Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/18—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for
  • F02M61/1806—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for characterised by the arrangement of discharge orifices, e.g. orientation or size
  • F02M61/1846—Dimensional characteristics of discharge orifices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/18—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for
  • F02M61/1806—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for characterised by the arrangement of discharge orifices, e.g. orientation or size
  • F02M61/182—Discharge orifices being situated in different transversal planes with respect to valve member direction of movement
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/18—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for
  • F02M61/1806—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for characterised by the arrangement of discharge orifices, e.g. orientation or size
  • F02M61/184—Discharge orifices having non circular sections

Definitions

• the present invention relates to an injection nozzle.
• the present invention relates to the formation and profile of an improved nozzle for the injection of a fluid from an internal nozzle volume into an external volume.
• the invention has particular application to fuel injection systems but may be applied to any device that utilises a nozzle arrangement to inject a fluid from a first volume to a second volume.
• fuel is typically injected from an injection nozzle which utilises multi-hole nozzle design in which each individual hole (nozzle outlet) has an internal geometry that has been precision manufactured from dedicated tooling.
• This internal hole geometry is defined and optimized in order to reach an efficient liquid fuel atomization allowing a rapid fuel and air mixture within the combustion chamber. Such optimisation leads to lower exhaust emissions, optimized combustion noise and lower fuel consumption.
• Djn and Dot/f are respectively the inlet and outlet nozzle orifice diameters given in microns ( ⁇ m).
• Q is the measured hole flow rate
• Pjn and Pout are respectively inlet and outlet hole pressure (fuel injection pressure and back pressure which could be combustion chamber gas pressure)
• S O ut is the hole outlet section
• p is the liquid fuel density at the inlet hole pressure and temperature conditions.
• Cd values for automotive applications typically are measured during manufacture as being between 0.80 and 0.88 (for nozzle upstream and downstream pressures of 101 bar and 1 bar respectively) and it is noted that current, known hole designs do not provide for nozzle hole discharge coefficients of more than 0.88.
• a further factor in the design of nozzle holes is the accuracy to which the hole needs to be manufactured in order for the nozzle hole to operate effectively.
• holes designed with kf ac tor values of between 1 and 2.5 are sensitive to the length of the hole such that variations in hole length can potentially adversely affect the performance of the injection nozzle.
• the machining of nozzle holes in current injection nozzles requires a high degree of accuracy which results in lengthy and costly manufacturing processes. It is therefore an object of the present invention to provide an injection nozzle that overcomes or substantially mitigates the above-mentioned problems.
• an injection nozzle for injecting a fluid
• the injection nozzle comprising: a nozzle body and a nozzle hole defining a flow passage for fluid, the flow passage comprising passage walls and the nozzle hole having an inlet in fluid communication via the flow passage with an outlet, wherein, the inlet is larger than the outlet and for at least one section through the inlet and outlet along the flow passage the nozzle hole is defined, for all distances x within a substantial length of the flow passage, by the condition: dS
• the present invention provides for an injection nozzle with a tapered injection hole (the inlet being larger than the outlet) that has a far greater level of tapering than in conventional nozzle designs.
• i.e. magnitude of the rate of change of wall separation (opposing internal hole walls) with distance
• the magnitude of the condition I — I (or ) at any given distance x along a substantial portion of the nozzle hole is greater than 45 microns per millimetre.
• the profile of the passage walls within the section may be linear.
• the profile of the walls may be parabolic or otherwise curved or a mixture of sections of curved and linear profile.
• injection nozzles in accordance with embodiments of the present invention demonstrate improved discharge coefficients, better fuel atomisation performance and improved pressure and velocity flows within the hole itself. It is also noted that in traditional hole designs which incorporate hole rounding the local wall separation values may exceed the wall condition stated above. However, this occurs over an extremely localised part of the traditional nozzle hole and is in contrast to the present invention in which the wall condition holds along a substantial length of the hole's length.
• An injection nozzle in accordance with an embodiment of the present invention may be used in a fuel injection system such as those described in the Applicant's patent applications EP0352926, EP1669157, EP1669158, EP1081374, EP1180596, EP1344931 , EP1496246, EP1498602, EP1522721 , EP1553287, EP1645749, EP17031 17, EP1744051 and EP1643117.
• the present invention is applicable to any fluid delivery system where a fluid is injected from a first volume to a second volume.
• the nozzle hole is defined, at any given x along a substantial length of the
• a nozzle hole satisfying this condition exhibits around a 5% performance increase based on an analysis of the discharge coefficient Cd compared to known tapered injection holes.
• the nozzle hole is defined, at any given x along a substantial length of the
• the improved performance of nozzle holes in accordance with embodiments of the present invention is observed when the wall condition holds for at least 40% of the length of the hole. Preferably, the condition should hold for the final 60% to 90% of the length of the hole.
• the hole inlet and outlet define a nozzle hole axis then the at least one section may be taken through the axis.
• the wall separation condition may be satisfied for all sections through the axis regardless of their orientation about the axis.
• the cross section of the nozzle hole may be circular or elliptical. Where the cross section is elliptical then sections taken through the hole axis and either the major or minor axes of the ellipse may satisfy the wall separation condition.
• the cross section of the nozzle hole may be triangular, rectangular, square or any other polygon.
• the nozzle body may be provided with a bore which is in communication with a source of fluid (e.g. pressurised fuel) and the injection nozzle may be arranged to inject fluid from the bore through the nozzle hole to a volume outside the nozzle, e.g. a combustion volume of an engine system.
• a source of fluid e.g. pressurised fuel
• the injection nozzle may be arranged to inject fluid from the bore through the nozzle hole to a volume outside the nozzle, e.g. a combustion volume of an engine system.
• the hole inlet opens into the bore and the hole outlet opens into the volume outside the injection nozzle.
• the injection nozzle comprises a plurality of nozzle holes in accordance with the nozzle hole described above and this plurality of holes may be arranged in one or more rows of holes such as those described in the Applicant's patent applications EP1645749, EP1703117, EP1744051 and EP1643117.
• the passage walls of the flow passage within the at least one section may comprise linear and non-linear arrangements, e.g. the walls may form a straight line taper, a parabola, a mixture of linear and non-linear profiles etc.
• the invention extends to a fuel injector for an internal combustion engine comprising an injection nozzle according to the first aspect of the present invention.
• FIGS 1 and 2 show sections through known fuel injector arrangements
• Figure 3 shows a section through a typical injection nozzle outlet hole
• Figures 4 and 5 show known injection hole arrangements in an injection nozzle;
• Figure 6 shows sections through an injection nozzle outlet hole in accordance with an embodiment of the present invention
• Figure 7 shows cross sections through injection nozzle outlet holes that may be used in conjunction with an embodiment of the present invention
• Figure 8 shows a plot of discharge coefficient Cd versus hole inlet radius
• Figures 9a to 9j show the effects of nozzle hole taper on internal hole fluid pressure and velocity
• Figure 10a is a plot of internal nozzle hole pressure with distance from the hole inlet
• Figure 10b is a plot of internal fluid velocity; with distance from the hole inlet;
• Figure 10c is a plot of internal fluid velocity with distance from the hole axis
• Figure 1 1a shows a plot of discharge coefficient improvement versus internal hole geometry for two nozzle holes of different lengths
• Figure 11 b shows a plot of discharge coefficient versus internal hole geometry for a first nozzle hole having no inlet rounding and for a second nozzle hole having inlet rounding;
• Figures 12a to 12f show a comparison in internal pressure and velocity fields for known hole geometries and hole geometries in accordance with embodiments of the present invention
• Figures 13a to 13d show the effects of increasing hole taper on fluid exit velocity for two holes of different lengths
• Figures 14a to 14f show the effect of hole taper on spray penetration into the combustion volume
• Figure 15 shows a plot of emission and particulate levels for a known hole geometry and a hole geometry in accordance with embodiments of the present invention
• Figure 16 shows a comparison of CO 2 emission levels for a known hole geometry and a hole geometry in accordance with embodiments of the present invention
• Figures 17a to 17d show plots of fuel consumption, filter smoke number (FSN), boost pressure and exhaust temperature for a known hole geometry and a hole geometry in accordance with embodiments of the present invention.
• FSN filter smoke number
• the present invention is discussed in relation to its application to fuel injection nozzles. It is to be noted however that the present invention may be applied to any type of injection nozzle used to inject a fluid from a first volume into a second volume.
• the injection nozzle may be used to inject liquid fuel from a supply volume into a heating/combustion chamber in a domestic heating system.
• Other applications for the present invention include gasoline direct injection systems and furnaces.
• S relates to the separation of the walls of the injection nozzle within a section taken along the passage way formed by the injection hole and the expression is taken to mean that at any given point along the section (or at any given point along a substantial length of the hole length) the "gradient" of the wall separation will always exceed the stated value.
• a fuel injection nozzle 1 comprising an injection needle 3 located in a bore 5 of the nozzle body 7.
• the nozzle further comprises a feedhole 9 for the supply of fuel to a fuel gallery 11.
• the needle 3 is constrained to move by an upper guide 13 and lower guide 15.
• a series of injection holes 17 in the tip of the body 7 allow fuel to be injected from a nozzle sac 19 at the base of the injection nozzle 1 into a combustion space (not shown) when the needle lifts from its seat 21.
• Figure 3 shows a section through a nozzle hole. It is noted that the hole inlet 25 has a diameter D 1n and the hole outlet 27 a diameter D out and that D ⁇ n >D 0Ut .
• Figure 4 shows a section through an injection nozzle 1 with a single row of injection holes 17.
• Figure 5 shows an alternative arrangement in which there are two rows 33 of injection holes.
• Figure 6 shows a section through a nozzle hole 17 in accordance with an embodiment of the present invention.
• Three separate hole internal geometries are shown in Figure 6 (denoted by the three wall positions 31 a, 31 b and 31c). It is noted that in comparison to the injection nozzle of Figure 3, the hole inlet 25 in Figure 6 is significantly larger than the hole outlet 27.
• D(x) and it is noted that 45 ⁇ m/mm.
• the minimum value of ⁇ dD/dx ⁇ along the central hole axis is > 45 microns per millimetre. It is noted however that the gradient of ⁇ dD/dx ⁇ may vary along the axis such that the profile of the hole walls is non-linear.
• the cross sectional profile of the hole need not be circular.
• Non-circular hole cross sections may offer performance advantages, e.g. a rectangular hole design may inject a sheet of fuel into a combustion chamber which may be preferable in certain circumstances to a jet as would be injected with a circular hole.
• Figures 9a to 9j show the effects of nozzle hole taper on internal hole fluid pressure and velocity.
• three different hole geometries are tested and it can be seen from Figure 9a that the hole taper increases from left to right across the figure.
• the exit diameter of the hole is a constant.
• Figures 9c and 9d show the internal hole velocity field.
• Figure 9c shows the velocity field along the axis of the hole.
• Figure 9d shows the velocity field through a cross section through the hole outlet. It can be seen from Figures 9c and 9d that the maximum fluid velocity occurs at the hole inlet and that the maximum velocities concentrate around the hole axis. Towards the hole walls the velocity drops off towards lower values.
• Figure 9e shows the internal hole pressure field for this hole arrangement and it can be seen that the pressure drop in the hole is more progressive than for the cylindrical hole geometry.
• the velocity field for this arrangement is shown in Figure 9f and this shows a more gradual flow acceleration than for the cylindrical hole arrangement.
• the velocity field at the outlet is still concentrated about the hole axis.
• hole taper 90 ⁇ m/mm
• hole length 0.6mm in this example.
• the nozzle arrangement in accordance with an embodiment of the present invention now shows a gradual pressure drop along the entire length of the nozzle hole.
• the velocity of the fluid accelerates towards the hole outlet and from Figure 9j it can be seen that the boundary layer in the outlet cross section is significantly thinner than in the first two hole geometries. This has the effect that the average speed of fluid exiting the hole is increased in comparison to the first two hole geometries.
• Figures 10a to 10c show the data from Figure 9 in the form of graphical plots.
• Figure 10a confirms that the pressure drop along the hole axis is more gradual for the hole designed in accordance with an embodiment of the present invention (labelled "extreme design" in Figure 10a).
• Figure 10b shows that for the cylindrical and current reference hole geometries there is an initial acceleration at the hole inlet followed by an extended period of substantially constant fluid velocity. In the geometry in accordance with an embodiment of the present invention by contrast there is a gradual acceleration along the entire hole length.
• Figure 10c confirms that the fluid velocity at across the hole outlet is more uniform with a hole geometry in accordance with an embodiment of the present invention.
• Figure 11 a shows a plot of improvement in discharge coefficient (compared to a reference geometry) versus internal hole geometry. Two separate plots are shown, the first for a nozzle hole of length 0.6mm and the second for a nozzle hole of length 1.2mm.
• Figure 11 b a plot of discharge coefficient versus hole geometry for a hole without inlet rounding and a hole with inlet rounding. It can be seen that for lower hole taper values hole rounding is more significant than at higher hole taper values.
• Figures 12a to 12f show a comparison in internal pressure and velocity fields for known hole geometries and hole geometries in accordance with embodiments of the present invention.
• Figures 12a and 12b relate to a hole with a ⁇ dD/dx ⁇ value of approximately 30 ⁇ m/mm. It can be seen that there is a large and sudden pressure drop within the hole and the velocity field shows a large high velocity area which leads to high energy losses.
• Figures 12c to 12f show two hole geometries with a ⁇ dD/dx ⁇ value of 180 ⁇ m/mm.
• Figures 12c and 12d relate to a hole that has a linear wall profile along the hole axis.
• Figures 12e and 12f relate to a hole that is initially parabolic in profile and then subsequently linear in profile. In both cases the ⁇ dD/dx ⁇ value is equal to or exceeds 180 ⁇ m/mm along the entire section of the hole.
• Figures 12c to 12f exhibit similar behaviour indicating that the actual profile of the hole along the axis does not affect the performance of the nozzle. In both cases it can be seen that there is a smooth discharge area and the higher fluid velocities are located in the vicinity of the hole outlet.
• Figures 13a and 13b show the effect of increasing the taper of a hole of length 0.6mm from 0 to 50 ⁇ m/mm . It can be seen from Figure 13a that the velocity field within the hole is substantially "U" shaped. In Figure 13b by contrast the velocity field is more uniform at the hole outlet.
• Figures 13c and 13d show a similar velocity field plot for a hole of length 0.9mm. Again, the increased taper geometry shows an improvement in homogenous velocity at the exit of the hole.
• Figures 14a to 14f show the effect of hole taper on spray penetration into a combustion volume.
• Figures 14a to 14c show spray penetration at three different crank angles (6 degrees before top dead centre; 24 degrees after top dead centre; and, 44 degrees after top dead centre) for a cylindrical nozzle hole. It can be seen that the spray does not mix well, especially in Figure 14c where there is an area of unused air (circled in Figure 14c).
• Figures 14d to 14f show spray penetration at the same three crank angles for a nozzle hole with relatively high taper (in this example the taper is 50 ⁇ m/mm). It can be seen that compared to the hole design of Figures 14a to 14c there is an improvement in spay penetration and mixing.
• Figures 15, 16 and 17a to 17d show results that compare a reference hole and a high performance hole geometry. It is noted that in each case the reference nozzle comprises a design at the limit of current production values (e.g. 25 ⁇ m/mm) and the high performance nozzle comprises a hole taper of approximately 100 ⁇ m/mm. In all cases the nozzles are 6 hole nozzles.
• Figure 15 shows a comparison of particulate emissions and NOx emissions for a reference (i.e. known) nozzle design and a nozzle in accordance with embodiments of the present invention. It can be seen that the nozzle in accordance with embodiments of the present invention demonstrates a reduction of particulate emissions of upto 40% compared to the known design.
• Figure 16 shows that a reduction in CO2 emissions may also be achieved with nozzles in accordance with embodiments of the present invention in comparison to known nozzle hole geometries.
• Figurse 17a to 17d illustrate an assessment of a nozzle in accordance with embodiments of the present invention on a multi-cylinder engine operating at full load. At full load an improved global combustion efficiency was observed in comparison to known nozzle hole designs. At the same power point the engine comprising nozzle designs in accordance with the present invention demonstrated lower fuel consumption (approximately a 1.5 % improvement compared to the reference system); lower smoke emissions (-1 FSN) and a lower exhaust temperature (approximately 10 0 C compared to the reference system).
• the present invention may be implemented in a fuel injector, such as a common rail injector, in which a common supply (rail) delivers fuel to at least one injector of the engine, or may be implemented in an electronic unit injector (EUI) in which each injector of the engine is provided with its own dedicated pump and, hence, high pressure fuel supply.
• a fuel injector such as a common rail injector, in which a common supply (rail) delivers fuel to at least one injector of the engine
• EUI electronic unit injector
• the invention may also be implemented in a hybrid scheme, having dual common rail/EUI functionality.
• the invention may also be implemented in any system where a fluid is injected from a first volume to a second volume.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)

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Citations (6)

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• 2008
  • 2008-11-14 EP EP08169097A patent/EP2187043A1/en not_active Withdrawn
• 2009
  • 2009-11-12 EP EP09748812A patent/EP2347116A1/en not_active Withdrawn
  • 2009-11-12 WO PCT/EP2009/065070 patent/WO2010055103A1/en not_active Ceased
  • 2009-11-12 CN CN200980145359.5A patent/CN102216602B/zh active Active
  • 2009-11-12 US US13/128,946 patent/US20110215177A1/en not_active Abandoned
  • 2009-11-12 JP JP2011536016A patent/JP5319780B2/ja active Active

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