US2753217A - Fuel injection nozzle for internal combustion engine - Google Patents

Description

y 3, 1956 R. J. PECORA, JR., ET AL 2,753,217

FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINE Filed Nov. 8, 1952 2 Sheets-Sheet l l w I F I I LIHEH H INVENTORS PAL/9H J. Pc0P/4 J sA/wusz, w. psm/ FEL/X w. FLEM/NG- AT TURKEY y 1956 R. J. PECORA, JR, ET AL M53 21? FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINE Filed Nov. 8, 1952 2 sheuts'sheet 2 W ATTOENE Y FUEL INJECTION NOZZLE FOR INTERNAL CGMBUSTION ENGINE Ralph J. Pecora, Jr., and Samuel W. Rein, Beacon, and Felix W. Fleming, Cold Spring, N. Y., assignors to The Texas Company, New York, N. Y., a corporation of Delaware Application November 8, 1952, Serial No. 319,484

3 Claims. (Cl. 299--107.6)

The present invention relates to fuel injection nozzles for internal combustion engines and more particularly to such nozzles of the variable flow-area type wherein fuelfiow quantity is controlled by the pressure of the fuel supplied to the nozzle.

Diificulties have been experienced in operation of prior 4 parts of the nozzle, which causes erratic operation and unpredictable irregularities in the rate and timing of fuel delivery.

These difiiculties seriously affect the utility of many prior art nozzles in internal combustion engines requiring for their proper performance a high degree of precision of fuel delivery to the combustion chamber. Avoiding such troubles often requires the exercise of extreme care in manufacturing the nozzles, with its attendant high cost.

It is an object of this invention, therefore, to provide an improved internal combustion engine fuel injection nozzle of the fuel pressure controlled type which is particularly suitable for use with engines requiring precision control of fuel delivery.

I t is another object to provide an improved fuel delivery nozzle for engines requiring delivery of fuel in a highly uniform manner, free from irregularities and unpredictable variations in fuel delivery timing, duration, and rate.

it is another object to provide an improved nozzle of simplified design which is particularly suited to manufacture at reduced cost without sacrificing desired precision of performance.

it is another object to provide an improved nozzle of the aforesaid type which is particularly suited to quick and easy assembly and disassembly, with reduced danger of injury to its precisely dimensioned surfaces.

Another object is to provide an improved nozzle of the aforesaid type having a portion functioning exclusively to control fuel flow rate, and another physically separated portion functioning exclusively to control the shape of the fuel spray delivered by the nozzle.

Another object is to provide an improved nozzle of the aforesaid type having an extended lower limit of fuel flow rate, without sacrifice of precision control of fuel delivery.

Another object is to provide an improved nozzle of the aforesaid type which is particularly suitable for economical production in a large number of sizes of flow capacity and with many different spray shapes.

Another object is to provide a nozzle of the aforesaid type enabling control of the fuel fiow rate separately and independently from control or variation of the shape of the fuel spray delivered by the nozzle.

These and other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings wherein:

Fig. l is a sectional view of a fuel injection nozzle constructed in accordance with the present invention.

Fig. 1a is a view showing the nozzle pintle and spring retainer prior to locked assembly.

Fig. 1b is a view taken along line Illa-1b of Fig. 1, showing the pintle in locked position with the spring retainer.

Fig. 2 is an enlarged sectional view of the nozzle shown in Fig. 1, taken on line 2-2 of Fig. 1.

Referring to Figs. 1 and 2, the nozzle includes a body member 1 enclosing a fuel chamber 5, and provided with a cylindrical bore forming a fuel discharge passage 3. At its outer end the fuel discharge passage 3 is preferably counterbored to form a shallow annular groove 19. At its inner end the fuel discharge passage 3 is provided with a restriction 10 slightly chamfered or lapped at its outer end to form a conical valve seat 11. Outwardly adjacent restriction 10, discharge passage 3 is provided with an annular enlargement 12.

Adapted to reciprocate in discharge passage 3 is a nozzle pintle 7. At its inner end, the pintle 7 is provided with a conical seating surface forming a valve 13, which is adapted to mate with the valve seat 11 to seal off fuel flow thrpugh the discharge passage 3. The outer diameter of valve 13 exceeds that of seat 11, so that when seated, a portion of the conical surface of valve 13 overlaps seat 11, and is sealed off from chamber 5. Extending from valve 13 through valve seat 11 and passage 3 in restriction Ill into fuel chamber 5 is a valve stem 21 of diameter substantially smaller than valve seat 11. Adjacent the valve 13, the pintle 7 is provided with flats 23 on several 8 sides relieved by longitudinal lands 25 which constitute a guiding surface for accurately supporting the pintle 7 coaxially in the cylindrical fuel discharge: passage 3.

Adjacent the outer end of lands 25, the pintle is turned down to provide a conical flow control surface 33 having its larger diameter at its outer end. This conical surface cooperates with the outer end 20 of discharge passage 3 to define an annular fuel emission orifice 34. The apex angle 39 included by this conical flow control surface 33 determines the rate of discharge of fuel through orifice 34 as the pintle 7 is reciprocated within the nozzle body ll, as will be more fully explained hereinafter.

The outer end of the pintle 7 is enlarged to form another conical portion 27, increasing in diameter toward its outer end, which is accommodated in and protected by the annular groove 19. The surface of conical portion 27 serves to deflect and assist in atomizing fuel emitted through orifice 34, and its apex angle 28 thus determines the shape or angular width of the conical spray pattern of fuel emitted from the nozzle.

The conical flow control surface 33 is preferably separated from conical portion 27 by a short: cylindrical portion 35 of pintle 7, which is preferably positioned so as to be partially enclosed within the outer end 29 of discharge passage 3 when valve 13 is seated on valve seat 11. The small inner end of flow control surface 33 is likewise preferably separated from lands 25 by a short cylindrical surface 37.

Enclosed within fuel chamber 5, and supported from its end wall 41, is a compression spring 43.. Also enclosed within fuel chamber 5 is a spring retainer 45, having a disc-shaped base with straight or flat edge portions at 45 and an opening 47 through the center thereof, communicating with an elongated opening on its upstream side shown as a rectangular slot 47', both openings being coaxial with the discharge passage 3. The spring retainer 45 is provided on its upstream side also with another elongated slot disposed at right angles to the rectangular slot 47' and shown as rectangular groove 49. The head of valve stem 21 is elongated and is shown as ground flat on opposite sides and enlarged to form a generally T- shaped head 22 which can pass through restriction 10 and is adapted to fit through the opening 47 and the rectangular slot 47 in spring retainer 45 during assembly of the nozzle. Upon rotation of the spring retainer 45 ninety degrees about the axis of valve stem 21, the rectangular head 22 of the valve stem. is aligned with the rectangular groove 49 in the face of spring retainer 45. The spring 43 acts against spring retainer 45, urging it in a direction away from discharge passage 3, thereby seating head 22 in groove 49 and tensioning stem 21 to bring valve 13 into seating relation with valve seat 11. The deflection of spring 43 may be any desired function of the force applied, and optionally the single spring depicted may be replaced with a plurality of springs, preferably disposed concentrically about stem 21, if desired.

In operation of the above described nozzle, fuel under pressure is admitted to the fuel chamber 5 through an inlet passage and preferably a filtering screen, not shown, and flowing past the fiat edge portions 45 on spring retainer 45, through the annular passage between stem 21 and discharge passage 3 through restriction 10, acts upon the projected area of pintle 7 surrounded by valve seat 11 to overcome the force of spring 43 and lift pintle 7 and valve 13 from its seat 11. Fuel then flows into the annular space 12, and outwardly of discharge passage 3 across flats 23 between lands 25, to the space surrounding the conical flow control surface 33. At the outer end of discharge passage 3 fuel is emitted through the annular orifice 34 formed between the circumference of end 20 and the nearest part of conical surface 33 or cylindrical surface 35, whichever is the closer, as determined by the axial displacement of pintle 7 in accordance with fuel pressure in chamber 5.

As soon as valve 13 is lifted from seat 11, the projected area of the remainder of the valve surface is subjected to fuel pressure, which immediately increases the force tending to hold the valve open, and counteracts the reduction in force on the valve caused by the drop in fuel pressure at the valve when it opens. This enables the valve to open smoothly, and stay open until the pressure of fuel to chamber 5 is decreased below valve closing pressure, this preventing hunting or chattering of the valve.

The rate of fuel emission from the nozzle is determined by the limiting area of the orifice 34 through which the fuel must pass. When the nozzle valve 13 is first lifted from its seat 11 and fuel first begins to flow, this limiting area occurs between the outer end 20 of discharge passage 3 and the cylindrical surface 35. When it is desired to increase the fuel rate through the nozzle, the fuel supply pressure in chamber 5 is increased, producing a greater force on the projected area of pintle 7, which further compresses spring 43 and forces the pintle further outward until the increased deflection force of the spring 43 balances the increased force on pintle 7. Fuel pressure required to open valve 13 can be varied by lapping the end of spring 43, or inserting shims between the spring and surface 41 or retainer 45.

Suflicient outward movement of the pintle extends the whole of the short cylindrical surface 35 beyond the outer end 20 of discharge passage 3. At this point, the minimum flow area begins to be determined by the clearance between the outer end 20 and the nearest part of the c0nical flow control surface 33. Thus, it will be recognized that as the pintle 7 is further and further extended in an outward direction, the limiting annular orifice which determines the fuel emission rate becomes larger and larger at a rate determined by the apex angle 39 of the conical flow control surface 33. When this apex angle 39 is large, a very small displacement of the pintle will produce a large change in this limiting annular orifice; when the apex angle is very small, a relatively large displacement 4 of the pintle 7 is required to produce the equivalent increase in fuel rate, and very fine control of the fuel rate is thereby achieved. A preferred value for this apex angle 39 is from five to fifteen degrees.

The non-tapering cylindrical surface 35 assists in preventing hunting of pintle 7 about a point of equilibrium where valve 13 is close to its seated position, because when cylindrical surface 35 determines one circumference of the limiting orifice area, movement of the pintle 7 is not accompanied by a variation in the orifice area. Pintle movement in this region without varying orifice area thus avoids feeding back a variation in fuel pressure to the valve seat, which could lead to hunting or rhythmic oscillation of the pintle.

The escaping fuel strikes the surface of the enlarged conical portion 27 and is atomized and deflected from it in a spray pattern of conical shape whose angular width is determined by the apex angle 28 of the conical portion 27. A preferred value for the apex angle 23 is from twenty to sixty degrees.

The particular arrangement by which the end of the valve stem 21 is connected to the spring retainer 45 permits assembly and removal of the pintle 7 from the nozzle body it merely by compressing spring 43 to free head 22 of valve stem 21 from the rectangular groove 49, and rotating spring retainer 45 ninety degrees about the axis of valve stem 21. The spring retainer 45 may then be removed from body 1 by passing the rectangular opening 47 over the head 22 of stem 21, after which pintle 7 can be withdrawn through discharge passage 3. This arrangement is particularly suited to eliminating the necessity for cocking r finely machined surfaces of the pintle 7 and discharge passage 3.

It will be recognized that in the nozzle above-described, the physical separation of that portion of the nozzle which determines the width of the spray pattern, i. e., the conical portion 27 at the outer end of pintle 7, from the portion of the nozzle which controls the rate of fuel emission in accordance with displacement of pintle 7, i. e., the conical flow control surface 33, enables the angular width of the fuel spray pattern to be made any desired value without affecting the flow rate control. And conversely desired flow rate characteristics can be achieved without affecting the shape of the spray pattern. Thus, nozzles of the type herein described are particularly suited to production in a Wide range of flow capacities having the same spray shape, or in a wide range of spray shapes having the same flow capacity, all using the same basic nozzle body 1 and discharge passage 3. The present invention affords the additional advantage that the very careful machining of flow control surfaces, which is required to achieve the desired degree of precision of fuel delivery, need only be devoted to the fiow control surface 33 and the end 20 of discharge passage 3 with which it cooperates to define the limiting annular fuel flow orifice. A lesser degree of care can be exercised in machining the conical spray shape control surface of portion 27 of the pintle 7 and the other surfaces of the nozzle, which enables a substantial reduction in manufacturing cost of the nozzle.

Thus, there has been shown and described a fuel injection nozzle for internal combustion engines which provides improved precision of control of fuel delivery, which is particularly suited to manufacture with reduced cost in a wide variety of flow capacities and spray shapes without sacrificing precision of performance, and which can be quickly and easily assembled and disassembled with reduced likelihood of injury to its precisely dimensioned surfaces.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A fuel nozzle comprising a body provided with a fuel chamber therein having a fuel inlet passage and a fuel discharge passage, a pintle reciprocably supported in said discharge passage for outward displacement proportional to fuel chamber pressure and carrying an outwardly opening valve thereon, spring means urging said pintle inwardly of said discharge passage, a constriction at the inner end of said discharge passage forming a valve seat adapted to cooperate with said valve to provide a rigid stop for said pintle and seal said discharge passage, means on said pintle and downstream of said valve for centering said pintle in said discharge passage, said pintle having a first conical portion outwardly spaced from said last mentioned means and increasing in diameter toward its outer end and cooperating with the outer end of said discharge passage to define an annular orifice for said discharge passage having an area proportional to the outward displacement of said pintle, a second conical portion on said pintle outwardly spaced from said first conical portion for atomizing and deflecting fuel emitted through said orifice into a conical spray pattern having an apex angle proportional to the apex angle of said second conical portion, and a cylindrical portion on said pintle intermediate said first and second conical portions substantially filling said discharge passage and positioned partially within said discharge passage outer end when said pintle has zero outward displacement, said first conical portion having an apex angle of from 5 to 15, said second conical portion having an apex angle of from 20 to 60, and said means for centering said pintle comprising longitudinal lands.

2. In a fuel nozzle as described in claim 1, a valve stem extending from said pintle into said fuel chamber, a spring retainer in said fuel chamber having an opening therethrough communicating with an elongated opening on the upstream face thereof with both openings coaxial with said discharge passage, an elongated slot on said upstream face of said spring retainer disposed substantially perpendicularly to said elongated opening, and an elongated head on the end of said valve stem adapted to pass through said openings in said spring retainer and to fit into said elongated slot to connect said stem and said spring retainer for urging said pintle into valve closing position in said discharge passage.

3. A fuel injection nozzle comprising a body member enclosing a fuel chamber provided with a fuel inlet passage and a fuel discharge passage, a pintle reciprocably supported in said discharge passage for outward displacement therein proportional to fuel chamber pressure and carrying an outwardly opening valve thereon, spring means urging said pintle inwardly of said discharge passage, a constriction at the inner end of said discharge passage forming a valve seat adapted to cooperate with said valve to provide a rigid stop for said pintle and thereby seal said discharge passage, means on said pintle downstream of said valve for centering said pintle in said discharge passage, said pintle having a first conical portion outwardly spaced from said last mentioned means and increasing in diameter toward its outer end and cooperating with the outer end of said discharge passage to define an annular orifice for said discharge passage having an area proportional to the outward displacement of said pintle, a second conical portion on said pintle outwardly spaced from said first conical portion for atomizing and defleeting fuel emitted through said orifice into a conical spray pattern having an apex angle proportional to the apex angle of said second conical portion, and a cylindrical portion on said pintle intermediate said first and second conical portions substantially filling said discharge passage and positioned partially within said discharge passage outer end when said pintle has zero outward displacement, a valve stem extending from said pintle into said fuel chamber, a disc-like spring retainer in said fuel chamber having an opening therethrough coaxial with said discharge passage and ending in a rectangular opening on the upstream side thereof, a rectangular slot on the upstream face of said spring retainer disposed perpendicularly to said rectangular opening, and an elongated head on the end of said valve stem adapted to pass through said openings and to fit into said slot to connect said stem and spring retainer for reacting against said spring means.

References Cited in the file of this patent UNITED STATES PATENTS 2,017,028 Heinrich Oct. 8, 1935 2,297,487 LOrange Sept. 29, 1942 2,375,492 Purdy May 8, 1945 2,376,292 Tabb May 15, 1945 2,439,832 Voit Apr. 20, 1948

Claims (1)

1. A FUEL NOZZLE COMPRISING A BODY PROVIDED WITH A FUEL CHAMBER THEREIN HAVING A FUEL INLET PASSAGE AND A FUEL DISCHARGE PASSAGE, A PINTLE RECIPROCABLY SUPPORTED IN SAID DISCHARGE PASSAGE FOR OUTWARD DISPLACEMENT PROPORTIONAL TO FUEL CHAMBER PRESSURE AND CARRYING AN OUTWARDLY OPENING VALVE THEREON, SPRING MEANS URGING SAID PINTLE INWARDLY OF SAID DISCHARGE PASSAGE, A CONSTRICTION AT THE INNER END OF SAID DISCHARGE PASSAGE FORMING A VALVE SEAT ADAPTED TO COOPERATE WITH SAID VALVE TO PROVIDE A RIGID STOP FOR SAID PINTLE AND SEAL SAID DISCHARGE PASSAGE, MEANS ON SAID PINTLE AND DOWNSTREAM OF SAID VALVE FOR CENTERING SAID PINTLE IN SAID DISCHARGE PASSAGE, SAID PINTLE HAVING A FIRST CONICAL PORTION OUTWARDLY SPACED FROM SAID LAST MENTIONED

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