Fluid sprinkling – spraying – and diffusing – Including valve means in flow line – Reciprocating
Reexamination Certificate
1999-05-14
2001-04-03
Douglas, Lisa Ann (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Including valve means in flow line
Reciprocating
C239S585300, C239S585500
Reexamination Certificate
active
06209805
ABSTRACT:
BACKGROUND OF THE INVENTION
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. In particular, the invention relates to a fuel injector of the type in which the commencement of injection is controlled using an electromagnetic actuator. The invention is particularly suitable for use in a pump/injector arrangement, but it will be appreciated that the invention may be used in other applications.
In a known pump/injector arrangement, the commencement of injection is controlled by controlling the fuel pressure within a control chamber, the fuel pressure within the control chamber applying a force to a valve needle urging the needle towards its seating. The fuel pressure within the control chamber is controlled using an appropriate electromagnetically actuated valve. Such an arrangement is relatively complex and difficult to control accurately.
SUMMARY OF THE INVENTION
According to the present invention there is provided a fuel injector comprising a valve needle biased by a spring towards a seating, and an electromagnetic actuator arrangement arranged to vary the magnitude of the biasing force applied to the needle by the spring.
In such an arrangement, the spring is conveniently arranged to apply a sufficiently large biasing force to the needle to ensure that injection does not occur when the actuator is energised to a first energization level. Upon energizing the actuator to a second energization level, the actuator acts against the spring to reduce the magnitude of the biasing force applied to the needle by the spring to a level sufficient to allow movement of the injector needle thus allowing injection to commence.
Preferably, the actuator includes an armature carried by a control member, the spring load being transmitted to the needle through the control member.
As the fuel injector does not rely upon the operation of a valve to control injection, the number of drillings, bores and other features which must be provided in the injector can be reduced thereby simplifying construction. The fuel injector is further relatively easy to control, thus permitting accurate control of the timing of injection.
The invention is particularly suitable for use in a pump/injector arrangement in which the timing of fuel injection relative to the timing of closing a drain valve controls the injection pressure. Clearly, in such an arrangement, the invention permits improved control of the injection pressure.
REFERENCES:
patent: 4221192 (1980-09-01), Badgley
patent: 4925112 (1990-05-01), Wahba
patent: 5494219 (1996-02-01), Maley et al.
patent: 6036120 (2000-03-01), Varble et al.
patent: 0 823 549 A2 (1998-02-01), None
patent: 0 823 549 A3 (1998-06-01), None
patent: 2 307 513 (1997-05-01), None
Harcombe Anthony Thomas
Male Andrew
Andrus Sceales, Starke & Sawall
Douglas Lisa Ann
Lucas Industries PLC
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