US 2627254 A
Description (OCR text may contain errors)
Feb. 3, 1953 K. J. DE .JUHAsz FUEL INJECTION NOZZVL Filed June 12, 1947 TTQRNE Ys Patented F eb. 3, 1953 FUEL INJECTION NOZZLE Kalman J. De Juhasz, State College, Pa., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application June 12, 1947, Serial No. 754,099
(Cl. 12B-32) 1 Claim.
This invention relates to a fuel injection nozzle for an internal combustion engine, and particularly to a nozzle of the type producing a pilot jet at one side of and slightly preceding a main jet during the injection period.
A principal object of the invention is to provide an improved fuel injection nozzle of this type wherein the pilot injection orifice is an open hole orifice independent of the main orifice and needle valve, whereby each orifice can be independently designed to produce a different controlled type of spray or jet.
Another object of the invention is to provide a fuel injection nozzle constructed to produce a preceding non-flaring directional pilot jet designed to facilitate prompt spark ignition, and a closely following flaring main jet alongside of the pilot jet designed for uniform air impregnation, the two jets functioning to promote rapid formation of the flame front and efficient combustion in a non-knockingl combustion cycle.
Still another object of the invention is to provide a fuel injection nozzle of this type, together with a fuel pump having a delivery valve with cylindrical cuff below the seat of the delivery valve to compensate for fuel back-iiow at the end of each injection period from both the needle valve closing space and also the open hole orifice to thereby prevent dribbling of fuel from the nozzle tip.
Other objects and advantages of the present invention will be apparent from the following description when taken in conjunction with the attached drawing and appended claims.
The fuel injection nozzle of the present invention is particularly designed for use in connection with the internal combustion engine kand method of operating the same with non-knocking combustion disclosed and vclaimed in the co pending application of Everett M. Barber, Serial No. 742,275, filed April 18, 1947, now Patent No. 2,595,915, dated May 6, 1952. In accordance with said application, injection of fuel into rapidly swirling compressed air is initiated toward the latter part of the compression stroke' by a pilot jet which is directed across a small chord of the combustion -space in the direction of air .swirl'and adjacent to the periphery of the combustion space. The resulting fuel vapor-air mixture formed from the first increment of inyjected fuel of said pilot jet is immediately spark ;formly impregnate the compressed air at one f side of the combustion space as it swirls past the locus of injection. The lag between the pilot jet and the main jet is just sufficient so that the leading edge of the main jet in combustible mixture form reaches the locus of ignition just after the formation of a name from the pilot jet, so that the flame rapidly spreads across the `leading edge of the main jet to establish a flame front across said one sideA of the combustion space, thereby avoiding the bypassing of any substantial quantity of unburned combustible mixture beyond the locus of the flame front before the latter can be established. Injection is then continued immediately upstream of the flame front to `develop `the power required on each cycle and in a manner such that additional portions of combustible Afuel vapor-air mixture are progressively formed and burned substantially as rapidly as produced, with the result that knocking of the engine is not possible.
A known type of fuel injection nozzle designed to produce a preceding pilot jet at one side of a, closely following and flaring main jet comprises a single orifice nozzle tip having a conical valve seat in the fuel passage leading to the injection orifice and controlled by the usual pintle valve opening under the influence of fuel under injection pressure, together with a small groove or' channel formed in one lside of the conical valve seat. Upon the application of fuel under injection pressure, a small stream of fuel rst passes through this channel or groove and escapes through the single injection orifice in the form of a small jet directed at an angle according to the inclination of the conical valve seat; and then the pintle valve lifts to produce the main liaring jet in a direction generally parallel to the longitudinal axis of the nozzle and pintle valve. a
i While this type of nozzle can be employed in carrying out the method of said prior application, certain practical difficulties are presented, particularly in the design of the nozzle tip and conical seat with groove, in order to attain the proper directions and congurations of the respective pilot and main jets. Moreover, insaid prior design, with thepintle valve lifted, the directional force of the pilot jet is largely destroyed, with the result that the two jets merge into a singlefiaring jet which has a tendency to shiftslightly from the initial locationofthe pilot jet. A
In accordance with-the present invention,
these difficulties are overcome by providing an injection nozzle 'having a tip formed with Vboth an open hole pilot orifice communicating directly with the fuel pressure chamber upstream f the needle valve seat, and with a separate main injection orifice controlled in the customary manner by the needle valve. In this way, the open hole pilot orifice is made entirely independent of the main orice and needle valve; and each orice can be independently designed as to angular inclination, length to diameter ratio, and size or diameter, to produce a preceding pilot jet closely followed by a main jet, each of the desired spray configuration, penetration and location. Preferably, in accordance with the present invention, the main orifice controlled by the needle valve is of larger diameter and has a smaller length to diameter ratio as well as angular inclination; while the pilot orifice is of smaller diameter and has greater length to diameter ratio and greater angular inclination.
Further, the present invention provides a fuel injection nozzle of this improved type in conjunction with a fuel pump having a delivery valve provided with an enlarged cuff to compensate for fuel back-now from both the vpintle valve closing space and also the open hole orice at the end of each injection period, to prevent dribbling of fuel from the `nozzl-e tip.
The invention is more particularly illustrated in the attached drawing which discloses a preferred embodiment thereof and wherein:
Fig. l is a vertical sectional view through a fuel injection nozzle constructed in accordance with the present invention;
Fig. 2 is an enlarged vertical sectional View through a portion of the nozzle tip and associated needle valve of Fig. l;
Fig. 3 is a partial vertical sectional view through the delivery valve assembly and associated mech-anism of a fuel pump employed in conjunction with the fuel injection nozzle of the present invention; and
Fig. 4 is a diagrammatic View, partly in elevation and partly in section, illustrating the application of the present invention to a cylinder of an internal combustion engine and the oper-ation taking place in the combustion space of said cylinder.
Referring particularly to Fig. l, the fuel injection nozzle comprises a body member I0 having a side boss il which threadedly receives a coupling l2 to which the fuel line I3 (Fig. 4) is connected. Boss l l is drilled to provide a fuel Vchannel I4 which communicates at its inner end with a downwardh7 extending fuel channel I5 drilled in the body member It.
The nozzle also comprises a tip member l1 held in engagement with the lower end of body member I0 by a coupling i3 threadedly received by exterior threads on the body member and engaging a shoulder I9 on tip member Il. The upper surface of the body portion of tip member I'l is formed with an annular groove 20 which registers with the lower end of fuel channel l5. Said groove'Z communicates in turn with a fuel passage 2| drilled in the body portion of the 21 formed on needle valve 25. Beyond the valve seat 26, the tip portion is formed with a smaller diameter extension 28 containing a fuel passage 29 which communicates with the main spray orilice 30 drilled through the extension 28. Drilled through the tip portion at one side of extension 28 is a pilot orifice 3| which communicates directly with the fuel pressure chamber 23 upstream of the needle valve seat, and thus constitutes an open hole orifice. Preferably the body portion and the tip portion of the tip member are integral as shown; although they may be formed in two parts to provide for exchangeable tips. This tip member with associated needle'valve is termed herein a nozzle tip assembly irrespective of whether or not the tip member is formed in one or more parts.
Again referring to Fig. 1, body member I0 is also formed with an axial bore slidably receiving a stem 34 which bears at its lower end in loose fitting engagment with the upper end of a pin 35 carried by needle valve 25. The upper end of a body member l0 is cup-shaped to receive a spring retainer 31 bearing on the upper end of stem 34, and a compression spring 38 whose lower flattened end engages va shoulder of spring retainer 3T. An enlarged bore at Vthe extreme upper end of the cup portion of body member i@ is interiorly threaded to receive a sleeve member 39 which surrounds the upper end of compression spring 38. The upper end of sleeve member 33 has an Vinteriorly threaded Vbore which receives the compression adjusting member 'it bearing at its lower end against upper spring retainer 4|, which in turn bears against the upper flattened end `of compression spring 38. The upper end of adjusting member it is formed with a slot 42 for the reception of a screwdriver, by means of which the member fi@ can be threaded in or out to adjust the compression in spring 38. The parts are locked in adjusted position by a nut 43 threaded on member 4i) and seating against the upper surface of sleeve 39. The entire upper vassembly is enclosed by a cover cap e4 which is threadedly received by exterior threads on sleeve 39 and` is adapted to seat against the upper surface of body member l0. The opening movement of needle valve 25, in response to fuel pressure in chamber 23 acting on the conical surface 46 of the valve, is limited by engagement of the upper end of needle 25 with a shoulder lll at the lower end of body member l0. y
Body member I also threadedly receives c. leakage coupling 5B connected to a return line 5| (Fig. 4) which functions to return any fuel leakage past the pintle valve to the source of supply.
Referring again to Fig. 2, it will be noted that the main spray orifice 3c is of comparatively large diameter and has a compa'artively small length to diameter ratio generally of the order of about 2:1 to 5:1. Moreover, this main spray orifice extends at a relatively smaller angle indicated by the arrows 52 to the longitudinal axis of the nozzle tip and needle valve. On the other hand, the pilot-orifice is of comparatively small diameter and has a relatively large length to diameter ratio of the order of about 16ml to 23:1.. The predetermined length to diameter ratio of this orifice is conveniently fabricated by milling the peripheral part of the tip portion at an angle as shown vat 53 and also by ycounter-'sinking of the outer end of the tip member opposite the orifice 3l as indicated at 53. Also this pilot `5 orifice 3l has a relatively large angular inclination indicated by the arrows 54 with respect to the longitudinal axis of the nozzle tipand needle valve. While the construction shown, with extension 28 containing an angular main orifice 39 of comparatively small length to diameter ratio, constitutes a preferred arrangement, it is to be understood that the main flaring spray can be formed in any suitable manner. Thus a pintle valve can control the discharge of a solid jet against the side wall of an outwardly flaring and angularly arranged spray passage in the tip, so that the main spray is defiected into the combustion space as a flaring jet with proper angular inclination. The construction shown is preferred due to better reproducability of the desired configuration and location of the main spray on succeeding cycles. Moreover, it will be understood that a spiral insert can be mounted in the fuel passage 29 to give the fuel a swirling movement as it passes to and through the main spray orifice 3i). Wherever the `expression needle valve is used in the claims, it is to be understood that this generi-cally covers the various constructions described above, including a simple shut-off valve for an orifice controlling the rate of fuel discharge, as well as a pintle valve wherein the pintle cooperates with the fuel passage or valve seat in controlling the rate of discharge.
The manner in which the fuel injection nozzle is mounted in the engine cylinder is illustrated in Fig. 4. The cylinder indicated diagrammatically at 55 is formed with a bore within which the nozzle is clamped by the customary bolts not shown. This bore may extend at an angle to a radius of the cylinder as illustrated, so that the nozzle is set somewhat tangentlally of the combustion space indicated at 51; or the bore may extend radially of the cylinder, and additional angular inclination as indicated by the arrows 52 and 54 in Fig. 2` given to the orices 3@ and 3 I, respectively. The nozzle is mounted with the tip I1 barely protruding through the cylinder wall into the periphery of the combustion space, and so that the orifices 3| and Bil are positioned on the air downstream side to produce the jets 58 and 59, respectively. As indicated, the pilot jet 58 is directed across a small chord of the combustion spa-ce adjacent the periphery thereof, and so as to just miss the electrodes d@ of a spark plug 5I mounted in the wall of the cylinder adjacent to the nozzle, generally about 20-60" from the nozzle as formed by radii passing through the locus of injection and the locus of ignition respectively. The main jet 59 is directed more toward the center of the combustion space and alongside the pilot jet 5B at one side of the combustion space.
As previously explained, the pilot orifice 3| is constructed with relatively small diameter and relatively large length to diameter ratio in order to produce a non-daring or pencil type of jet which can be accurately designed with respect to penetration and angular inclination to facilitate prompt spark ignition of the first entering portion of fuel from said jet as soon as combustible fuel vapor-air mixture is formed therefrom. The jet 58 just misses the electrodes 50, while combustible mixture diffusing from the edge thereof into the small recess 62 in the cylinder wall contacts electrodes E for prompt spark ignition. The main orifice 3l! on the otherhand is constructedbf relativelylarge diameter and relatively small length to diameter ratio to produce a daring `jet 59 whose main function is to 6 uniformly impregnate the compressed swirling air on one side of the combustion space 51 as it rotates past the locus of fuel injection. It will be understood that the cylinder is provided with air intake means, such as an inlet valve with shroud set tangentially, to impart a high velocity of swirling movement to the air as it is introduced into the combustion space l, which swirling movement is maintained during the compression stroke of the engine piston, as indicated by arrow 63.
Fuel is supplied to fuel line I3 by fuel pump 65 having a fuel pump plunger 66 reciprocated by cam y'6l carried by cam shaft @il driven from the engine at one-half engine speed for four cycle operation. Pump plunger 6B forces fuel under injection pressure from the plunger chamber` it past delivery valve 'II opposed by spring 'l2 into the delivery chamber I3 formed in fitting 14. The latter is connected by union nut 'I5 with the fuel line I3. It will be understood that the fuel pump is of the conventional type wherein the plunger 6E on its upward or pumping stroke forces fuel under injection pressure into delivery chamber 13 andthen through fuel line i3 to the nozzle for a predetermined portion of its pumping stroke as determined by load, and then opens communication between the plunger chamber Ill `with a spill port (not shown)` to immediately release the injection pressure within the fuelline and allow needle valve 25 and delivery valve 'H to come to their seats thus terminating injection.
In accordance with the present invention, delivery valve 1I is formed with a cylindrical cuff TI which is slidably received within the surrounding bore of check valve holder 18. On opening movement of delivery valve 1I, the latter rises until the cuff 'Il moves completely out of the bore of holder 13, thus permitting fuel to pass from plunger chamber 'l0 into delivery chamber 73. This movement reduces the effective fuel volume of delivery chamber I3 by an amount equivalent to the volume displaced by cuff ll. Conversely, when delivery valve 1I returns to its seat at the termination of injection, movement of cuir 'Il from' chamber 'I3 back into the bore of holder 78 increases the effective fuel volume of delivery chamber 'I3 by that amount.
The length and diameter of cuff 'il is so selected in accordance with the present invention as to compensate for back-now of fuel resulting from both the closing of needle valve 25, which reduces the effective volume of fuel pressure chamber 23, and also back-flow of fuel from the open hole orifice 3|. It will be appreciated that when the injection pressure in fuel line I3 is released at the termination of the injection period, the pressure within the combustion space 5l during the immediately succeeding portion of the combustion stroke will yexceed the fuel pressure within chamber 23, the connecting passages 2I, I5 and Ill,` andffuel line I3. Consequently, sufficient back-flow of-fuel is permitted by the closing movement of delivery valve 1I to drain pilot orifice 3| back into chamber 23, which avoids dribbling of fuel from this open. hole orifice. Since the delivery valve lI then remains on its seat until the succeeding injection period, now of fuel from chamber 23 through open hole orice 3| is impeded throughout the balance of the cycle, including the suction stroke of the engine piston, thereby preventing the escape of fue1fromthis orifice anni the-succeeding injectionperiod Y .A
" l `In operation, -a'ir is drawn inte the combustion v7 space El of the engine cylinder 56 on the suction stroke of the piston in a manner to produce a high velocity swirling movement therein. This air is Icompressed on the compression stroke while the high velocity swirling movement is maintained. Generally about 75 to 30 before top dead center of the piston, injection of fuel is initiated under the control of pump plunger 65, which forces fuel under injection pressure, thus opening delivery valve ll, into delivery chamber T3, fuel line I3 and the injection nozzle. This injection pressure is thus communicated to fuel pressure chamber 23, thereby producing immediate injection of pilot jet 53 through the open hole orifice 3|. The rst increment of injected fuel of pilot jet 58 is spark ignited at electrodes E!) of plug 6| substantially as soon as combustible mixture is formed therefrom to establish a name. lromptly following the beginning of injection of pilot jet 58, the increasing pressure of fuel in chamber 23 caused by the continuing motion of plunger 56, acting on conical surface 46 of needle valve 25, opens the latter and initiates injection of the main flaring spray 59. The 16g between the start of pilot injection is just suiiicient so that the leading edge of the first increment of injected fuel of the main spray e has barely reached the locus of ignition at the time a llame has been established by spark ignition of the pilot jet 58. This flame rapidly sweeps across the leading edge of the main spray 59, thereby establishing a name front extending generally across a radius of the combustion Space Thereafter. injection 0f fuel is continued Vfrom beth the pilot et se and the main jet te im'- mediately in advance of the established flame front,A so that additional portions of combustible fuel vapor-air mixture are progressively formed and burned substantially as rapidly as formed, whereby knocking of the engine is prevented.
Injection is continued on each -cycle to develop the power required, which for full load may be for a duration of about 40-75 crank-angle degrees or sufficient to substantially completely impregnate the mass o f compressed swirling air within the combustion space on one complete rotation thereof. Injection is then terminated by releasing the injection pressure within the fuel line, causing the needle valve 25 to slam shut on its seat, and also resulting in the closing of delivery valve 1l. Movement of cylindrical cuff ll back into holder 'i8 prevents dribbling of fuel from the open hole orifice 3l, while closing of needle valve 25 prevents dribbling from the main orifice 3i). The power stroke of the piston is completed and the exhaust stroke takes place in the customary manner; when the cycle is then repeated.
By way of example of the present invention, the main spray orifice 30 may have a diameter of .014 inch with a length to diameter ratio of 2:1, and an angular inclination of 30. The pilot orifice 3|v may have a diameter of .006 inch and is countersunk sufficiently to provide a length to diameter ratio of 16:1, with an angular inclination of 45. The nozzle is mounted partially tangentially so that the longitudinal axis of the nozzle makes an angle of about 20 with the Y radius extending through the nozzle tip; and the spark plug 6l is mounted at a radial angle of 45 from the locus of injection in the direction of air swirl.
While the present invention has been particularly described above as applied to an eneine operating with the non-knocking combustion, it is to be understood that the pilot injection nozzle disclosed herein is of more general application to fuel injection engines, such as diesel engines, as well as spark ignition engines operating on the Otto cycle.
Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereofy and therefore only such limitations should be imposed as are indicated in the appended claims.
What I claim is:
In an internal combustion engine, the combination with a cylinder, of a fuel injection nozzle mounted through said cylinder wall with the tip thereof adjacent the periphery of the cylinder combustion space, said nozzle provided with a tip assembly having a body portion with a fuel supply passage and a tip portion, said parts enclosing a fuel pressure'chamber in open oommunication with said fuel supply passage, a valve seat formed at the inner side of said fuel pressure chamber, a spring loaded outwardly opening needle valve normally in engagement with said valve seat, means for supplying fuel under injection pressure to said fuel supply passage and pressure chamberv during the fuel injection period of each cycle and for then releasing said pressure to terminate injection, said spring loading being such that the injection pressure of fuel in said pressure chamber during each fuel injection period is sufficient to overcome the spring loading to open said needle valve throughout the entire load range of said engine, said tip portion having a bulbous extension be- ,vond said valve seat and valve containing a fuel passage and a main injection orifice extending through the wall of said bulbous extension at one side thereof to communicate with said last mentioned fuel passage, said tip portion also having an open hole pilot injection orifice extending through the wall of said tip portion outn wardly of said bulbous extension and valve seat to communicate directly with said pressure chamber, said pilot injection orifice being located on the same side of said tip member as said main orifice and so that both orifices lie substantiall1 in the same plane of a cross-section taken through the tip member along the longitudinal axis thereof, said pilot orifice having a relatively small diameter, a relatively large length to diarneter ratio, and a relativelylarge angular inclination to the longitudinal axis of the nozzle tip and needle valve adapted to provide a thin pencil-like pilot jet directed across a small chord of the combustion space adjacent the periphery thereof, and said main orice having a relatively large diameter, a relatively small length to diameter ratio, and a relatively small angular inclination to the longitudinal axis of the nozzle tip and needle valve adapted to provide a flaring main jet alongside of the'pilot jet which substantially encompasses the balance of the space across a radius of the combustion space between the pilot jet and the center of the combustion space, and an inwardly opening delivery check valve connected to said fuel supply passage, said delivery check valve having a cuff of suncient volume to compensate for fuel backfiow from both said needle valve closing space and said open hole orifice at the end of each injection period to prevent dribbling of fuel from said nozzle tip.
l-KAlIiMAN J. .DE JUHASZ.
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