US 5,419,492 AGranted

Force balanced electronically controlled fuel injector

AssigneeCummins Engine Company, Inc.

InventorsGary L. Gant, George L. Muntean, Julius P. Perr, O. Eddie Sturman, Dennis A. Wilber, Charles R. Kelso

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Abstract

A unit fuel injector is provided comprising an injector body containing a pumping chamber for receiving fuel at a low pressure level from a fuel supply passage for subsequent discharge at a high pressure level, a discharge orifice and a transfer passage communicating with the pumping chamber and the discharge orifice. A valve element is provided for movement between (i) an advanced position wherein the supply passage communicates with the pumping chamber through the transfer passage and (ii) a retracted position wherein communication between the supply passage and the pumping chamber is blocked to allow fuel to flow from the pumping chamber through the transfer passage and out the discharge orifice. The valve element includes a control valve integrally formed with a tip valve, and a force balancing element for tending to balance the forces acting on the valve element by reducing the force tending to bias the valve element toward its second position closing the discharge orifice, when the pressure within the pumping chamber increases to the high pressure level.

Claims24

Dependent claims

A unit fuel injector comprising:

an injector body containing a pumping chamber for receiving fuel at a low pressure level for subsequent discharge at a high pressure level, a discharge orifice, and a transfer passage communicating with said pumping chamber and said discharge orifice;
fuel supply means including a supply passage for supplying fuel at said low pressure level to said injector body;
a valve element reciprocally mounted within said injector body and subject to biasing forces produced by said fuel pressures, said valve element movable between (i) an advanced position in which said discharge orifice is closed and said transfer passage communicates with said pumping chamber and said supply passage and (ii) a retracted position in which communication between said supply passage and said pumping chamber is blocked and said discharge orifice is opened to allow fuel to flow from said pumping chamber through said transfer passage and out of said discharge orifice;
and
force balancing means for tending to balance the fuel biasing forces on said valve element, wherein said force balancing means includes a first valve seat positioned at a first end of said transfer passage, said first valve seat conforming to a first end of said valve element and being of a predetermined cross-sectional area for tending to balance the forces acting on said valve element.

2 more elements

A unit fuel injector, comprising:

(a) an injector housing containing a fuel pumping chamber, a discharge orifice through which fuel can be periodically injected into a combustion chamber and a valve cavity fluidically communicating with said pumping chamber and said discharge orifice;
(b) a fuel supply means for supplying fuel at low pressure to said pumping chamber, said fuel supply means including a fuel supply passage communicating with said valve cavity;
(c) a plunger mounted within said pumping chamber for moving cyclically through successive advancement and retraction strokes to collapse and expand, respectively, said pumping chamber;
(d) valve means operating in response to a control signal for causing a predetermined quantity of fuel to be injected through said discharge orifice at a predetermined time during the advancement stroke of said plunger, said valve means including a valve element mounted for reciprocal movement within said valve cavity between (i) an advanced position in which fluid communication between said pumping chamber and said fuel supply passage is established through said valve cavity and in which the fluid communication between said pumping chamber and said discharge orifice is closed, and (ii) a retracted position in which fluid communication between said pumping chamber and said fuel supply passage is closed and in which fluid communication between said .pumping chamber and said discharge ,orifice is established;
and
(e) control signal generating means connected with said valve means for producing a control signal during the advancement stroke of said plunger for causing said valve element to move from said advanced position said retracted position to commence fuel injection through said orifice and, during the same advancement stroke of said plunger, for returning said valve element to said advanced position to terminate injection;
wherein said valve cavity is positioned between said pumping chamber and said discharge orifice to improve the accuracy of control over the timing and metering of fuel injection and wherein said valve cavity and said valve element are shaped to tend to balance fuel pressure biasing forces on said valve element to minimize the force required to move said valve element between its advanced and retracted positions.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/208,363Filed 10 Mar 1994 · division
Priority: 19 Jun 1990
Granted: 30 May 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

F02M 59/366
By variably-timed valves controlling fuel passages to pumping elements or overflow passages: valves being actuated electrically
F02M 45/08
With a small initial part , e.g. initial part for partial load and initial and main part for full load: injectors peculiar thereto
F02M 51/0621
Having two or more electromagnets: acting on one mobile armature
F02M 51/0635
Characterised by arrangement of mobile armatures: having a plate-shaped or undulated armature not entering the winding