CN219344856U - Nozzle for fuel injector - Google Patents

Abstract

A fuel injector and a nozzle for a fuel injector are provided. The nozzle includes at least one orifice formed through the hardened nozzle body. The nozzle body is hardened again after the at least one nozzle hole is formed to harden the nozzle body along the at least one nozzle hole.

Description

Nozzle for fuel injector

Technical Field

The present disclosure relates generally to a fuel injection system for an internal combustion engine, and more particularly to a fuel injector nozzle and a method of manufacturing the same.

Background

Some fuel injectors include one or more orifices extending through a nozzle of the fuel injector. The nozzle holes are subjected to high mechanical loads and stresses during the fuel injection process. Thus, cavitation and erosion of material along the nozzle hole may change the injection pattern and the amount of fuel passing through the nozzle hole. These changes can lead to difficulties in meeting emission limits and can lead to engine damage. Therefore, the fuel injector nozzles must be replaced at appropriate intervals. While various attempts have been made to improve the durability of nozzle orifices, there remains a need for further improvements, such as those disclosed herein.

Disclosure of illustrative embodiments

In order to clearly, concisely, and accurately describe the illustrative embodiments of the present disclosure, the manner and process of making and using the same, and to enable the practice, making and using thereof, reference will now be made to certain exemplary embodiments, including the exemplary embodiments illustrated in the drawings, and reference terms will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the utility model is thereby intended, and that the utility model includes and protects such alterations, modifications and other applications of the exemplary embodiments as would occur to one skilled in the art.

Disclosure of Invention

The present disclosure includes a unique nozzle for a fuel injector and a fuel injection system for an internal combustion engine. The nozzle includes at least one orifice for ejecting fuel from the fuel injector. The orifice includes a layer of material along the orifice that enhances wear resistance of the at least one orifice, thereby improving performance and life of the fuel injector.

In an embodiment, a nozzle for a fuel injector is shown. The nozzle includes an elongated body extending along a longitudinal axis from a first end of the elongated body to an opposite second end of the elongated body. The elongated body includes a longitudinally extending fuel passage extending from the first end of the elongated body to the second end of the elongated body. The elongated body further includes at least one orifice located at the second end of the elongated body. The at least one orifice is defined by a hard wear layer extending along the orifice on the elongated body.

With further reference to FIG. 3, a method for producing a fuel injection nozzle is disclosed. The method comprises the following steps: an operation or step of hardening the nozzle body; an operation or step of forming at least one orifice through the hardened nozzle body; and an operation or step of re-hardening the nozzle body after forming the at least one nozzle hole to form a hard wear-resistant material layer along the at least one nozzle hole through the hardened nozzle body.

This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Other embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

Drawings

The description herein makes reference to the accompanying drawings wherein like numerals refer to like parts throughout the several views, and wherein:

FIG. 1 is a schematic illustration of a fuel injector according to an embodiment of the present disclosure.

Fig. 2 is a cross-sectional view illustrating certain aspects of a nozzle for a fuel injector according to an embodiment of the present disclosure.

Fig. 3 is a flow chart of a process of producing a nozzle for a fuel injector according to an embodiment of the present disclosure.

Detailed Description

Referring to fig. 1-2, a nozzle 30 for a fuel injector 20 is shown. The nozzle 20 includes an elongated body 32 extending along a longitudinal axis 34 from a first end 42 of the elongated body to an opposite second end 44 of the elongated body 32. The elongate body 32 includes a longitudinally extending fuel passage 36 that extends from a first end 42 of the elongate body 32 to a second end 44 of the elongate body 32. The elongate body 32 further includes at least one orifice 38, 40 located at a second end 44 of the elongate body 32. At least one orifice 38, 40 is defined by a hard wear layer 70 extending along the orifice 38, 40 on the elongated body 32.

With further reference to FIG. 3, a method 300 for producing the fuel injection nozzle 30 is disclosed. The method 300 comprises the following steps: an operation or step 302 of hardening the nozzle body 32; an operation or step 304 of forming at least one orifice 38, 40 through the hardened nozzle body 32; and an operation or step 306 of re-hardening the nozzle body 32 after forming the at least one orifice 38, 40 to form a layer 70 of hard wear-resistant material along the at least one orifice 38, 40 through the hardened nozzle body 32.

Referring to FIG. 1, a fuel injector system 10 includes an accumulator 12 connected to a fuel injector 20 by a connecting member 14. Accumulator 12 may be part of a high pressure common rail fuel injector system, for example. The connecting member 14 may include, for example, valves, throttles, control chambers, piping, and other components that may be generally provided to connect the fuel injector 20 to the accumulator 12.

The fuel injector 20 includes a nozzle 30 that houses the needle 22. The nozzle 30 includes an elongated body 32 extending along a central longitudinal axis 34. The body 32 includes a fuel passage 36 that receives the needle valve 22 therein. Needle 22 is elongate and extends between a proximal end 24 and a distal end 26 of needle 22. The needle valve 22 moves longitudinally up and down in the fuel passage 36 to selectively start and stop fuel injection from the fuel passage 36 through one or more injection orifices 38, 40 of the nozzle 30.

Although only two orifices 38, 40 are shown, embodiments having only one orifice or having three or more orifices are contemplated. In addition, the orifices 38, 40 may be arranged in any pattern on the nozzle 30. In the illustrated embodiment, the orifices 38, 40 are circular and include a uniform diameter from the inlet to the outlet. However, non-circular orifices and orifices that are non-uniform in size along the axial length are also contemplated.

The nozzle 30 includes a first end 42 oriented proximally and an opposite second end 44 oriented distally. The fuel passageway 36 forms a bladder 46 in a nozzle seat 48 located at the second end 44 of the body 32. The orifices 38, 40 extend through the body 32 at a seat 48. The distal end 26 of the needle valve 22 moves within the pocket 46 to engage and disengage the nozzle seat 48 to selectively close and open the orifices 38, 40 to inject fuel.

For example, during a fuel injection event, the closing force is removed from the needle 22 to allow the needle 22 to lift from the nozzle seat 48 such that fuel is injected from the bladder 46 into an engine cylinder (not shown) through the injection orifices 38, 40. A needle spring 28 surrounding a portion of the needle 22 may be disposed in the fuel passage 36 to assist in controlling longitudinal movement of the needle 22.

Further details of the orifices 38, 40 will now be discussed with reference to fig. 2 and orifice 38, with the understanding that the details are applicable to any other orifice provided with the nozzle 30. The orifice 38 includes an inlet 60 that opens at an inner surface 50 of the body 32 at the bladder 46. The orifice 38 opens at an outlet 62 located on the outer surface 52 of the body 32 adjacent the second end 44. The orifice 38 is defined by a surface 64 of the body 32 that extends around the orifice 38, and the surface 64 extends from the inlet 60 to the outlet 62.

In an embodiment, the surface 64 is formed from a layer 70 of hard wear resistant material that is created by hardening the nozzle body 32 after forming the orifices 38, 40, such as via an Electrical Discharge Machining (EDM) process. In embodiments, the hard wear layer is a layer of material that appears white when viewed under grinding, polishing, and etching conditions at a magnification of more than 100 times.

Other embodiments contemplate other techniques for forming the orifices 38, 40, such as electro-mechanical chemical machining, laser drilling, and the like. Preferably, the nozzle body 32 is also hardened before forming the orifice 38, such that the hard wear layer 70 is formed during a second hardening of the nozzle 30 after forming the orifice 38 in the pre-hardened nozzle body 32.

Hardening of the nozzle body 32 creates a diffusion layer 72 between the hard wear layer 70 and the substrate 74. In an embodiment, the substrate 74 is the original core material of the nozzle body 32 prior to hardening the nozzle body 32. The core material of the substrate 74 may be any material suitable for use in a fuel injector nozzle, including, for example, any suitable metal and/or metal alloy.

In an embodiment, the first hardening and the second hardening of the nozzle body 32 are accomplished using a first gas nitriding process and a second gas nitriding process. The second nitriding process is designed to produce a uniform compound layer comprising the hard wear layer 70 and a porous layer over the hard wear layer 70 and a diffusion layer 72 between the hard wear layer and the substrate 74.

The hard wear layer 70 comprises iron nitride. In embodiments, the hard wear layer 70 consists essentially of or consists of iron nitride. Diffusion layer 72 comprises a nitrogen-rich martensitic matrix. In embodiments, diffusion layer 72 consists essentially of or consists of a nitrogen-rich martensitic matrix.

In an embodiment, the pores of the porous layer over the hard wear layer 70 formed by the second nitriding process are removed by an abrasive flow machining process after the second nitriding process. The abrasive flow process is controlled to leave the hard wear layer 70 and remove the porous layer. In addition, the thickness of the diffusion layer 72 generated in the second nitriding process is limited to about half the thickness of the diffusion layer 72' formed during the first nitriding process, thereby avoiding excessive precipitation of nitride along grain boundaries to prevent the surface from becoming excessively fragile.

In an embodiment, the second nitriding process is designed to limit the thickness of the hard wear layer 70 to less than 15 microns after the abrasive stream machining process is completed. In an embodiment, the hard wear layer 70 consists essentially of gamma '(gamma' -Fe 4N) and epsilon (epsilon-Fe 2-3N) iron nitrides, and is free of excessive porosity after abrasive stream processing. In embodiments, the hard wear layer 70 is free of surface porosity after abrasive flow machining.

In an embodiment, diffusion layer 72' includes a first thickness and diffusion layer 72 includes a second thickness measured from orifice surface 64 along at least one orifice 38. In embodiments, the second thickness is less than the first thickness.

Since the injection holes 38 are formed in the hardened material and the second nitriding process is performed after the injection holes 38 are formed, the injection holes 38 have enhanced mechanical and chemical properties. For example, the nozzle holes 38 have improved wear and erosion performance characteristics compared to nozzles formed via a single stage nitriding process. The first nitriding process in the present disclosure forms a very hard outer "shell" layer with compressive residual stress on the nozzle body 32. When forming the orifice 38, the orifice forming tool compresses this hard nitride layer and the inlet 60 of the orifice 38 is compressed, making the orifice 38 very robust against wear and fatigue. Next, a second nitriding process is used to create a hard wear layer along the nozzle holes 38 from the inlet 60 to the outlet 62.

A method 300 for producing a fuel injector nozzle according to the present disclosure is shown in fig. 3. The method 300 includes an operation 302 of hardening the rough-turning nozzle body 32. The rough-turned nozzle body 32 may be machined from a solid, soft blank of core material that will ultimately form the substrate 74. The rough-turned nozzle 30 may include soft machining to form the exterior shape and interior shape of the nozzle 30, such as the fuel passage 36. However, the injection holes 38, 40 have not been formed in the rough-turned nozzle body 32. The rough-turning nozzle body 32 may be cleaned prior to the hardening process. The hardening treatment of the rough-turned nozzle body 32 may be, for example, a gas nitriding process to enhance the surface hardness to a certain depth to facilitate subsequent machining. This first hardening treatment forms a hard wear layer and a diffusion layer on the exposed surface of the rough-turning nozzle body 32.

The method 300 continues at operation 304 to finish the hardened rough turning nozzle body 32. Operation 304 may also include further rough turning of the hardened nozzle body 32 as necessary. The inner and outer surfaces of the nozzle body 21 may then be refined and cleaned and/or demagnetized. The orifice locations are marked by the laser and the orifices 38, 40 are now formed in the nozzle body 30 using any suitable orifice forming device and/or technique, as discussed above. Forming the holes in the hardened material provides compressive residual stress at the inlets of the orifices 38, 40, such as at the inlet 60 of the orifice 38.

The method 300 continues at operation 306 to re-harden the nozzle 30 after forming the orifices 38, 40. The nozzle 30 may be cleaned before being hardened again. This second hardening treatment provides hardening along the axial length of the nozzle holes 38, 40 from the inlet to the outlet of the nozzle holes. As discussed above, this hardening is provided by the hard wear layer 70 extending from the inlet to the outlet of the orifice. Additionally, the hard wear layer 70 may extend outwardly from the inlets 60 of the orifices 38, 40 along the inner surface 50 of the bladder 44. The hard wear layer 70 may also extend outwardly from the outlets 62 of the nozzle bores 38, 40 along the outer surface 52 of the nozzle body 32. After re-hardening, the nozzle 30 may be cleaned and laser marked.

The method 300 may include the further operation of abrasive flow machining the nozzle 30 including the orifices 38, 40 after the second hardening process. The abrasive flow machining may be controlled such that only the porous layer or porous material resulting from the second hardening treatment is removed from the hard wear layer 70. However, the hard wear layer 70 remains along the exposed surfaces of the nozzle holes 38, 40.

Additional written descriptions of aspects of the disclosure will now be provided. According to one aspect, a nozzle for a fuel injector is provided. The nozzle includes an elongated body extending along a longitudinal axis from a first end of the elongated body to an opposite second end of the elongated body. The elongated body includes a longitudinally extending fuel passage extending from the first end of the elongated body to the second end of the elongated body. The elongated body further includes at least one orifice located at the second end of the elongated body. The at least one orifice is defined by a hard wear layer extending along the orifice on the elongated body.

In an embodiment of the nozzle, the hard wear layer extends from a fuel passage through the elongated body at the second end of the elongated body. In an embodiment of the nozzle, the at least one orifice comprises a plurality of orifices, and each of the plurality of orifices is defined by a hard wear layer on the elongated body.

In an embodiment of the nozzle, the elongated body comprises a substrate formed from a core material of the elongated body, a diffusion layer on the substrate, and a hard wear layer on the hardened layer. In a refinement of this embodiment, the diffusion layer is a nitrogen-rich martensitic matrix.

In another refinement of the above embodiment, the diffusion layer includes a first diffusion layer having a first thickness along the fuel passageway and a second diffusion layer having a second thickness along the fuel passageway and along the at least one orifice, and the second thickness is less than the first thickness. In another refinement, the second thickness is about half the first thickness.

In an embodiment of the nozzle, the at least one orifice extends from an inlet at the fuel passageway to an outlet on an outer surface of the elongated body, and the hard wear layer extends from the inlet to the outlet of the at least one orifice. In a refinement of this embodiment, the hard wear layer extends outwardly from the outlet of the at least one orifice along the outer surface of the elongated body. In another refinement, the hard wear layer extends outwardly from an inlet of the at least one orifice along an inner surface of the elongated body.

In an embodiment of the nozzle, the hard wear layer comprises iron nitride. In a modification of this embodiment, the iron nitride comprises gamma' (Fe 4N) and epsilon (Fe 2-3N) iron nitrides.

In an embodiment of the nozzle, the hard wear layer is less than 15 microns. In embodiments of the nozzle, the hard wear layer is free of surface porosity.

According to another aspect of the present disclosure, a method for producing a fuel injection nozzle is provided. The method comprises the following steps: a) Hardening the nozzle body; b) Forming at least one orifice through the hardened nozzle body; and c) re-hardening the hardened nozzle body after forming the at least one spray orifice to form a hard wear resistant material layer along the at least one spray orifice through the hardened nozzle body.

In embodiments, the method includes machining the nozzle body along the orifice to remove porous material from the hard wear layer. In one refinement, machining the nozzle body includes machining porous material from the hard abrasive layer abrasive stream. In another refinement, the hard wear layer is less than 15 microns after removing the porous material.

In an embodiment of the method, forming at least one orifice includes electro-discharge machining the at least one orifice through a hardened layer of the nozzle body. In a refinement of this embodiment, electro-discharge machining the at least one orifice comprises compressing a hardened material around an inlet of the at least one orifice.

In an embodiment of the method, hardening the nozzle body in steps a) and c) comprises subjecting the nozzle body to a diffusion thermal process to form the hard wear layer. In a modification of this embodiment, the diffusion thermal process is a gas nitriding process.

In an embodiment of the method, the nozzle body is rough turned prior to step a) to form a fuel passage in the nozzle body, and the at least one nozzle orifice formed in step b) extends from the fuel passage through the nozzle body to an outer surface of the hardened body.

While illustrative embodiments of the disclosure have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the claimed utility model are desired to be protected. It should be understood that while the use of words such as those utilized in the description above, which may be preferred, preferred or more preferred, may be more desirable to have the features so described, it is nevertheless not necessary and embodiments without such words are contemplated as falling within the scope of the utility model, which is defined by the appended claims. The claims are to be read with the intent that when words such as "a," "an," "at least one," or "at least a portion" are used, it is not intended that the claims be limited to only one item unless expressly stated to the contrary in the claims. When the language "at least a portion" and/or "a portion" is used, the term can include a portion and/or the entire term unless specifically stated to the contrary.

Claims (13)

1. A nozzle for a fuel injector, the nozzle comprising:

an elongate body extending along a longitudinal axis from a first end of the elongate body to an opposite second end of the elongate body, the elongate body comprising:

a longitudinally extending fuel passage extending from the first end of the elongated body to the second end of the elongated body; and

at least one orifice located at the second end of the elongated body, the at least one orifice defined by a hard wear layer extending over the elongated body along the orifice.

2. The nozzle of claim 1, wherein the hard wear layer extends from the fuel passageway through the elongated body at the second end of the elongated body.

3. The nozzle of claim 1, wherein the at least one orifice comprises a plurality of orifices, and each of the plurality of orifices is defined by the hard wear layer on the elongated body.

4. The nozzle of claim 1, wherein the elongated body comprises:

a substrate formed from a core material of the elongate body;

a diffusion layer on the substrate; and

the hard wear layer is positioned on the hardening layer.

5. The nozzle of claim 4 wherein the diffusion layer is a nitrogen-rich martensitic matrix.

6. The nozzle of claim 4, wherein the diffusion layer comprises: a first diffusion layer having a first thickness along the fuel passage; and a second diffusion layer having a second thickness along the fuel passageway and along the at least one nozzle hole, and the second thickness being less than the first thickness.

7. The nozzle of claim 6, wherein the second thickness is about half of the first thickness.

8. The nozzle of claim 1, wherein the at least one orifice extends from an inlet at the fuel passageway to an outlet on an outer surface of the elongated body, and the hard wear layer extends from the inlet to the outlet of the at least one orifice.

9. The nozzle of claim 8, wherein the hard wear layer extends outwardly from the outlet of the at least one orifice along the outer surface of the elongated body.

10. The nozzle of claim 8, wherein the hard wear layer extends outwardly from the inlet of the at least one orifice along an inner surface of the elongated body.

11. The nozzle of claim 1, wherein the hard wear layer comprises iron nitride.

12. The nozzle of claim 1, wherein the hard wear layer is less than 15 microns.

13. The nozzle of claim 1, wherein the hard wear layer is free of surface voids.

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