Injector nozzle spray hole with Venturi and air entertainment feature

1. An apparatus for fuel injection, comprising:

an inner sac with one or more primary passages extending therefrom, the one or more primary passages configured to inject fuel therethrough and comprising a first portion, a second portion, and a third portion, wherein the second portion is disposed between the first portion and the third portion and has a cross-sectional area smaller than that of both the first portion and the third portion; and

one or more secondary passages extending from an outer surface of the apparatus to fluidly couple with the second portion of the one or more primary passages, the one or more secondary passages configured to pass air therethrough to form fuel-and-air mixture with the fuel injected from the one or more primary passages,

wherein each of the one or more primary passages defines a first central axis, and each of the one or more secondary passages defines a second central axis, such that the first and second central axes are offset from and nonplanar with each other to cause a swirling motion of air injected into the second portion of the one or more primary passages.

2. The apparatus of claim 1 , wherein each of the one or more primary passages is fluidly coupled with a single secondary passage of the one or more secondary passages.

3. The apparatus of claim 2 , wherein the first and second central axes are configured to cause the swirling motion in the injected air when mixing with the fuel to form the fuel-and-air mixture.

4. The apparatus of claim 2 , wherein a location of the first central axis is defined by a centroid on a cross-section of the primary passage, and a location of the second central axis is defined by a centroid on a cross-section of the secondary passage.

5. The apparatus of claim 1 , wherein each of the one or more primary passages is angularly offset from a longitudinal axis of the apparatus, and each of the one or more secondary passages is angularly offset from the one or more primary passages.

6. The apparatus of claim 1 , wherein each of the one or more primary passages is fluidly coupled with only one of a plurality of the secondary passages.

7. The apparatus of claim 1 , wherein each of the one or more primary passages has a configuration resembling an hourglass shape.

8. The apparatus of claim 1 , wherein the one or more secondary passages have a cylindrical configuration.

9. The apparatus of claim 1 , wherein the one or more secondary passages have a frustoconical configuration.

10. The apparatus of claim 1 , wherein the one or more secondary passages are configured to inject the air therethrough using a fluid pressure differential between the one or more primary passages and the one or more secondary passages.

11. The apparatus of claim 2 , wherein a relationship between a length (“B”) of the primary passage and a distance (“A”) of the second portion from the outer surface, as measured along the first central axis, is represented as: 0<A/B<1.

12. The apparatus of claim 1 , wherein a relationship between a diameter (“V”) of the second portion and a diameter (“C”) of the first portion is represented as: 0<V/C<1.

13. The apparatus of claim 1 , wherein a relationship between a diameter (“V”) of the second portion and a diameter (“D”) of the third portion is represented as: 0<V/D<1.

14. A method of conducting fuel injection in an engine, comprising:

opening a fuel injecting apparatus in response to an operation signal from an engine control system;

inserting fuel through a primary passage formed in the fuel injection apparatus, the primary passage comprising a first portion, a second portion, and a third portion, wherein the second portion is disposed between the first portion and the third portion and has a cross-sectional area smaller than that of both the first portion and the third portion;

directing air into the primary passage through a secondary passage that is fluidly coupled with the second portion of the primary passage, wherein the primary passage defines a first central axis, and the secondary passage defines a second central axis, such that the first and second central axes are offset from and nonplanar with each other to cause a swirling motion of air injected into the second portion of the one or more primary passages; and

combusting a mixture of air and fuel inside the engine.

15. The method of claim 14 , wherein redirecting the air into the fuel passage occurs in response to a pressure differential the primary passage and the secondary passage, wherein the primary passage has a lower pressure than the secondary passage.

16. An engine system comprising:

a plurality of cylinder heads, each cylinder head defining a combustion chamber;

a plurality of fuel injectors, each fuel injector coupled with one of the plurality of cylinder heads and comprising:

an inner sac with one or more primary passages extending therefrom, the one or more primary passages configured to inject fuel into the combustion chamber and comprising a first portion, a second portion, and a third portion, wherein the second portion is disposed between the first portion and the third portion and has a cross-sectional area smaller than that of both the first portion and the third portion, and

one or more secondary passages extending from the combustion chamber to fluidly couple with the second portion of the one or more primary passages, the one or more secondary passages configured to inject air from the combustion chamber to form fuel-and-air mixture with the fuel injected from the one or more primary passages, wherein each of the one or more primary passages defines a first central axis, and each of the one or more secondary passages defines a second central axis, such that the first and second central axes are offset from and nonplanar with each other to cause a swirling motion of air injected into the second portion of the one or more primary passages; and

a plurality of pistons, each piston coupled to the combustion chamber of the one of the plurality of cylinder heads.

17. The apparatus of claim 1 , wherein the one or more secondary passages consists of one secondary passage, and the first central axis of one primary passage is offset from and nonplanar with the second central axis of the one secondary passage to cause the swirling motion of the fuel-and-air mixture as a result of air injected from the one secondary passage entering into the one primary passage off-axis from the first central axis of the one primary passage.

18. The method of claim 14 , wherein the one or more secondary passages consists of one secondary passage, and the first central axis of one primary passage is offset from and nonplanar with the second central axis of the one secondary passage to cause the swirling motion of the fuel-and-air mixture as a result of air injected from the only one secondary passage entering into the one primary passage off-axis from the first central axis of the one primary passage.

19. The system of claim 16 , wherein the one or more secondary passages consists of one secondary passage, and the first central axis of one primary passage is offset from and nonplanar with the second central axis of the one secondary passage to cause the swirling motion of the fuel-and-air mixture as a result of air injected from the only one secondary passage entering into the one primary passage off-axis from the first central axis of the one primary passage.