WO2007082634A2

WO2007082634A2 - Laser device and method and device for igniting an air/fuel mixture in a combustion chamber of an internal combustion engine and internal combustion engine

Info

Publication number: WO2007082634A2
Application number: PCT/EP2006/070272
Authority: WO
Inventors: Sven Eisen; Andre Kaufmann; Jürgen Rink
Original assignee: Continental Automotive Gmbh
Priority date: 2006-01-19
Filing date: 2006-12-29
Publication date: 2007-07-26
Also published as: DE102006002694A1; WO2007082634A3

Abstract

The invention relates to a laser device and to a method and device for igniting an air/fuel mixture in a combustion chamber of an internal combstution engine. Said laser device comprieses a solid body actuator (52), a laser (40) and an electrically deformable lens (56). Said lens (56) is arranged on the outside of the laser (40), is optically coupled to the laser (40) and is mechanically coupled to the soild body actuator (52) in such a manner that it can be elastically deformed by controlling the solid body actuator (52).

Description

description

Laser apparatus and method and apparatus for igniting an air / fuel mixture in a combustion chamber of an internal combustion engine and internal combustion engine

The invention relates to a laser device comprising a laser and a solid state actuator. Furthermore, the invention relates to an internal combustion engine with a laser ignition device. Furthermore, the invention relates to a method and a device for igniting an air / fuel mixture in a combustion chamber of the internal combustion engine.

From JP 100 94 886 A a laser device is known which comprises an optical lens which is arranged in a cylindrical piezo-element. An extension of the piezoelectric element due to a corresponding input signal of the piezoelectric element is transmitted to the circumference of the optical lens. As the piezo element expands, the optical lens, and thus a focal point of the optical lens, is adjusted along the optical axis of the optical lens. The optical lens is arranged coaxially with the piezoelectric element.

From DE 20 2004 019 626 Ul an ignition system for an internal combustion engine is known. The ignition system includes at least one laser emitter capable of delivering a high energy beam of sufficient intensity for fuel-air mixture ignition and an optical fiber directing the laser beam to a combustion chamber of the engine. Furthermore, the ignition system comprises a combustion chamber light window which is attached to the combustion chamber, which is heat-resistant and is coupled to the light guide, and a laser control, the laser operation, the ignition pulses of the Laser or a light switch, which can interrupt the light in the light guide or directly in front of the combustion chamber window, depending on phases of the internal combustion engine controls.

The object of the invention is to provide a laser device which enables a very fast and precise adjustment of a laser beam of the laser device. In particular, it is an object of the invention to provide an internal combustion engine, a method and an apparatus for igniting an air / fuel mixture in a combustion chamber of the internal combustion engine, which enables a very precise combustion.

The object is solved by the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized in terms of a first aspect of the invention by a laser device. The laser device includes a solid state actuator, a laser, and an elastically deformable lens external to the laser. The elastically deformable lens is optically coupled to the laser. Furthermore, the elastically deformable lens is so coupled to the solid state actuator that it is elastically deformable by driving the Festkörperaktuators.

The deformation of the lens with the solid state actuator allows a very precise and very fast shifting of a focal point of the lens. This makes it possible to focus a laser beam of the laser very precisely and very quickly at different points. This allows, in particular when using the laser device for igniting an air / fuel mixture in a combustion chamber of an internal combustion engine. machine, during only a combustion process of the internal combustion engine to ignite the air / fuel mixture several times at different points in the combustion chamber. This can lead to a very precise combustion of the

Air / fuel mixture and thus contribute to a precise control of the internal combustion engine.

In addition, the elastic deformation of the lens allows for a relatively small Aktorstellweg the Festkörperaktua- sector adjusting the focal point in a relatively large spatial area with respect to the Aktorstellweg.

In an advantageous embodiment of the first aspect of the invention, the elastically deformable lens is coupled in the axial direction with the solid state actuator. The solid-state actuator acts on the lens in the axial direction. This makes it possible to adjust and / or deform the lens so that the focal point of the lens is displaced along an optical axis of the lens and / or that the optical axis is tilted with the focal point.

In a further advantageous embodiment of the first aspect of the invention, the elastically deformable lens is coupled in the radial direction with the solid-state actuator, in such a way that the solid-state actuator acts in the radial direction on the elastically deformable lens. This makes it possible to adjust and / or deform the lens so that the focal point of the lens is displaced along the optical axis of the lens and / or that the optical axis is tilted with the focal point.

In a further advantageous embodiment of the first aspect of the invention, the laser via a light guide with - A -

coupled to the elastically deformable lens. This allows the laser arbitrarily spaced to arrange the combustion chamber.

The invention is characterized in terms of a second aspect of the invention by an internal combustion engine. The internal combustion engine comprises at least one cylinder with a combustion chamber. Furthermore, the internal combustion engine comprises a laser ignition device and a window transparent in the cylinder for laser beams of the laser ignition device. The laser ignition device comprises a solid state actuator, a laser, and a lens outside the laser. The lens is optically coupled to the laser. Further, the lens is mechanically coupled to the solid state actuator such that by driving the solid state actuator, the laser beams are focused at different points in the combustion chamber. Through the window, the laser ignition device is optically coupled to the combustion chamber.

In an advantageous embodiment of the second aspect of the invention, the laser ignition device is designed according to the laser device.

The invention is characterized in a third aspect of the invention by a method and a device for igniting the air / fuel mixture in the combustion chamber of the internal combustion engine. For igniting the air / fuel mixture in the combustion chamber of the internal combustion engine, a laser beam is focused within a combustion process on different points in the combustion chamber, that

Air / fuel mixture is ignited in the combustion chamber at the different points. In an advantageous embodiment of the third aspect of the invention, the focus of the optical axis of the lens is shifted to focus the laser beam at the different points. This allows the air / fuel mixture to ignite at the different points and thus contributes to a very precise combustion of the air / fuel mixture in the combustion chamber. In particular, in a stratified operation of the internal combustion engine and / or at other local fluctuations of the air / fuel ratio in the combustion chamber, the ignition of the air / fuel mixture at the different points in the combustion chamber can contribute to a very precise combustion.

In a further advantageous embodiment of the third aspect of the invention, the focal point of the lens is displaced along the optical axis. This makes it possible to ignite the air / fuel mixture in the combustion chamber along the optical axis at different points.

In a further advantageous embodiment of the third aspect of the invention, the optical axis of the lens is adjusted. This makes it possible to ignite the air / fuel mixture at any different points in the combustion chamber 9.

In a further advantageous embodiment of the third aspect of the invention, the lens is elastically deformed for adjusting the focal point. The elastic deformation of the lens alters radii of the lens. This leads to a shift of the focal point. Even a slight change of one of the two radii of the lens can cause a shift of the focal point in a relatively large area. Relatively large is related in this context to Aktorstellweg. Advantageous embodiments of the invention are explained in more detail below.

Show it:

1 shows an internal combustion engine,

FIG. 2 shows a first embodiment of an actuator device,

FIG. 3 shows a section through the actuator device according to FIG. 2,

FIG. 4 shows the actuator device according to FIG. 2 with the solid state actuator under tension,

FIG. 5 shows a second embodiment of the actuator device,

FIG. 6 shows a section through the second embodiment of the actuator device according to FIG. 5,

FIG. 7 shows the second embodiment of the actuator device with a solid state actuator under tension,

FIG. 8 shows a third embodiment of the actuator device,

FIG. 9 shows a fourth embodiment of the actuator device,

FIG. 10 shows a section through the fourth embodiment of the actuator device according to FIG. 9,

11 shows a program for igniting a

Air / fuel mixture in a combustion chamber of the internal combustion engine. Elements of the same construction or function are identified across the figures with the same reference numerals.

An internal combustion engine (FIG. 1) comprises an intake tract 1, an engine block 2, a cylinder head 3 and an exhaust tract 4. The intake tract 1 preferably comprises a throttle valve 5, a collector 6 and an intake manifold 7, which leads to a cylinder Z1 via an intake passage in FIG a combustion chamber 9 of the engine block 2 is guided. Furthermore, the intake tract 1 may comprise a pulse charging valve 16. The engine block 2 comprises a crankshaft 8, a connecting rod 10 and a piston 11. The crankshaft 8 is coupled via the connecting rod 10 with the piston 11 of the cylinder Zl. The internal combustion engine preferably comprises, in addition to the cylinder Z1, further cylinders Z2, Z3, Z4. However, the internal combustion engine can also comprise any desired larger number of cylinders Z1 to Z4. The internal combustion engine is preferably arranged in a motor vehicle.

Preferably, an injection valve 18 is arranged in the cylinder head 3. Alternatively, the injection valve 18 may also be arranged in the intake manifold 7. In the exhaust tract 4, an exhaust gas catalyst 21 is preferably arranged, which is preferably designed as a three-way catalyst.

A control device 25 is provided, which is associated with sensors which detect different measured variables and in each case determine the measured value of the measured variable. The control device 25 determines dependent on at least one of the measured variables manipulated variables, which are then converted into one or more actuating signals for controlling the actuators by means of corresponding actuators. The sensors are, for example, a pedal position sensor 26, which detects an accelerator pedal position of an accelerator pedal 27, an air mass sensor 28, which detects an air mass flow upstream of the throttle valve 5, a first temperature sensor 32, which detects an intake air temperature, a Saugrohrdrucksen- sensor 34, the intake manifold pressure in the Collector 6 detects, a crankshaft angle sensor 36 which detects a crankshaft angle, which is then assigned a speed N of the internal combustion engine.

Depending on the embodiment of the invention, any subset of said sensors may be present, or additional sensors may be present.

The actuators are, for example, the throttle valve 5, the gas inlet and gas outlet valves 12, 13, the pulse charging valve 16, the injection valve 18 and / or a laser ignition device, in particular a solid-state actuator 52 of the laser ignition device (FIG. 2).

The laser ignition device is a part of the internal combustion engine. The laser ignition device comprises an actuator device 44, a laser 40 and preferably a light guide 42. The actuator device 44 is optically coupled to the laser 40 via the light guide 42. The power of the laser 40 is so high that by focusing a laser beam L of the laser 40, an air / fuel mixture in the combustion chamber 9 can be ignited. The actuator device 44 is optically coupled to the combustion chamber 9 via a window 46 in the cylinder Z1 to Z4. The window 46 is formed so as to be transparent to the laser beams L from the laser 40. The laser 40 is thus via the light guide 42, the actuator device 44 and the Window 46 optically coupled to the combustion chamber 9 of the internal combustion engine.

The actuator device 44 comprises the solid-state actuator 52 (FIG. 2) and a lens 56. Furthermore, the actuator device 44 preferably comprises a holder 54 for the lens 56, an actuator housing 50 and a base plate 60. The solid-state actuator 52 is arranged in the actuator housing 50. At an axial end of the solid-state actuator 52, the solid-state actuator 52 preferably rests on the base plate 60 and acts on the lens 56 in the radial direction. The solid-state actuator 52 may, for example, be tubular (FIG. 3).

If an appropriate voltage is applied to the solid state actuator 52, it will expand. An extent X of the solid state actuator 52 is representative of an actuator travel of the solid state actuator 52. For example, a period of time required for the solid state actuator 52 to expand may be in the range of a few microseconds. Furthermore, the extent X can be specified very precisely by the correspondingly precise predetermined voltage. The solid-state actuator 52 is mechanically coupled to the lens 56 and thus enables a very fast and precise shifting of a focal point of the lens 56. Hereinafter, the focal point of the lens 56 in the de-energized state of the solid-state actuator 52 is referred to as the output focal point F 0 and as the final focal point F 1. when the voltage is applied to the solid state actuator 52.

Moving the focal point of the lens 56 allows the laser beam L of the laser 40 to focus very quickly and very precisely on different points in the combustion chamber 9. The very fast and very precise focusing of the laser beams L allows a multiple ignition of the same air / fuel mixture in a combustion process of the internal combustion engine at the different points in the combustion chamber 9. In particular, in a stratified operation of the internal combustion engine, in which the air / fuel ratio in the combustion chamber 9 predetermined is subject to local fluctuations, and / or systemic local fluctuations in the air / fuel ratio in the combustion chamber 9, for example, due to a non-uniform spray pattern of the injector 18, so can be targeted during a combustion process at the different points in the combustion chamber 9 ignited. The different points are preferably in local areas of the combustion chamber 9, where, for example, a predetermined air / fuel ratio is expected. A combustion process in this context refers to the burning of the air / fuel mixture in the combustion chamber 9 within a working cycle of the crankshaft 8, in particular at the end of a compression stroke and at the beginning of a power stroke.

To shift the focal point of the lens 56 to the different points in the combustion chamber 9, the entire lens 56 can be adjusted and / or the lens 56 can be elastically deformed. If the lens 56 is elastically deformed, the lens 56 preferably comprises an elastically deformable material, for example silicone and / or a hydrogel.

The elastic deformation of the lens 56 (FIG. 4) makes it possible, with a relatively small extent X of the solid-state actuator 52, to shift the focal point of the lens 56 to a relatively large extent relative to the extent X of the solid-state actuator 52 she can become preferably held stationary by the holder 54. The solid state actuator then moves relative to the lens 56 and support 54. When the lens 56 is deformed, at least one of its radii thereby deforms. This causes the displacement of the output focal point F 0. The relationship between the size of the radii of the lens 56 and the position of the focal point can be determined, for example, based on a lens equation used in the optics. For example, the solid state actuator 52 may act on the lens 56 in the axial direction and so may at an inner radius of the solid actuator 52 of 1 mm, a lens diameter of 5 mm, a first radius of the lens 56 of 15 mm and a second radius of the lens 56 of FIG mm at an extent X of the Festkörperaktuators 52, for example, 40 microns move the focal point of the lens 56 along an optical axis O_A of the lens 56 from a Ausgangsbrennpunkt F_0 to a final focal point F 1, which have a distance Y of about 1.1 mm to each other. This corresponds to an adjustment factor of approximately 30. That is, the focal point is shifted by thirty times the extent X of the solid-state actuator 52.

The solid state actuator 52 may also act in the radial direction on the lens 56 (FIG. 5) to deform the lens 56. Preferably, then a plurality of solid state actuators 52 are provided and the lens 56 is held by the correspondingly formed solid state actuators 52 (Figure 6). The application of the voltage to the solid state actuator 52 then causes the lens 56 to compress in the radial direction (FIG. 7). This leads to a reduction of the radii of the lens 56 and thus to a shift of the output focal point F 0 towards the lens 56 to the final focal point F 1. Adjustment of the lens 56 includes shifting, twisting, tilting, and / or other mechanical motion that displaces the lens 56 as a whole. If the lens 56 is adjusted, it is advantageous if the holder 54 of the lens 56 is coupled to the solid state actuator 52 (FIG. 8). The solid state actuator 52, the lens 56 and optionally the holder 54 are then moved uniformly relative to one another. If now the preferably tubular solid-state actuator 52 is activated, it has, for example, the extension X of 50 micrometers. The distance Y of the Ausgangsbrennpunkts F 0 and the final focal point F 1 then be 50 microns.

Alternatively, it is also possible to use a plurality of axially acting solid-state actuators 52 for adjusting the lens 56 (FIG. 9, FIG. 10). The solid-state actuators 52 can act, for example, in the axial direction on the lens 56 and / or the holder 54. Furthermore, the solid-state actuators 52 may, for example, be distributed uniformly around the circumference of the lens 56. If the same voltage is applied to each of the solid state actuators 52, the operation of the solid state actuators 52 corresponds to a single solid state tubular actuator 52. However, if different voltages are applied to the individual solid state actuators 52, the lens 56 is tilted. As a result, the optical axis O_A of the lens 56 is also tilted and the focus is shifted with the optical axis OA. The laser beams L no longer incident parallel to the optical axis OA are no longer focused on the final focal point F_1, but scatter around the final focal point F1. The power of the laser 40 must be selected in this case so high that still the ignition of the air / fuel mixture in the combustion chamber 9 is possible. A program (Figure 11) for igniting the

Air / fuel mixture in the combustion chamber is preferably stored in the control device 25. The control device 25 may be referred to in this context as a device for igniting the air / fuel mixture in the combustion chamber 9 of the internal combustion engine. The program is preferably started shortly before the ignition of the air / fuel mixture in the combustion chamber 9 in a step Sl, in which variables are initialized if necessary.

In a step S2, the end focal point F_l is determined at which the air / fuel mixture is to be ignited.

In a step S3, a control signal SG for the solid state actuator 25 is determined for shifting the focal point of the lens 56 to the final focal point F 1.

In a step S4, the focal point is shifted along the optical axis O_A of the lens 56. The optical axis O_A is not adjusted.

In a step S5, the optical axis O A of the lens 56 is adjusted so that the focus of the lens 56 is shifted.

In step S4 and / or in step S5, the focal point of the lens 56 may be shifted by adjusting and / or deforming the lens 56.

In a step S6, the air / fuel mixture is ignited in the combustion chamber 9. In a step S7, the program is ended. Preferably, however, during a combustion process, the steps S2 to S6 are processed several times and so the

Air / fuel mixture ignited at the different points in the combustion chamber 9. Alternatively, a plurality of actuating signals SG for the solid-state actuator 52 can be determined and stored before the first ignition. The solid state actuator 52 is then driven depending on the stored actuating signals SG.

The fast and precise focusing of the laser beam L can be used independently of the internal combustion engine in many different technical fields, for example in medical technology, electrical engineering and / or in manufacturing processes in general. The manufacturing processes may include, for example, welding, cutting and / or drilling with the laser beams L. The laser ignition device is then preferably referred to as a laser device. In the laser device, the focal point of the lens 56 is preferably displaced by elastically deforming the lens 56.

The invention is not limited to the specified embodiments. For example, the different embodiments can be combined. For example, the lens 56 may be deformed and displaced by the solid state actuator 52. Further, the lens 56 can be adjusted in the axial and in the radial direction. Further, the lens 56 can be deformed and displaced in the radial and axial directions. The program for igniting the air / fuel mixture may comprise further or fewer steps S1 to S7, in which the focus is shifted accordingly.

Claims

claims

1. comprising a laser device

a solid state actuator (52),

a laser (40),

- An elastically deformable lens (56) outside of the laser (40), which is optically coupled to the laser (40) and which is mechanically coupled to the Festkörperaktuator (52) that it is elastically deformable by driving the Festkörperaktuators (52) ,

2. A laser device according to claim 1, wherein the elastically deformable lens (54) in the axial direction with the Festkörperaktuator (52) is coupled and in which the Festkörperaktuator (52) acts in the axial direction of the lens (54).

3. Laser device according to one of the preceding claims, wherein the elastically deformable lens (54) in the radial direction with the solid-state actuator (52) is coupled in such a way that the solid-state actuator (52) in the radial direction on the elastically deformable lens (54). acts.

4. Laser device according to one of the preceding claims, wherein the laser (40) via a light guide (58) with the elastically deformable lens (56) is optically coupled.

5. Internal combustion engine comprising

- At least one cylinder (Zl - Z4) with a combustion chamber (9),

a laser ignition device comprising a solid state actuator (52), a laser (40) and outside the laser (40)

Lens (56) which is optically coupled to the laser (40) and which is mechanically coupled to the solid state actuator (52). coupled is that by driving the Festkörperaktuators (52) a laser beam (L) is focused on different points (F 0, F 1) in the combustion chamber (9),

a window (46) transparent to the laser (40) in the cylinder (Z1 - Z4), by which the laser ignition device is optically coupled to the combustion chamber (9).

6. Internal combustion engine according to claim 5, wherein the laser ignition device is formed according to the laser device according to one of claims 1 to 4.

7. A method for igniting an air / fuel mixture in a combustion chamber (9) of the internal combustion engine according to one of claims 5 or 6, wherein a laser beam (L) within a combustion process so on different points (F 0, F_l) in the combustion chamber (9 ) that is focused

Air / fuel mixture in the combustion chamber (9) at the different points (F_0, F_l) is ignited.

8. The method of claim 7, wherein for focusing the laser beam (L) at the different points (F 0, F 1) a focal point of an optical axis (O_A) of the lens (56) is moved.

9. The method of claim 8, wherein the focal point (F 0) along the optical axis (O_A) is moved.

10. The method according to any one of claims 8 or 9, wherein the optical axis (O_A) of the lens (56) is adjusted.

11. The method according to any one of claims 8 to 10, wherein for moving the focal point, the lens (56) is elastically deformed.

12. A device for igniting an air / fuel mixture in a combustion chamber (9) of the internal combustion engine according to one of claims 6 or 7, which is adapted for focusing a laser beam (L) on different points (F_0, F_l) in the combustion chamber (9) within a combustion process of the internal combustion engine, so that the air / fuel mixture in the combustion chamber (9) at the different points (F 0, F 1) is ignited.