Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Reexamination Certificate
1998-03-27
2001-09-11
Kashinikow, Andres (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
C239S600000
Reexamination Certificate
active
06286768
ABSTRACT:
TECHNICAL FIELD
The present invention is directed to a unit fuel injector for internal combustion engines which minimizes nonaxial forces on the injector body thereby reducing injector plunger wear, scuffing and seizure.
BACKGROUND
Unit fuel injectors operated by cams, have long been used in compression ignition internal combustion engines for their accuracy and reliability. The unit injector, whether of the open or closed nozzle type, typically includes an injector body having injector orifices at one end and a cam driven injector plunger assembly mounted for reciprocal movement within a central bore formed the injector body. In a typical unit injector, fuel is metered into an injection chamber with the amount of fuel being controlled on a cycle by cycle basis. The plunger assembly reciprocates through an advancement stroke to pressurize the metered fuel and force the fuel through the injector orifices into an engine combustion chamber, and a retraction stroke to permit metering of injection and perhaps timing fluid for the next injection event.
One of the major challenges to unit injector designers is limiting injector plunger wear and failure. Injector plungers are sized to form a diametrical clearance between the outer surface of the plunger and the inner surface of the corresponding bore formed in the injector body. However, nonaxial forces acting on the injector body cause distortion of the injector body and thus the bore. As a result, the diametrical clearance between the plunger and bore is reduced causing undesirable plunger scuffing and wear, and possible seizure or failure of the plunger. One source of nonaxial or transverse forces on the injector body are threaded connections between an upper barrel of the injector body and a lower injector body assembly. Threaded connections inherently produce nonaxial or transverse forces in the injector body due to the angled surfaces of the threads.
For example, U.S. Pat. Nos. 4,467,772; 5,094,215; and 5,441,027 all disclose unit fuel injectors having an outer barrel threadably connected to a lower injector body assembly. The threaded connection is positioned axially along the injector directly radially adjacent a plunger bore. As a result, the threads inherently impart a transverse load to the injector body distorting the plunger bore and thus disadvantageously causing plunger wear and possibly failure.
Consequently, there is a need for a unit fuel injector having an improved connection between the injector body components which reduces nonaxial assembly forces thereby minimizing plunger wear.
SUMMARY OF THE INVENTION
It is an object of the present invention, therefore, to overcome the disadvantages of the prior art and to provide a unit fuel injector which reduces plunger wear.
Another object of the present invention is to provide a unit fuel injector which is inexpensive to manufacture and simple to assemble.
Yet another object of the present invention is to provide a unit fuel injector which permits the attachment of the upper and lower sections of the injector body, and subsequent mounting on an engine, while avoiding imparting transverse loads to the injector body.
Still another object of the present invention is to provide a unit fuel injector which avoids the use of a threaded connection between the upper barrel section of the injector body and the lower section of the body.
Yet another object of the present invention is to provide a unit fuel injector having a plunger bore wherein distortion of the plunger bore is minimized.
It is a further object of the present invention is to provide a unit fuel injector which allows the injector clamping load to create internal sealed engagement between the injector sections.
These and other objects of the present invention are achieved by providing a unit fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, comprising an injector body including an upper body section, a central bore formed in the upper body section, a lower body section and an injection orifice formed in one end of the injector body to discharge fuel into the combustion chamber. The unit injector further includes a plunger assembly mounted in the central bore for reciprocal movement through advancement and retraction strokes. In addition, a threadless injector body attaching device is positioned at an interface between the upper body section and the lower body section for attaching the upper body section to the lower body section while avoiding imparting a transverse load to the upper body section. The threadless injector body attaching device is preferably positioned along a longitudinal axis of the injector body radially adjacent the central bore. In addition, the threadless injector body attaching device is preferably positioned at the interface on at least two opposite sides of the injector body. Moreover, the threadless injector body attaching device may include a pin aperture formed in one of the upper body section and the lower body section, and a pin positioned in the pin aperture. The threadless injector body attaching device may also include a groove formed in one of the upper body section and the lower body section wherein the pin is positioned in the groove. The groove and the pin aperture form a cavity having a peripheral extent and the pin includes a width less than the cavity peripheral extent to create a slip fit between the components and the pin. The groove may be in the form of an annular groove extending around one of the upper body section and the lower body section. Preferably, the groove is formed in an outer surface of the upper body section and positioned in a recess formed in an upper end of the lower body section. The pin aperture may be formed in the lower body section and positioned tangential to the annular groove. In a preferred embodiment, the threadless injector body attaching device includes a first pin aperture formed in one side of the lower body section, a second pin aperture formed on an opposite side of the lower body section, a first pin positioned in the first pin aperture and a second pin positioned in the second pin aperture.
A unit fuel injector assembly is also provided for injecting fuel into the combustion chamber of an internal combustion engine, comprising an injector body including an upper body section including a lower surface, a central bore formed in the upper body section, a lower body section including an upper surface positioned adjacent the lower surface of the upper body section and an injection orifice formed in one end of the injector body to discharge fuel into the combustion chamber. A plunger assembly is mounted in the central bore for reciprocal movement through the advancement and retraction strokes. Also in this assembly, an injector body attaching device is positioned at an interface between the upper body section and the lower body section for attaching the sections while avoiding imparting an axial sealing load between the upper and the lower body sections. Importantly, a sealing load applying device, including an injector clamp for securing the injector body to the engine, is mounted for abutment against the injector body for applying a sealing load to the injector body of sufficient magnitude necessary to create a fluid seal between the upper surface of the lower body section and the lower surface of the upper body section.
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patent: 5564633 (
Hickey Daniel K.
Varney Bruce E.
Vetters Daniel K.
Brackett, Jr. Tim L.
Cummins Engine Company, Inc.
Kashinikow Andres
Leedom Jr. Charles M.
Nguyen Dinh Q.
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