DE102015119216A1 - Ignition device for an internal combustion engine - Google Patents

Abstract

The invention relates to an ignition device (10) for an internal combustion engine (12) for igniting a combustion mixture (16) in a combustion chamber (14) of the internal combustion engine (12), ignition of the combustion mixture (16) being provided by means of a laser, characterized a microdisplay (18) with at least two light-emitting diodes (20) is provided, with which a plurality of light beams (38) of high-energy density can be coupled into the combustion chamber (14) of the internal combustion engine (12), the at least two light-emitting diodes (20) in each case emit a high energy density light beam (38) suitable for igniting a combustion mixture in the combustion chamber (14) of the internal combustion engine (12). The invention further relates to an internal combustion engine (12) having at least one combustion chamber (14) in which an ignitable combustion mixture (16) can be stored and ignited, wherein the internal combustion engine (12) has a window (32) for coupling in a high-energy light beam (38). and such ignition device (10).

Description

The invention relates to an ignition device for an internal combustion engine according to the preamble of claim 1 and to an internal combustion engine with such an ignition device.

In spark-ignited internal combustion engines, it is necessary to ignite an ignitable combustion mixture in the combustion chamber of the internal combustion engine by an igniter. As a rule, for this purpose, the ignition of the combustion mixture by means of a transistor coil ignition system with static high-voltage distribution, wherein at each combustion chamber of the internal combustion engine, a spark plug is arranged, which is located at a fixed position and the combustion of the combustion mixture by a spark always on the same Point of the combustion chamber initiates.

In order to increase the combustion speed in the combustion chambers of the internal combustion engine and to improve the ignition conditions, internal combustion engines are known in which two spark plugs per combustion chamber are arranged in order to start combustion in the combustion chamber starting from several locations of the combustion chamber and thus a faster and / or or more complete implementation of the combustion mixture.

In addition to the classic ignition via spark plugs, other ignition methods and ignition systems, such as corona ignition systems, in which the ignitable mixture is ignited in the combustion chamber of the internal combustion engine by means of a multiplicity of plasma flashes, microwave ignition systems or laser ignition systems are known.

In the further optimization of the combustion process, conventional ignition systems reach their limits since the combustion mixture in the combustion chamber can only be ignited once per combustion cycle at a permanently defined position. Therefore, ignition systems are sought, which are able to ignite larger volumes of combustion mixture and ignite at any location in the combustion chamber.

From the DE 10 2011 100 991 A1 a laser ignition system for an internal combustion engine is known, wherein the laser ignition system is adapted to couple laser beams to at least two arranged in a combustion chamber of the internal combustion engine ignition locations. For this purpose, a laser beam is split by suitable means such as prisms, lenses and mirrors in several sub-beams and coupled into the combustion chamber of the internal combustion engine. In this case, the deflection of the laser or the partial beams by means of adjustable mirrors, whereby the proposed ignition system is complicated, expensive and sensitive to mechanical adjustment. In addition, the ignition locations are not independent of each other, but largely forcibly coupled by the optical element for splitting the laser beam.

From the DE 10 2013 216 552 A1 an ignition device is known with a light emitting diode designed as a laser diode, wherein the light emitting diode has sufficient power to emit laser pulses into the combustion chamber of an internal combustion engine. Furthermore, an arrangement with two light-emitting diodes is provided, which can be switched via a selection switching element, wherein each combustion cycle only one of the diodes emits a laser pulse.

The invention is based on the object of providing an ignition device with which an ignitable combustion mixture can be ignited at arbitrary time periods, at arbitrary positions in the combustion chamber and several times per combustion cycle.

According to the basic idea of the invention, an ignition device for an internal combustion engine for igniting a combustion mixture in a combustion chamber of the internal combustion engine is proposed, wherein an ignition of the combustion mixture is provided by means of a laser, wherein a microdisplay is provided with at least two light emitting diodes, with which a plurality of light beams of high energy density can be coupled into the combustion chamber of the internal combustion engine, wherein the at least two light-emitting diodes each emit a light beam of high energy density, which is suitable to ignite the combustion mixture in the combustion chamber of the internal combustion engine. The microdisplay allows the light beams of high energy density to be concentrated, as it were, at arbitrary locations of the combustion chamber, a light field being built up by the lenses of the microdisplay. As a result, it is possible, depending on the number of light-emitting diodes and the lenses used, to achieve ignition temperatures for the combustion mixture at several locations of the combustion chamber at the same time or with a time delay, so that a combustion mixture can be ignited even in applications in which ignition by means of a conventional spark plug not possible. A microdisplay is generally understood to mean a device which allows the viewer to focus different points in space and thus to display a three-dimensional image. In the context of this application, a microdisplay is to be understood as a light-field display which, instead of imaging elements, consists of individual light-emitting displays light emitting diodes with high energy density is composed. The terms "high energy density light rays" and "laser beams" are used synonymously in this patent application.

The measures listed in the dependent claims advantageous improvements and developments of the ignition device specified in the independent claim are possible.

According to a preferred embodiment, it is provided that the microdisplay is arranged at least two light-emitting diodes and the combustion chamber, wherein the light pulses of the at least two light-emitting diodes can be coupled into the combustion chamber of the internal combustion engine, that within at least two independent locations of the combustion engine within a working cycle of the internal combustion engine Combustion chamber, the ignition conditions of the combustible combustion mixture can be achieved. As a result, a combustion can be started in which a flame front propagates from a plurality of locations and thus enables a faster and / or more complete implementation of the combustion mixture.

According to an advantageous development, it is provided that the microdisplay spans a volume of high-energy light within the combustion chamber. As a result, in contrast to a spark not only at a locally very limited location, but in a larger volume portion of the combustion chamber, the ignition conditions of the combustion mixture can be achieved, whereby a better combustion is possible.

An advantageous further development consists in that a laser light field formed by the at least two light-emitting diodes and the microdisplay is introduced at an edge of the combustion chamber of the internal combustion engine. Preferably, the microdisplay is arranged on the combustion chamber roof, so that the microdisplay at any time by the movable piston or other moving parts, such as the possibly existing valves of the combustion chamber, can be shaded to ensure ignition at any time can. As a result, temperatures which are sufficient for igniting a combustion mixture can also be achieved in the peripheral regions of the combustion chamber. Furthermore, a heating of the combustion chamber walls is possible in this way, so that the internal combustion engine reaches its operating temperature after a cold start faster and less emissions caused by unburned or incompletely burned combustion mixture.

According to a further advantageous embodiment, it is provided that a laser light field formed by the at least two light-emitting diodes and the microdisplay can be regulated in such a way that laser beams of the light-emitting diodes can be focused at arbitrary spatial coordinates in the combustion chamber. Thus, it is possible, for example, to focus the light pulses from two or more light-emitting diodes or to focus them at a common point in order to locally reach a particularly high temperature in the combustion chamber.

In an advantageous embodiment of the ignition device, each pixel of the microdisplay is set up to emit a light beam which, when intersecting with another light beam of another pixel, is suitable for igniting a combustible combustion mixture in the combustion chamber. For this purpose, one or more separate light-emitting diodes are / are preferably provided for each pixel of the microdisplay. As a result, a particularly simple and particularly variable adjustment of the light beams is possible, wherein the ignition conditions are achieved in a focal point of at least two light beams.

According to an advantageous embodiment, it is provided that a plurality of light emitting diodes is provided, wherein the light beams of a first diode group and a second diode group of the at least two light emitting diodes are introduced simultaneously into the combustion chamber. This allows a simultaneous ignition of the combustion mixture at two independent locations in the combustion chamber. In this context, mutually independent locations are to be understood as meaning locations in the combustion chamber which do not lie on a common light beam of a light-emitting diode.

Alternatively, it is advantageously provided that the light beams of two groups of different light-emitting diodes with a time delay of up to 5 ms in the Combustion chamber of the internal combustion engine are initiated. Thus, a time-delayed ignition can take place at two independent locations, wherein also a first volume of combustion mixture and a second volume of combustion mixture in the sense of a pre-combustion and a main combustion or a main combustion and a post-combustion can be ignited independently. Particularly advantageous is a time delay of a maximum of 2 ms, in particular of a maximum of 1 ms in order to find sufficiently good compression conditions for both combustion points within a combustion cycle.

According to an advantageous development, it is provided that the light beams of the light-emitting diodes are introduced as pulsed light beams into the combustion chamber of the internal combustion engine. If the light beams are not introduced into the combustion chamber as continuous light beams but as pulsed light beams, on the one hand less energy is required to generate the light beams, on the other hand a higher energy density of the light pulses compared to continuous light beams is possible in this way.

According to the invention, an internal combustion engine with at least one combustion chamber is also described.

Further preferred embodiments of the invention will become apparent from the remaining, mentioned in the dependent claims characteristics.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

1 a schematic representation of an internal combustion engine with an ignition device according to the invention,

2 2 shows a two-dimensional representation of a simple microdisplay of an ignition device according to the invention with four light-emitting diodes,

3 a two-dimensional representation of an ignition device with a microdisplay and a course of the light beams,

4 another illustration of the ignition device 3 and

5 a schematic representation of potential ignition positions of the ignition device according to the invention.

1 shows a simplified, schematic representation of an internal combustion engine 12 with an ignition device according to the invention 10 , The internal combustion engine 12 is shown for reasons of clarity as a single-cylinder engine, but the invention is also applicable to internal combustion engines with two and more cylinders, preferably with a number of cylinders between two and twelve. The internal combustion engine 12 has a combustion chamber 14 in which a combustion mixture 16 limited in time for a combustion cycle can be stored. The combustion chamber 14 has a window 32 on, over which the high-energy light beams of the ignition device 10 in the combustion chamber 14 can be coupled. The combustion chamber 14 is through combustion chamber walls and a piston 34 limited. The ignition device 10 has several light-emitting diodes 20 which turns into a microdisplay 18 put together. The light-emitting diodes 20 are matrix-shaped behind individual microlenses 36 of the microdisplay 18 arranged. The microdisplay 18 is preferably located at a location where there is no time of moving component, in particular of the piston 34 or valves, not shown, is covered, so that at any time a combustion pulse in the combustion chamber 14 can be triggered. Alternatively to the arrangement of the microdisplay shown for reasons of simplification 18 on the side of the cylinder is an arrangement in the cylinder head or a combustion chamber roof of the combustion chamber 14 intended.

In 2 is a two-dimensional representation of a simple microdisplay 18 with four light emitting diodes 20 shown, that of the light emitting diodes 20 emitted, high energy light rays 38 through a lens 36 be directed and in a focal point 42 are focused. By focusing at least two high-energy light beams 38 in a focal point 42 be at the focal point 42 Temperatures reached, which for the ignition of the combustion mixture 16 are sufficient.

In 3 is a schematic representation of a generation of an ignition pulse for the combustion mixture 16 in the combustion chamber 14 through the ignition device 10 shown. By a defined turning on and off of certain single pixels 30 that is, individual light-emitting diodes 20 behind the lenses 36 can with the respective light beam 38 targeted specific coordinates in the combustion chamber 14 to be hit. The lenses 36 can have a fixed focusing point or be made adjustable. In the proposed ignition device 10 No additional mechanism is necessary for setting up or adjusting mirrors, so that the ignition device 10 comparatively robust against disturbances and external influences, for example vibrations in a vehicle enterprise is, there the focussing of the light rays 38 in a focal point 42 in a first place 22 in the combustion chamber 14 solely by the switching on or off of the light-emitting diodes 20 as well as the lenses 36 is reached. The rays of light 38 meet in focus 32 together and ignite locally the combustion mixture 16 , wherein, after ignition, a flame front becomes star-shaped from the focal point 42 out into the combustion chamber 14 can spread.

4 shows the ignition device 10 out 3 in another operating position. In addition to the focus of the light rays in the first place 22 in the combustion chamber 14 in which four beams of light 38 in a focal point 42 meet at two other places 24 in the combustion chamber 14 by crossing two beams of light 38 also the ignition conditions for a combustion mixture 16 be achieved, provided that even in this local area of the combustion chamber 14 an ignitable combustion mixture 16 present and the intersection of two beams of light 38 leads to a sufficient compression of the energy that an ignition temperature of the combustion mixture 16 is reached. Assuming that all rays of light 38 the light emitting diodes 20 each may have the same energy density, but thus also specifically different hot spots in the combustion chamber 14 be created, with the temperature in the first place 22 , on the four beams of light 38 are generally higher than in one place 24 on which only two beams of light 38 are focused. The lenses 36 are preferably designed as converging lenses, so that the light beams 38 in a focal point 42 behind the lens 36 to meet. This not only serves to concentrate multiple beams of light 38 on a common focal point 42 but also allows the window 32 for coupling the light beams 38 in the combustion chamber 14 correspondingly small and compact.

5 shows a schematic representation of potential ignition positions of the ignition device according to the invention 10 , As in 5 can be seen are by a corresponding interconnection of the light-emitting diodes 20 and an appropriate selection or adjustment of the lenses 36 Ignition pulses at quasi arbitrary positions in the combustion chamber 14 possible. There is a distinction between "strong" ignition locations 22 , where more than two beams of light 38 clash and "weak" ignition locations 24 , where exactly two beams of light 38 the light emitting diodes 20 meet, possible. The number of possible ignition pulses per combustion cycle is determined by the number of independent nodes of the light rays 38 limited. The area of the combustion chamber 14 , in which an ignition pulse can be triggered, is determined by the size of the window 32 , the refractive index of the lenses 36 , as well as the arrangement of the ignition device 10 limited. Furthermore, in 5 a place 40 shown at the currently not the ignition conditions for an ignitable combustion mixture 16 be achieved.

In addition to ignition of the combustion mixture 16 can the ignition device according to the invention 10 can also be used for further purposes. For example, the coupling of the light beams 38 a preconditioning of the combustion chamber 14 possible, so that the device can replace the classic glow plug, for example, in self-igniting internal combustion engines. Furthermore, just after a cold start, the raw emissions of the internal combustion engine 12 by a corresponding conditioning of the combustion chamber 14 be reduced because a flame front goes out due to cold combustion chamber walls and an associated incomplete combustion of the combustion mixture 16 is avoided. Alternatively or additionally, the ignition device can also be used to the combustion chambers 14 be conditioned so that exhaust aftertreatment devices can reach their full capacity as soon as possible after a cold start.

Even if the function of the ignition device 10 in the 2 to 5 For the sake of clarity and simplicity have been shown two-dimensional, so is a deflection and focusing of the light rays 38 in all three dimensions in the combustion chamber 14 possible. By the proposed ignition device 10 It is thus possible, at arbitrary times at quasi arbitrary locations 22 . 24 of the combustion chamber 14 trigger a plurality of ignition pulses, which by the number of light-emitting electrodes 20 and the number of composites of light-emitting electrodes 20 and lenses 36 is limited. Thus, the combustion of the combustion mixture 16 and thus the efficiency of the internal combustion engine 12 be improved.

LIST OF REFERENCE NUMBERS

10

 detonator

12

 internal combustion engine

14

 combustion chamber

16

 combustion mixture

18

 microdisplay

20

 light emitting diodes

22

 Place in the combustion chamber

24

 Place in the combustion chamber

26

 volume

28

 edge

30

 pixel

32

 window

34

 piston

36

 lens

38

 Light beam of high energy density

40

 Location in the combustion chamber where the ignition condition is currently not reached

42

 focus

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102011100991 A1 [0006]
• DE 102013216552 A1 [0007]

Claims (10)

Ignition device ( 10 ) for an internal combustion engine ( 12 ) for igniting a combustion mixture in a combustion chamber ( 14 ) of the internal combustion engine ( 12 ), wherein ignition of the combustion mixture ( 16 ) is provided by means of a laser, characterized in that a microdisplay ( 18 ) with at least two light-emitting diodes ( 20 ) is provided, with which several light beams ( 38 ) high-energy density in the combustion chamber ( 14 ) of the internal combustion engine ( 12 ) can be coupled, wherein the at least two light-emitting diodes ( 20 ) each have a light beam ( 38 ) emit high energy density, which is suitable to a combustion mixture in the combustion chamber ( 14 ) of the internal combustion engine ( 12 ) to ignite. Ignition device ( 10 ) according to claim 1, characterized in that the microdisplay ( 18 ) at least two light emitting diodes ( 20 ), wherein the light pulses of the at least two light-emitting diodes ( 20 ) in the combustion chamber ( 14 ) of the internal combustion engine ( 12 ) can be coupled, that within a working cycle of the internal combustion engine ( 12 ) in at least two independent locations ( 22 . 24 ) of the combustion chamber ( 14 ) the ignition conditions of the combustible combustion mixture ( 16 ) are reachable. Ignition device ( 10 ) according to claim 1 or 2, characterized in that the microdisplay ( 18 ) within the combustion chamber ( 14 ) a volume ( 26 ) spans on high-energy light. Ignition device ( 10 ) according to one of claims 1 to 3, characterized in that one of the at least two light-emitting diodes ( 20 ) and the microdisplay ( 18 ) trained laser light field to the edge ( 28 ) of the combustion chamber ( 14 ) of the internal combustion engine ( 12 ) is introduced. Ignition device ( 10 ) according to one of claims 1 to 4, characterized in that one of the at least two light-emitting diodes ( 20 ) and the microdisplay ( 18 ) formed laser light field is controllable such that light rays ( 38 ) of the light-emitting diodes ( 20 ) at any spatial coordinates in the combustion chamber ( 14 ) can be focused. Ignition device ( 10 ) according to one of claims 1 to 5, characterized in that each pixel ( 30 ) of the microdisplay ( 18 ) is adapted to receive a light beam ( 38 ) emitted at an intersection with another light beam ( 38 ) of another pixel ( 30 ) is suitable for producing a combustible combustion mixture ( 16 ) in the combustion chamber ( 14 ) to ignite. Ignition device ( 10 ) according to one of claims 1 to 6, characterized in that a plurality of light-emitting diodes ( 20 ), the light beams ( 38 ) of a first diode group and a second diode group of the at least two light-emitting diodes ( 20 ) at the same time in the combustion chamber ( 14 ) of the internal combustion engine ( 12 ) be initiated. Ignition device ( 10 ) according to one of claims 1 to 6, characterized in that a plurality of light-emitting diodes ( 20 ), the light beams ( 38 ) of a first diode group and a second diode group of the at least two light-emitting diodes ( 20 ) with a time delay of a maximum of 5 ms, preferably of a maximum of 2 ms, into the combustion chamber ( 14 ) of the internal combustion engine ( 12 ) be initiated. Ignition device ( 10 ) according to one of claims 1 to 8, characterized in that the light beams ( 38 ) the at least two light emitting diodes ( 20 ) as pulsed light beams ( 38 ) in the combustion chamber ( 14 ) of the internal combustion engine ( 12 ) be initiated. Internal combustion engine ( 12 ) with at least one combustion chamber ( 14 ), in which an ignitable combustion mixture ( 16 ) can be stored and ignited, the internal combustion engine ( 12 ) a window ( 32 ) for coupling a high-energy light beam ( 38 ), characterized in that at the window ( 32 ) an ignition device ( 10 ), in particular a microdisplay ( 18 ) is arranged according to one of claims 1 to 9.

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