Fuel injection valve for an internal combustion engine
A fuel injection valve for an internal combustion engine may include an injector body having a receiving hole for an injector needle. The receiving hole may be implemented as a blind hole and may form an injector ring chamber in the injector shaft and a cone-shaped valve seat at the base thereof, and a blind injector hole at the tip of the valve seat cone, from which at least one injector hole extends. The injector needle may include an at least partially cone-shaped needle tip and may seal off the blind injector hole, and thus the at least one injector hole, from the injector ring chamber. The needle tip may include a needle pilot adapted in contour and extent to the blind injector hole in the valve seat, the pilot protruding into the blind injector hole and thus reducing a compression volume formed between the valve seat and injector hole.
1. A fuel injection valve for an internal combustion engine, comprising:
an injector body having an injector shaft and a receiving hole for an injector needle, wherein the receiving hole defines:
an injector ring chamber in the injector shaft,
a cone-shaped valve seat at one end, and
a blind injector hole formed by a wall extending from a tip region of the cone-shaped valve seat, wherein the blind injector hole has a smaller angle of taper than the cone-shaped valve seat, with respect to a longitudinal axis of the receiving hole,
at least one injector tip hole formed in a tip portion of the injector shaft, the at least one injector tip hole extending from the blind injector hole and connecting the injector ring chamber below the valve seat to an outer region, and
an injector needle being movable in a longitudinal direction in the receiving hole and having a needle tip comprising:
a cone-shaped needle portion extending downstream from an elongated needle body, and
a needle pilot extending downstream from the cone-shaped needle portion, wherein the needle pilot has a smaller angle of taper than the cone-shaped needle portion, with respect to the longitudinal axis of the receiving hole,
wherein the cone-shaped valve seat has an angle of taper that is smaller than the angle of taper of the cone-shaped needle portion of the injector needle, such that in a closed state of the fuel injection valve the cone-shaped needle portion of the needle tip rests on the cone-shaped valve seat only at a circumferential line of transition between the cone-shaped needle portion and the elongated needle body, thereby defining a contiguous chamber between the cone-shaped needle portion and the cone-shaped valve seat and between the needle pilot and the blind injector hole wall, the contiguous chamber being sealed off from the injector ring chamber in the closed state of the fuel injection valve, and
wherein the needle pilot of the needle tip has a needle pilot tip having a cross-sectional shape with respect to the longitudinal axis corresponding to the cross-sectional shape of the blind injector hole with respect to the longitudinal axis to protrude into the blind injector hole reducing a compression volume formed between the valve seat and the at least one injector tip hole extending from the blind injector hole in the closed state of the fuel injection valve.
2. The fuel injection valve of claim 1 , wherein the blind injector hole of the valve seat defines a cone-shaped portion.
3. The fuel injection valve of claim 1 , wherein a cross-section area of an annular gap formed between the blind injector hole of the valve seat and the needle pilot of the needle tip is widened in at least one location by at least one partial depression formed in a periphery of the needle pilot or in a periphery of the blind injector hole.
4. The fuel injection valve of claim 3 , wherein in the closed state of the fuel injection valve a particular partial depression is located directly across from an inlet end of each injector tip hole.
5. The fuel injection valve of claim 3 , wherein the at least one partial depression comprises an annular groove.
6. The fuel injection valve of claim 3 , wherein the at least one partial depression comprises a punctiform depression.
7. The fuel injection valve of claim 1 , wherein in an open state of the fuel injection valve a cross-sectional area of an annular gap formed between the blind injector hole and the needle pilot is smaller than the sum of cross-sectional areas of outlet ends of all injector tip holes that extend from the blind injector hole of the valve seat.
8. The fuel injection valve of claim 3 , wherein in the closed state of the fuel injection valve a particular partial depression is located upstream from an inlet end of each injector tip hole.
9. The fuel injection valve of claim 1 , comprising at least two annular depressions formed in the needle pilot.
10. The fuel injection valve of claim 9 , wherein at least one of the annular depressions is aligned with inlet ends of the at least one injector tip hole.
11. The fuel injection valve of claim 1 , comprising at least two non-annular depressions formed in the needle pilot.
12. The fuel injection valve of claim 1 , wherein the angle of taper of the cone-shaped valve seat is smaller than the angle of taper of the cone-shaped needle portion of the injector needle but larger than the angle of taper of the needle pilot.
13. A fuel injection valve for an internal combustion engine, comprising:
an injector body defining an injector shaft and a receiving hole for an injector needle, wherein the receiving hole defines:
a cone-shaped valve seat, and
a blind injector hole formed by a wall extending from the cone-shaped valve seat, wherein the blind injector hole has a smaller angle of taper than the cone-shaped valve seat, with respect to a longitudinal axis of the receiving hole,
at least one injector tip hole formed in a tip portion of the injector shaft, each injector tip hole extending from the blind injector hole that extends from the cone-shaped valve seat, and
an injector needle being axially movable within the receiving hole, the injector needle comprising:
a cone-shaped needle portion, and
a needle pilot having a needle pilot tip, the needle pilot extending from the cone-shaped needle portion, wherein the needle pilot has a smaller angle of taper than the cone-shaped needle portion with respect to the longitudinal axis of the receiving hole,
wherein in a closed state of the fuel injection valve the cone-shaped needle portion of the injector needle rests on the cone-shaped valve seat with the needle pilot protruding into the blind injector hole, and the needle pilot tip having a cross-sectional shape with respect to the longitudinal axis corresponding to the cross-sectional shape of the blind injector hole with respect to the longitudinal axis,
wherein an annular gap formed between the blind injector hole and the needle pilot when the fuel injection valve is in a closed state is wider in at least one location by at least one depression formed in the blind injector hole wall.
14. The fuel injection valve of claim 13 , wherein the at least one depression formed in the blind injector hole wall comprises an annular groove.
15. The fuel injection valve of claim 13 , wherein the at least one depression formed in the blind injector hole wall comprises at least two annular grooves.
16. The fuel injection valve of claim 13 , wherein the at least one depression formed in the blind injector hole wall comprises at least one punctiform depression.
17. The fuel injection valve of claim 13 , wherein in the closed state of the fuel injection valve a particular depression formed in the blind injector hole wall is located upstream from an inlet end of each injector tip hole.
18. An internal combustion engine, comprising:
at least one cylinder, and
at least one injection valve corresponding to the at least one cylinder, each injection valve comprising:
an injector body defining an injector shaft and a receiving hole for an injector needle, wherein the receiving hole defines:
a cone-shaped valve seat, and
a blind injector hole extending from the cone-shaped valve seat, wherein the blind injector hole has a smaller angle of taper than the cone-shaped valve seat, with respect to a longitudinal axis of the receiving hole,
at least one injector tip hole formed in a tip portion of the injector shaft, each injector tip hole extending from the blind injector hole that extends from the cone-shaped valve seat, and
an injector needle being axially movable within the receiving hole, the injector needle comprising:
a cone-shaped needle portion extending downstream from an elongated needle body, and
a needle pilot extending downstream from the cone-shaped needle portion, wherein the needle pilot has a smaller angle of taper than the cone-shaped needle portion, with respect to the longitudinal axis of the receiving hole,
wherein the cone-shaped valve seat has an angle of taper that is smaller than the angle of taper of the cone-shaped needle portion of the injector needle, such that in a closed state of the fuel injection valve the cone-shaped needle portion of the injector needle rests on the cone-shaped valve sea only at a circumferential line of transition between the cone-shaped needle portion and the elongated needle body, thereby defining a contiguous chamber between the cone-shaped needle portion and the cone-shaped valve seat and between the needle pilot and the blind injector hole such that the needle tip seals off the contiguous chamber and the at least one injector tip hole in the closed state of the fuel injection valve, and
the needle pilot having a cross-sectional shape with respect to the longitudinal axis corresponding to the cross-sectional shape of the blind injector hole with respect to the longitudinal axis.