Flow straightener for fuel injector

Abstract

 A fuel injection valve for fuel injection systems of internal combustion engines straightens fuel flow, thereby providing an improved flow pattern. The injection valve comprises an armature movable in a first direction and a second direction for causing a needle valve (38) to contact and separate from a seat assembly (30). The injection valve further comprises a fuel metering device (34) for affecting fuel flow. Finally, the injection valve comprises an insert element (42) for straightening fuel flow. The insert element (42) is located in a passageway between the seat assembly and the fuel metering device for decoupling the turbulence in the seat assembly area from the metering and targeting of the metering device.

Description

Field of the Invention

[0001] This invention relates generally to fuel injectors of the type that are used to inject liquid fuel into the induction system of an internal combustion engine, and particularly to a flow straightener for straightening the flow of fuel as it leaves the injector.

Background of the Invention

[0002] The movement of certain electrically-operated valves, such as certain fuel injectors, comprises a needle that is reciprocated axially within the interior of the valve's body in response to electrical energization and de-energization of an electro-mechanical actuator to thereby selectively open and close a flow path through the valve.

[0003] The fuel injector meters fuel and sprays and atomizes fuel. With injector valves for fuel injection systems of internal combustion engines, the valve is in communication with an engine intake tube. The valve has a movable valve element associated with a fixed valve seat body, so fuel under pressure flows out of the injector nozzle. Unfortunately, in existing systems, when the fuel flow is injected into the intake tube in a limited or nonuniform dispersal pattern, pressure surges, disturbed flow and flow obstructions can occur.

[0004] It is seen then that a need exists for an injection valve having an improved spray pattern.

Summary of the Invention

[0005] This need is met by the flow straightener according to the present invention, wherein an insert element is placed in the passageway between the fuel injector valve seat and the orifice disk.

[0006] In accordance with one aspect of the present invention, a flow straightener in the form of a porous element is placed in the passageway between the fuel injector valve seat and the usual orifice disk, or fuel metering device. The insert element decouples the turbulence above the orifice disk from the metering orifice. This provides the advantage of allowing for improved direction and targeting of the fuel spray from the metering orifice.

[0007] The invention, and the features, advantages, and benefits that characterize it, are disclosed in the following detailed description of a presently preferred embodiment that illustrates the best mode for carrying out the invention. The description is accompanied by drawings.

Brief Description of the Drawings

[0008] In the Drawings:

Fig. 1 is a cross section view of a prior art typical fuel injector, for describing the present invention;

Fig. 2 is an enlarged view of the outlet end of the typical injector of Fig. 1, illustrating one embodiment for controlled disbursement of fuel, in accordance with the present invention; and

Fig. 3 is an enlarged view of the outlet end of the typical injector of Fig. 1, illustrating an alternative embodiment for controlled disbursement of fuel.

Description of the Preferred Embodiment

[0009] Referring to FIG. 1 there is illustrated in cross section, a typical fuel injector 10 having a tubular housing 12. The inside of the tubular housing 12 contains an armature 14 and a plurality of different diameters to form typical various shoulders for a variety of different functions. Positioned along the outside of the housing 12 are sealing means 18 and 20 to seal the injector 10 in a bore of an engine or manifold where it is located. The housing 12 has an open end 22, and an outlet end 24. The outlet end 24 is counterbored to form a shoulder 26 for locating a seat assembly 28, which may be comprised of a valve seat 30.

[0010] Figs. 2 and 3 illustrate in cross section, a representative lower portion of the fuel injector 10 of Fig. 1, such as a DEKA™ injector of the type manufactured by Siemens Automotive Corporation. The outlet end 24 encloses the seat assembly 28, including the valve seat 30 which contains an orifice or metering device 34. The valve seat 30 can operate as a stop means for the armature 14 located within the housing 12 and movable against the valve seat 30 in response to a magnetic force, typically generated by a coil and a return spring.

[0011] A spherical radius at one end of the needle valve 38 mates with the valve seat 30 to close the injector 10 when the armature moves in a first, or closing, direction. If the needle valve 38 is not biased against the valve seat 30, as when the armature 14 is moving in a second, or opening, direction, turbulence can occur. Fuel is allowed to seep through crevice volumes created between the needle valve 38 and the valve seat 30. The motion of the needle valve 38, therefore, must be accompanied by the flow of fuel in and out of these crevice volumes while controlling fuel seepage past the valve seat 30 into the engine by means of the O-ring seal 32.

[0012] The fuel metering device 34 operates as the final metering or targeting device for controlling the fuel flow. Unfortunately, in existing fuel injectors, turbulence within the injector occurring above the orifice disk 34, such as around the needle seat 30, affects the efficiency and directionality of the resultant fuel spray. The present invention, therefore, introduces an insert means or flow straightener means 40 which decouples the seat assembly, and associated turbulence, from the metering device 34. The flow straightner 40 straightens fuel flow, thereby providing an improved flow pattern. The flow straightener 40 is located in the passageway between the fuel injector valve seat 30 and the metering orifice 34. With the flow straightner 40, when the needle 38 is opened, turbulence is essentially eliminated, allowing the metering orifice 34 to provide a more targeted fuel spray.

[0013] Continuing with Figs. 2 and 3, the flow straightner 40 may be of a variety of constructions. The flow straightner 40 is preferably a porous material such as sintered metal, ceramic, porous plastic, screen or other mesh; and may be any suitable shape including, but not limited to, approximately flat, tubular, square, round or oval. For example, Fig. 2 illustrates one embodiment for controlled disbursement of fuel, wherein the flow straightner 40 is essentially a flat section of material, such as a screen. Alternatively, Fig. 3 illustrates an embodiment for controlled disbursement of fuel, wherein the flow straightner 40 comprises an approximately flat section 40a and a tubular plug section 42, such as a ceramic or plastic material. The embodiment of Fig. 3 has the desirable advantage of decreasing the volume between the needle 38 and the orifice disk 34, an area without metered fuel.

[0014] In accordance with the present invention, the fuel flow and fuel spray performance can be maximized by controlling the porosity and size of the flow straightner 40. For example, a less porous material will result in less of a fuel flow drop; whereas a more porous material will introduce more obstructions, resulting in more flow straightening. Additionally, as the flow straightner 40 element comprises more length, less porosity is required to achieve flow straightness, since the additional length positively affects flow straightness.

[0015] Having described the invention in detail and by reference to the preferred embodiment thereof, it will be apparent that other modifications and variations are possible without departing from the scope of the invention defined in the appended claims.

Claims

1. A fuel injection valve for fuel injection systems of internal combustion engines comprising:

an armature movable in a first direction and a second direction for causing a needle valve to contact and separate from a seat assembly;

a fuel metering device for affecting fuel flow;

an insert means for straightening fuel flow, said insert means located in a passageway between said seat assembly and said fuel metering device.

2. A fuel injection valve as claimed in claim 1 wherein said insert means decouples said seat assembly from said metering device.

3. A fuel injection valve as claimed in claim 1 wherein said insert means comprises a porous material.

4. A fuel injection valve as claimed in claim 3 wherein porosity of said insert means affects fuel flow straightness.

5. A fuel injection valve as claimed in claim 3 wherein said porous material comprises sintered metal.

6. A fuel injection valve as claimed in claim 3 wherein said porous material comprises a screen.

7. A fuel injection valve as claimed in claim 3 wherein said porous material comprises plastic.

8. A fuel injection valve as claimed in claim 3 wherein said porous material comprises ceramic.

9. A fuel injection valve as claimed in claim 1 wherein said insert means is approximately flat.

10. A fuel injection valve as claimed in claim 1 wherein said insert means is approximately tubular.

11. A fuel injection valve as claimed in claim 1 wherein said insert means is approximately square.

12. A fuel injection valve as claimed in claim 1 wherein said insert means is approximately oval.

13. A fuel injection valve as claimed in claim 1 wherein said insert means is approximately round.

Drawing