Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
  • F02P23/00—Other ignition
  • F02P23/04—Other physical ignition means, e.g. using laser rays

Definitions

• the invention relates to an ignition device for an internal combustion engine, wherein the ignition is triggered by an ignition laser.
• an ignition which is referred to below as laser ignition, is known for example from WO 2005/066488 A1.
• the ignition laser has a combustion chamber window which is transmissive to the laser pulses emitted by the ignition laser.
• the combustion chamber window must withstand the high pressures and temperatures prevailing in the combustion chamber over the entire service life of the internal combustion engine, without the optical properties of the combustion chamber window being adversely affected.
• the invention has for its object to make the laser ignition more reliable, trouble-free and low-maintenance.
• This object is achieved with a laser ignition device for an internal combustion engine, comprising an ignition laser with a laser-active solid, a combustion chamber window and a housing, achieved in that at the end of the housing, on which the combustion chamber window is arranged, a diaphragm is provided.
• This diaphragm ensures that the surface of the combustion chamber window is not affected by the exhaust gases and the gas flows in the combustion chamber. As a result, the formation of deposits on the combustion chamber window is drastically reduced. These deposits originate from the exhaust gases in the combustion chamber of the internal combustion engine.
• the diaphragm according to the invention By the diaphragm according to the invention, first, the amount of precipitating on the combustion chamber window residues is drastically reduced. Secondly, the momentum with which these residues impinge on the surface of the combustion chamber window is significantly reduced. Both effects ensure that the deposits on the combustion chamber window are significantly reduced and that the few deposits adhere less firmly to the combustion chamber window. As a result, the laser ignition device according to the invention is more reliable, trouble-free and low-maintenance.
• the diameter of the laser pulse which can also be referred to as the beam diameter, can be determined according to the standard DIN EN ISO 11 145. This standard belongs to the expertise of a specialist in the field of laser technology, so that detailed explanations of the determination of the beam diameter by reference to the standard are dispensable.
• the laser pulse of the laser ignition device is focused on an ignition point ZP and the optical precision of the focusing optics is very high, it is possible to dimension the diaphragm so that a gap of less than 1 mm exists between the outer contour of the laser pulse and that of the diaphragm , preferably of less than 0.5 mm, and more preferably less than 0.25 mm.
• a further advantageous embodiment of the invention provides that the diaphragm is conical, wherein the diameter of the diaphragm increases in the direction of the combustion chamber window and a cone angle of the diaphragm substantially corresponds to an exit angle of the laser pulse.
• the aperture over the entire length with a distance of less than 1 mm, preferably less than 0.5 mm and particularly preferably with a distance of less than 0.25 mm, is arranged around the laser pulse around , The length of the aperture in the direction of the optical axis of the ignition laser, the penetration of exhaust gases and the attachment of impurities on the combustion chamber window is further reduced.
• An advantageous embodiment of the laser ignition device according to the invention provides that the diaphragm is designed as a separate component and is attached to the housing of the ignition laser, in particular on a shoulder of the housing.
• the ignition laser has a combustion chamber window, this is acted upon by the use of the diaphragm according to the invention only with comparatively low temperatures and with a significantly smaller amount of exhaust gases. As a result, the transmissivity of the combustion chamber window remains sufficiently high over the entire service life of the internal combustion engine to ensure undisturbed operation of the internal combustion engine.
• the diaphragm shields the ignition laser only in regions, namely via a
• the main flow direction of the exhaust gases in the combustion chamber must be determined separately for each engine type. So that the aperture is correctly positioned to the ignition laser, it is recommended to secure the ignition laser in a form-fitting and secure against rotation in the cylinder head of the internal combustion engine.
• a mounted on the ignition laser nose which cooperates with a correspondingly shaped recess in the cylinder head, it can be ensured that the aperture is positioned in the manner described above relative to the ignition laser.
• the diaphragm shields the ignition laser over a circumferential angle of less than 200 °, preferably from 160 ° to 180 °. This ensures sufficient shielding for many applications with minimal costs and minimal influence on the gas flow in the combustion chamber.
• Figure 1 a is a schematic representation of an internal combustion engine with a laser-based ignition device
• Figure 1 b is a schematic representation of the ignition device of Figure 1 and
• FIGS 2 and 3 embodiments of inventive ignition laser.
• FIG. 1 a An internal combustion engine in FIG. 1 a bears the reference number 10 overall. It can be used to drive a motor vehicle (not shown).
• the internal combustion engine 10 comprises a plurality of cylinders, of which only one is designated by the reference numeral 12 in FIG.
• a combustion chamber 14 of the cylinder 12 is limited by a piston 16.
• Fuel enters the combustion chamber 14 directly through an injector 18 which is connected to a fuel rail, also referred to as a rail.
• fuel 22 is ignited by means of a laser pulse 24 which is radiated from an ignition laser 26 comprehensive ignition device 27 into the combustion chamber 14.
• the ignition laser 26 is fed via a light guide device 28 with a pumping light, which is provided by a pumping light source 30.
• the pumping light source 30 is controlled by a control unit 32, which also controls the injector 18.
• the pumping light source 30 feeds a plurality of optical waveguide devices 28 for different ignition lasers 26, which are each assigned to a cylinder 12 of the internal combustion engine 10.
• the pumping light source 30 has a plurality of individual laser light sources 340, which are connected to a pulse power supply 36.
• a "stationary" distribution of pump light to the various ignition lasers 26 is realized so that no optical distributors or the like between the pump light source 30 and the ignition lasers 26 are required.
• the ignition laser 26 has, for example, a laser-active solid 44 with a passive Q-switching circuit 46, which together with a Einkoppelapt 42nd and an output mirror 48 forms an optical resonator.
• the ignition laser 26 Upon application of a pumping light generated by the pumping light source 30, the ignition laser 26 generates a laser pulse 24 in a manner known per se, which is focused by focusing optics 52 onto an ignition point ZP located in the combustion chamber 14 (FIG.
• Components are separated from the combustion chamber 14 by a combustion chamber window 58.
• FIG 2 the detail X of Figure 1 b is shown greatly enlarged in partial longitudinal section. From this greatly enlarged illustration it becomes clear that the combustion chamber window 58 is sealingly connected to the housing 38.
• the seal between the housing 38 and the combustion chamber window may be formed in the region of the reference numeral 60 in the form of a cohesive or non-positive connection.
• the housing 38 is made of a heat-resistant material and, as a result, also has sufficient fatigue strength at the operating temperatures prevailing in the combustion chamber.
• the housing 38 is formed in two parts. It comprises an inner sleeve 62 and an outer sleeve 64.
• the outer sleeve 64 has a shoulder 66 at an end facing the combustion chamber 14 (see FIG. 1 a).
• the shoulder 66 serves to press the combustion chamber window 58 against the inner sleeve 62 and thereby increase the tightness in the region of the reference numeral 60.
• a female thread is provided on the outer sleeve 64, which cooperates with a corresponding bolt thread of the inner sleeve 62. This thread, consisting of female thread and bolt thread is indicated in its entirety by the reference numeral 68.
• a further sealing surface 72 is formed between the shoulder 66 and the combustion chamber window.
• the end facing the combustion chamber 14 of the ignition laser 26 is shown significantly enlarged.
• focusing optics which focuses the laser pulse 24 to the ignition point ZP, which corresponds to the focus of the optics of the ignition laser 26.
• the outer contour of the focused laser pulse 24 is indicated by the conical H ü ulia (without reference numeral). These envelope lines intersect in the Ignition point ZP and exit with a diameter D A from the combustion chamber window 58.
• the invention provides to see between the combustion chamber window 58 and the ignition point ZP to arrange a panel 74.
• the diameter of the diaphragm is denoted by the reference numeral D 6 .
• the diameter D 6 of the aperture 74 is selected as small as possible. As a result, it is sufficient if the diaphragm 74 has a radial distance to the laser pulse 24 or its outer contour of less than 1 mm, preferably less than 0.5 mm and particularly preferably less than 0.25 mm. This dimensioning of the diameter D 6 of the diaphragm 74 results in that the ignition power of the laser pulse 24 is not reduced and, on the other hand, the gas exchange between the combustion chamber and the "dead space" 70 present between the diaphragm 74 and the combustion chamber window 58 is minimized.
• Aperture 74 may for example be soldered, welded or otherwise secured in the form of a sheet metal disc to the outer sleeve 64.
• FIG. 3 shows a further embodiment of an aperture according to the invention
• the aperture 74 is shown. The main differences can be seen in the fact that the aperture 74 is part of the outer sleeve 64 and the aperture 74 is conical.
• the cone angle ß of the aperture 74 corresponds to the angle ⁇ of the laser pulse 24.
• Dead space 70 was further reduced in this embodiment compared to the embodiment shown in Figure 2, even fewer deposits on the combustion chamber window 58 are deposited.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Combustion Methods Of Internal-Combustion Engines (AREA)
• Lasers (AREA)

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Citations (3)

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• 2008
  • 2008-11-21 DE DE102008043961A patent/DE102008043961A1/de not_active Withdrawn
• 2009
  • 2009-11-18 US US13/129,052 patent/US8783221B2/en not_active Expired - Fee Related
  • 2009-11-18 WO PCT/EP2009/065364 patent/WO2010057904A1/de active Application Filing
  • 2009-11-18 JP JP2011536846A patent/JP2012509433A/ja active Pending
  • 2009-11-18 CN CN200980146404.9A patent/CN102224337B/zh not_active Expired - Fee Related
  • 2009-11-18 EP EP09752835A patent/EP2358991A1/de not_active Withdrawn
• 2013
  • 2013-10-25 JP JP2013222308A patent/JP2014043861A/ja active Pending

Patent Citations (3)

Non-Patent Citations (1)

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