Method for nitriding a component of a fuel injection system

Patent metadata

Field	Value
Publication number	US-10125734-B2
Application number	US-201515325426-A
Country	US
Kind code	B2
Filing date	May 5, 2015
Priority date	Jul 11, 2014
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

The invention relates to a method for nitriding a component of a fuel injection system, said component being loaded under high pressure and being composed of an alloyed steel. The method comprises the following steps: —activating the component in inorganic acid, —pre-oxidizing the component in oxygen-containing atmosphere between 380° C. and 420° C., —nitriding the component between 520° C. and 570° C. at a high first nitriding potential KN,1 in the ε nitride range, —nitriding the component between 520° C. and 570° C. at a lower second nitriding potential KN,2 in the γ′ nitride range.

First claim

The invention claimed is:

1. A method for nitriding a component of a fuel injection system, said component being subject to high pressure and being composed of an alloyed steel,
said method comprising the following method steps:
activating the component in inorganic acid,
pre-oxidizing the component in an oxygen-containing atmosphere between 380° C. and 420° C.,
nitriding the component between 520° C. and 570° C. at a high first nitriding potential K N,1 in the ε nitride range, and
nitriding the component between 520° C. and 570° C. at a low second nitriding potential K N,2 in the γ′ nitride range.

2. The method as claimed in claim 1 , characterized in that the first nitriding potential K N,1 is between 1 and 10.

3. The method as claimed in claim 1 , characterized in that the second nitriding potential K N,2 is between 0.2 and 0.4.

4. The method as claimed in claim 1 , wherein the component is nitrided such that a percentage of nitrogen by mass at a surface of the component is between 11% and 25%.

5. The method as claimed in claim 4 , wherein the component is nitrided such that the percentage of nitrogen by mass at a first depth t 1 of 10 μm from the surface of the component is between 3% and 8%.

6. The method as claimed in claim 5 , wherein the component is nitrided such that the percentage of nitrogen by mass at a second depth t 2 of 15 μm from the surface of the component is between 2% and 7%.

7. The method as claimed in claim 6 , wherein the component is nitrided such that the percentage of nitrogen by mass at a third depth t 3 of 20 μm from the surface of the component is between 2% and 6%.

8. A method of manufacturing a fuel injector ( 1 ) for injecting fuel into a combustion chamber of an internal combustion engine, having a nozzle needle ( 3 ) which is guided for longitudinal movement in a nozzle body ( 4 ), wherein the nozzle body ( 4 ) is the component nitrided by the method as claimed in claim 4 .

9. A component nitrided by a method in claim 1 , characterized in that a percentage of nitrogen by mass at a surface of the component is between 11% and 25%.

10. The component as claimed in claim 9 , characterized in that the percentage of nitrogen by mass at a first depth t 1 of 10 μm from the surface of the component is between 3% and 8%.

11. The component as claimed in claim 10 , characterized in that the percentage of nitrogen by mass at a second depth t 2 of 15 μm from the surface of the component is between 2% and 7%.

12. The component as claimed in claim 11 , characterized in that the percentage of nitrogen by mass at a third depth t 3 of 20 μm from the surface of the component is between 2% and 6%.

13. A fuel injector ( 1 ) for injecting fuel into a combustion chamber of an internal combustion engine, having a nozzle needle ( 3 ) which is guided for longitudinal movement in a nozzle body ( 4 ), characterized in that the nozzle body ( 4 ) is a component as claimed in claim 9 .

Assignees

• Bosch Gmbh Robert

Inventors

• Paulus Christian
• Werger Heinrich

Classifications

• F02M61/168 Primary

  Assembling; Disassembling; Manufacturing; Adjusting · CPC title

• F02M2200/9038

  Coatings · CPC title

• C23C8/02 Primary

  Pretreatment of the material to be coated (C23C8/04 takes precedence) · CPC title

• F02M61/10

  Other injectors with elongated valve bodies, i.e. of needle-valve type · CPC title

• C23C8/34

  more than one element being applied in more than one step · CPC title