Injection nozzle for fuels

Patent metadata

Field	Value
Publication number	US-10508634-B2
Application number	US-201515537728-A
Country	US
Kind code	B2
Filing date	Oct 27, 2015
Priority date	Dec 18, 2014
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

The invention relates to an injection nozzle ( 1 ) for fuels, comprising a nozzle body ( 2 ), in which a pressure chamber ( 4 ) that can be filled with fuel under high pressure is formed, in which pressure chamber a piston-shaped nozzle needle ( 3 ) is arranged in such a way that the nozzle needle can be moved longitudinally. A sealing surface ( 6 ) is formed at one end of the nozzle needle ( 3 ) and an end face ( 9 ) is formed at the opposite end, wherein the sealing surface ( 6 ) interacts with a nozzle seat ( 5 ) in order to open and close at least one injection opening ( 8 ). A control chamber ( 10 ) that can be filled with fuel under changing pressure is bounded by the end face ( 9 ) of the nozzle needle ( 3 ) such that a force can be applied to the end face ( 9 ) in the direction of the nozzle seat ( 5 ) by means of the hydraulic pressure. The nozzle needle ( 3 ) has an elastic longitudinal segment ( 25 ), which has a longitudinal stiffness of less than 40,000 N/mm.

First claim

What is claimed is:

1. An injection nozzle ( 1 ) for fuels, comprising a nozzle body ( 2 ) having therein a pressure chamber ( 4 ) which is configured to be filled with fuel under high pressure and in which a piston-shaped nozzle needle ( 3 ) is arranged in longitudinally mobile manner, the nozzle needle having at one end a sealing surface ( 6 ) and at an opposite end an end surface ( 9 ), said sealing surface ( 6 ) interacting with a nozzle seat ( 5 ) for opening and closing at least one injection port ( 8 ), and with the injection nozzle also comprising a control chamber ( 10 ) which is configured to be filled with fuel under variable pressure and which the nozzle needle ( 3 ) delimits with the end surface ( 9 ), so that a force is exerted on the nozzle seat ( 5 ) by a hydraulic pressure on the end surface ( 9 ), characterized in that the nozzle needle ( 3 ) has an elastic longitudinal portion ( 25 ) which has a longitudinal stiffness of less than 40,000 N/mm, wherein the elastic longitudinal portion has a diameter and a length, wherein the nozzle needle ( 3 ) includes guide portions ( 30 ; 31 ) formed on the nozzle needle ( 3 ) respectively upstream and downstream of the elastic longitudinal portion ( 25 ), wherein the guide portions limit radial movement of the nozzle needle, wherein the guide portions each have a diameter larger than the diameter of the elastic longitudinal portion and a length shorter the length of the elastic longitudinal portion, and wherein the guide portions include respective passages ( 33 ; 34 ) that ensure a throttle-free flow of fuel to the at least one injection port ( 8 ) within the pressure chamber ( 4 ).

2. The injection nozzle ( 1 ) as claimed in claim 1 , characterized in that the elastic longitudinal portion ( 25 ) of the nozzle needle ( 3 ) has a stiffness (c) of less than 20,000 N/mm.

3. The injection nozzle as claimed in claim 1 , characterized in that the elastic longitudinal portion ( 25 ) has a circular cylindrical shape.

4. The injection nozzle ( 1 ) as claimed in claim 1 , characterized in that the nozzle needle ( 3 ) is manufactured from a steel, and the diameter of the elastic longitudinal portion ( 25 ) is from 1.3 mm to 2.0 mm.

5. The injection nozzle ( 1 ) as claimed in claim 4 , characterized in that the steel has a modulus of elasticity from 200,000 N/mm 2 to 230,000 N/mm 2 .

6. The injection nozzle ( 1 ) as claimed in claim 1 , wherein the length of the elastic longitudinal portion ( 25 ) is less than 30 mm.

7. The injection nozzle ( 1 ) as claimed in claim 6 , characterized in that more than one elastic longitudinal portion ( 25 ; 26 ) have been provided, each elastic longitudinal portion ( 25 ; 26 ) having a length (L) of less than 30 mm.

8. The injection nozzle ( 1 ) as claimed in claim 7 , wherein overall combined stiffness of the more than one elastic longitudinal portions ( 25 ; 26 ) amounts to less than 20,000 N/mm.

9. The injection nozzle ( 1 ) as claimed in claim 1 , characterized in that the sealing surface ( 6 ) of the nozzle needle ( 3 ) has an annular sealing line ( 27 ) with which in the closed state of the injection nozzle ( 1 ) the nozzle needle rests on the nozzle seat ( 5 ) and seals the pressure chamber ( 4 ) against the at least one injection port ( 8 ).

10. The injection nozzle ( 1 ) as claimed in claim 3 , characterized in that the sealing surface ( 6 ) of the nozzle needle ( 3 ) has an annular sealing line ( 27 ) with which in the closed state of the injection nozzle ( 1 ) the nozzle needle rests on the nozzle seat ( 5 ) and seals the pressure chamber ( 4 ) against the at least one injection port ( 8 ), and the diameter (d) of the elastic longitudinal portion ( 25 ) is at least equal to a diameter (db) of the annular sealing line ( 27 ).

11. The injection nozzle ( 1 ) as claimed in claim 1 , characterized in that the end of the nozzle needle ( 3 ) facing away from the sealing surface ( 6 ) is accommodated in a sleeve ( 23 ) which radially delimits the control chamber ( 10 ).

12. The injection nozzle ( 1 ) as claimed in claim 11 , characterized in that a closing spring ( 24 ) under initial compressive tension, which exerts a force on the nozzle needle ( 3 ) in a direction toward the nozzle seat ( 5 ), is arranged between the sleeve ( 23 ) and the nozzle needle ( 3 ).

13. A fuel injector ( 100 ) for injecting fuel into a combustion chamber of an internal-combustion engine, the fuel injector comprising an injection nozzle ( 1 ) as claimed in claim 1 .

14. The injection nozzle ( 1 ) as claimed in claim 1 , characterized in that the elastic longitudinal portion ( 25 ) of the nozzle needle ( 3 ) has a stiffness (c) from 12,000 N/mm to 16,000 N/mm.

15. The injection nozzle ( 1 ) as claimed in claim 1 , characterized in that the elastic longitudinal portion ( 25 ) of the nozzle needle ( 3 ) has a stiffness (c) from 14,000 N/mm to 16,000 N/mm.

16. The injection nozzle ( 1 ) as claimed in claim 1 , characterized in that the nozzle needle ( 3 ) has been manufactured from a steel, and the diameter of the elastic longitudinal portion ( 25 ) is from 1.4 mm to 1.6 mm.

17. The injection nozzle ( 1 ) as claimed in claim 4 , characterized in that the steel has a modulus of elasticity of at least 210,000 N/mm 2 .

18. The injection nozzle ( 1 ) as claimed in claim 1 , wherein the length of the elastic longitudinal portion ( 25 ) is from 15 mm to 28 mm.

Assignees

• Bosch Gmbh Robert

Inventors

• Rau Andreas

Classifications

• F02M61/205

  Means specially adapted for varying the spring tension or assisting the spring force to close the injection-valve, e.g. with damping of valve lift · CPC title

• F02M61/12

  characterised by the provision of guiding or centring means for valve bodies · CPC title

• F02M61/042 Primary

  The valves being provided with fuel passages · CPC title

• F02M47/027 Primary

  Electrically actuated valves draining the chamber to release the closing pressure · CPC title

• F02M2200/9053

  Metals · CPC title