Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Reexamination Certificate
1999-06-02
2001-04-24
Hook, James (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
C239S546000, C239S585500
Reexamination Certificate
active
06220528
ABSTRACT:
TECHNICAL FIELD
This invention relates to a fuel injector for use in supplying fuel, under pressure, to a combustion space of a compression ignition internal combustion engine.
BACKGROUND OF THE INVENTION
In order to reduce emissions levels, it is known to provide fuel injectors in which the total area of the openings through which fuel is delivered can be varied, in use. One technique for achieving this is to use two valve needles, one of which is slidable within a bore provided in the other of the needles to control the supply of fuel to some of the outlet openings independently of the supply of fuel to others of the outlet openings.
Such arrangements have the disadvantages that fuel may be able to flow between the inner and outer needles giving rise to substantially continuous delivery of fuel at a low rate. Further in order to control the movement of the inner and outer needles, separate actuators may be required resulting in the injector being of increased complexity.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a fuel injector comprising an outer valve needle, an inner valve needle slidable within a bore formed in the outer valve needle, an inner end of the inner valve needle being located within the bore, the inner end of the inner valve needle being provided with a recess whereby the application of fuel under pressure to the bore deforms the inner valve needle to form a substantially fluid tight seal between the inner and outer valve needles.
Such an arrangement is advantageous in that leakage and fuel delivery at undesirable points in the engine operating cycle can be reduced or avoided.
According to another aspect of the invention there is provided an injector comprising an outer valve needle and an inner valve needle, the inner needle being slidable within a bore formed in the outer needle, the inner and outer needles being exposed to the fuel pressure within a control chamber, and a single actuator controlling the fuel pressure within the control chamber.
The actuator may take the form of an electromagnetically actuated valve, or alternatively may comprise a piston moveable by a piezoelectric actuator.
Such an arrangement permits independent control of the inner and outer valve needles using a single actuator, movement of the inner and outer needles being dependent upon the pressure differential between the upper and lower ends thereof, the effective cross sectional areas exposed to fuel under pressure and the effect of any spring biasing.
REFERENCES:
patent: 3913537 (1975-10-01), Ziesche et al.
patent: 4202500 (1980-05-01), Keiczek
patent: 4546739 (1985-10-01), Nakajima et al.
patent: 4570853 (1986-02-01), Schmied
patent: 4826081 (1989-05-01), Zwick
patent: 5458292 (1995-10-01), Hapeman
Cooke Michael Peter
Greeves Godfrey
Bocanegra Jorge
Hook James
Lucas Industries
Wells, St. John, Roberts Gregory & Matkin P.S.
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