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Home , Fuel injection, Injector

(19) TZZ Z_ZZ_T

(11) EP 2 901 005 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.: of the grant of the patent: F02M 61/18 (2006.01) F02M 61/16 (2006.01) 15.11.2017 Bulletin 2017/46 F02B 23/06 (2006.01) F02B 25/08 (2006.01) F02B 75/28 (2006.01) F01B 7/14 (2006.01) (21) Application number: 13771692.4 (86) International application number: (22) Date of filing: 18.09.2013 PCT/US2013/060429

(87) International publication number: WO 2014/052126 (03.04.2014 Gazette 2014/14)

(54) INJECTION WITH SWIRL SPRAY PATTERNS IN OPPOSED- KRAFTSTOFFEINSPRITZUNG MIT WIRBELSPRÜHMUSTERN IN MOTOREN MIT ENTGEGENGESETZTEN KOLBEN INJECTION DE CARBURANT AVEC FORMES DE JET À TOURBILLON DANS DES MOTEURS À OPPOSÉS

(84) Designated Contracting States: • KLYZA, Clark, A. AL AT BE BG CH CY CZ DE DK EE ES FI FR GB San Diego, CA 92110 (US) GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO • REDON, Fabien, G. PL PT RO RS SE SI SK SM TR San Diego, CA 92124 (US)

(30) Priority: 25.09.2012 US 201261705561 P (74) Representative: Hanna Moore + Curley Garryard House (43) Date of publication of application: 25/26 Earlsfort Terrace 05.08.2015 Bulletin 2015/32 Dublin 2, D02 PX51 (IE)

(73) Proprietor: Achates Power, Inc. (56) References cited: San Diego, CA 92121 (US) JP-A- 2009 138 718 US-A- 5 042 441 US-A1- 2012 073 541 (72) Inventors: • ABANI, Neerav San Diego, CA 92130 (US)

Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 2 901 005 B1

Printed by Jouve, 75001 PARIS (FR) 1 EP 2 901 005 B1 2

Description [0006] To reduce the heat transfer across the pistons and walls, the spray angle of the multiple holes is re- RELATED APPLICATIONS duced. However, this leads to interaction of opposing spray plumes that concentrates fuel-vapor, entrained air, [0001] This application contains subject matter related 5 and some hot combustion products around the central to thesubject matter ofUS patentapplication 13/136,954, region of the . This inhibits air/fuel filed 08/15/2011, for " Spray Patterns for mixing, which results in increasing burn time. Opposed Piston Engines", and published as US[0007] To achieve both faster burn and reduced heat 2012/0073541 A1 on 03/29/2012. transfer to the and piston surfaces in op- [0002] This application contains subject matter related 10 posed piston operation, it is desirable that fuel injection to thesubject matter ofUS patentapplication 13/066,589, spray patterns minimize interaction of sprays (both from filed 04/18/2011, for "Combustion Chamber Construc- the same and opposite ), minimize the tions for Opposed Piston Engines", and published as US transfer of heat to the piston and cylinder bore surfaces, 2011/0271932 A1 on 11/10/2011. and encourage faster fuel/air mixing. 15 [0008] The present state of the art is also represented BACKGROUND by US 5,042,441 A and JP 2009/138718 A.

[0003] The field is fuel injection in opposed-piston en- SUMMARY gines in which a combustion chamber is defined between end surfaces of pistons disposed in opposition in the bore 20 [0009] The present invention provides a fuel injection of a ported cylinder. More particularly, the field includes system for an opposed-piston , and methods of direct fuel injection through the side of a cylinder into the operating same, in accordance with claims which follow. combustion chamber of an opposed-piston engine. Embodiments of the invention provide a fuel injection [0004] Fuel injection is an important component of spray pattern in which the individual spray plumes have combustion in diesel engines and is one of the processes 25 both radial and tangential components with respect to an that affect the efficiency with which the op- injection axis adds a swirl component to a spray pattern erates. It is desirable to manage fuel injection so as to of fuel directly injected into the combustion chamber of maximize the heat produced by combustion while - an opposed piston engine. As compared to a spray pat- mizing transfer of the heat of combustion to engine com- tern that has only a radial component, a spray pattern ponents such as cylinder bore and piston surfaces. An 30 with a swirl component minimizes the interaction of in- opposed piston engine typically employs two fuel injec- jected fuel sprays so as to provide a faster burn time. At tors that inject fuel in opposing directions along a diam- the same time, the addition of a tangential component eter of the cylinder. See, for example, the fuel injection provides additional distance for a spray plume to travel constructions described and illustrated in commonly- without encountering piston surfaces, the cylinder bore, owned US publication 2012/0073541 A1. 35 and/oropposing spray plumes, which reducesheat trans- [0005] A diesel injector typically includes a nozzle with fer across the piston and cylinder walls while promoting a plurality of holes through which fuel is injected. The faster air/fuel mixing. holes are arranged radially with respect to an axis of the [0010] In some aspects, the swirl spray pattern is di- injector. Injection through multiple holes produces a rectly injected into the combustion chamber through a spray pattern constituted of one or more plumes that40 cylinder sidewall. In some aspects, the swirl spray pattern project radially outward from the injector axis. Typically has an injection axis that is aligned with a longitudinal a plume is represented by a vector that forms an angle axis of the combustion chamber; in some of these as- (a "spray angle") in a respective plane shared with the pects, the injection axis is transverse to the longitudinal injector axis. A wider spray angle results in a plume being axis of the cylinder. injected at a higher angle away from the injector axis. 45 [0011] In other aspects, direct side injection includes This is desirable because the fuel of each individual injection of swirl spray patterns in opposing radial direc- plume burns in the presence of air independently of the tions of a cylinder bore into a combustion chamber of an other plumes. There is less interaction of individual opposed-piston engine wherein charge air has a com- plumes and hence, a faster burn time. However, in an plex, turbulent motion. Preferably, the air motion includes opposed piston engine, a wider spray angle also pushes 50 swirl and tumble components. the plume and hence the flame closer to the cylinder bore [0012] A fuel injector having a nozzle with a multi-hole and piston surfaces, resulting in combustion near those construction that produces a swirl spray pattern is here- surfaces. This can result in excessive heat transfer into inafter referred to as a multiple-hole swirl injector (MHSI). the cylinder liner and piston walls. Such heat transfer While conventional multiple-hole injector nozzle con- results in a loss of power; and a higher heat transfer loss 55 structions are designed such that a plane can pass means lower indicated thermal efficiency of the engine. through a vector representing an individual plume and Heat transfer can be reduced by directing the plumes the injector axis, a MHSI produces a swirl spray pattern away from the cylinder bore surface. characterized by one or more spray plumes whose vec-

2 3 EP 2 901 005 B1 4 tors do not lie in a plane that contains the injector axis. FIGS. 13, 14, 15, 16, and 17 are schematic sectional views of a nozzle construction for a multiple-hole BRIEF DESCRIPTION OF THE DRAWINGS swirl injector taken on a central plane that illustrate construction effects resulting from various combina- [0013] 5 tions of primary and secondary angles.

FIGS. 1A and 1B are schematic diagrams that illus- DETAILED DESCRIPTION OF THE PREFERRED EM- trate the effect of adding a swirl component to a fuel BODIMENTS spray pattern with respect to the injector axis of an 8-hole injector. 10 [0014] In the following description, "fuel" is any fuel that can be used in an opposed-piston engine. The fuel may FIG. 2A is a schematic diagram that illustrates a plu- be a relatively homogeneous composition, or a blend. rality of 3-hole groups of an 18-hole injector having For example, the fuel may be or any other fuel a multiple-hole swirl injection pattern: FIG. 2B is an ignitable by compression ignition. Further, the descrip- enlarged schematic view showing a swirl spray pat- 15 tions contemplate ignition resulting from compression of tern of a three-hole group. an air/fuel mixture; however it may be desirable to provide additional mechanisms, such as glow plugs, to assist FIGS. 3A and 3B illustrate a cylinder of an opposed compression ignition. The descriptions contemplate in- piston engine in which fuel injectors are positioned jection of fuel into a compressed gas in a combustion for direct side injection of fuel into a combustion20 chamber when opposed pistons are at or near TDC lo- chamber formed when the opposed pistons in the cations. The gas is preferably pressurized ambient air; cylinder are near top dead center positions. however, it may include other components such as ex- haust gases or other diluents. In any such case, the gas FIG. 4 is a sectional view of one of the fuel injectors is referred to as "charge air. seen in FIG. 3. 25 [0015] FIGS. 1A and 1B schematically illustrate the ef- fect of a swirl component in the individual plumes of an FIG. 5 is an enlarged perspective view of a portion injected spray pattern with respect to the injector axis for of the nozzle portion of the multi-hole fuel injector of an 8-hole injector. FIG. 1A represents the end-on view FIG. 4. of an 8-hole nozzle of a conventional fuel injector, and 30 FIG. 1B represents the end-on view of an 8-hole nozzle FIG. 6 is an enlarged side sectional view of the nozzle of an MHSI. In each figure, the dark arrows are spray portion of the multi-hole fuel injector of FIG. 4. plume vectors and the central cross is the injector axis. As per FIG. 1A, in a conventional 8-hole fuel injector noz- FIG. 7 is an enlarged planar sectional view of the zle, the spray plume vectors are oriented radially away nozzle portion of the multi-hole fuel injector of FIG. 4. 35 from the injector axis and have no tangential component. The result is a spray pattern having the shape of an ax- FIG. 8 is an enlarged perspective view of the nozzle isymmetric cone. As per FIG. 1B, in addition to a radial portion of the multi-hole fuel injector of FIG. 4 show- component, each plume vector of an 8-hole MHSI has a ing a spray pattern produced by multiple-hole swirl tangential component; that is to say, each plume vector injection construction of the nozzle portion of FIGS. 40 has both a radial and a skew component with respect to 5, 6, and 7. an injection axis which is collinear with the injector axis. As a consequence of the skew component, an axisym- FIG. 9 is a schematic sectional view taken along a metric spray pattern with circumferential velocity is pro- central plane containing the vertical centerline of a duced, and the effect is to cause the spray pattern to swirl nozzle for a multi-hole fuel injector showing a radial 45 with respect to the injection axis. Hereinafter, a spray hole pattern with a single angle. pattern with a swirl component is referred to as a "swirl spray pattern". As shown in FIG. 1B, the swirl has a clock- FIG. 10 is a schematic sectional view of a nozzle wise (CW) direction, although this is for illustration only construction for a multiple-hole swirl injector taken and is not meant to exclude other swirl directions includ- on a central plane defining a primary hole angle. 50 ing counter-clockwise (CCW). [0016] Beneficially, the swirl spray pattern of FIG. 1B FIG. 11 is a schematic sectional view of the nozzle increases mixing of fuel-vapor with surrounding air and construction of FIG. 10 taken on a primary angle also reduces impingement of fuel spray plumes onto the plane defining a secondary hole angle. piston and bore surfaces. The reduction in the impinge- 55 ment of spray plumes comes because each spray plume FIG. 12 is a representational drawing showing the tip requires more penetration to reach the same normal spray area of a swirl spray pattern produced by a distance from the injector as the cone-shaped spray pat- multiple-hole swirl injector. tern of FIG. 1A. Also the swirling effect of the spray pat-

3 5 EP 2 901 005 B1 6 terns provides more coherent structure of sprays to pen- air enters the cylinder 10 through the open port etrate the air and hence provides faster burn time. This 14, driving exhaust gasses out of the cylinder through also reduces emissions such as soot and CO, thereby the exhaust port 16. After further movement of the pis- increasing combustion efficiency. tons, the exhaust port 16 closes before the intake port [0017] FIG. 2A schematically represents an end-on 5 14 while the intake piston 20 continues to move away view of an 18-hole injector MHSI, in which each arrow from BDC. Typically, the charge of air is swirled as it represents an injection axis of a group of three injector passes through ramped openings of the intake port 14. holes. As seen in FIG. 2B, the plume vectors of each of With reference to FIG. 3A, the swirling motion (or simply, the three-hole groups have both radial and skew com- "swirl") 30 of the charge air is a generally helical move- ponents. As a consequence of the skew components, 10 ment of charge air that circulates around the cylinder’s angular momentum is imparted to the spray pattern of longitudinal axis and moves longitudinally through the each three-hole group and the effect is to cause the spray bore of the cylinder 10. pattern to swirl with respect to an injection axis of the [0021] As seen in FIG. 3B, as the pistons move to TDC group. As shown in FIG. 2B, the swirl pattern of each positions, a combustion chamber structure 40 is defined three-hole group has a counter-clockwise (CCW) direc- 15 between contoured features of the opposing end surfac- tion, although this is for illustration only and is not meant es 20e, 22e of the pistons. The combustion chamber in- to exclude other swirl directions including clockwise cludes a cavity defined between opposing bowls formed (CW). in the end surfaces. Construction and operation of an [0018] A combustion chamber construction in an op- opposed pistoncombustion chamber similarto the cham- posed piston engine is explained with reference to FIGS. 20 ber seen in FIG. 3B can be understood with reference to 3A and 3B. FIG. 3A shows the cylinder in cross section, the two related US patent applications. In some aspects, with the opposed pistons near bottom dead center (BDC) each fuel injector 17 injects a spray pattern 50 of fuel into positions at the end of a power , the exhaust port the combustion chamber cavity along an injection axis fully open, and blow-down initiated; FIG. 3B shows the that is oriented at least generally in a diametrical direction cylinder in cross section, with the opposed pistons near 25 52 of the cylinder; preferably, the spray patterns 50 are top dead center (TDC) positions near the end of a com- injected in opposing radial directions of the cylinder. In pression stroke, the combustion chamber formed, and some aspects, the spray patterns 50 are injected in op- direct side injection into the combustion chamber initiat- posing directions along a major axis of the combustion ed. chamber. According to some aspects, each spray pattern [0019] As per FIG. 3A, the opposed piston engine in- 30 is a swirl spray pattern. The swirl spray patterns can be cludes at least one cylinder 10 with a bore 12 and longi- longitudinally and rotationally oriented so that the plumes tudinally-separated intake and exhaust ports 14 and 16. are oriented in opposition in the combustion chamber. In One or more fuel injectors 17 are secured in injector ports another example, the opposing spray patterns can be (ports where injectors are positioned) that open through mutually rotationally offset so that the plumes are inter- the side surface of the cylinder. Preferably, but not nec- 35 digitated. See FIGS. 10B and 10C of related US essarily, two fuel injectors 17 are mounted for direct side 2012/0073541 in this regard. injection into the cylinder; in some aspects, the fuel in- [0022] In some further aspects, the combustion cham- jectors are oriented in opposition along a generally dia- ber 40 is constructed so as to generate turbulent bulk air metrical direction of the cylinder. According to one as- motion, including swirl, squish, and tumble components, pect, each fuel injector 17 is an MHSI constructed to inject 40 of the charge air compressed between the end surfaces a swirl spray pattern into the cylinder 10. Two pistons 20, as the pistons approach TDC. Interaction of swirl fuel 22 are disposed in the bore 12 with their end surfaces spray patterns with such complex, turbulent bulk air mo- 20e, 22e in opposition to each other. For convenience, tion produces good air/fuel mixing in the combustion the piston 20 is denominated as the "intake" piston be- chamber ofan opposed-piston engine. For example, con- cause of its proximity to the intake port 14. Similarly, the 45 sider the opposed-piston combustion chamber 300 illus- piston 22 is denominated as the "exhaust" piston be- trated in FIG. 15B of related US 20110271932, in which cause of its proximity to the exhaust port 16. a tumbling motion 343 is generated when squish flows [0020] In some aspects, a phase offset is introduced encounter the outwardly-directed end surface portions into the piston movements. For example, the exhaust 292 of two opposed pistons 280. In this example, the piston 22 leads the intake piston 20 and the phase offset 50 tumbling motion is a circulating motion of charge air in causes the pistons to move around their BDC positions the combustion chamber that is at least generally trans- in a sequence in which the exhaust port 16 opens as the verse to the longitudinal axis of the cylinder 220 in which exhaust piston 22 moves through BDC while the intake the pistons are disposed; in the case of the tumbling mo- port 14 is still closed so that combustion gasses start to tion 343, the circulation is generally around the major flow out of the exhaust port 16. As the pistons continue 55 axis 302 of the combustion chamber. Presume at least moving away from each other, the intake piston 20 moves onemulti-hole swirl injector according tothis specification through BDC causing the intake port 14 to open while injects a swirl spray pattern having an injection axis that the exhaust port 16 is still open. A charge of pressurized is collinear with the major axis 302. The swirl spray pat-

4 7 EP 2 901 005 B1 8 tern can rotate with or against the tumble circulation, as jectors for an opposed-piston engine have a sac-type needed to accomplish a particular fuel/air mixing objec- construction. FIG. 9 illustrates a schematic side section tive. of a sac type injector nozzle 100, in which hole location [0023] With reference to FIG. 4, a multi-hole swirl in- is defined by an axis that extends from a point along the jector 60 has a nozzle 65 constructed for direct injection 5 vertical centerline of the nozzle body through a point on of fuel having a swirl spray pattern; preferably, the injector the sac surface 101 at or near a horizontal plane through 60 is an accumulator-type device. The injector includes the vertical midpoint of the sac volume 90. The location an inlet 67 and fuel flows from the inlet, through the fuel of the point along the vertical centerline 102 of the nozzle injector, to the nozzle. While the nozzle is closed, pres- body 100 is determined by the desired angle of the hole surized fuel is accumulated in a chamber 68 in the interior 10 from the vertical centerline. In this regard, point A in FIG. of the fuel injector. An elongate needle 69 disposed in 9 is on the vertical centerline 102 of the nozzle body 100 the body of the fuel injector includes a tip 70 (best seen and point B is a point on the sac surface 101 at or near in FIG. 6) that engages a seat 72 that is in axial alignment a horizontal plane 104 through the vertical midpoint of with the nozzle. An actuator 75 is operated to retain the the sac volume 90. An axis 105 through the two points needle in a normally seated position in the seat to close 15 and extending through the wall of the tip defines the cen- holes in the nozzle. When the actuator is operated to terline of the hole. release the retaining force, the pressure of fuel accumu- [0027] Compound angles are used to create holes that lated in the chamber lifts the needle from the seat, which have an inherent swirl component. In this regard, a com- causes fuel to flow along the needle and out through pound angle of an injector hole of a multi-hole swirl nozzle holes (not seen in this figure) in the nozzle. As the accu- 20 has two components: a primary angle (providing a radial mulated pressure in the chamber falls, a spring 76 returns component) and a secondary angle (providing a tangen- the tip to its normally seated position in the seat, where tial component). With reference to FIG. 10, the primary it is retained by the actuator. angle is defined by an axis 110 that extends from a point [0024] As per FIGS. 5 and 6, the nozzle 65 is provided 112 along the vertical centerline 114 of the nozzle body with holes in the form of fuel passages 80 through which 25 116 through a point 117 on the sac surface 101 at or near fuel flows when the needle tip 70 is lifted from the seat a horizontal plane 118 through the vertical midpoint 119 72. The passages 80 are disposed in a generally circum- of the sac volume 90. As per FIGS. 10 and 11, a second- ferential array around the tip 66 of the nozzle. Although ary angle is oriented on a plane 120 that goes through onesuch array is shownin FIG. 5,there may beadditional the two points 112, 117 defining the primary angle and and other arrays of passages at greater and/or smaller 30 is at the same angle as the primary angle from a center radial distances from the tip 66 of the nozzle. Each pas- plane 121 shown in the cross section thru the central sage is drilled or machined in the nozzle 65 so as to nozzle plane in FIG. 9. The secondary angle is defined extend from a sac volume 90 under the seat 72 to the by an axis 123 that extends from the end point 117 of the outer surface of the nozzle 65 and thus permit pressu- primary angle through a second point 125 located on the rized fuel to flow from the fuel injector body and be in- 35 primary angle plane and at a horizontal distance from the jected into the cylinder. As per FIGS. 6 and 7, each pas- center plane of the nozzle as defined by the desired an- sage 80 is formed at a non-zero radial angle and a non- gle. zero circumferential angle with respect to the injector ax- [0028] The secondary angle dictates the degree of is. Thus, the passages 80 are skewed with respect to the swirl induced in the plumes with a larger angle providing axis of the injector. As a result, an angular momentum is 40 more swirl and at its lower limit of 0 degrees providing imposed on a plume of fuel ejected through the passage. no swirl component as in the case of a single-angled As best seen in FIG. 8, with all of the passages 80 skewed hole. As per FIG. 12, the primary angle allows for adjust- in the same direction, the resulting spray pattern 82 has ment of the spray area; defined by the circular area 130 a swirl produced by the plumes 84. MHSI construction in which the spray plumes 131 are contained at a set can be applied to a 2-hole, 3-hole, 4-hole, 5-hole, 6-hole, 45 distance from the nozzle tip 132. For a given primary 7-hole, 8-hole and up to as many radial nozzle holes as angle the spray area is increased as the secondary angle can be drilled in an injector. is increased. In order to vary the spray area for a given [0025] The injector and nozzle may be fabricated from secondary angle, the primary angle has to be adjusted. conventional materials such as, for example, heat treated A smaller primary angle will provide a smaller spray area alloy steel. Hole counts, pitches, and form characteristics 50 for a given secondary angle and conversely a larger pri- of the passages such as shape, size, proportion, straight- mary angle provides a larger spray area for a given sec- ness, and taper, are selected according to the require- ondary angle. The compound angle defining a swirl noz- ments of an opposed piston engine design. zle hole thus provides a means to control the spray area for a given component of swirl. SWIRL NOZZLE CONSTRUCTIONS AND LIMITA- 55 [0029] The ability to control the spray area and or the TIONS swirl component on a swirl nozzle is limited. As the sec- ondary angle is increased for a given primary angle the [0026] Presume that the nozzles of multi-hole swirl in- intersection at the sac surface elongates and a limit is

5 9 EP 2 901 005 B1 10 reached where a smooth entrance to the hole is not pos- cluding a nozzle (65) having a sac volume (90) sible. In FIG. 13 the hole entrance 140 using a primary with a sac surface (101) and a plurality of injec- angle of 10 degrees and secondary angle of 20 degrees tion holes (80) opening through the sac surface is shown. FIG. 14 illustrates how the hole entrance 140 and being disposed at a radial angle and a cir- tilts and elongates as the secondary angle is increased 5 cumferential angle with respect to an injection to 30 degrees while maintaining a primary angle of 10 axis, wherein the plurality of injection holes is degrees. A limit of 34 degrees is reached for the second- disposed in at least one generally circumferen- ary angle with a 10 degree primary angle as shown in tial array on the nozzle, and wherein the radial FIG. 15. The limiting value for the secondary angle occurs angle is defined by an axis (110) that extends as a result of the hole interfering with the sac surface 10 from a point (112) along a vertical centerline before a smooth entrance can be achieved. The maxi- (114) of the nozzle (116) through a point (117) mum value for the secondary angle (that permits a sat- on the sac surface (101) at or near a horizontal isfactory hole entrance) varies with the magnitude of the plane (118) through a vertical midpoint (119) of primary angle. Examples of maximum values for the sec- the sac volume (90); ondary angle with various primary angles are shown in 15 characterized in that; FIGS. 15-17. As shown in FIG. 15 the limiting value for the circumferential angle is oriented on a plane the secondary angle is reached at 28 degrees for a pri- (120) containing the two points (112, 117) and mary angle of 5 degrees. As previously mentioned the is at the same angle as the radial angle from a limiting value of the secondary angle for a primary angle center plane (121) of the nozzle, the circumfer- of 10 degrees is 34 degrees as shown in FIG. 16. A max- 20 ential angle being defined by an axis (123) that imumsecondary angle of42 degrees with a primaryangle extends from the point (117) through a second of 20 degrees is shown in FIG. 17. Decreasing values of point (125) located on the plane (120) and at a the primary angle lower the maximum value of the sec- horizontal distance from the center plane (121). ondary angle. Increasing the value of the primary angle raises the maximum allowable value of the secondary 25 2. A method for operating an internal combustion en- angle. gine having a fuel injection system according to [0030] The degree to which swirl and spray area are claim1, in which: limited is also a function of the particular sac geometry. The magnitude of the secondary angle possible for a set charge air enters the bore (12) through the in- primary angle with a conical sac (as shown in the various 30 take port (14) as the pistons move from respec- figures) will differ from a cylindrical sac geometry. The tive bottom dead center positions in the bore, sac diameter and orifice diameter also influence the max- a combustion chamber (40) is defined between imum allowable secondary angle possible for a given pri- the end surfaces (20e, 22e) as the pistons ap- mary angle. proach top dead center positions in the bore, and [0031] Although fuel injection with swirl spray patterns 35 swirl spray patterns of fuel are injected into the in opposed-piston engines has been described with ref- combustion chamber. erence to preferred embodiments, it should be under- stood that various modifications can be made without 3. The method of claim 2, wherein the swirl spray pat- departing from the principles thereof. Accordingly, the terns of fuel are injected into the combustion cham- scope of patent protection should be limited only by the 40 ber in opposing directions of the cylinder following claims. 4. The method of claim 2, wherein a tumble component is added to the motion of the charge air. Claims 45 5. The method of claim 4, in which each spray pattern 1. Afuel injection system for an opposed-piston engine, includes a plurality of plumes disposed in an array comprising: with respect to an axis of injection.

at least one cylinder (10) with longitudinally-sep- 6. The method of claim 5, in which the axis of injection arated intake and exhaust ports (14 and 16); 50 is a fuel injector axis. a pair of pistons (20 and 22) disposed in oppo- sition in a bore (12) of the cylinder; and, 7. The method of claim 2, in which the charge air swirls a plurality of multi-hole fuel injectors (17, 60) po- in the bore. sitioned for direct side injection of fuel into the cylinder, between end surfaces (20e, 22e) of the 55 8. The method of claim 7, in which a circulating tumble pistons, each respective fuel injector defining an component is added to a swirling motion of the injection axis (102, 114); charge air as the pistons approach top dead center each of the multi-hole fuel injectors (17, 60) in- positions in the bore.

6 11 EP 2 901 005 B1 12

9. The method of claim 8, in which each spray pattern mindestens einen Zylinder (10) mit in Längsrich- includes a plurality of plumes disposed in an array tung getrennten Einlass- und Auslassöffnungen with respect to an axis of injection. (14 und 16); ein Kolbenpaar (20 und 22), das einander ent- 10. The method of claim 8, in which at least one spray 5 gegengesetzt in einer Bohrung (12) des Zylin- pattern has a motion that rotates with or against the ders angeordnet ist; und tumble circulation. eine Vielzahl von Mehrloch-Kraftstoffeinspritz- vorrichtungen (17, 60), die für eine direkte Kraft- 11. A method for operating an internal combustion en- stoffseiteneinspritzungin den Zylinder zwischen gine including a fuel injection system according to 10 Endflächen (20e, 22e) der Kolben positioniert claim 1, by: sind, wobei jede jeweilige Kraftstoffeinspritzvor- richtung eine Einspritzachse (102, 114) defi- admitting charge air into the bore (12) through niert; the intake port (14) as the pistons (20, 22) move wobei jede der Mehrloch-Kraftstoffeinspritzvor- from respective bottom dead center positions in 15 richtungen (17, 60) eine Düse (65) einschließt, the bore, die ein Sackvolumen (90) mit einer Sackfläche causing a tumbling motion in the charge air be- (101) und eine Vielzahl von Einspritzlöchern tween the opposing end surfaces (20e, 22e) of (80), die sich durch die Sackfläche öffnen, auf- the pistons as the pistons move toward respec- weist und in einem Radialwinkel und in einem tive top dead center positions in the bore, and 20 Umfangswinkel relativ zu einer Einspritzachse side-injecting opposing swirl spray patterns (82) angeordnet ist, wobei die Vielzahl von Einspritz- of fuel into the charge air between the opposing löchern in mindestens einer im Wesentlichen end faces. umlaufenden Anordnung an der Düse angeord- net ist und wobei der Radialwinkel durch eine 12. The method of claim 11, including defining a com- 25 Achse (110) definiert ist, die sich von einem bustion chamber (40) between the opposing end sur- Punkt (112) entlang einer vertikalen Mittellinie faces of the pistons as the pistons near top dead (114) der Düse (116) durch einen Punkt (117) center positions. auf der Sackfläche (101) an einer oder in der Nähe einer horizontalen Ebene (118) durch ei- 13. The method of claim 12, in which injecting a charge 30 nen vertikalen Mittelpunkt (119) des Sackvolu- of fuel into the charge of air includes injecting the mens (90) erstreckt; fuel along a major axis of the combustion chamber. dadurch gekennzeichnet, dass:

14. The method of claim 12, in which each spray pattern der Umfangswinkel an einer die zwei Punk- includes a plurality of plumes disposed in an array 35 te (112, 117) enthaltenden Ebene (120) with respect to an axis of injection. ausgerichtet ist und denselben Winkel wie der Radialwinkel von einer Mittelebene 15. The method of claim 11, in which a swirling motion (121) der Düse bildet, wobei der Umfangs- is imposed on the air admitted into the bore. winkel durch eine Achse (123) definiert ist, 40 die sich von dem Punkt (117) durch einen 16. The method of claim 15, including defining a com- zweiten Punkt (125) erstreckt, der sich auf bustion chamber between the opposing end surfac- der Ebene (120) und in einem horizontalen es of the pistons as the pistons near top dead center Abstand zur Mittelebene (121) befindet. positions. 45 2. Verfahren zum Betreiben eines Verbrennungsmo- 17. The method of claim 16, in which injecting a charge tors, der ein Kraftstoffeinspritzsystem nach An- of fuel into the charge of air includes injecting the spruch 1 aufweist, wobei: fuel along a major axis of the combustion chamber. Ladeluft durch die Einlassöffnung (14) in die 18. The method of claim 17, in which each spray pattern 50 Bohrung (12) eintritt, wenn sich die Kolben aus includes a plurality of plumes disposed in an array jeweiligen unteren Totpunktpositionen in der with respect to an axis of injection. Bohrung herausbewegen, eine Brennkammer (40) zwischen den Endflä- chen (20e, 22e) definiert ist, wenn die Kolben Patentansprüche 55 sich oberen Totpunktpositionen in der Bohrung nähern, und 1. Kraftstoffeinspritzsystem für einen Motor mit entge- Kraftstoffwirbelsprühmuster in die Brennkam- gengesetzten Kolben, umfassend: mer eingespritzt werden.

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3. Verfahren nach Anspruch 2, wobei die Kraftstoffwir- 13. Verfahren nach Anspruch 12, bei dem das Einsprit- belsprühmuster in entgegengesetzten Richtungen zen einer Kraftstoffladung in die Luftladung das Ein- vom Zylinder in die Brennkammer eingespritzt wer- spritzen des Kraftstoffs entlang einer Hauptachse den. der Brennkammer einschließt. 5 4. Verfahren nachAnspruch 2, wobeieine Taumelkom- 14. Verfahren nach Anspruch 12, bei dem jedes ponente zur Bewegung der Ladeluft hinzugefügt Sprühmuster eine Vielzahl von Federn einschließt, wird. die in einer Anordnung in Bezug auf eine Ein- spritzachse angeordnet ist. 5. Verfahren nach Anspruch 4, bei dem 10 jedes Sprühmuster eine Vielzahl von Federn einschließt, 15. Verfahren nach Anspruch 11, bei dem die in die Boh- die in einer Anordnung in Bezug auf eine Ein- rung eingelassene Luft in eine Wirbelbewegung ver- spritzachse angeordnet ist. setzt wird.

6. Verfahren nach Anspruch 5, bei dem die Ein-15 16. Verfahren nach Anspruch 15, einschließend das De- spritzachse eine Kraftstoffeinspritzvorrichtungsach- finieren einer Brennkammer zwischen den gegenü- se ist. berliegenden Endflächen der Kolben, wenn die Kol- ben sich oberen Totpunktpositionen nähern. 7. Verfahren nach Anspruch 2, bei dem die Ladeluft im Bohrloch herumwirbelt. 20 17. Verfahren nach Anspruch 16, bei dem das Einsprit- zen einer Kraftstoffladung in die Luftladung das Ein- 8. Verfahren nach Anspruch 7, bei dem eine zirkulie- spritzen des Kraftstoffs entlang einer Hauptachse rende Taumelkomponente zu einer Wirbelbewe- der Brennkammer einschließt. gung der Ladeluft hinzugefügt wird, wenn die Kolben sich oberen Totpunktpositionen in der Bohrung nä- 25 18. Verfahren nach Anspruch 17, bei dem jedes hern. Sprühmuster eine Vielzahl von Federn einschließt, die in einer Anordnung in Bezug auf eine Ein- 9. Verfahren nach Anspruch 8, bei dem jedes spritzachse angeordnet ist. Sprühmuster eine Vielzahl von Federn einschließt, die in einer Anordnung in Bezug auf eine Ein-30 spritzachse angeordnet ist. Revendications

10. Verfahren nach Anspruch 8, bei dem mindestens ein 1. Système d’injection de carburant pour un moteur à Sprühmuster eine Bewegung aufweist, die sich mit pistons opposés, comprenant : der oder gegen die Taumelzirkulierung dreht. 35 au moins un cylindre (10) avec des orifices d’ad- 11. Verfahren zum Betreiben eines Verbrennungsmo- mission et d’échappement séparés longitudina- tors, der ein Kraftstoffeinspritzsystem nach An- lement (14 et 16) ; spruch 1 einschließt, durch: une paire de pistons (20 et 22) disposés en op- 40 position dans un alésage (12) du cylindre ; et, Einlassenvon Ladeluft indie Bohrung (12) durch unepluralité d’injecteurs de carburant multitrous die Einlassöffnung (14), wenn sich die Kolben (17, 60) positionnée pour une injection directe (20, 22) aus jeweiligen unteren Totpunktpositi- par le côté de carburant dans le cylindre, entre onen in der Bohrung herausbewegen, des surfaces d’extrémité (20e, 22e) des pistons, Verursachen einer Taumelbewegung in der La- 45 chaque injecteur de carburant respectif définis- deluft zwischen den entgegengesetzten Endflä- sant un axe d’injection (102, 114) ; chacun des chen (20e, 22e) der Kolben, wenn sich die Kol- injecteurs de carburant multitrous (17, 60) com- ben auf jeweilige obere Totpunktpositionen in portant une buse (65) ayant un volume de sac der Bohrung zubewegen, und (90) avec une surface de sac (101) et une plu- Seiteneinspritzen entgegengesetzter Kraftstoff- 50 ralité de trous d’injection (80) s’ouvrant à travers wirbelsprühmuster (82) in die Ladeluft zwischen la surface de sac et disposée à un angle radial den entgegengesetzten Endflächen. et un angle circonférentiel par rapport à un axe d’injection, dans lequel la pluralité de trous d’in- 12. Verfahren nach Anspruch 11, einschließend das De- jection est disposée dans au moins un réseau finieren einer Brennkammer (40) zwischen den ent- 55 généralement circonférentiel sur la buse, et gegengesetzten Endflächen der Kolben, wenn sich dans lequel l’angle radial est défini par un axe die Kolben oberen Totpunktpositionen nähern. (110) qui s’étend depuis un point (112) le long d’une ligne centrale verticale (114) de la buse

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(116) à travers un point (117) sur la surface de que forme de jet comporte une pluralité de panaches sac (101) au niveau ou près d’un plan horizontal disposée dans un réseau par rapport à un axe d’in- (118) à travers un point milieu vertical (119) du jection. volume de sac (90) ; caractérisé en ce que ; 5 10. Procédé selon la revendication 8, dans lequel au l’angle circonférentiel est orienté sur un plan moins une forme de jet a un mouvement qui tourne (120) contenant les deux points (112, 117) et avec ou contre la circulation de tourbillon transver- est au même angle que l’angle radial depuis un sal. plan central (121) de la buse, l’angle circonfé- rentiel étant défini par un axe (123) qui s’étend 10 11. Procédé de fonctionnement d’un moteur à combus- depuis le point (117) à travers un second point tion interne comportant un système d’injection de (125) situé sur le plan (120) et à une distance carburant selon la revendication 1, par : horizontale du plan central (121). l’admission d’air de suralimentation dans l’alé- 2. Procédé de fonctionnement d’un moteur à combus- 15 sage (12) à travers l’orifice d’admission (14) à tion interne ayant un système d’injection de carbu- mesure que les pistons (20, 22) se déplacent rant selon la revendication 1, dans lequel : depuis des positions respectives de point mort bas dans l’alésage, de l’air de suralimentation entre dans l’alésage la création d’un mouvement de tourbillon trans- (12) à travers l’orifice d’admission (14) à mesure 20 versal dans l’air de suralimentation entre les sur- que les pistons se déplacent depuis des posi- faces d’extrémité opposées (20e, 22e) des pis- tions respectives de point mort bas dans l’alé- tons à mesure que les pistons se déplacent vers sage, des positions respectives de point mort haut une chambre de combustion (40) est définie en- dans l’alésage, et tre les surfaces d’extrémité (20e, 22e) à mesure 25 l’injection par le côté de formes de jet à turbu- que les pistons approchent des positions de lence opposées (82) de carburant dans l’air de point mort haut dans l’alésage, et suralimentation entre les faces d’extrémité op- des formes de jet à turbulence de carburant sont posées. injectées dans la chambre de combustion. 30 12. Procédé selon la revendication 11, comportant la dé- 3. Procédé selon la revendication 2, dans lequel les finition d’une chambre de combustion (40) entre les formes de jet à turbulence de carburant sont injec- surfaces d’extrémité opposées des pistons à mesure tées dans la chambre de combustion dans des di- que les pistons se rapprochent de positions de point rections opposées du cylindre. mort haut. 35 4. Procédé selon la revendication 2, dans lequel une 13. Procédé selon la revendication 12, dans lequel l’in- composante de tourbillon transversal est ajoutée au jection d’une charge de carburant dans la suralimen- mouvement de l’air de suralimentation. tation d’air comporte l’injection du carburant le long d’un axe principal de la chambre de combustion. 5. Procédé selon la revendication 4, dans lequel cha- 40 que forme de jet comporte une pluralité de panaches 14. Procédé selon la revendication 12, dans lequel cha- disposée dans un réseau par rapport à un axe d’in- que forme de jet comporte une pluralité de panaches jection. disposée dans un réseau par rapport à un axe d’in- jection. 6. Procédé selon la revendication 5, dans lequel l’axe 45 d’injection est un axe d’injecteur de carburant. 15. Procédé selon la revendication 11, dans lequel un mouvement de turbulence est imposé sur l’air admis 7. Procédé selon la revendication 2, dans lequel l’air dans l’alésage. de suralimentation tourbillonne dans l’alésage. 50 16. Procédé selon la revendication 15, comportant la dé- 8. Procédé selon la revendication 7, dans lequel une finition d’une chambre de combustion entre les sur- composante de tourbillon transversal de circulation faces d’extrémité opposées des pistons à mesure est ajoutée à un mouvement de turbulence de l’air que les pistons se rapprochent de positions de point de suralimentation à mesure que les pistons appro- mort haut. chent des positions de point mort haut dans l’alésa- 55 ge. 17. Procédé selon la revendication 16, dans lequel l’in- jection d’une charge de carburant dans la suralimen- 9. Procédé selon la revendication 8, dans lequel cha- tation d’air comporte l’injection du carburant le long

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d’un axe principal de la chambre de combustion.

18. Procédé selon la revendication 17, dans lequel cha- que forme de jet comporte une pluralité de panaches disposée dans un réseau par rapport à un axe d’in- 5 jection.

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REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• US 13136954 B [0001] • US 5042441 A [0008] • US 20120073541 A1 [0001] [0004] • JP 2009138718 A [0008] • US 13066589 B [0002] • US 20120073541 A [0021] • US 20110271932 A1 [0002] • US 20110271932 A [0022]

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