Internal combustion engine

Abstract

An internal combustion engine including at least one cylinder with a piston moveable therein in an engine block in which microwaves are introduced into a combustion chamber through a microwave window, wherein the combustion chamber is formed by a piston base and a cylinder head, characterized in that the combustion chamber includes a combustion chamber wall which functions as a microwave window at least in portions wherein the combustion chamber wall is made from a wall layer that is made from a ceramic material in which wall layer at least one annular circumferential hollow conductor cavity is arranged with at least one inlet opening for the microwave and which includes at least one outlet opening for the microwave that is run in the annular hollow conductor cavity of the wall layer. In general the invention provides safe ignition of lean fuel air mixtures.

Claims

1. An internal combustion engine, comprising: at least one cylinder with a piston moveable therein in an engine block in which microwaves are injected into a combustion chamber through a microwave window, wherein the combustion chamber is formed by a piston base and a cylinder head, wherein the combustion chamber includes a combustion chamber wall which functions as a microwave window at least in portions of the combustion chamber wall, wherein the combustion chamber wall is made from a ceramic material, wherein the combustion chamber wall includes at least one circumferential annular hollow conductor cavity, wherein the at least one circumferential annular hollow conductor cavity includes at least one inlet opening for the microwaves and at least one outlet opening for the microwaves that are run in the at least one circumferential annular hollow conductor cavity of the combustion chamber wall, wherein the at least one circumferential annular hollow conductor cavity is formed as a running bushing for the piston in the engine block, wherein the at least one circumferential annular hollow conductor cavity is defined in an axial direction of the running bushing by inserted or coated metal surfaces, and wherein the at least one circumferential annular hollow conductor cavity is defined in a radial direction of the running bushing by at least partial metal coating of the running bushing.

2. The internal combustion engine according to claim 1, wherein a plurality of gaps are provided between the at least one circumferential annular hollow conductor cavity and the combustion chamber wall, wherein the plurality of gaps are arranged perpendicular to a propagation direction of the microwaves.

3. The internal combustion engine according to claim 1, wherein the engine block includes a feed for the microwaves which ends at the at least one inlet opening of the at least one circumferential annular hollow conductor cavity.

4. The internal combustion engine according to claim 1, wherein the at least one inlet opening for the microwaves is arranged at a first end of the at least one circumferential annular hollow conductor cavity and includes a first wall surface that is oriented at a first angle relative to the at least one circumferential annular hollow conductor cavity and deflects the microwaves into the at least one circumferential annular hollow conductor cavity, wherein the at least one outlet opening for the microwaves is arranged at a second end of the at least one circumferential annular hollow conductor cavity and includes a second wall surface that is oriented at a second angle relative to the at least one circumferential annular hollow conductor cavity and deflects the microwaves from the at least one circumferential annular hollow conductor cavity into the combustion chamber.

5. The internal combustion engine according to claim 4, wherein the first wall surface and the second wall surface are arranged on opposite sides of a metal wall.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is subsequently can be described in more detail with reference to schematic drawing figures. Additional features of the invention can be derived from the subsequent description in combination with the patent claims and the appended drawing figures, wherein:

(2) FIG. 1 illustrates a detail of an internal combustion engine in a top view without cylinder head;

(3) FIG. 2 illustrates a sectional view along the line A-A of the detail of FIG. A with a cylinder head;

(4) FIG. 3 illustrates a blown up view of the detail X in FIG. B; and

(5) FIG. 4 illustrates a sectional view along the line B-B of FIG. B.

DETAILED DESCRIPTION OF THE INVENTION

(6) The individual figures are subsequently described jointly since there is only one embodiment that is illustrated in different views. The figures schematically illustrate a detail of an internal combustion engine 1 with a cylinder head 2 and an engine block 3. The engine block 3 includes a cylinder 4 with a piston 5 that is moveable therein and a combustion chamber 6 that is arranged above the cylinder 4 partially in the cylinder head 2 between the piston base 5 and the cylinder head 2. A schematically illustrated inlet 7 for the fuel air mixture leads into the combustion chamber 6. Outlets for an exhaust gas which can be configured in a manner that is known to a person skilled in the art are not illustrated. The schematically illustrated cylinder head 2 with a central inlet 7 for the fuel air mixture can certainly include additional spark plugs or outlets for exhaust gases. The cylinder 4 includes an additional inner wall 8 which is made from a material which is suitable to perform a function of a microwave window. This can be for example a ceramic material, advantageously with a high level of purity or another suitable microwave permeable and abrasion resistant material.

(7) The combustion chamber wall 8 is formed by a wall layer provided as a sleeve shaped running bushing 9 formed from a ceramic material that is arranged in the cylinder 4, wherein an annular hollow conductor cavity 10 is arranged in the wall of the sleeve shaped running bushing. The annular hollow conductor cavity 10 is connected with a feed 16 for the microwaves which is connectable outside of the engine block 3 to a non illustrated energy source and whose end oriented towards the annular hollow conductor cavity 10 forms the inlet opening 11 into the annular hollow conductor cavity 10 for the microwaves. In the wall of the running bushing 9 the annular hollow conductor cavity 10 is defined in axial direction by metal strips 14 inserted before sintering (can also be doted). Additionally a slanted divider wall 16 is arranged at an outlet of the feed 16 into the annular hollow conductor cavity 10 wherein the divider wall is used for deflecting the incoming microwave into the annular hollow conductor cavity 10 and for deflecting into the combustion chamber 6 after running about the annular hollow conductor cavity 10. Additionally this prevents back reflections of the microwave. The radial walls of the annular hollow conductor cavity 10 are formed at the radial outer wall of the running bushing 9 by the metal wall 17 of the engine block 3 and are formed at the combustion chamber wall 8 by a metal layer 15 applied by well-known methods. The metal layer 15 is etched away at locations where the microwaves shall exit. The embodiment shows multiple outlet openings 12 configured as gaps which are evenly distributed over a length of the annular hollow conductor cavity 10. This provides an injection of the microwave energy as described supra.

(8) Components of the engine like engine block, cylinder head etc. are made from a typical material, typically metal, wherein the material can be selected according to the application. The boundary for the microwaves in the illustrated hollow conductor cavities is made from metal, wherein additional measures can be taken in order to optimize conductivity, for example by surface coating with a highly electrically conductive material.