US3368761A - Variable flow rate fuel injection nozzle - Google Patents

Description

United States Patent 3,368,761 VARIABLE FLGW RATE FUEL INJECTION NOZZLE Winton John Pelizzoni, Hagerstown, Md., assignor to Mack Trucks, Inc, Montvale, N.J., a corporation of- New York Filed Oct. 15, 1965, Ser. No. 496,306 2 Claims. (Cl. 239-533) ABSTRACT OF THE DISCLQSURE A fuel injection nozzle of the multiple orifice type suitable for use in compression ignition engines and having a pintle displaceable by fuel pressure to open a valve This invention relates to fuel injecting systems for internal combustion engines and, more particularly, to fuel injection nozzles, wherein the fuel flow rate may be controlled so as to operate an internal combustion engine more efficiently.

Injection nozzles currently in use include a body having a bore in which a pintle member is slidably mounted, a communicating conduit formed in the body connecting a cavity section of the bore to a source of pressurized fuel, and an annular passage provided in the bore between the pintle and the body providing communication from the cavity to the discharge orifices or ports in the nozzle tip through which fuel is injected into the engine for combustion therein. The pintle member normally is urged by resilient means against a valve seat in the nozzle to prevent injection of fuel into the engine. An enlarged piston area on the pintle member is subjected to the pressure of the fuel in the nozzle, such that when the fuel Within the cavity reaches a predetermined opening pressure, the force exerted upon the piston area of the pintle lifts the pintle from off its seat allowing fuel to be discharged from the nozzle. As the pintle continues to move away from its seat, the fuel flow rate increases until a maximum flow rate is reached. Thereafter, the fuel flow rate will be maintained at this level until the pressue of the fuel diminishes, at which time the pintle will reseat, and the fuel flow will be shut off.

The present invention is an improvement in fuel injection nozzles, whereby the flow rate of fuel injected through the nozzles may be varied to provide rates which are more in keeping with the functional requirements of internal combustion engines.

More particularly, by use of the invention, the flow rates may be varied by providing one or more lands and grooves on the pintle body and cooperating lands on the nozzle body. The lands and grooves are so related that when the pintle is moved from its seat, and when a corresponding land on the body is adjacent to the corresponding land on the pintle, the area of the passage for the flow of fuel to the nozzle will be reduced, and the 3,368,761 Patented Feb. 13, 1968 ice fuel flow rate will be also reduced; and when the land is adjacent to a groove, the area of the fuel passage will be increased and the fluel flow rate increased.

For a better understanding of the present invention, reference may be had to the accompanying drawings, in which:

FIGURE 1 is an illustrative view in cross-section, partially broken away, of an injection nozzle embodying the invention;

FIGURE 2 is an enlarged cross-sectional view of the nozzle of FIGURE 1, partially broken away;

FIGURES 3 and 4 are views in cross-section, partially broken away, illustrating several other embodiments of the invention;

FIGURE 5 is a sectional view taken along line 55 of FIGURE 1;

'FIGURE 6 is an illustrative graph showing the fuel flow rate in relation to time for the embodiment of FIG- URES 1 and 2; and

FIGURE 7 is a graph of fuel flow in relation to time for the embodiments of FIG-UR'E'S 3 and 4.

In FIGURE 1, an injection nozzle 10, adapted to spray or .atomize fuel into the cylinder or intoa precombustion chamber of an internal combustion engine or the like, includes a body 11 provided with a bore 12 extending therethrough. Just after the cylindrical section 12a of the bore 12 is a cup-shaped cavity 12b of generally greater diameter than the cylindrical section 12a. A conduit or duct 14, formed in the body 11, communicates with the cavity 12b, and by being connected to a source of pressurized fuel, permits the fuel to be conducted into the cavity 12b, down through a cylindrical section 120, formed just forward of the cavity 12b, into a channel 12d in the nozzle tip.

The channel 12d, provided at the forward end of the body 11, has a frustoconical seat 15, which is interposed between the cylindrical section and a cylindrical approach section 16. Located at the forward end of the section 16, the tip of the nozzle body 11 has a plurality of small orifices 18 provided therein, which are adapted to spray or atomize the fuel as it passes therethrough under pressure. It will be understood, however, that any number of orifices 18 may be employed with the nozzle 14 A pintle member 20, having sections of varying circular cross-section, is slidably mounted within the bore 12 of the body 11. The rearward cylindrical piston section 20a of the pintle is lap fit within the cylindrical section 12a of the body 11, so as to prevent the escape of any fuel from the cavity 12b out through the rear end of the body 11. The pintle 20 has a piston face, embodied by an inclined or frustoconical surface 20b, positioned just forward of the rearward section of the cavity 12a when the pintle 20 is in the position shown in FIGURE 1, which provides a transition from the larger cylindrical section 20a of the pintle 20 to a somewhat smaller cylindrical section 200. The piston face 20]) need not be inclined but could, for example, be perpendicular to the central axis of the pintle 20. The forward end of the cylindrical section 20c, in turn, merges into a land having a frustoconical surface 20d, which provides a transition to a much shorter cylindrical section 20e with a smaller cross-sectional area than section 20c. The cross-sectional area of the section 20:: does not, of course, necessarily have to be smaller than the cross-sectional area of the section 200.

A's shown in FIGURE 1, when no fuel is being injected, a conical valve portion 20f, disposed adjacent the section 219e, engages the frustoconical seat thereby preventing the discharge of fuel through the channel 12d and orifices 18. A plunger member 22 bears against or extends from the rear end of the pintle 2t} and is engaged by a compression spring 23 which also engages an adjustment member 24. The spring 23 normally urges the pintle into a seated position, thereby preventing any flow of fuel from the nozzle 10. The member 24 may be threaded and, by rotation, increases or decreases the compression of the spring 23, acting upon the plunger 22, to vary the pintle opening and closing pressures.

Pressurized fuel, supplied by a fuel pump, is fed through the conduit 14, into the cavity 12b, and from the cavity 125 along the passage 26, that portion of the section 12c, defined between the cylindrical section 12c and the body 11. As shown in FIGURE 5, the passage 26 is annular in cross-section. When the fuel pressure reaches a selected value, it provides a force by acting on the piston 20!; of the pintle 20, which overcomes the pressure of the spring 23 to the extent that the pintle will lift off the seat 15, and, as a result, fuel will flow from the passage 26 into the channel 12d and through the tip orifices 18.

The present invention illustrates a means of developing a fuel flow rate which is more in keeping with the functional requirements of the operated device. For example, if an internal combustion engine requires a fuel flow rate as illustrated in FIGURE 6, the embodiment of FIGURES 1 and 2 can be employed to accomplish same.

Just rearward of the land 20d on the pintle 20 is a groove 30. A raised or land portion 33 is provided in the nozzle body 11 and is arranged just rearward (in the noflow condition) of the land 20d of the pintle 20, so that it is adjacent to the groove 30 of the pintle 20. In this position, the flow area of the passage 26 will be relatively unobstructed. When the fuel pressure is raised to a selected opening level, and as the pintle 20 begins to move, the flow rate will increase. However, shortly thereafter, when the land 20a on the pintle 20 is aligned or substantially coplanar with the land 33 on the body 11, the area of the passage 26 between the lands is reduced and the fuel flow rate will also be reduced.

As illustrated by the graph of FIGURE 6, as long as the lands 20d and 33 remain in alignment, the fuel flow rate will be held relatively constant at a diminished value. However, when the land 20d on the pintle 29 is finally moved to a position where it is completely behind the land 33 on the body 11, the flow area of the passage 26 will be increased, and the fuel flow rate will again increase up to the maximum value. Thereafter, of course, as the pressure of the fuel diminishes, the pintle 20 will again reseat and shut off the fuel flow.

FIGURE 7 illustrates another flow rate which is effective for operating other internal combustion engines. The structures of FIGURES 3 and 4 will both afit'ect substantially the fuel flow rate shown in FIGURE 7.

In FIGURE 3, a piston face embodied by an inclined surface 12% is located rearward of a cavity 112b, and a land portion 135 is provided on the body 111, intermediately between the piston area 120a and the cavity 1121). Provided on a cylindrical section 1200 of the pintle 120 is a land 136, which in the illustrated seated position, is adjacent to the cavity 112!) and the outer end of the an nular passage 126 around the pintle 120, which communicates with the passage 112d in the'nozzle tip. In operation, when the fuel pressure, acting on the piston 112a, reaches a selected value, the pintle will begin to lift from off a seat 115, and fuel will flow from the passage 126 into a channel 112d and through the tip orifice 118.

Initially, with the land 136 adjacent to the cylindrical section 1126, the fuel flow rate will reach an intermediate value. This intermediate flow rate will remain substantially constant until the land 136 on the pintle 12G moves away from the cylindrical section 1126 of the body 111 into the cavity 112b, increasing the area of the annular passage 126. At this time, the fuel flow rate will increase rapidly up to some maximum value. Thereafter when the fuel pressure is sufiiciently reduced, the pintle will again reseat and block the communication of the pressurized fuel with the channel 112d FIGURE 4 is a variation of the FIGURE 3 arrangement, wherein a raised land 238 is disposed on the body 211, adjacent to the section 22% of the pintle 220, when it is seated. In the seated position, the annular passage area 226 is reduced in an area adjacent to the surface of the cylindrical section 2200. When the pintle 220 raises so that the inclined surface 220d is adjacent to the rearward edge 240 ofthe land 238, the area of the annular passage 226 will be increased, and consequently the fuel flow rate will rapidly increase to a maximum value.

In the illustrated embodiments of FIGURES 24, the injection nozzle is provided with acavity, located relatively far from its'orifices, which is the general configuration used for compression ignition engines, inasmuch as it avoids the binding of the pintle in the body from overheating by removing the closely fitting parts of the pintle and the body from proximity with the combustion chamber of the engine. However, injection nozzles are also in use wherein the cavity is relatively close to the orifice, and of course, it will be understood that the present invention may also be applied therewith.

In the operation of all of the illustrated embodiments, the annular passage area is, by the provision of various lands and grooves on the pintle and the body, adapted to be reduced in one position of the pintle and increased in another thereby providing a means for varying the fuel flow rate.

Therefore, it will be understood by those skilled in the art that the above described embodiments are meant to be merely exemplary, and that they are susceptible to modification and variation. For example, in the preferred embodiments, an annular passage is defined between a cylindrical section and the body; however, it will be understood that this passage is not limited to an annular configuration. Therefore, all such variations and modifications are included within the scope of the invention as set forth in the appended claims.

I claim:

1. A fuel injection nozzle for internal combustion engines comprising a nozzle body having a central bore, a hollow tip containing a plurality of orifices adjacent to one end of said body and communicating with said bore, a valve seat in said body between said bore and said tip, means for introducing fuel under pressure into said bore, a pintle movable lengthwise of said bore and of smaller cross-section than said bore to afford a passage for flow of fuelfrom said means for introducing fuel to said orifices, a valve portion on and adjacent to one end of said pintle movable therewith into and out of engagement with said valve seat, a first annular land on said body extending into said bore toward said pintle and spaced lengthwise of said bore from said valve seat, a second annular land on said pintle further to position said lands in spaced opposiportion and disposed between said first land and said valve seat when said valve portion engages said seat and means responsive to pressure of fuel introduced into said bore for moving said pintle to disengage said valve portion from said seat and (1) allow fuel to flow to and discharge through said orifices at a predetermined rate, (2) move said pintle further to posiiton said lands in spaced opposition to provide a restricted passage for flow of fuel therethrough and reduce the rate of flow of fuel to and through said orifices, and (3) move said pintle still further and position said lands in olfset relation to increase the rate of flow of fuel to and through said orifices.

2. The nozzle set forth in claim 1 comprising a groove in said pintle opposing said first land when said valve portion engages said valve seat and prior to movement 5 of said lands into opposition to provide a higher fuel flow 2,214,757 rate than when said lands are opposed. 3,249,308

References Cited 5 908,905 UNITED STATES PATENTS 1, 9 4 1,085 1,737,985 12/1959 Tllrsky 239-533 7 1,833,080 11/1931 Kenworthy 239-584 X 1,952,816 3/1934 Mock 239--533 X 6 9/ 1940 Alden 239-584 X 5/1966 Cadiou 239-533 X FOREIGN PATENTS l/ 1965 Great Britain. 7/ 1938 Italy. 5/ 1952 Italy.

M. HENSON WOOD, 111., Primary Examiner. VAN C. WILKS, Assistant Examirver.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,368,761 February 13, 1968 Winton John Pelizzoni It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 60, for "further to position said lands in spaced opposi-" read spaced lengthwise of said pintle from said valve line 67, for "posiiton" read position Signed and sealed this 1st day of April 1969.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer

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