Pump injector including valve needle and spill valve

Details Pump injector including valve needle and spill valve Pump injector including valve needle and spill valve

1999-09-14

2001-07-17

Scherbel, David A. (Department: 3752)

Fluid sprinkling, spraying, and diffusing

Unitary injection nozzle and pump or accumulator plunger

C239S096000, C239S127000, C239S533900, C239S585100, C251S129100, C123S447000

Reexamination Certificate

active

06260768

ABSTRACT:

This invention relates to a fuel injector for use in supplying fuel under high pressure to a combustion space of an associated engine. In particular, the invention relates to a unit pump injector.
In a known unit pump injector, a valve needle is spring biased into engagement with a seating to control the delivery of fuel. The needle includes thrust surfaces which are exposed to fuel at substantially the output pressure of a pump upon which a nozzle body including a bore within which the needle is slidable is mounted. A spill valve is used to control the timing of commencement of fuel pressurization and to control the timing of termination of fuel injection.
In such an arrangement, charging of the pump occurs through the spill valve. Where the injector is designed to be received within a bore of approximately 17 mm diameter, the spill valve is of small dimensions. Such a spill valve may be incapable, throughout the engine speed range, of allowing sufficient fuel to flow to the pump in the time available during the filling cycle of the pump. Further, at the termination of injection, the fuel may be unable to escape at a sufficiently high rate to ensure that the needle moves into engagement with its seating at a desired rate and remains in engagement with its seating; again when the engine and the injector are operating at high speeds.
It is an object of the invention to provide an injector suitable for use in such an application in which these disadvantages are overcome or of reduced effect.
According to a first aspect of the invention there is provided a pump injector comprising a pumping chamber, a valve needle controlling communication between the pumping chamber and at least one outlet opening, a spill valve controlling communication between the pumping chamber and a low pressure reservoir, in use, and an inlet non-return valve arranged to permit fuel to flow from the low pressure reservoir to the pumping chamber, in use, but substantially preventing fuel flow in the reverse direction.
In such an arrangement filling of the pumping chamber in the time available can be achieved, even when the spill valve is of small dimensions, as fuel is able to by-pass the spill valve, flowing through the inlet non-return valve to the pumping chamber.
The valve needle may be engageable with an abutment piston, the abutment piston defining, in part, a control chamber, a control valve controlling communication between the pumping chamber and the control chamber.
Such an arrangement is advantageous in that, when the spill valve is opened to terminate injection, the control valve can also be opened to apply relatively high pressure to the abutment piston resulting in movement of the piston to increase the magnitude of the force urging the needle into engagement with its seating and reducing the risk of the needle lifting from its seating at a subsequent point in the operating cycle of the unit pump injector.
According to a second aspect of the invention there is provided a pump injector comprising a valve needle engageable with a seating to control communication between a pumping chamber and at least one outlet opening, a spill valve controlling communication between the pumping chamber and a fuel reservoir, in use, an abutment piston engageable with the needle and which defines, in part, a control chamber, a control valve controlling communication between the pumping chamber and the control chamber.


REFERENCES:
patent: 4129253 (1978-12-01), Bader, Jr. et al.
patent: 4448169 (1984-05-01), Badgley et al.
patent: 4628881 (1986-12-01), Beck et al.
patent: 5413081 (1995-05-01), Collingborn
patent: 5915623 (1999-06-01), Knight et al.
patent: 6012430 (2000-01-01), Cooke
patent: 0845791 (1998-03-01), None

Affiliated with

Also associated with

Rating

Pump injector including valve needle and spill valve does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Pump injector including valve needle and spill valve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pump injector including valve needle and spill valve will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2435029