Fuel injector

Patent metadata

Field	Value
Publication number	US-9765738-B2
Application number	US-201514644417-A
Country	US
Kind code	B2
Filing date	Mar 11, 2015
Priority date	Mar 14, 2014
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A fuel injector includes a fuel valve with a valve seat and a movable valve needle, a calibration spring and an electromagnetic actuator with a solenoid and a movable armature. The calibration spring exerts a pressing force on the valve needle for pressing the valve needle in a closing direction towards the valve seat. When the solenoid is electrically energized, the electromagnetic actuator is operable to transfer a lifting force to the valve needle by engagement with the armature for lifting the valve needle from the valve seat to a fully open position against the pressing force of the calibration spring. The calibration spring and the electromagnetic actuator are configured such that the lifting force equals the pressing force in the fully open position.

First claim

What is claimed is:

1. A fuel injector, comprising:
a fuel valve comprising a valve seat and a movable valve needle that cooperate for controlling a flow of fuel through the injector;
a calibration spring; and
an electromagnetic actuator comprising a solenoid and a movable armature;
wherein the calibration spring exerts a pressing force on the valve needle for pressing the valve needle in a closing direction towards the valve seat;
wherein when the solenoid is electrically energized, the electromagnetic actuator transfers a lifting force to the valve needle by engagement with the armature to lift the valve needle from the valve seat to a fully open position against the pressing force of the calibration spring; and
wherein the calibration spring and the electromagnetic actuator are configured such that the lifting force equals the pressing force in the fully open position.

2. The fuel injector according to claim 1 , wherein the armature is displaceable in an opening direction, opposite to the closing direction, from a start position to an end position for lifting the valve needle from a closing position to the fully open position, and wherein the armature is further displaceable in the opening direction from said end position.

3. The fuel injector according to claim 2 , wherein the displacement of the armature between the start position and the end position is greater than 90 μm.

4. The fuel injector according to claim 1 , wherein the calibration spring has a stiffness of 400 N/mm or more.

5. The fuel injector according to claim 1 , further comprising a stopper arranged such that the stopper is approached by the armature upon the opening motion of the armature, wherein the stopper and the armature have facing surfaces that are parallel to each other.

6. The fuel injector according to claim 5 , wherein the surfaces are perpendicular to a direction of the opening motion of the armature.

7. The fuel injector according to claim 5 , wherein a gap between the facing surfaces is hydraulically connected to a path of the fuel through the injector towards the valve.

8. The fuel injector according to claim 1 , wherein the armature is displaceable in an opening direction, opposite to the closing direction, from a start position to an end position for lifting the valve needle from a closing position to the fully open position, and wherein the armature is further displaceable in the opening direction from said end position,
wherein the fuel injector further comprises a stopper arranged such that the stopper is approached by the armature upon the opening motion of the armature, wherein the stopper and the armature have facing surfaces that are parallel to each other, and
wherein the facing surfaces are separated from each other when the armature is in the end position.

9. The fuel injector according to claim 1 , wherein the calibration spring comprises a spring sleeve.

10. An internal combustion engine, comprising:
a plurality of fuel injectors, each comprising:
a fuel valve comprising a valve seat and a movable valve needle that cooperate for controlling a flow of fuel through the injector;
a calibration spring; and
an electromagnetic actuator comprising a solenoid and a movable armature;
wherein the calibration spring exerts a pressing force on the valve needle for pressing the valve needle in a closing direction towards the valve seat;
wherein when the solenoid is electrically energized, the electromagnetic actuator transfers a lifting force to the valve needle by engagement with the armature to lift the valve needle from the valve seat to a fully open position against the pressing force of the calibration spring; and
wherein the calibration spring and the electromagnetic actuator are configured such that the lifting force equals the pressing force in the fully open position.

11. The internal combustion engine according to claim 10 , wherein for each fuel injector, the armature is displaceable in an opening direction, opposite to the closing direction, from a start position to an end position for lifting the valve needle from a closing position to the fully open position, and wherein the armature is further displaceable in the opening direction from said end position.

12. The internal combustion engine according to claim 11 , wherein the displacement of the armature between the start position and the end position is greater than 90 μm.

13. The internal combustion engine according to claim 10 , wherein for each fuel injector, the calibration spring has a stiffness of 400 N/mm or more.

14. The internal combustion engine according to claim 10 , wherein each fuel injector further comprises a stopper arranged such that the stopper is approached by the armature upon the opening motion of the armature, wherein the stopper and the armature have facing surfaces that are parallel to each other.

15. The internal combustion engine according to claim 14 , wherein the surfaces are perpendicular to a direction of the opening motion of the armature.

16. The internal combustion engine according to claim 14 , wherein a gap between the facing surfaces is hydraulically connected to a path of the fuel through the injector towards the valve.

17. The internal combustion engine according to claim 10 , wherein for each fuel injector:
the armature is displaceable in an opening direction, opposite to the closing direction, from a start position to an end position for lifting the valve needle from a closing position to the fully open position, and wherein the armature is further displaceable in the opening direction from said end position,
the fuel injector further comprises a stopper arranged such that the stopper is approached by the armature upon the opening motion of the armature, wherein the stopper and the armature have facing surfaces that are parallel to each other, and
the facing surfaces are separated from each other when the armature is in the end position.

18. The internal combustion engine according to claim 10 , wherein for each fuel injector, the calibration spring comprises a spring sleeve.

Assignees

• Continental Automotive Gmbh

Inventors

• Izzo Ivano
• Mechi Marco

Classifications

• F02M51/0685

  the armature and the valve being allowed to move relatively to each other or not being attached to each other · CPC title

• F02M51/061 Primary

  using electromagnetic operating means · CPC title

• F02D41/40

  with means for controlling injection timing or duration · CPC title

• F02M2200/50

  Arrangements of springs for valves used in fuel injectors or fuel injection pumps · CPC title

• F02D41/2467

  for injectors · CPC title