Fuel injection valve
A fuel injection valve which injects fuel from a nozzle hole includes a cavitation generation flow path in which a cavitation bubble is generated in fuel flowing inside the injection valve, and a bubble storage flow path which is connected to the cavitation generation flow path and the nozzle hole and which stores the cavitation bubble generated in the cavitation generation flow path. A fuel containing the cavitation bubble stored in the bubble storage flow path is injected from the nozzle hole so that atomization of an injected fuel spray is enhanced.
1. A fuel injection valve which injects fuel from a nozzle hole, the fuel injection valve comprising:
a cavitation generation flow path in which a cavitation bubble is generated in fuel flowing inside the injection valve;
a nozzle hole disposed downstream of the cavitation generation flow path at an outermost portion of a flow path formed within the fuel injection valve along the direction of flow; and
a bubble storage flow path which is connected to the cavitation generation flow path and the nozzle hole and which stores the cavitation bubble generated in the cavitation generation flow path, wherein
a flow path is rapidly expanded in transition from the cavitation generation flow path to the bubble storage flow path,
the bubble storage flow path, in which a wall bordering the bubble storage flow path is provided to oppose a direction of a fuel jet flowing in the cavitation generation flow path, is directly connected to the cavitation generation flow path and the nozzle hole in a state where an exit to the nozzle hole is offset in the same direction as the flow path is rapidly expanded in a transition from the cavitation generation flow path to the bubble storage flow path with respect to a direction of a fuel jet flowing in the cavitation generation flow path, and
the fuel injection valve injects, from the nozzle hole, fuel containing the cavitation bubble stored in the bubble storage flow path in a state wherein the cavitation generation flow path has a flow path area which is smallest in the flow path from the cavitation generation flow path to the nozzle hole.
2. A fuel injection valve according to claim 1 , wherein
the fuel injection valve injects the fuel from the nozzle hole while a cross sectional area of the bubble storage flow path is larger than a cross sectional area of the cavitation generation flow path.
3. A fuel injection valve according to claim 1 , wherein
a cross sectional area of an entrance portion of the cavitation generation flow path is gradually reduced toward the bubble storage flow path.
4. A fuel injection valve according to claim 1 , wherein
a cross sectional area of the cavitation generation flow path is reduced toward the bubble storage flow path.
5. A fuel injection valve according to claim 1 , wherein
the fuel injection valve has a wall which forms a part of the bubble storage flow path;
the exit which connects the bubble storage flow path and the nozzle hole is provided in the bubble storage flow path, and
the wall has a curved surface which curves from a region which approximately opposes a fuel jet flowing in the cavitation generation flow path to the exit to the nozzle hole.
6. A fuel injection valve according to claim 1 , wherein
a swirl generation flow path in which a swirl flow is generated in fuel flowing inside the injection valve is formed upstream of the cavitation generation flow path.
7. A fuel injection valve according to claim 1 , wherein
a swirl generation flow path in which a swirl flow is generated in fuel flowing inside the injection valve is formed in the cavitation generation flow path.
8. A fuel injection valve according to claim 1 , wherein a point where the flow path is rapidly expanded comprises, in cross-section, a vertex of two linear segments.
9. A fuel injection valve according to claim 8 , wherein the two linear segments intersect at a right angle.
10. A fuel injection valve according to claim 8 , wherein one of the linear segments is disposed perpendicular to the fuel jet flowing in the cavitation generation flow path.