WO2014210148A1

WO2014210148A1 - Fuel injector including features to reduce viscous heating in a control valve and a drain circuit

Info

Publication number: WO2014210148A1
Application number: PCT/US2014/044084
Authority: WO
Inventors: Peter J. HERMAN; Arun P. JANAKIRAMAN; Frank HUSMEIR; Christopher E. Holm; Lester L. Peters; David L. Buchanan; W. Beale DELANO, Jr.
Original assignee: Cummins Inc.
Priority date: 2013-06-26
Filing date: 2014-06-25
Publication date: 2014-12-31

Abstract

High-pressure fuel systems use very precise components with tight clearance tolerances that place high demands on fuel filtration efficiency. High efficiency next-generation nanofiber filter media can meet these demands and have ample "large particle" efficiency, but it has been found that, in some cases or under certain conditions, fuel filter life is insufficient due to clogging of the filter with very small particles, which may be carbon particles that are typically less than three microns in size. The disclosure provides improvements to a fuel injector that decreases the shear in a fuel injector, reducing the creation of small particles.

Description

FUEL INJECTOR INCLUDING FEATURES TO REDUCE

VISCOUS HEATING IN A CONTROL VALVE AND A DRAIN CIRCUIT

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application Serial No.

61/839,551, filed June 26, 2013, the disclosure of which is hereby expressly incorporated by reference herein in its entirety.

FIELD OF THE DISCLOSURE

[0002] This disclosure relates to valve controlled fuel injectors and drain circuits associated with such valves.

BACKGROUND OF THE DISCLOSURE

[0003] Fuel injectors often use one or more valves to control a fuel injection event. The configuration of such valves can lead to extreme heating in fuel flowing through the valves due to highly-localized viscous shear.

SUMMARY

[0004] High-pressure fuel systems use very precise components with tight clearance tolerances that place high demands on fuel filtration efficiency. High efficiency next-generation nanofiber filter media can meet these demands and have ample "large particle" efficiency, but it has been found that, in some cases or under certain conditions, fuel filter life is insufficient due to clogging of the filter with very small particles, which may be carbon particles that are typically less than three microns in size. The disclosure provides improvements to a fuel injector that decreases the shear in a fuel injector, reducing the creation of small particles.

[0005] According to an exemplary embodiment of the present disclosure, a fuel injector for delivering fuel to a combustion chamber of an engine is provided comprising an injector body defining an injector cavity; a control volume having at least one inlet and at least one outlet, the at least one inlet arranged in fluid communication with the control volume to deliver fuel to the control volume along an inlet axis, the at least one outlet arranged in fluid

communication with a drain circuit to drain fuel from the control volume along an outlet axis; and a valve moveable in the injector cavity between an open position, in which fuel from the injector cavity is delivered to the combustion chamber, and a closed position, the valve having a longitudinal axis and a guiding surface that receives fuel from the at least one inlet along the inlet axis, wherein a line containing at least part of the guiding surface is arranged one of parallel and oblique to the inlet axis.

[0006] According to another exemplary embodiment of the present disclosure, a fuel injector for delivering fuel to a combustion chamber of an engine is provided comprising an injector body defining an injector cavity; a control volume having at least one inlet arranged along an inlet axis and at least one outlet arranged along an outlet axis, wherein the inlet axis is one of oblique and skewed in relation to a longitudinal axis; and a valve moveable in the injector cavity along the longitudinal axis in response to a pressure in the control volume between an open position, in which fuel from the injector cavity is delivered to the combustion chamber, and a closed position.

[0007] According to yet another exemplary embodiment of the present disclosure, a fuel injector for delivering fuel to a combustion chamber of an engine is provided comprising an injector body defining an injector cavity; a control volume having at least one inlet arranged along an inlet axis and at least one outlet arranged along an outlet axis; and a valve moveable in the injector cavity along a longitudinal axis in response to a pressure in the control volume between an open position, in which fuel from the injector cavity is delivered to the combustion chamber, and a closed position, the valve having a guiding surface that receives fuel from the at least one inlet, wherein a line containing at least part of the guiding surface is arranged one of perpendicular, oblique, and skewed to the longitudinal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0009] FIG. 1 is a cross-sectional view of a portion of a conventional internal combustion engine showing a portion of a fuel injector, including an actuator and a control valve;

[0010] FIG. 2 is a cross-sectional view of a portion of the internal combustion engine of

FIG. 1, showing a fuel injector control valve drain path;

[0011] FIG. 3 is a view of a portion of the fuel injector of FIG. 1, showing fluid velocity contours of fluid flow into a control volume and into a drain passage when the control valve is open;

[0012] FIG. 4 is a view of a portion of the fuel injector of FIG. 1, showing fluid velocity contours of fluid flow past a control valve seat when the control valve is open;

[0013] FIG. 5 is a view of a portion of the fuel injector of FIG. 1, showing surface temperatures during fluid flow through an inlet orifice and on a nozzle valve element of the fuel injector;

[0014] FIG. 6 is a view of a portion of the drain passage of FIG. 3, showing localized surface heating at the location of a nozzle valve element or float gap and at a drain passage transition corner;

[0015] FIG. 7 is a view of portion of the drain passage and control valve seat of FIG. 4, showing surface temperatures during an injection event;

[0016] FIG. 8 is a cross-sectional view of a portion of a fuel injector in accordance with a first exemplary embodiment of the present disclosure; [0017] FIG. 9 is a cross-sectional view of a portion of a fuel injector in accordance with second and third exemplary embodiments of the present disclosure;

[0018] FIG. 10 is a perspective cross-sectional view of a portion of a fuel injector in accordance with a fourth exemplary embodiment of the present disclosure;

[0019] FIG. 11 is a side cross-sectional view of the embodiment of FIG. 10;

[0020] FIG. 12 is a perspective cross-sectional view along the lines 12-12 in FIG. 11;

[0021] FIG. 13 is a cross-sectional view of a portion of a fuel injector in accordance with a fifth exemplary embodiment of the present disclosure;

[0022] FIG. 14 is a perspective cross-sectional view of the embodiment of FIG. 13;

[0023] FIG. 15 is a bottom view of a nozzle element seal in accordance with a sixth exemplary embodiment of the present disclosure;

[0024] FIG. 16 is a perspective view of a proximal end of a nozzle valve element in accordance with a seventh exemplary embodiment of the present disclosure;

[0025] FIG. 17 is a cross-sectional view of a proximal end of a nozzle valve element in accordance with an eighth exemplary embodiment of the present disclosure;

[0026] FIG. 18 is a cross-sectional view of a proximal end of a nozzle valve element in accordance with a ninth exemplary embodiment of the present disclosure;

[0027] FIG. 19 includes a cross sectional view of a portion of a conventional fuel injector and a similar view of a fuel injector in accordance with a tenth exemplary embodiment of the present disclosure;

[0028] FIG. 20 is a cross sectional view of a portion of the fuel injector on the left side of

FIG. 19, with a nozzle valve element in a down or closed position;

[0029] FIG. 21 is a view similar to FIG. 20, showing the nozzle valve element in an up or raised position; and

[0030] FIG. 22 is a portion of a control valve drain circuit in accordance with an eleventh exemplary embodiment of the present disclosure. [0031] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate exemplary embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION

[0032] High-pressure fuel systems use very precise components with tight clearance tolerances that place high demands on fuel filtration efficiency. High efficiency next-generation nanofiber filter media can meet these demands and have ample "large particle" efficiency, but it has been found that in some cases or under certain conditions that fuel filter life is insufficient due to clogging of the filter with very small particles, which may be carbon particles and which may be less than three microns in size. After extensive experimentation and analysis, the source of these small particles is understood by the applicant to be thermal degradation of the fuel that returns to a fuel tank via an injector drain path. The drain fuel is throttled from rail pressure, which is often greater than 2000 Bar, down to atmospheric pressure, which is approximately 1 Bar. Conservation of energy requires that the throttling and subsequent decrease in pressure, which may be defined as work dP, manifests as heat in the return or drain fuel, with bulk fuel temperatures (T_Buik) soaring above 200 degrees Celsius in some circumstances. For the simplified case of incompressible fluid and constant specific heat (C_p), the throttling work is the product of the volumetric flow rate and the pressure drop, such that the temperature rise may be expressed as in Equation (1).

dP

= ₍C_px_Densi_ty) ^ECl^Uati0n ^

[0033] In a representative example, the value of C_p for #2 diesel fuel is approximately

0.038 and the bulk temperature rise T_Rise for #2 diesel fuel is thus approximately equal to 0.038 * dP, where dP is equal to the throttling pressure drop. Thus the bulk fuel temperature T_Buik may be expressed as Equation (2).

Teulk ^~ ^Initial + T_Rise Equation (2)

[0034] In one example, if the pressure drop dP is 2500 Bar, with the previously provided specific heat and the known density for #2 diesel fuel, the value of T_Rise would be approximately 95 degrees Celsius. If the incoming or initial fuel temperature Ti_nitiai from a fuel system high- pressure pump (not shown) is 100 degrees Celsius, then according to Equation (2) the temperature of the drain fuel would be approximately 195 degrees Celsius.

[0035] The heating of fuel in a fuel injector drain circuit, typically caused by high- pressure drop "throttle" locations in the fuel injector drain circuit, in addition to leakage from the fuel system high-pressure pump, are well-known phenomena. What was not well understood, and which was learned through computational fluid dynamics (CFD) analysis, is that much higher local temperatures, T_Max are created in a very thin boundary layer, which may be less than 50 microns in thickness, where viscous shear rates are extremely intense, with local temperatures increasing to about 400 degrees Celsius. While the significantly higher temperature fuel mixes with the cooler surrounding fuel to reach the lower T_Bui_k defined by energy conservation, the reaction rates of fuel oxidation and/or pyrolysis typically increase at a very rapid rate with increasing temperature, per the well-known Arrhenius relationship, depending upon the activation energy of the reaction mechanism. A common, though crude, rule-of-thumb for oxidation-type reactions is a double rate of reaction for every 10 degree Celsius increase above a baseline of room temperature, which implies an activation energy of about 51 kilo-Joules per mole. The implication of this activation energy is that the degradation products, e.g., carbon, created in even an exceedingly tiny fraction of the total flow in a high-shear viscous boundary layer can easily be a dominant source of particles smaller than three microns in size. Using the crude rule-of-thumb with a T_Bui_k of 200 degrees Celsius and a ¾„ of 400 degrees Celsius, the reaction rate could be approximately one million times higher at T_Max as compared to the reaction rate at 7_/¾¾, which would generate relative large numbers of small particles with the potential to clog a high-efficiency nanofiber fuel filter.

[0036] Applicant recognized that it was necessary to take steps to locate and reduce the relative high localized heating described hereinabove in order to reduce formation of particulates smaller than three microns. Applicant performed various tests and analyses to identify areas where flowing fuel might be subjected to high temperature in an internal combustion engine and determined that certain specific locations in a fuel injector, such as a fuel injector 10 in FIG. 1 , are susceptible to such localized heating. The applicant then developed designs that includes geometry to spread the shear, reducing the throttling effect to combat high temperatures to provide a ratio of T_Maxl Buik as close to unity or one as possible to reduce the thermal degradation rate of fuel and thus formation of particulates smaller than three microns, decreasing the rate at which high-efficiency fuel filters clog with such small particles and increasing the effectiveness of such filters. Such designs focus on reducing abrupt velocity changes and gradients and the corresponding shear rates that lead to a ratio of T T that is much greater than one. By increasing the effectiveness of such fuel filters, the wear rates in a fuel system of an internal combustion engine may be decreased, thus increasing the reliability and life of a fuel system of an internal combustion engine.

[0037] Referring to FIGS. 1 and 2, a conventional internal engine is shown and generally indicated as 12. Engine 12 includes an engine body 14, which includes an engine block (not shown) and a cylinder head 16 attached to the engine block. Engine 12 also includes a fuel system that includes one or more fuel injectors 10, a fuel pump, a fuel accumulator, valves, and other elements (not shown) that connect to fuel injector 10. Fuel injector 10 is adapted to inject metered quantities of fuel into a combustion chamber of internal combustion engine 12 in timed relation to the reciprocation of an engine piston.

[0038] Engine body 14 includes a mounting bore 18, one or more cylinders (not shown), one or more pistons (not shown), one or more combustion chambers (not shown), and an engine drain circuit. Mounting bore 18 is formed by an inner wall or surface 22, sized to receive fuel injector 10. Each cylinder may include a cylinder liner positioned therein, and one piston is positioned for reciprocal motion in each cylinder. Each combustion chamber is formed by cylinder head 16, a piston, and the exposed portion of the cylinder that extends between a piston and cylinder head 16. Throughout this specification, inwardly and distally are longitudinally in the direction of a combustion chamber, and outwardly and proximally are longitudinally away from the direction of a combustion chamber.

[0039] Fuel injector 10 includes an injector body 24, which further includes an injection control valve assembly 26, a drain circuit 28, and a longitudinal axis 30. The structural and functional details of fuel injector 10 may be similar to those are disclosed in U.S. Patent Nos. 5,676,114, 6,155,508, and 7,156,368, the entire contents of which are hereby incorporated by reference. Injector body 24 may include an outer housing 32, which secures injection control valve assembly 26, a nozzle module (not shown), and other elements of fuel injector 10 in a fixed relationship, and an upper body or barrel portion 34.

[0040] In addition to locating the elements of fuel injector 10, outer housing 32 includes an interior surface 36 and an exterior surface 38. Interior surface 36 forms an injector cavity 42 in which is positioned a plunger, nozzle valve element, or needle valve element 44 for reciprocal movement along longitudinal axis 30. Upper body or barrel portion 34 includes a valve cavity 40 for receiving injection control valve assembly 26. Injection control valve assembly 26 is adapted to receive a control signal from a controller (not shown) to energize, which causes nozzle valve element 44 to permit fuel flow from injector cavity 42 in the combustion chamber.

[0041] Injector body 24 may also include a nozzle housing (not shown) either attached or connected to outer housing 32. The nozzle housing forms a portion of injector cavity 42. The nozzle housing or outer housing 32 includes one or more injector orifices (not shown) positioned at a distal end of the nozzle housing. The injector orifice(s) communicate with one end of injector cavity 42 to discharge fuel from injector cavity 42 into the combustion chamber. Nozzle valve element 44 is movable between an open position in which fuel may flow through the injector orifice(s) into the combustion chamber and a closed position in which fuel flow through the injector orifice(s) is blocked.

[0042] Fuel injector 10 also includes a floating sleeve 46 positioned in injector cavity 42, and floating sleeve 46 includes a nozzle element seal, end portion, or proximal cap 48. A control volume 50 is formed between a proximal end portion 52 of nozzle valve element 44 and an interior surface 54 of proximal cap 48 when nozzle valve element 44 and proximal cap 48 are mounted in injector cavity 42. Proximal cap 48 includes at least one proximal cap passage or outlet 56, which may also be referred to as a longitudinal cap passage, having an outlet axis 53 that is illustratively collinear with longitudinal axis 30 and extends longitudinally through proximal cap 48. Proximal cap 48 also includes at least one transverse cap passage or inlet orifice 58 having an inlet or transverse cap passage axis 59. Control volume 50 receives high- pressure fuel from injector cavity 42 by way of transverse cap passages 58.

[0043] The pressure of fuel in control volume 50 determines whether nozzle valve element 44 is in an open position or a closed position, which is further determined by injection control valve assembly 26, described in more detail hereinbelow. When nozzle valve element 44 is positioned in injector cavity 42, proximal cap 48 is positioned longitudinally between nozzle valve element 44 and injection control valve assembly 26.

[0044] Injection control valve assembly 26 is positioned along drain circuit 28 in valve cavity 40 and includes a fuel injector control valve 60 positioned within valve cavity 40. Injector control valve 60 includes a control valve member 62, an actuator 64 positioned in valve cavity 40 to cause movement of control valve member 62 between an open and a closed position, and a control or pilot valve seat 80 on which is formed a valve seat surface 82. Pilot valve seat 80 further includes a longitudinal valve passage 84 that is in fluid communication with longitudinal cap passage 56 and with valve cavity 40. Control valve member 62 is positioned in valve cavity 40 to move reciprocally between the open position permitting flow through drain circuit 28 and a closed position against valve seat surface 82, blocking flow through drain circuit 28. Actuator 64 includes a solenoid assembly 66 that includes a stator housing 68 having a first end 70 and a second end 72, a stator core 74, an annular coil assembly 76 positioned circumferentially in and around stator core 74, and an armature 78 operably connected to control valve member 62.

[0045] Drain circuit 28 extends from control volume 50 through injection control valve assembly 26, through upper body or barrel portion 34, to an engine drain passage (not shown). More specifically, drain circuit 28 includes longitudinal cap passage 56, longitudinal valve passage 84, valve seat surface 82, valve cavity 40, and a passage connecting valve cavity 40 with an engine drain circuit (not shown). When injection control valve assembly 26 is energized by an engine control system (not shown), solenoid assembly 66 is operable to move armature 78 longitudinally toward stator core 74. Movement of armature 78 causes control valve member 62 to move longitudinally away from valve seat surface 82, which causes drain circuit 28 to be connected with control volume 50. Fuel is immediately able to flow outwardly through longitudinal cap passage 56 and longitudinal valve passage 84. Fuel then flows between control valve member 62 and valve seat surface 82 into valve cavity 40. The fuel in valve cavity 40 continues to flow through other passages (not shown) to an exterior of fuel injector 10 and into an engine drain circuit.

[0046] With connection of control volume 50 to engine drain circuit 28, fuel pressure in control volume 50 is significantly reduced in comparison to fuel pressure in injector cavity 42. The pressure on the distal end of nozzle valve element 44 is significantly greater than the pressure on the proximal end of nozzle valve element 44, forcing nozzle valve element 44 longitudinally away from the injector orifices, permitting high-pressure fuel to flow from injector cavity 42 into the combustion chamber and starting an injection event. When solenoid assembly 66 is de-energized, control valve member 62 is biased by springs, such as a valve spring 88, to cause fuel injector control valve 60 to close. When injector control valve 60 is closed, pressure builds in control volume 50, causing, in combination with a nozzle element bias spring 86, nozzle valve element 44 to move longitudinally toward the injector orifice(s), closing or blocking the injector orifice(s), which stops fuel flow to the combustion chamber and ends the injection event.

[0047] Referring now to FIGS. 3-7, various portions of the aforementioned components or elements are shown analytically in terms of shear zones or temperature zones. In FIG. 3, several high shear zones are identified with high-pressure fuel flow during a fuel injection event. Transverse cap passage 58 includes an entrance aperture or orifice 90 that has high shear zones 92 as fuel enters entrance aperture 90. The high velocity fuel flow or fuel jet through transverse cap passage 58 impinges upon or strikes a side wall 94 of nozzle valve element 44, causing a side wall high shear zone 96. Fuel then spreads out and flows longitudinally toward an entrance 98 to longitudinal cap passage 56. As fuel flows from a control volume 100 located between nozzle valve element 44 and proximal interior surface 54 into entrance 98, a shear zone 102 is created between a float pad 110 formed at the proximal end of nozzle valve element 44 and a facing proximal internal surface 54 of proximal cap 48 just prior to the location where fuel flows into longitudinal cap passage entrance 98.

[0048] Turning now to FIG. 4, when control valve member 62 lifts from valve seat surface 82, high-pressure fuel flow between control valve member 62 and valve seat surface 82 creates high shear zones 104. It should be understood that the hereinabove shear zones may be annular when such zones exist in areas where such zones are created adjacent to circular features. Thus, the representations in FIGS. 3 and 4 show but a portion of the shear zones.

[0049] The high shear zones shown in FIGS. 3 and 4 lead to localized high temperatures in the high-pressure fuel flow, as shown in FIGS. 5-7. In FIG. 5, the temperature on the surface adjacent to side wall high shear zone 96 and the surface adjacent to entrance aperture 90 is shown. The peak temperature on the surfaces adjacent to side wall high shear zone 96 and on the surfaces surrounding entrance aperture 90 may be as high as 400 degrees Celsius during a fuel injection event. In FIG. 6, shear zones on the surfaces that form longitudinal cap passage 56 are shown. Shear zone 102 exists at the surface surrounding longitudinal cap passage entrance 98, and has peak temperatures over 200 degrees Celsius. Another, smaller shear zone 106, which may also be referred to as a longitudinal cap passage shear zone, exists within longitudinal cap passage 56 at a transition corner 108 where the diameter decreases from the diameter at longitudinal cap passage entrance 98 to the smallest diameter of longitudinal cap passage 56. The temperature on transition corner 108 adjacent to longitudinal cap passage shear zone 106 may be as high as 400 degrees Celsius. Referring now to FIG. 7, the temperature on the surface of control valve member 62 and valve seat surface 82 adjacent to valve seat surface shear zone 104 may be as high as 300 degrees Celsius.

[0050] As noted hereinabove, the high temperatures that exist in the high shear zones leads to particulate formation in the fuel flowing through the drain circuit. This fuel returns to the fuel tank (not shown), which is then filtered before returning to fuel injector 10. One function of a high-efficiency fuel filter, such as a fuel filter containing a nanofiber filtration medium, is to remove particulates formed in the hereinabove described high shear zones.

However, because the quantity of such particles can be significant, a high-efficiency fuel filter can reach capacity because of the small, e.g., less than three micron, particles formed in the high shear zones.

[0051] FIGS. 8-22 describe features that reduce or eliminate the high shear zones described hereinabove to decrease or eliminate the formation of small particles such as those less than three microns in size. Multiple features may be used in combination to decrease shear across the nozzle valve element. In general, fuel traveling from a transverse cap passage along an inlet axis may avoid colliding with a perpendicular surface of the nozzle valve element, and may instead spread gradually across the nozzle valve element.

[0052] In certain embodiments, the feature may include a guiding surface on the nozzle valve element that at least initially guides fuel traveling from a transverse cap passage along an inlet axis over the nozzle valve element in a manner that decreases shear across the nozzle valve element. As used herein, the "guiding surface" may be the surface of the nozzle valve element that makes the closest approach to the inlet axis or first intersects the inlet axis. In this embodiment, a line containing the guiding surface may be arranged parallel or oblique to the inlet axis. As used herein, the line containing the guiding surface is arranged "oblique" to the inlet axis if the two lines are arranged in the same plane and intersect at an oblique angle other than 90 degrees, such that the line containing the guiding surface is not perpendicular to the inlet axis. For example, the line containing the guiding surface may intersect the inlet axis at an oblique angle of 1-89 degrees or 91-179 degrees, more specifically 1-45 degrees or 135-179 degrees, such as about 1, 5, 10, 15, 20, 25, 30, 35, 40, or 45 degrees or 135, 140, 145, 150, 155, 160, 165, 170, 175, or 179 degrees.

[0053] In other embodiments, the feature may include a transverse cap passage having an inlet axis that is arranged to direct fuel over or around the nozzle valve element in a manner that decreases shear across the nozzle valve element. In this embodiment, the inlet axis may be oblique or skewed relative to the longitudinal axis. As discussed above, the inlet axis is

"oblique" relative to the longitudinal axis if the two lines are arranged in the same plane and intersect at an oblique angle other than 90 degrees. Also, the inlet axis is "skewed" relative to the longitudinal axis if the two lines are arranged in different planes.

[0054] Turning now to FIG. 8, a fuel injector 120 includes a first exemplary embodiment of the present disclosure that reduces the shear zone due to impingement of high-pressure fuel against an exterior surface of a nozzle valve element 124. Fuel injector 120 accomplishes this improvement by including a concave guiding surface 127 that forms an annular "U"-shaped groove or indentation 122 in an outside diameter of a nozzle valve element 124. The result of the inclusion of groove 122 is that when nozzle valve element 124 is in the position shown in FIG. 8, which is the position nozzle valve element 124 attains during a fuel injection event, fuel flow from transverse cap passage 58 along an inlet axis 129 first enters groove 122 oblique or parallel to a line containing at least portion of the guiding surface 127, which spreads the fuel flow over a larger area and reduces the amount of shear to which the flowing fuel is subjected. In the illustrated embodiment of FIG. 8, a line containing guiding surface 127 is arranged at an oblique angle of about 20 degrees in relation to inlet axis 129 and at an oblique angle of about 110 degrees in relation to longitudinal axis 30, and inlet axis 129 is arranged perpendicular in relation to the longitudinal axis 30. The flowing fuel, shown as stylized fuel flow 126, follows the curvature of groove 122, turning the flow of fuel approximately 270 degrees from the direction of transverse cap passage 58 along inlet axis 129 to a direction that is toward the proximal end of fuel injector 120 along longitudinal axis 30. While the entrance of flowing fuel along the inlet axis 129 into the indentation 122 is shown on a "top" side of groove 122, the entrance may also be on an opposite, "bottom" side of groove 122.

[0055] Turning to FIG. 9, a fuel injector 130 in accordance with a second exemplary embodiment and a third exemplary embodiment of the present disclosure is shown that includes a nozzle element seal or proximal cap 132 and a nozzle valve element 134. Proximal cap 132 includes a transverse cap passage 136 having an entrance aperture or orifice 138. Proximal cap 132 further includes a longitudinal cap passage 140 including a transition region 142 positioned between a longitudinal cap passage entrance 144, which has a first diameter, and a smaller diameter a spaced distance along longitudinal cap passage 140 from longitudinal cap passage entrance 144. Nozzle valve element 134 also includes a raised "float pad" region 146 that is larger than existing float pads. In the second exemplary embodiment, the surface that forms entrance aperture or orifice 138 includes a radius versus a sharp edge, such as that shown for the surface that forms entrance aperture 90 in FIG. 3. The radius on the surface that forms entrance aperture or orifice 138 significantly reduces the shear zone on the surface that forms entrance aperture or orifice 138, decreasing the temperature on that surface. In the third exemplary embodiment, the surface that forms transition region 142 includes a larger radius that significantly decreases the shear zone on that surface as compared to transition corner 108 adjacent to longitudinal passage high shear zone 106 shown in FIG. 6. Larger float pad 146 similarly decreases the amount of shear between float pad 146 and an interior surface of proximal cap 132 as compared to shear zone 102 shown in FIG. 6. Larger float pad 146 may be included as a part of the third exemplary embodiment or may be a separate embodiment.

[0056] FIGS. 10-12 show a fuel injector 150 in accordance with a fourth exemplary embodiment of the present disclosure that includes a nozzle element seal or proximal cap 152, a nozzle valve element 154, and a longitudinal axis 158. Proximal cap 152 includes a transverse cap passage 156 having an inlet axis 160. Nozzle valve element 154 has a first diameter 162 and includes a guiding surface 157 that is formed along a proximal edge of nozzle valve element 154 in an annular concave recessed portion 164 of nozzle valve element 154, which has a smaller diameter than the first diameter 162 and forms a swirl cavity 168 around nozzle valve element 154. . As shown in FIG. 12, a line containing guiding surface 157 and inlet axis 160 are both skewed in relation to longitudinal axis 158. In FIG. 12, inlet axis 160 and longitudinal axis 158 are arranged in such a way that the inlet axis 160, if on the same plane as longitudinal axis 158, would be perpendicular to longitudinal axis 158, but inlet axis 160 is spaced a perpendicular distance 166 apart from longitudinal axis 158 at the closest approach of inlet axis 160 to longitudinal axis 158. Fuel flow from transverse cap passage 156 along inlet axis 160 is configured to be oblique or parallel, and in certain embodiments tangential, to a line containing guiding surface 157, as shown in FIG. 12, spreading the flow of fuel over a relatively large area when the high-pressure fuel impinges on the guiding surface 157 of nozzle valve element 154, decreasing the amount of shear on the flowing fuel.

[0057] FIGS. 13 and 14 show a fuel injector 170 in accordance with a fifth exemplary embodiment of the present disclosure that includes a nozzle element seal or proximal cap 172, a nozzle valve element 174, and longitudinal axis 178. Proximal cap 172 includes a transverse cap passage 176 having an inlet axis 180. Nozzle valve element 174 includes a convex guiding surface 177 formed along a proximal edge of nozzle valve element 174 near a discrete and concave recessed portion 184 in nozzle valve element 154. In FIG. 13, inlet axis 180 intersects longitudinal axis 178 at an oblique angle 182 of about 60 degrees, while a line containing at least a portion of guiding surface 177 also intersects longitudinal axis 178 at an oblique angle. Inlet axis 180 also passes approximately parallel or tangential to a line containing guiding surface 177, spreading the flow of fuel over a relatively large area when the high-pressure fuel impinges on guiding surface 177 of nozzle valve element 174, decreasing the amount of shear on the flowing fuel.

[0058] FIG. 15 shows a nozzle element seal or proximal cap 190 in accordance with a sixth embodiment of the present disclosure. Proximal cap 190 includes one or more transverse inlet passages 192 each having an inlet axis 199 that is skewed in relation to longitudinal axis 198 of proximal cap 190. In FIG. 15, inlet passages 192 are skewed such that each inlet axis 199 would be perpendicular to the longitudinal axis 198 if both axes were on the same plane, but each inlet axis 199 is spaced apart a distance 200 from longitudinal axis 198. Proximal cap 190 further includes one or more transverse outlet passages 196 having outlet axis 193 that is also skewed in relation to longitudinal axis 198. Outlet passage 196 is also skewed such that the outlet axis would be perpendicular to longitudinal axis 198, but is located a spaced distance 202 from longitudinal axis 198 that may be less than spaced distance 200. The benefit of skewed input passages 192 is that fluid flow that impinges a surface 194 of proximal cap 190 is spread over a large area, decreasing the amount of shear in the high-pressure fuel. The benefit of tangential transverse outlets 196 is that the transition from the circular surface 194 of proximal cap 190 to tangential transverse outlet 196 decreases the shear on the flowing fuel as the fuel flows into tangential outlet 196 from an interior volume or chamber 204 of proximal cap 190. A nozzle valve element (not shown) can be at least partially positioned within chamber 204 so that a lift of the nozzle valve element can change the volume of chamber 204. Flow entering through inlets 192 can be introduced parallel or tangentially to a guiding surface of the nozzle valve element in this embodiment and flow around the nozzle valve element towards the one or more outlets 196. In some embodiments, the flow over the top of the nozzle valve element can be substantially slower than flow along the circumference of the nozzle valve element.

[0059] FIG. 16 shows a nozzle valve element 210 in accordance with a seventh exemplary embodiment of the present disclosure. Nozzle valve element 210 includes a concave guiding surface 217, which forms a transverse groove or recess 212 that extends through the proximal end portion of the nozzle valve element 210 and through a longitudinal axis 214 of nozzle valve element 210. The illustrated nozzle valve element 210 may be used with a transverse cap passage (not shown) having an inlet axis (not shown) that intersects longitudinal axis 214 approximately perpendicularly, which is the case in many of the previous embodiments, excluding the embodiments of FIGS. 10-15. In this arrangement, the inlet axis would be aligned with the transverse groove 212 to direct fuel into the transverse groove 212 and provide for an extended zone for the high-pressure fuel flow to enter a control volume, thus reducing the shear on the high-pressure fuel. Techniques for alignment are described further hereinbelow. In this arrangement, a line containing at least a portion of the guiding surface 217 may be parallel or oblique in relation to the inlet axis (not shown) and perpendicular or oblique in relation to the longitudinal axis 214.

[0060] FIG. 17 shows a nozzle valve element 220 in accordance with an eighth exemplary embodiment of the present disclosure. Nozzle valve element 220 includes a guiding surface 227 which forms a transverse passage or hollow recess 222 that extends through an interior region of nozzle valve element 220 in a direction perpendicular to a longitudinal axis 226. The illustrative transverse passage 222 intersects longitudinal axis 226 and continues entirely through the interior region of nozzle valve element 220. A longitudinal passage or hollow recess 224 extends from transverse passage 222 to a proximal end surface 228 of nozzle valve element 220. As with the embodiment of FIG. 16, transverse passage 222 of FIG. 17 may be aligned with an inlet axis of a transverse cap passage (not shown) such that fuel enters the transverse passage 222 along the inlet axis in a direction parallel to guiding surface 227 and perpendicular to longitudinal axis 226.

[0061] FIG. 18 shows a nozzle valve element 240 in accordance with a ninth exemplary embodiment of the present disclosure. Nozzle valve element 240 includes a guiding surface 247 which forms a transverse passage or hollow recess 242 that extends through an interior region of nozzle valve element 240 in a direction perpendicular to longitudinal axis 244. As with the embodiments of FIGS. 16 and 17, transverse passage 242 may be aligned with an inlet axis of a transverse cap passage (not shown)such that fuel enters the transverse passage 242 along the inlet axis in a direction parallel to guiding surface 247 and perpendicular to longitudinal axis 244. Such alignment may be accomplished through an alignment feature, such as a physical mating element 246 on an outer housing or nozzle housing that keys or mates with nozzle valve element 240 and/or a permanent magnet between the housing and nozzle valve element 240, for example.

[0062] FIGS. 19-21 show a fuel injector 250 in accordance with a tenth exemplary embodiment of the present disclosure. FIG. 19 provides a visual comparison with fuel injector 250 on the left and a prior art fuel injector on the right. Fuel injector 250 includes nozzle valve element 252 and proximal cap 254. This embodiment features a transverse cap passage 266 having an inlet axis 269, which is arranged perpendicular in relation to longitudinal axis 261 of the nozzle valve element 252. Compared to the prior art fuel injector on the right, inlet axis 269 is moved longitudinally "higher" or in a proximal direction to be closer to an internal surface 268 of a nozzle element seal or proximal cap 254 in FIG. 19. Also, nozzle valve element 252 includes a chamfered, conical, or beveled proximal guiding surface 267 that leads to a proximal tip or peak 262 on nozzle valve element 252 to provide a decreased shear on the fuel that flows between nozzle valve element 252 and proximal cap 254 in a control volume 264. A line containing at least a portion of guiding surface 267 is oblique relative to both the inlet axis 269 and the longitudinal axis 261 in FIG. 19.

[0063] FIG. 20 shows nozzle valve element 252 in a down or closed position, and FIG.

21 shows nozzle valve element 252 in a raised or open position. Proximal cap 254 includes longitudinal cap passage 256 formed therein. Proximal cap 254 further includes aperture 258 formed in proximal cap 254 that forms the beginning of longitudinal cap passage 256. In order to minimize shear as high-pressure fuel flows from a control volume 260 into longitudinal cap passage 256, aperture 258 may have a large radius relative to longitudinal cap passage 256. For example, the diameter of aperture 258 may be 0.63 millimeters and the radius of the edge of aperture 258 may be 0.25 millimeters. This embodiment may also include a shortened nozzle valve element 252 and an increase maximum lift, so that hovering is not controlled by the throttling of the fuel on the face of the nozzle valve element 252 in order to eliminate the hovering face viscous shear fuel heating. Hydraulics in the lower plunger (not shown) and the selection of the size or diameter of transverse cap passage 266 and longitudinal cap passage 256 will control the amount of nozzle valve element 252 lift instead of the geometry between the tip or peak 262 and a nozzle valve element 252 stop (not shown).

[0064] FIG. 22 shows a schematic of an internal combustion engine 270 in accordance with an eleventh embodiment of the present disclosure. Internal combustion engine 270 includes a drain fuel passage 272 and a coolant passage 274. A capillary action heat pipe or heat exchanger 276 is positioned in drain fuel passage 272 and in coolant passage 274 to transfer heat from drain fuel passage 272 into coolant passage 274. Heat pipe 276 is preferably positioned as close to the hottest portion of the drain circuit as possible, in view of space available to install such a heat pipe. The illustrative heat pipe 276 of FIG. 22 includes an outer casing 280, an intermediate wick 282, and an inner vapour cavity 284.

[0065] While this invention has been described as having exemplary designs, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A fuel injector for delivering fuel to a combustion chamber of an engine, the fuel injector comprising:

an injector body defining an injector cavity;

a control volume having at least one inlet and at least one outlet, the at least one inlet arranged in fluid communication with the control volume to deliver fuel to the control volume along an inlet axis, the at least one outlet arranged in fluid communication with a drain circuit to drain fuel from the control volume along an outlet axis; and

a valve moveable in the injector cavity between an open position, in which fuel from the injector cavity is delivered to the combustion chamber, and a closed position, the valve having a longitudinal axis and a guiding surface that receives fuel from the at least one inlet along the inlet axis, wherein a line containing at least part of the guiding surface is arranged one of parallel and oblique to the inlet axis.

2. The fuel injector of claim 1, wherein the valve lacks an intervening surface between the at least one inlet and the guiding surface that is intersected by the inlet axis and arranged perpendicular to the inlet axis.

3. The fuel injector of claim 1, wherein the combustion chamber is located adjacent to a distal end of the valve and the control volume is located adjacent to a proximal end of the valve.

4. The fuel injector of claim 1, wherein the inlet axis is tangential to the guiding surface of the valve.

5. The fuel injector of claim 1, wherein the guiding surface forms a hollow recess that extends through an interior region of the valve.

6. The fuel injector of claim 5, wherein the hollow recess is in fluid communication with the control volume.

7. The fuel injector of claim 5, further comprising at least one alignment feature configured to align the hollow recess with the at least one inlet.

8. The fuel injector of claim 3, wherein the guiding surface is a beveled surface on the proximal end of the valve.

9. The fuel injector of claim 3, wherein the guiding surface forms an edge of the proximal end of the valve, wherein at least part of the edge is concave.

10. The fuel injector of claim 3, wherein the guiding surface forms a recess in the proximal end of the valve, wherein the recess runs along the proximal end.

11. The fuel injector of claim 1 , wherein the guiding surface forms an indentation in the valve, wherein the indentation is adjacent to the at least one inlet.

12. The fuel injector of claim 1, wherein the inlet axis is one of oblique and skewed in relation to the longitudinal axis.

13. The fuel injector of claim 1, wherein the outlet axis is one of parallel and skewed in relation to the longitudinal axis.

14. A fuel injector for delivering fuel to a combustion chamber of an engine, the fuel injector comprising:

an injector body defining an injector cavity;

a control volume having at least one inlet arranged along an inlet axis and at least one outlet arranged along an outlet axis, wherein the inlet axis is one of oblique and skewed in relation to a longitudinal axis; and

a valve moveable in the injector cavity along the longitudinal axis in response to a pressure in the control volume between an open position, in which fuel from the injector cavity is delivered to the combustion chamber, and a closed position.

15. The fuel injector of claim 14, wherein the outlet axis is one of parallel and skewed in relation to the longitudinal axis.

16. The fuel injector of claim 14, wherein the valve further comprises a guiding surface that receives fuel from the at least one inlet along the inlet axis, wherein a line containing at least part of the guiding surface is arranged one of parallel and oblique to the inlet axis to decrease shear across the valve.

17. The fuel injector of claim 14, further comprising a heat exchanger between the drain circuit and a coolant line to transfer heat to the coolant line.

18. A fuel injector for delivering fuel to a combustion chamber of an engine, the fuel injector comprising:

an injector body defining an injector cavity;

a control volume having at least one inlet arranged along an inlet axis and at least one outlet arranged along an outlet axis; and

a valve moveable in the injector cavity along a longitudinal axis in response to a pressure in the control volume between an open position, in which fuel from the injector cavity is delivered to the combustion chamber, and a closed position, the valve having a guiding surface that receives fuel from the at least one inlet, wherein a line containing at least part of the guiding surface is arranged one of perpendicular, oblique, and skewed to the longitudinal axis.

19. The fuel injector of claim 18, wherein the guiding surface extends through the longitudinal axis.

20. The fuel injector of claim 18, wherein the guiding surface is concave.