Fuel injector and method of making same

Abstract

The invention relates to a fuel injector (1) for an internal combustion engine. The fuel injector (1) is comprised of an injector body (5) with an injector tip (6). The injector tip (6) is used for the injection of fuel into the combustion chamber (4) of the internal combustion engine. For this reason, the injector tip (6) is designed so as to be at least partially extended into the combustion chamber (4). If the injector tip (6) is designed to be flush with the surface of the combustion chamber (4), the injector tip (6) is arranged so that it directly faces toward the combustion chamber (4). Furthermore, the injector tip (6) is at least partially coated with a first oxide layer (9). According to the invention, a catalytic second oxide coating (10) composed of cerium oxide (CeO.sub.2), praseodymium oxide (PrO.sub.2), zirconium oxide (ZrO.sub.2), or any bi-component combination thereof is applied on top of the first oxide coating (9). The present invention also discloses a method of producing a fuel injector (1) which is at least partially coated with a first oxide coating (9) and a second oxide coating (10) applied over the first oxide coating (9), where the second oxide coating (10) is composed of at least one or more compounds from the group comprising cerium oxide (CeO2), praseodymium oxide (PrO2), or zirconium oxide (ZrO2) and is applied as a washcoat.

Claims

1. A fuel injector having a tip comprising: a first oxide coating, and a second oxide wash coating on top of the first oxide coating, the second oxide selected from the group consisting of cerium oxide (CeO2), praseodymium oxide (PrO2), zirconium oxide (ZrO2), or any bi-component combination thereof.

2. The fuel injector of claim 1, the first oxide coating further comprising impregnated copper oxide (CuO).

3. The fuel injector of claim 1, the second oxide coating further comprising impregnated copper oxide (CuO).

4. The fuel injector of claim 1, the first oxide further comprising a platinum group metal catalyst selected from the group consisting of ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd) or platinum (Pt).

5. The fuel injector of claim 1, the second oxide further comprising a platinum group metal catalyst selected from the group consisting of ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd) or platinum (Pt).

6. The fuel injector of claim 1, wherein the first oxide coating is selected from the group consisting of titanium oxide (TiO2), aluminum oxide (Al2O3) or mixtures thereof.

7. The fuel injector of claim 1, wherein the tip is at least partially from a powder metallurgical AlSi material or from a titanium alloy.

8. A method for producing a fuel injector comprising: applying a first oxide coating to said injector; and applying a second oxide coating over the first oxide coating, the second oxide coating composed of at least one or more compounds from the group consisting of cerium oxide (CeO2), praseodymium oxide (PrO2), or zirconium oxide (ZrO2).

9. The method of claim 8, further comprising impregnating copper oxide (CuO) in the first oxide coating.

10. The method of claim 8, further comprising impregnating copper oxide (CuO) in the second oxide coating.

11. The method of claim 8, wherein the first oxide coating further comprising a platinum group metal catalyst selected from the group consisting of ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd) or platinum (Pt).

12. The method of claim 8, wherein the second oxide coating further comprising a platinum group metal catalyst selected from the group consisting of ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd) or platinum (Pt).

13. The method of claim 8, wherein the first oxide coating is selected from the group consisting of titanium oxide (TiO2), aluminum oxide (Al2O3) or mixtures thereof.

14. The method of claim 8, wherein the tip is at least partially from a powder metallurgical AlSi material or from a titanium alloy.

15. The method of claim 14, wherein the tip is at least partially from a powder metallurgical AlSi material (PEAK 5250) or from a titanium alloy (Ti.sub.6Al.sub.4V) by melt spinning.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic illustration of a fuel injector according to the invention in a side view,

(2) FIG. 2 shows the fuel injector from FIG. 1, in a view of the end-side injector tip thereof, and

(3) FIG. 3 shows a diagram illustrating the weight of soot in relation to its different oxidation temperatures on an uncoated injection tip, and on a coated injection tip of the fuel injector from FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) FIG. 1 shows a schematic illustration of a fuel injector (1) according to the invention. The fuel injector (1) is provided for use in an internal combustion engine (not illustrated in any more detail). Also indicated is a section of a wall (2) of a cylinder head (3) of the internal combustion engine (not shown in any more detail), through which the fuel injector (1) is arranged. A sub-region of the fuel injector (1) extends into a combustion chamber (4) of the internal combustion engine.

(5) The fuel injector (1) is comprised substantially of a fuel injector body (5). The section of the fuel injector's body (5) which faces toward the combustion chamber (4), and is located partially in the combustion chamber, has an injector tip (6). The injector tip (6) is at least partially formed from a powder metallurgical AlSi material (PEAK 5250) or from a titanium alloy (Ti.sub.6Al.sub.4V). The dotted lines running in a longitudinal direction (a) of the fuel injector (1) serve for illustrating a duct (7) within the fuel injector (1). A fuel (not shown in any more detail) can be injected by means of the fuel injector (1) into the combustion chamber (4) through the duct (7).

(6) In the present invention, at least one face side (8) of the injector tip (6) is provided, as indicated, with a first oxide coating (9) and with a second oxide coating (10) arranged on top of the first oxide coating (9). The first oxide coating (9) is formed from titanium oxide (TiO.sub.2) and/or aluminum oxide (Al.sub.2O.sub.3). By contrast, the second oxide coating is applied as a wash coat and is composed of cerium oxide (CeO.sub.2), praseodymium oxide (PrO.sub.2), zirconium oxide (ZrO.sub.2), or any bi-component combination thereof.

(7) Furthermore, the first oxide coating (9) and/or the second oxide coating (10) are impregnated, in a manner not shown in any more detail, with copper oxide (CuO). A further impregnation of the first oxide coating (9) and/or the second oxide coating (10) with at least one or more elements (likewise not illustrated in any more detail) from the platinum group metals is likewise provided. The platinum group is composed of ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd) and platinum (Pt).

(8) FIG. 2 shows the fuel injector (1) from FIG. 1, in a view of the face side (8) of the injector tip (6). To make the present view in the longitudinal direction (a) of the fuel injector (1) as clear as possible, the wall (2) of the cylinder head (3) and the region of the fuel injector (1) which is situated outside the combustion chamber (4) in FIG. 1 are not indicated.

(9) As can be seen, the injector tip (6) has multiple outlet openings (11) from which the fuel can enter the combustion chamber (4) in a manner not illustrated in any more detail. Six outlet openings (11) are distributed about the central longitudinal axis (a) of the fuel injector (1), so as to be at the same radial distance from the longitudinal axis. These outlet openings are all equidistant from one another, so as to be arranged offset with respect to one another by the same angle (b).

(10) FIG. 3 shows a diagram of test results. Two curves (c), (d) are shown within the diagram. The two curves (c), (d) depict the weight (e) of soot deposited on the injector tip (6) in relation to the initial starting weight of soot. The soot is oxidized over time, such that the weight (e) thereof decreases. The curves (c), (d) of FIG. 3 are plotted versus a temperature (f) in C. The first curve (c), shown by a solid line, shows the measurement results for a normal, uncoated injector tip (6). The remaining curve (d), shown by a dashed line, illustrates the measurement results for an injector tip (6) coated and impregnated according to the invention.

(11) The present diagram serves for illustrating the improved combustion of soot on an injector tip (6) that is coated with a catalytic second oxide coating (10) composed of cerium oxide (CeO.sub.2) and praseodymium oxide (PrO.sub.2). The injector tip (6) was formed from the aluminum material AlSi.sub.20Fe.sub.5Ni.sub.2 and was coated with the first oxide coating (9) and a second oxide coating (10) which was composed of cerium oxide (CeO.sub.2) and praseodymium oxide (PrO.sub.2) and impregnated with copper oxide (CuO). The copper oxide (CuO) is preferably embedded only in the second oxide coating (10).

(12) The soot shown in the first curve (c) is a synthetic soot which is more stable than diesel and gasoline soot and which burns at higher temperatures. The oxide catalyst coating comprised of cerium oxide (CeO.sub.2), praseodymium oxide (PrO.sub.2) and copper oxide (CuO) was able to lower the combustion temperature of the synthetic soot by 70 C. Seeing as this is resistant synthetic soot, the combustion temperature will most likely be even lower when using naturally produced soot.

(13) The plotted measurement results in FIG. 3 were obtained using a thermogravimetric analysis (TGA) unit to test the combustion of synthetic soot in a laboratory. The synthetic soot used was produced by Hiden, UK with a quartz tube. For these tests, approximately 40.0 milligrams of soot were mixed with 120.0 milligrams of silicon carbide (SiC) as well as a catalyst. The injector tip thus prepared was placed into the basket of the thermogravimetric analysis (TGA) unit in an atmosphere containing 8% oxygen (O.sub.2). The sample was subsequently heated to 800 C. with a temperature rise of 10 C. per minute. The gases generated during the reaction were measured by a mass spectrometer.

LIST OF REFERENCE SIGNS

(14) 1 Injection valve 2 Wall of 3 3 Cylinder head 4 Combustion chamber 5 Valve body of 1 6 Valve head of 1 7 Duct in 1 8 Face side of 6 9 First oxide coating 10 Second oxide coating 11 Outlet opening in 6 a Longitudinal direction of 1 b Angle between 11 c First curve in diagram d Second curve in diagram e Weight of soot in relation to initial weight in diagram f Temperature in diagram