Injector tip for a fuel injector

An injector tip for a fuel injector includes an exterior surface, and an interior surface defining a sac region therein. The injector tip is also configured to define at least one orifice radially extending from the interior surface to the exterior surface. The orifice is disposed in communication with the sac region located adjacent to the interior surface. Further, the injector tip also includes a mound that is defined on the interior surface such that the mound is integrally formed with the interior surface adjacent to the sac region. The mound is configured to extend along an axis of the sac region and terminate prior to a perimeter of the at least one orifice.

TECHNICAL FIELD

The present disclosure relates to a fuel injector. More particularly, the present disclosure relates to an injector tip for a fuel injector having a reduced possibility of fuel dribble during and upon completion of a fuel discharge event.

BACKGROUND

Fuel injectors are used to deliver fuel to a combustion chamber of an engine. In many cases, these fuel injectors have high fuel pressure within that would be provided from a pump and rail arrangement located upstream of the fuel injectors. This high pressure of the fuel combined with an inter-relative geometry of a sac region and a needle tip of the fuel injector may influence one or more parameters associated with discharge and combustion of the fuel. These parameters in turn, affect the quality of emissions before being released into the atmosphere. For instance, during a fuel discharge event, many conventional fuel injectors have been known to dribble fuel to at least about a droplet size from their sac regions into the combustion chamber of the engine. This could lead to undesired effects including, amongst other things, the presence of unburned hydrocarbons in the emissions released by the combustion chamber.

Many strategies have been developed to reduce this dribble effect so that the quality of emissions from combustion chambers of an engine can be improved. One such strategy is disclosed in PCT Publication WO 1992/019859 (hereinafter referred to as ‘the '859 publication’). The '859 publication discloses a fuel injection nozzle having a nozzle body in which is formed a bore having a seating defined at one end. A valve member is movable in the bore and is shaped to cooperate with the seating to control fuel flow into a sac volume defined by a blind drilling formed in the body. Outlet orifices extend to an exterior of the body from the drilling and in order to reduce the volume of the sac volume an insert is positioned in the drilling. However, this insert may be displaceable in position when subject to extreme working pressures typically encountered in fuel injection nozzles. Moreover, due to a possibility of displacement in position of the insert, the body, and in particular, the sac region of the injection nozzle may be subject to collisions or abrasion from the insert thereby reducing a service life of the injection nozzle.

Hence, there is a need for a fuel injector having a sac region that is capable of withstanding high operational forces while also being configured to minimize fuel dribble from occurring during or after a fuel discharge event.

SUMMARY OF THE DISCLOSURE

In an aspect of the present disclosure, an injector tip for a fuel injector includes an exterior surface, and an interior surface defining a sac region therein. The injector tip is also configured to define at least one orifice radially extending from the interior surface to the exterior surface. The orifice is disposed in communication with the sac region located adjacent to the interior surface. Further, the injector tip also includes a mound that is defined on the interior surface such that the mound is integrally formed with the interior surface adjacent to the sac region. The mound is configured to extend along an axis of the sac region and terminate prior to a perimeter of the at least one orifice. In aspects of this disclosure, the mound is convex in shape.

In another aspect of this disclosure, ends of the mound may terminate tangentially with respect to the perimeter of the at least one orifice. Optionally, a concave ridge portion could be disposed between the mound and the at least one orifice.

In yet another aspect of this disclosure, a fuel injector includes a body having an injector tip according to the present disclosure.

In yet another aspect of this disclosure, claims have been directed to an engine having a combustion chamber, and the fuel injector of the present disclosure partially received in the combustion chamber to deliver a pressurized supply of fuel into the combustion chamber.

DETAILED DESCRIPTION

Reference numerals appearing in more than one figure indicate the same or corresponding parts in each of them. References to elements in the singular may also be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims.

FIG. 1illustrates an exemplary engine100, in accordance with an embodiment of the present disclosure. As shown, the engine100is embodied as an internal combustion diesel engine of the reciprocating type. In other embodiments, the engine100could include, a natural gas direct injection engine, or other types of engine configurations known to persons skilled in the art.

Referring toFIG. 1, the engine100includes four combustion chambers102, which are individually denoted with alpha-numerals102a-102d. Each of these combustion chambers102is provided with a fuel injector104. Although four combustion chambers102a-102dare shown in the illustrated exemplary engine100ofFIG. 1, in other embodiments, fewer or more combustion chambers102may be included in the engine100depending on specific requirements of an application. For example, a single cylinder engine may be contemplated for use in lieu of the multi-cylinder engine100depicted in the illustrated embodiment ofFIG. 1.

Moreover, although a single fuel injector104is shown associated with each of the combustion chambers102a-102din the exemplary engine100ofFIG. 1, in other embodiments, more than one fuel injector104may be associated with each combustion chamber102of the engine100. Therefore, a number of combustion chambers102and a number of fuel injectors104used with each combustion chamber102is merely exemplary in nature, and hence non-limiting of this disclosure. Persons skilled in the art will acknowledge that the number of combustion chambers102and the number of fuel injectors104used with each combustion chamber102may vary depending upon specific requirements of an application.

Each of the fuel injectors104a-104dis disposed in fuel communication with a fuel rail106with the help of a supply line108, one supply line108a-108dfor corresponding ones of the fuel injectors104a-104d. A pump110located upstream of the fuel rail106is configured to draw fuel from a tank112via a suction line111. The pump110pressurizes the fuel drawn within and supplies the pressurized fuel into the fuel rail106. From the fuel rail106, fuel is supplied, independently and selectively, to each of the fuel injectors104a-104dvia corresponding ones of the supply lines108a-108drespectively.

FIG. 2illustrates a sectional view of the fuel injector104, in accordance with an embodiment of the present disclosure. As shown, the fuel injector104includes a body220having an injector tip222. The fuel injector104also includes a needle224disposed within the body220. The needle224is configured to operatively move in relation to a valve seat226defined by the body220for permitting fuel to flow downstream of the valve seat226and into a sac region228of the injector104.

As shown, the injector tip222includes an exterior surface230, and an interior surface232defining the sac region228therein. The injector tip222is also configured to define at least one orifice234radially extending from the interior surface232to the exterior surface230. For example, the injector tip222shown in the illustrated embodiment ofFIG. 2is configured to define six orifices of which four orifices234are visible in the cross-sectional view ofFIG. 2. Each orifice234is disposed in communication with the sac region228located adjacent to the interior surface232.

Further, the injector tip222also includes a mound236that is defined on the interior surface232. As shown, the mound236is convex in shape. In embodiments of this disclosure, it may be noted that the mound236is integrally formed with the interior surface232adjacent to the sac region228. As shown, the mound236is configured to extend along an axis AA′ of the sac region228.

In the illustrated embodiment ofFIG. 2, the mound236is configured to terminate prior to a perimeter P of the orifices234. That is, ends238of the mound236are configured to end partway along a distance D between the axis AA′ and each orifice234to tangentially merge with the interior surface232of the injector tip222. Moreover, in this embodiment, the interior surface232also has a concave annular ridge240defined between ends238of the mound236and each orifice234.

However, in other embodiments, the ends238of the mound236may be configured to terminate tangentially with the perimeter P of each orifice234. That is, the ends238of the mound236could be disposed on a smallest locus of points subtended from the axis AA′ on the interior surface232and coinciding with the perimeters P of the orifices234. Further, although it is shown in the illustrated embodiment ofFIG. 2that an apex244of the mound236coincides with the axis AA′ of the sac region228, in other embodiments, the apex244may be offset from the axis AA′. For instance, if the axis BB′ of each orifice234is not equiangular with respect to the axis AA′, then it can be contemplated to define the mound236such that the apex244of the mound236is offset from the axis AA′. It may be noted that the amount of offset between the apex244of the mound236and the axis AA′ of the sac region228may vary depending on specific requirements of an application.

Since the mound236protrudes into the sac region228, the sac region228is rendered with a reduced volume. This reduced volume of the sac region228helps obviate a presence of excess fuel in the sac region228during and upon completion of a fuel discharge event by the fuel injector104into the combustion chamber102. In fact, with the help of embodiments disclosed herein, it is envisioned that the mound236can be configured to help ensure that the sac region228is devoid of excess fuel during receipt, containment, and upon discharge of fuel from the sac region228of the fuel injector104into the combustion chamber102via the orifices234when the needle224travels towards the valve seat226(in a direction D as shown inFIG. 2) and co-operates with the mound236for delivering fuel into the sac region228and discharging fuel out of the sac region228into the combustion chamber102via the orifices234. This way, the mound236contributes, at least in part, to an optimization in the metering of fuel before it is discharged into the combustion chamber102and therefore, minimizes the possibility of any fuel, excess or otherwise, from residing back in the sac region228and dribbling into the combustion chamber102during or after the fuel discharge event.

In the illustrated embodiment ofFIG. 2, the needle224includes an end portion242that is configured to co-operate with the mound236. This end portion242is convex in shape. Although a convex shape of this end portion242is disclosed herein, other shapes such as a flattened shape, or a concave shape may be used in lieu of the convex shape disclosed herein. It may be noted that the shape of the end portion242of the needle224may be varied to suit various requirements of a fuel-injection application including, but not limited to, a shape and/or size of the mound236, a volume of the sac region228that would be required to optimize the metering of fuel contained within the sac region228during receipt, containment, and discharge of fuel by the sac region228, an amount of time associated with movement of the needle224in relation to the valve seat226for permitting fuel into and discharging fuel out of the sac region228via the orifices234into the combustion chamber102.

FIGS. 3-4illustrate sectional and perspective sectional views of the fuel injector104having an injector body320and showing an injector tip322in accordance with another embodiment of the present disclosure. Referring toFIGS. 3-4, a mound336is defined on and integrally formed with an interior surface332of the injector tip322. As shown, the mound336extends along an axis AA′ of the sac region328with ends338of the mound336terminating prior to a perimeter P of each orifice334.

Moreover, in this embodiment, the mound336extends substantially to a height H along axis AA′. For sake of the present disclosure, this height H of the mound336may be regarded as being greater than a height h associated with the mound236shown in the illustrated embodiment ofFIG. 2. As shown in this embodiment, the end portion342of the needle324is configured to define a concave recess346corresponding in shape to the elongated convex shape of the mound336. Further, a depth D1of the concave recess346may be selected, depending on specific requirements of a fuel-injection application as disclosed earlier herein, to correspond with the height H of the mound336in that the concave recess346may not receive, at least partially receive, or fully receive the mound336therein when the needle324is in abutment with a valve seat326defined by an injector body320. For instance, in the illustrated embodiment ofFIGS. 3-4, the depth D1of the concave recess346is less than the height H of the mound336and the concave recess336is therefore, configured to partially receive the mound336therein when the needle324is in abutment with the valve seat326.

In embodiments herein, it may be noted that the mounds236/336are also configured to impart additional strength to the injector tip222/322as these mounds236/336are integrally formed with interior surfaces232/332of corresponding ones of the injector tips222/322disclosed herein. Various processes including, but not limited to, end milling, 3D printing, or any other material removal or material additive processes known to persons skilled in the art are contemplated for forming the mounds236/336integrally with the interior surfaces232/332of corresponding ones of the injector tips222/322respectively.

Also, when forming the mounds236/336disclosed herein, ends238/338of corresponding mounds236/336may be configured to, optionally, terminate at regions of the interior surfaces232/332between successive ones of corresponding orifices238/338. These regions may be located on a locus of points that are different from that where the ends238/338of the mounds236/336terminate prior to, or tangentially with the perimeters P/P1of the corresponding orifices234/334. The ends238/338of the mounds236/336at these regions may be contoured with corresponding ones of the interior surfaces232/332itself so that these ends238/338of the corresponding mounds236/336can help improve a flow of fuel from the orifices234/334of corresponding ones of the injector tips222/322into the combustion chamber102.

Various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., connected, coupled and the like) are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other.

Additionally, all numerical terms, such as, but not limited to, “first”, “second”, or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements, embodiments, variations and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to or over another element, embodiment, variation and/or modification.

It is to be understood that individual features shown or described for one embodiment may be combined with individual features shown or described for another embodiment. The above described implementation does not in any way limit the scope of the present disclosure. Therefore, it is to be understood although some features are shown or described to illustrate the use of the present disclosure in the context of functional segments, such features may be omitted from the scope of the present disclosure without departing from the spirit of the present disclosure as defined in the appended claims.

INDUSTRIAL APPLICABILITY

Embodiments of the present disclosure have applicability for use and implementation in reducing fuel dribble out of fuel injectors and into combustion chambers of engines during fuel-injection events. With implementation of the injector tips222/322disclosed herein, manufacturers and users of engines can improve a quality of emissions released from an engine. A reduced level of unburned hydrocarbons (UHC) could be present in the released emissions that would otherwise increase if fuel-dribble occurred from the injectors into the combustion chamber/s of an engine.

In many countries, efforts have been made to regulate the quality of emissions with the help of various emissions norms that mandate the level of UHC permitted in a pre-determined amount of emissions released by an engine. With use of embodiments disclosed herein, manufacturers can improve an overall performance of engines in terms of emission quality while, optionally or additionally, helping the engines to reduce fuel consumption for improving fuel mileage as the injector tips222/322of the present disclosure define sac regions228/328that are rendered with a reduced volume as opposed to a volume associated with previously known configurations of conventional sac regions.

Additionally, with inclusion of the mound236/336, additional strength may be imparted to corresponding ones of the injector tips222/322thereby improving a service life and reliability of the injector tips222/322in withstanding extreme forces encountered during operation. Therefore, use of the injector tips222/322may also reduce costs, time, and effort typically incurred with frequent service of conventionally configured fuel injector tips and/or replacement of previously known fuel injectors.