Claims
- 1. A fuel injector, comprising:a valve member for opening and closing a fuel injection hole by leaving a valve seat and seating on the valve seat; a moving core provided integrally with the valve member, the moving core having an annular groove at an outer periphery thereof; a first fixed core facing one end of the moving core; a second fixed core facing the other end of the moving core; a tubular housing surrounding the moving core, the first fixed core, and the second fixed core, the tubular housing being made of magnetic material portions and nonmagnetic material portions disposed alternately in an axial direction, the nonmagnetic material portions being positioned around facing parts of the moving core and the first fixed core, around facing parts of the moving core and the second fixed core, and around the annular groove; a first coil, mounted at one end of the moving core, for magnetizing the first fixed core when the first coil is energized by an electrical current and attracting the moving core toward a valve opening direction; and a second coil, mounted at the other end of the moving core, for magnetizing the second fixed core and attracting the moving core toward a valve closing direction.
- 2. A fuel injector according to claim 1, wherein energizing of the second coil is started before an end of energizing of the first coil for holding the valve open, and in a valve-closing stroke, energizing of the second coil is ended before the valve member seats on the valve seat.
- 3. A fuel injector according to claim 2, wherein the energizing of the second coil is started such that at the end of the energizing of the first coil holding the valve open, an attracting force toward the valve opening direction and an attracting force toward the valve closing direction on the moving core are equal.
- 4. A fuel injector according to claim 2, wherein the energizing of the second coil is started after the end of the energizing of the first coil holding the valve open.
- 5. A fuel injector according to claim 2, wherein the energizing of the second coil is started such that the amount of fuel injected from valve-opening to valve-closing is not greater than a predetermined value within a range where the amount of fuel injected is linear.
- 6. A fuel injector according to claim 2, whereinwhen fuel is injected through the injection hole, an energizing time of the second coil is controlled to overlap with the end of the energizing time of the first coil by a predetermined period, and the energizing of the second coil is stopped just before the valve member seats on the valve seat.
- 7. A fuel injector according to claim 6, wherein the predetermined period is at least 0.2 milliseconds.
- 8. A fuel injector according to claim 6, wherein the timing at which the energizing of the second coil is stopped is at least 0.1 milliseconds before the nozzle needle seats on the valve seat.
- 9. A fuel injector according to claim 6, wherein a facing area where the moving core and the second fixed core contact with each other and the fuel flow passage area downstream thereof are set such that a state of fuel compression arises in a direction in which the nozzle neddle seats on the valve seat.
- 10. A fuel injector, comprising:a valve member for opening and closing a fuel injection hole by leaving a valve seat and seating on the valve seat; a moving core provided integrally with the valve member; a first fixed core facing the moving core for attracting the moving core toward a valve opening direction when magnetic flux is supplied; a second fixed core facing the moving core for attracting the moving core toward a valve closing direction when magnetic flux is supplied; a first coil mounted at one end of the moving core, for supplying magnetic flux through the first fixed core and the moving core; a second coil mounted at another end of the moving core, for supplying magnetic flux through the second fixed core and the moving core; and an energizing means for energizing the first and second coils so that the first coil is energized for valve opening, the second coil is energized for valve closing, and after the end of energizing of the first coil, energizing of the second coil is ended before the valve member seats on the valve seat in a valve-closing stroke.
- 11. A fuel injector according to claim 10, wherein said means for energizing starts energizing of the second coil before an end of energizing of the first coil such that at the end of the energizing of the first coil, an attracting force on the moving core toward the valve opening direction and an attracting force on the moving core toward the valve closing direction are equal.
- 12. A fuel injector according to claim 10, wherein said means for energizing starts energizing of the second coil after the end of the energizing of the first coil.
- 13. A fuel injector according to claim 10, wherein said means for energizing starts energizing of the second coil such that the amount of fuel injected from valve-opening to valve-closing is not greater than a predetermined value within a range where the amount of fuel injected is linear.
- 14. A fuel injector according to claim 10, wherein when fuel is injected through the injection hole, said means for energizing controls an energizing time of the second coil to overlap with the end of the energizing time of the first coil by a predetermined period, and said means for energizing stops the energizing of the second coil just before the valve member seats on the valve seat.
- 15. A fuel injector according to claim 14, wherein the predetermined period is at least 0.2 milliseconds.
- 16. A fuel injector according to claim 14, wherein the timing at which the energizing of the second coil is stopped is at least 0.1 milliseconds before the nozzle needle seats on the valve seat.
- 17. A fuel injector, comprising:a valve member for opening and closing a fuel injection hole by leaving a valve seat and seating on the valve seat; a moving core provided integrally with the valve member; a first fixed core facing the moving core for attracting the moving core toward a valve opening direction when magnetic flux is supplied; a second fixed core facing the moving core for attracting the moving core toward a valve closing direction when magnetic flux is supplied; a first coil mounted at one end of the moving core, for supplying magnetic flux through the first fixed core and the moving core; and a second coil mounted at another end of the moving core, for supplying magnetic flux through the second fixed core and the moving core, wherein the moving core provides two magnetic flux paths therein, the paths flowing the magnetic flux generated by the first coil and the magnetic flux generated by the second coil independently.
- 18. A fuel injector according to claim 17, further comprising a means for providing two independent magnetic flux paths, the first path flowing the magnetic flux generated by the first coil through the first fixed core and a part of the moving core, and the second path flowing the magnetic flux generated by the second coil through the second fixed core and another part of the moving core.
Priority Claims (2)
Number |
Date |
Country |
Kind |
11-347555 |
Dec 1999 |
JP |
|
2000-072375 |
Mar 2000 |
JP |
|
CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application Nos. Hei. 11-347555 filed on Dec. 7, 1999, and 2000-72375 filed on Mar. 15, 2000.
US Referenced Citations (8)
Foreign Referenced Citations (3)
Number |
Date |
Country |
6-129323 |
May 1994 |
JP |
0 629 711 |
Jun 1994 |
JP |
7-239050 |
Sep 1995 |
JP |