4 is chosen only for easy or better representability and not necessarily close to reality. As can be seen from FIG. 5, the dead time 32 of the first ignition system 26i overlaps in time with the high-voltage pulse 18 in the second ignition system 26 ₂ . However, since the first ignition system 26i is connected to the first high-frequency voltage source 12i and the second ignition system 26 _{2 is} connected to the second high-frequency voltage source 12 ₂ , the first high-frequency voltage source 12i can remain switched off for the necessary dead time 32 in the first ignition system 26i while the second ignition system 26 ₂ already remains is acted upon by the high frequency AC voltage 14 from the second high frequency voltage source 12 ₂ and the high voltage pulse 18. The same applies to the second and third ignition systems 26 ₂ , 26 ₃ and to the third and fourth ignition systems 26 ₃ , 26 ₄ in the time sequence of dead times 32 and high-voltage pulses 18.

The invention also relates to a method for igniting an air-fuel mixture in m combustion chambers with m EN (natural numbers without zero) and m> 2, in particular an internal combustion engine, wherein in a predetermined period of time in at least one combustion chamber, an ignitable mixture is generated. With an electrical high-voltage pulse, an electrically conductive channel between at least two electrodes of the respective combustion chamber is generated in the at least one combustion chamber with ignitable mixture, wherein the at least two electrodes with the conductive channel, a high-frequency electrical AC voltage for generating and maintaining a plasma in the at least a combustion chamber is supplied with ignitable mixture. In this case, the electrical high-frequency AC voltage is supplied to the at least two electrodes in the at least one combustion chamber with ignitable mixture in time prior to the generation of the electrically conductive channel between the at least two electrodes of the respective combustion chamber. This has the advantage that the generation or maintenance of the plasma takes place automatically immediately after the electrically conductive channel has been generated, without the need for an external trigger for the electrical high-frequency AC voltage. A concern of high frequency before ignition additionally improves the take-over. The electrical high-frequency AC voltage is for example also supplied to the at least two electrodes of at least one such combustion chamber, in which no ignitable mixture is present. After a predetermined period of time after the generation of the plasma, the electrical high-frequency AC voltage is separated from at least those at least two electrodes of a respective combustion chamber for at least a predetermined dead time over which the plasma was generated. As a result, a deletion of the plasma is achieved, so that in the respective combustion chamber with plasma for re-ignition a new ignitable mixture can be generated.

In a method according to the preceding paragraph, it is optionally provided that the predetermined dead time is 0.5 ms to 2 ms, in particular 1 ms. The invention also relates to a method for operating an ignition device for igniting an air-fuel mixture in at least one combustion chamber, in particular an internal combustion engine, with at least one ignition system for each combustion chamber, at least one high voltage source for generating a high voltage electrical pulse at an output of the high voltage source and at least one High-frequency voltage source for generating a high-frequency electrical AC voltage at an output of the high-frequency power source, wherein m ignition systems with me N (natural numbers without zero) and m> 2 are provided. The electrical high-frequency AC voltage at the output of a high-frequency voltage source is supplied to n ignition systems, where n E N and 2 <n <m. As a result, a high-frequency voltage source can be used for a plurality of ignition systems, resulting in a reduction of the required hardware outlay.

The output of at least one high-frequency voltage source is, for example, permanently electrically connected to all n ignition systems in terms of time.

The output of at least one high-frequency voltage source is, for example, temporarily electrically connected simultaneously to all n ignition systems, whereby a reduction of the required high-frequency energy is possible. The output of at least one high-frequency voltage source is connected in chronological succession and temporarily electrically connected to one of the n ignition systems for a predetermined period of time.

At least one power distribution device is preferably electrically connected to q high frequency voltage sources, where </ E, and q <k.

The output of at least one high-frequency voltage source is, for example, also electrically separated one after the other and temporarily electrically connected to p ignition systems of the n ignition systems, where 2 3 and n> 3. As a result, a targeted supply of high-frequency energy from the high-frequency source to respective groups of spark plugs is possible. For example, m high-voltage sources are provided and the output of a respective high-voltage source is electrically connected to an ignition system in each case. This allows an individual and timely exact delivery of a high voltage pulse to a respective spark plug. of at least one high-frequency voltage source, the electrical high-frequency AC voltage is permanently output at its output over time. This achieves a further simplification of the circuitry and tax technical effort. The invention also relates to a method for igniting an air-fuel mixture in m combustion chambers with m EN (natural numbers without zero) and m> 2, in particular an internal combustion engine, wherein in a predetermined period of time in at least one combustion chamber, an ignitable mixture is generated. With an electric high-voltage pulse in the at least one combustion chamber with ignitable mixture, an electrically conductive channel between at least two electrodes of the respective combustion chamber is generated, wherein the at least two electrodes with the conductive channel, a high-frequency electrical AC voltage for generating and maintaining a plasma in the at least a combustion chamber is supplied with ignitable mixture. This is the electrical high-frequency AC voltage also supplied to the at least two electrodes of at least one such combustion chamber, in which no ignitable mixture is present. The ignition system is characterized by only one source for the electrical high frequency AC voltage for multiple combustion chambers.

The electrical high-frequency AC voltage is supplied, for example, to the at least two electrodes in the at least one combustion chamber with ignitable mixture in time prior to the generation of the electrically conductive channel between the at least two electrodes of the respective combustion chamber. The generation or maintenance of the plasma is carried out automatically immediately after generating the electrically conductive channel, without the need for an external trigger for the electrical high-frequency AC voltage is necessary. After a predetermined period of time after the generation of the plasma, the electrical high-frequency AC voltage is separated from at least those at least two electrodes of a respective combustion chamber for at least a predetermined dead time over which the plasma was generated. As a result, a deletion of the plasma is achieved, so that in the respective combustion chamber with plasma for re-ignition a new ignitable mixture can be generated.

In a method according to the preceding paragraph, it is optionally provided that the predetermined dead time is 0.5 ms to 2 ms, in particular 1 ms.

Claims

claims:

Ignition device for igniting an air-fuel mixture in at least one combustion chamber, in particular an internal combustion engine, with at least one ignition system (10,) with electrodes for each combustion chamber, at least one high voltage source (16) for generating a high voltage electrical pulse (18) at an output of the high voltage source (16). 16) and at least one high-frequency voltage source (12j) for generating a high-frequency electrical alternating voltage (14) at an output of the high-frequency voltage source (12 _j ), wherein m ignition systems (10,) with m EN (natural numbers without zero) and m> 2 , are provided,

characterized ,

in that k high-frequency voltage sources (12 _j ) with k EN and k <m are provided, wherein at least one power distributor device (20) is provided, which on the one hand is connected to at least one high-frequency voltage source (12 _j ) and on the other hand to n ignition systems (10, ·) , where n EN and 2 <n <m, is electrically connected, wherein the power distribution device (20) couples the high frequency AC voltage (14) voltages from and to the power distribution device (20)

High frequency voltage source (12 _j ) or sources to the n with this power distribution device (20) electrically connected n ignition systems (10 j) transmits.

Ignition device according to Claim 1, characterized in that at least one power distributor device (20) is designed such that, during operation of the ignition device, the latter is electrically connected to the output of at least one high-frequency voltage source (12 _j ) which is electrically connected to this power distributor device (20). Permanently permanently connected with all n ignition systems (10,).

3. Ignition device according to claim 1 or 2, characterized in that at least one power distributor device (20) is designed such that it during operation of the ignition device, the output of at least one high frequency power source (12 _j ), which with this power distribution device (20). electrically connected, temporarily with all n ignition systems

(10,) at the same time electrically connects.

Ignition device according to at least one of the preceding claims, characterized in that at least one power distributor device (20) is designed such that during operation of the ignition device, the output of at least one high-frequency voltage source (12 _j ), which with this power distribution device (20) electrically is connected, temporally successively and temporarily electrically connected for a predetermined period of time with each of the n ignition systems (10,).

Ignition device according to at least one of the preceding claims, characterized in that at least one power distribution device (20) is electrically connected to q high-frequency voltage sources (12 _j ), where qe N, and q <k, wherein the power distribution device (20) as q-to-n demultiplexer is formed.

Ignition device according to at least one of the preceding claims, characterized in that at least one power distributor device (20) is designed such that during operation of the ignition device, the output of at least one high-frequency voltage source (12 _j ), which with this power distribution device (20) electrically is connected, temporally separated successively and temporarily with each p ignition systems (10,) of the n ignition systems (10,) electrically connects, where 2 3 and n> 3.

Ignition device according to at least one of the preceding claims, characterized in that m high-voltage sources (16) are provided and the output of a respective high-voltage source (16) is electrically connected to a respective ignition system (10,). I. Ignition device according to at least one of the preceding claims, characterized in that at least one

High-frequency voltage source (12j), which is electrically connected to n ignition systems (10,), is designed such that it permanently emits the electrical high-frequency AC voltage (14) at its output during operation of the ignition device. i. Ignition device according to at least one of the preceding claims, characterized in that at least one high-voltage source (16) is designed as an ignition coil.

0. A method for igniting an air-fuel mixture in m combustion chambers with m EN (natural numbers without zero) and m> 2, in particular an internal combustion engine, wherein in a predetermined period of time in at least one combustion chamber, an ignitable mixture is generated, with an electrical high voltage pulse in which at least one combustion chamber with ignitable mixture, an electrically conductive channel between at least two electrodes of the respective combustion chamber is generated, wherein the at least two electrodes with the conductive channel, a high frequency electrical AC voltage for generating and maintaining a plasma in the at least one combustion chamber with ignitable Mixture is supplied,

characterized ,

in that the electrical high-frequency AC voltage is supplied to the at least two electrodes in the at least one combustion chamber with ignitable mixture in time prior to the generation of the electrically conductive channel between the at least two electrodes of the respective combustion chamber.

1. The method according to claim 10, characterized in that the electrical high-frequency AC voltage is also supplied to the at least two electrodes at least one such combustion chamber, in which no ignitable mixture is present.

2. The method of claim 10 or 1 1, characterized in that after a predetermined period of time after the generation of the plasma, the electrical high-frequency AC voltage of at least those at least two electrodes of a respective combustion chamber is separated for at least a predetermined dead time over which the plasma was generated.

13. The method according to claim 12, characterized in that the predetermined dead time is 0.5 ms to 2 ms, in particular 1 ms.

14. A method for operating an ignition device for igniting an air-fuel mixture in at least one combustion chamber, in particular an internal combustion engine, with at least one ignition system for each combustion chamber, at least one high voltage source for generating an electrical

High-voltage pulse at an output of the high-voltage source and with at least one high-frequency voltage source for generating a high-frequency electrical alternating voltage at an output of the high-frequency voltage source, wherein m ignition systems with m e N (natural numbers without zero) and m> 2 are provided,

characterized ,

in that the electrical high-frequency AC voltage at the output of a high-frequency voltage source is supplied to n ignition systems, where n e N and 2 <n <m.

15. The method according to claim 14, characterized in that the output of at least one high-frequency voltage source is permanently electrically connected to all n ignition systems in time. 16. The method according to claim 14 or 15, characterized in that the output of at least one high frequency voltage source is temporarily electrically connected to all n ignition systems simultaneously.

17. The method according to any one of claims 14 to 16, characterized in that the output of at least one high-frequency power source is connected in chronological succession and temporarily electrically connected to one of the ignition systems for a predetermined period of time.

18. The method according to any one of claims 14 to 17, characterized in that at least one high frequency power source is electrically connected to q power distribution devices, wherein q E N, and q <k.

Method according to one of Claims 14 to 18, characterized in that the output of at least one high-frequency voltage source is electrically connected in succession and temporarily electrically connected to p ignition systems of the n ignition systems, where 2 3 and n> 3 is.

Method according to one of claims 14 to 19, characterized in that m high-voltage sources are provided and the output of each of a high voltage source is electrically connected to a respective ignition system.

Method according to one of claims 14 to 20, characterized in that at least one high-frequency voltage source permanently outputs the high-frequency electrical alternating voltage at its output.

Method for igniting an air-fuel mixture in m combustion chambers with m EN (natural numbers without zero) and m> 2, in particular an internal combustion engine, wherein in a predetermined period of time in at least one combustion chamber, an ignitable mixture is generated, with an electrical high voltage pulse in the at least one combustion chamber with ignitable mixture an electrically conductive channel between at least two electrodes of the respective combustion chamber is generated, wherein supplied to the at least two electrodes with the conductive channel, a high frequency electrical AC voltage for generating and maintaining a plasma in the at least one combustion chamber with ignitable mixture becomes,

characterized ,

the electrical high-frequency AC voltage is also supplied to the at least two electrodes of at least one such combustion chamber in which no ignitable mixture is present.

23. The method according to claim 22, characterized in that the electrical high-frequency AC voltage to the at least two electrodes in the at least one combustion chamber with ignitable mixture is supplied temporally before generating the electrically conductive channel between the at least two electrodes of the respective combustion chamber. 24. The method of claim 22 or 23, characterized in that after a predetermined period of time after the generation of the plasma, the electrical high frequency AC voltage is separated from at least those at least two electrodes of a respective combustion chamber for at least a predetermined dead time over which the plasma was generated ,

25. The method according to claim 24, characterized in that the predetermined dead time 0.5 ms to 2 ms, in particular 1 ms, is.