US2243995A - Nozzle - Google Patents

Description

C. R. ALDEN June 3, 1941.

NOZZLE Filed Aug. 12, 1937 v Patented June 3, 1941 NOZZLE Carroll R. Alden, Detroit, Mich., assignor to Ex- Cell-O Corporation, tion oi Michigan Detroit, Mich, a corpora- Application August 12, 1937, Serial No. 158,639

15 Claims.

The present invention relates to improvements in nozzles adapted particularly for delivering timed metered injections of liquid fuel in connection with the operation of internal combustion engines.

One of the important objects of the present invention is to provide a novel fuel injection nozzle in which proper atomization of the fuel and maximum penetration consistent therewith of the issuing jet or spray into the combustion space are obtained at all "rates of injection.

Another object is to provide a new and improved plain orifice nozzle in which the manner of approach of the fuel to the orifice is varied to change the discharge characteristics in accordance with changes in the rate of injection.

A further object is to provide a novel plain orifice nozzle in which the coefiicient of discharge of the orifice is controlled by the flow of the fuel.

A more specific object is to provide a new and improved fuel injection nozzle with a plain discharge orifice in which the fuel is caused to issue from the orifice as a jet or spray varying progressively from a centrifugal form to a non-centrifugal form in the course of the valve opening movement, whereby the coeflicient of discharge and hence the flow capacity of the orifice are progressively increased to obtain the required dispersion and penetration characteristics not only at maum rates of delivery but also at low and medium rates 01 delivery.

Still another object is to provide a novel flowcontrolled fuel injection nozzle with a plain discharge orifice in which initial, intermediate and final flow restrictions of progressively increased flow areas are successively efiective to set up opening pressure assistances in the course of the valve opening movement, and in which the intermediate restriction is also efi'ective within its range to vary the coeficient of discharge of the orifice as required to maintain a proper injection pressure at low and medium rates of delivery.

Further objects and advantages will become apparent as the description proceeds.

In the accompanying drawing,

Figure l is a longitudinal sectional view of a nozzle tip embodying the features of my invention.

Figs. 2 and 3 are transverse sectional views taken respectively along lines 22 and 3-3 of Fig. 1.

Figs. 4 and 6 are fragmentary longitudinal sectional views of two modified forms of nozzle tips embodying the general features of the invention.

(Cl. 299-10Z.6)

Fig. 5 is a detail sectional View taken along line 5 -5 of Fig. 4.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawing and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

The present invention is an improvement of the nozzle disclosed in my copending application, Serial No. 152,074 filed July 6, 1937.

Referring more particularly to the drawing, the fuel injection nozzle illustrated in Figs. 1 to 3 comprises a suitable body or housing H. Preferably, the body ii is in the form of a tubular shell defining an axial bore 52, and having an external peripheral flange it at the base end and an internal peripheral flange M at the discharge end.

The discharge end of the shell ii is closed by an orifice head it which has suitable orifice means with the desired fuel discharge characteristics, and which preferably is removable to permit substitution for different spray patterns and characteristics. The orifice head may be provided in any desired form, and in the present instance is shown as a circular plate or block extending snugly through and beyond the flange i i, and having an external peripheral mounting flange i6 seating snugly within the bore i2 against the inner face of the flange it.

A generally tubular spacer ll, having an inner peripheral flange it at the outer end defining an axial guide bore i9, is removably fitted into the shell H and serves to hold the plate IS in position. Removably positioned against the inner end of the spacer H is a tubular valve body 29 having an inner peripheral end flange 2|.

A stationary member 22 in the form of a cylindrical valve plug is removably fitted into the base end of the shell ii against the body 20, and serves to hold the various parts within the shell M in assembled position. Suitable plastic means 23 may be pressed into an annular groove 24 having opposed complementary sections in the base end of the shell M and the member 22, and serves to seal and maintain the assembly. The member 22 is formed with an axial fuel inlet passage 25 adapted for a fluid-tight connection with a fuel pump or other suitable means (not shown for supplying the fuel to be injected.

It will be understood that the assembly just described constitutes the rigid structure of the nozzle tip, and as such is adapted to be connected to the source of fuel supply, and to be clamped or secured to the engine at thedesired point of injection. A nozzle holder or other suitable means, not specifically disclosed herein since per se it forms no part of the present invention, may be utilized for this purpose as is well understood in the art. The rigid structure of the nozzle tip is susceptible of various modifications and alternative forms without departing from the broad aspects of the present invention, and in general provides an internal chamber 26, defined by the spacer I1 and the body 20, and adapted for communication with the inlet passage 25 and to discharge through the orifice body I5.

The supply of fuel under pressure, from the inlet passage 25 to the chamber 26 for injection through the orifice head i into the combustion space, is under the control of a nozzle valve 21. Within the broad aspects of the invention, the valve 217 may be of any suitable form or character. in the present instance, the valve 21 is spring seated against the pressure of the fuel, and opens outwardly in the direction of the fuel how. More particularly, the valve 2? comprises a flat annular valve seat-28 formed in the inner end of the valve plug 82, and encircling a valve passage Ell opening from the passage 25. movable valve memlcer so, herein shown in the form. of a partial or hall? hall, has a flat valve face i i adapted ior engagement with the seat "When the valve member 35B is seated, the seat defines a central pressure area Av on the face it exposed to the fuel pressure in the passage Any suitable means may he provided for sup-= porting the valve member 3t, and m the present instance this means comprises a retainer 32 in the form of a circular head slidably guided in the valve body Eli and rigid with the inner end of an axial stem guided in the bore is. To permit self-alignment with the valveseat "28, the spheri= cal portion of the valve member it is seated for universal adjustment in a partial spherical socket 36 formed in the free end face otthe retainer head A coiled compression spring closely encircles the stem tit, and abuts at oppoiste ends against the spacer flange i8 and the head to urge the valve member Elli toward or against the valve seat it with a predetermined spring pressure. I

The valve member tilt is reoiprocably disposed within the confines of the flange 2i, and coacts therewith to define an annular flow passage Formed in the periphery of the head 32 are a plurality of longitudinal flutes ill! (see Fig. 2) which provide unrestricted flow passages from the passage 36 to the chber 22% alooutthe stem The outer end portion of the stem 33 is formed with a peripheral groove to defining a head 39 slidable' with a close fit in the outer end of the bore no, and is also formed on the perlph cry with a plurality of longitudinal flats do (see Fig. 3) deg flow passages opening from the chamber in to the groove 38. A plurality of grooves ii in the periphery of the head it serve to connect the groove 38 to the orifice means in the orifice head it. It will be understood that the not; path of the fuel from the valve 21 to the orifice head I 5 leads through the passage 36, the flutes 31, the chamber 26, the passages along the flats 40, the groove 38 and the grooves 4 i area 01' the ball element 30 exposed to the valve passage 29 at the valve seat 28, i. e., the valve opening pressure area Av. When the hydraulic pressure times the area Av overbalances the pressure of the spring 35, the valve 21 will open to permit the flow of fluid to the orifice head l5. at which point hydraulic pressure is again built up by reason of the orifice restriction.

The opening of the valve 21 is made at least in part responsive to the rate of fuel flow so that the applied hydraulic pressure may be limited and controlled as desired throughout the range of valve movement. More particularly, a pinrality of flow restrictions or resistances of difierent flow areas are'interposed in the path of fuel fiow, and are successively eflfective over different portions of the injection range in the opening and closing movements of the valve 21. Each of these restrictions when in control tends to build up a difierential pressure responsive to the rate of flow and separate from the injection pressure and acting on a lifting area Ad larger than the valve opening area Av. By reason of this difierence in area, a relatively small pressure olifierential is required to move and hold the valve filopen, and hence the remaining pressure of the total applied pressure is relatively high and is utilized solely for injection purposes to obtain the desired atomization and penetration. The subdivision of the pressure to perform the separate functions makes possible a heavy lifting action without on it wi l he understood that the flow restrictions may he provided in any suitable manner, and may he varied Widely in form and character depending on the operating characteristics de sired.

The assistance A is in control when the valve member 3t is in close proximity to the seat 28, and causes the initial opening movement and the final closing movement or the valve 2?] to occur with extreme rapidity. It is transient or disappearing in character in the opening movement of the valve ii. To obtain the assistance A, the annular valve seat 28 is peripherally relieved by an encircling groove or recess 52 formed in the plug 22, thereby providing a. small seat area. As a result, the seat pressure is suinciently high to collapse or extrudethe oil film between the valve faces when the valve 2?! is closed. The bottom of the groove 32 is inclined outwardly toward the face iii of the valve memher it, and coacts with the peripheral edge of the latter to define a annular flow restriction 33. By mmthe bottom of the groove 32, the seat 28 is conveniently provided with a substantial relief, and the efiective um area or clearance of the small flow restriction 53 y be readily and accurately determined by the use of mathematics, the depth of the seat relief, the angle and the radial dimensions of the half ball at and seat 28 being known. The bottom of the groove 42 being closely spaced from the peripheral edge of the half ball SI also serves approximately to square up the latter with the seat 28. Hence, the hall ball 30 cannot engage the seat 28 at an angle sufiiciently large to cause damage or result in valve leakage.

When the hydraulic pressure from the source of supply acting on the closed valve area Av is sufficient to overcome the force of the spring 33, the valve 21 will open. After the initial opening movement, the annular restriction 43 builds up a pressure differential which is applied to the fiat face area of the valve member 30, and which assists the initial force to accelerate rapidly the first portion of the valve movement, so

that the valve member 30 is caused to leave the tion. The assistance A also serves to accelerate rapidly the final closing movement of the valve 21. As the valve member moves into close proximity to the seat 28, the restriction 32 again becomes effective, and sets up a differential pressure acting on the ball area 3| in opposition to the closing movement. However, when the rate of flow drops to a point where the assistance A is no longer effective to balance the closing force, the spring 35 will move the valve member 30 rapidly toward the seat 28 to close the valve 21 with a popping action.

The assistance B becomes effective after disappearance of the assistance A, and serves to control the transition from the slowest rates of delivery to medium rates of delivery. To obtain this assistance, the grooves 4| are formed to define a fiow restriction tending to set up a differential pressure acting outwardly on an efiective area equal to the transverse area of the stem 33. As the head 39 moves outwardly of the bore IS in the opening movement of the valve 21, the effective length of the grooves ii is shortened, thereby reducing the flow restriction. Hence, the assistance B also is transient or disappearing in character so as to be effective only over the intermediate range of injection.

The final assistance C becomes efiective after disappearance of the assistance B, and hence controls the transition from medium rates of delivery to maximum rates of delivery. To obtain this resistance, the clearance between the flange 2i and the peripheral edge of the valve member 30 is small so that the passage 36 defines a flow restriction tending to set up a differential pressure acting outwardly on theface 3i. It will be understood that the valve may open to any point in the range of movement depending on the rate and quantity of injection. The assistances A, B and 0 would be relatively so proportioned as to cooperate to obtain the desired result. For further details as to the function and operation of the assistances A, B and C, reference may be had to the aforesaid copending application.

The orifice head i5 may be provided in various forms depending on the spray characteristics desired. In Fig. 1, the head I! is formed in the inner face with an injection pressure chamber 44 which registers with the bore I3 to receive the head 39 in the opening movement of the valve 21, and which opens axially to a single plain hole discharge orifice ll. Preferably, the 'free end of 'the head I! and the walls of the chamber 44 are tapered or stream-lined in the direction of fuel fiow.

One of the important features of the present invention is to vary the discharge characteristics of the orifice I in accordance with the rate of fuel fiow so as to obtain proper atomization and penetration at all rates of delivery, and particularly to permit the delivery of very small quantities of fuel without the presence of objectionable solids through a fixed orifice otherwise of sumcient size for maximum injection. This is accomplished by changing the manner of approach of the fuel to the orifice 45 whereby to vary the coefilcient of discharge as required. The degree of atomization is a function of the pressure applied at the orifice, and the pressure varies as the square of the velocity times the coeificient of discharge. If this coeificient'is constant, the pressure at low rates of delivery may be too low to break up the fuel. By varying the coemcient, an effect comparable to a variation in the size of the orifice is obtained.

To control the coemcient of discharge of the orifice 45, a variable centrifugal action is imparted to the entering fuel. In Fig. 1, the centrifugal action is obtained by means of the grooves ll which preferably are V-shaped and of suitable fiow area and proportions in crosssection, and which are formed with a suitable helical lead to impart a swirl to the fuel passing therethrough. The swirl of the fuel reduces the coeflicient of discharge, and hence builds up an injection pressure in the chamber 44 suificient to effect proper atomization. Since the head 39 moves outwardly into the chamber 44, the effective length of the grooves 4| is progressively decreased in the course of the valve opening 'movement. Hence, the coeflicient of discharge is the lowest at minimum rates of delivery and increases progressively through the range of the assistance 3. Upon movement of the peripheral groove 33 into direct communication with the chamber 44, the grooves 4i cease to be effective, and the fuel jet issuing from the orifice 45 becomes non-centrifugal. The assistance C accomplishes the last step in removing the centrifugal action to whatever extent it is to be removed depending upon the particilar penetration and dispersion characteristics required.

The groove belt defined by the head 39 has a clos and uniform sliding fit with the bore l9 so that the grooves ll will have maximum effectiveness in defining the flow passages therethrough and in varying their restrictive action with changes in the valve lift.

The spiral grooves ll should have a fiow area sufliciently restricted to make the assistance B effective, but not restricted to an extent resulting in interference with th proper functioning of the assistance A.

The helix angle of the grooves, i. e. the lead along the stem axis, may be varied within limits depending on the atomization and penetration characteristics-desired, without departing from the invention. Ordinarily, the helix angle should be the maximum consistent with desired atomization at low rates of injection. Decreasing th helix angle results in a greater centrifugal action and a corresponding decrease in the coeflicient of discharge. A greater cone spray angle, with increased atomization, is thereby obtained, and the jet penetration is decreased. In-

creasing the helix angle results in a smaller spray cone angle and increased jet penetration.

Figs. 4 to 6 illustrate various modified forms eliminating stream-lining and having different types and arrangements of discharge orifices. In all other respects, these modified forms are the same as the form of Figs. 1 to 3, and the same reference characters are therefore employed to identify corresponding parts.

In the form of Figs. 4 and 5, the head or groov belt 39 is cylindrical throughout its length and fiat at the end, and the chamber 44 is similarly shaped. A plurality of discharge orifices 45b, for example two diametrically spaced orifices, open from the chamber 44 to discharge radially from the orifice head l5. To provide the orifices 45b, two radial bores 46 are formed in opposite sides of the head 15 adjacent the exterior of the flange l4, and at their inner ends longitudinally intersect the outer end surface of the chamber 44. Bushings 41 with axial apertures defining the orifices 45b. ar tightly fitted into the outer ends of the bores 46.

The coefficient of discharge of the orifices 45b is controlled in the same manner as in Fig. 1. During low rates of delivery, the groove 4| impart a centrifugal action to the fuel entering the chamber 44. The centrifugal action in the chamber 44 imparts to the fuel entering the bores 46 a secondary swirl about each of the orifice axes. In the full opening movement of the valve, the fuel issues from each orifice 45b first in the form of a centrifugal envelope of progressively diminishing cone angle, and then in the form of a non-centrifugal spray or jet.

The form of Fig. 6 is exactly like that of Figs. 4 and with the exception that the two radial orifices 450 open directly from the chamber 44 and along diverging axes. In these various forms, the coeflicient of orifice discharge is fiowcontrolled as described. By reason of the flat transverse end faces of the head 39 and the chamber 44, a softer non-centrifugal jet is obtainable than in the stream-lined form of Figs. 1 to it.

I claim as my invention:

1. In a fuel injection nozzle, in combination, a body having a fuel inlet and a fixed cylindrical hole discharge orifice of constant restricted flow area and length, spring seated reciprocatory valve means for controlling th supply of fuel under pressure for discharge through said orifice, and means fixed with said means for effecting a centrifugal approach of the fuel to said orifice and for'varying the angle of said approach progressively in direct response to changes in the degree of valve opening so as to alter the spray characteristics for different rates of delivery and to vary the coefiicient of discharge of said hole orifice.

2. In a fuel injection nozzle, in combination,

a body having a fuel inlet and a fixed dischargeorifice of constant restricted flow area, spring seated reciprocatory valve means for controlling the supply of fuel under pressure for discharge through said orifice, and means movable positively with said valve means and operable in direct response to the opening movement of said valv means to cause the fuelto issue through said orifice initially in the form of a centrifugal envelope of' progressively decreasing cone angle and finally in the form of a non-centrifugal spray.

3. In a fuel injection nozzle, in combination, a hollow body having a central chamber with a plain hole discharge orifice at one end and an inlet passage at the other end, means defining an annular valve seat at the discharge end of said passage, a clearance groove encircling said seat and having a bottom inclined outwardly toward the plane of the seat face, a valve head movable in said chamber and coacting therewith to define a fiow restriction, a valve element mounted for self adjustment on said head and having a flat area disposed for engagement with said seat and coacting with the bottom of said groove to define another flow restriction when said valve element is in close proximity to said seat, spring means acting on said head in a direction to move said ,valve element toward said seat, and means movable with said head and coacting with the inlet of said discharge orifice to cause the emission of the fuel first in the form of a centrifugal envelope and then in the form of a non-centrifugal core as said valve element moves into fully open position.

4. In a fuel injection nozzle, in combination, a body having a circular chamber with an axial inlet bore opening thereto, a spring-seated valve for controlling the supply of fuel to said bore and opening in the direction of fuel flow, a head movable with said valve and slidable with a close fit progressively into and out of the outlet end of said bore, a plurality of helical grooves formed in the periphery of said head and opening to the opposite ends thereof, said head when in said bore coacting with said bore to constitute said grooves restricted fiow passages in the path of fuel flow from said bore to said chamber variable in effective length in accordance with the extent of valve opening, said passages being adapted to im art a centrifugal action to the fuel in said chamber and to build up a differential pressure acting as a valve Op ning assistance, and a fixed discharge orifice opening axially from said chamber.

5. In a fuel injection nozzle, in combination, a body having-a chamber with an inlet passage opening thereto, spring-seated valve means for controlling the supply of fuel to said passage and opening in the direction of fuel fiow, a head movable with said valve means and slidable with a close fit progressively into and out of the outletend of said passage, an inclined groove formed in the periphery of said head and opening to the opposite ends thereof, said head when in said passage coacting with said passage to constitute said groove a flow restriction in the path of fuel flow from said passage to said chamber variable in effect in accordance with the extent of valve opening, said restriction being adapted to impart a centrifugal action to the fuel in said chamber and to build up a differential pressure acting as a valve opening assistance and tending to move said head outwardly of said passage, and a discharge orifice opening from said chamber.

6. In a fuel injection nozzle, in combination, a body having a chamber with a fuel inlet, valve means for controlling the supply of fuel to said inlet, a head movable with said valve means and slidable with a close fit progressively out of said inlet into said chamber, said head being constructed to coact with said inlet when therein to define a restricted fiow passage along said head setting up a resistance to flow variable in effect in accordance with the position of said head in said inlet and arranged to direct the fuel centrifugally into said chamber, said passage being ineffective when said head is positioned out of said inlet, and a restricted pressure injectionorifice opening from said chamber.

7. In a fuel injection nozzle, in combination,

a body having a chamber'with a fuel inlet, valve means for controlling the supply of fuel to said inlet, a head movable with said valve means and slidable with a'close fit progressively into and out of said inlet, said head being constructed to coact with said inlet to define a restricted fiow passage means along said head when in said inlet to set up a resistance to fiow, said passage means being variable in effective length in ac-- cordance with the position of said head in said inlet and arranged to direct the fuel centrifugally about said chamber, and a plurality of fixed restricted pressure injection orifices opening from said chamber.

8. In a fuel injection nozzle, in combination, a body having a chamber with a fuel inlet, valve means for controlling the supply of fuel to said inlet, a head movable with said valve means and slidable with a close fit progressively into and out of said inlet, said head being constructed to coact with said inlet to define a fiow restriction variable in effect in accordance with the position of said head in said inlet and to direct the fuel centrifugally into said chamber, and a pluraiity of bores opening from said chamber along elements of a cone having its axis in said nozzle, and constituting plain hole discharge orifices.

9. In a fuel injection nozzle, in combination, a hollow body having an inner chamber with a fuel inlet at one end and a fixed discharge orifice at the other end, a spring seated valve for controlling the supply of fuel through said inlet to said chamber and opening in the direction of fuel fiow, and means for defining a plurality of peripherally inclined restricted flow passages in said inlet decreasing progressively in effective length in accordance with the opening movement of said valve for causing the fuel to enter said orifice centrifugally.

10. In a fuel injection nozzle, in combination, a hollow body having an internal chamber with a fuel inlet and having a second chamber with an outlet orifice and separated from said internal chamber by a connecting passage, a spring seated valve for controlling the supply of fuel from said inlet to said internal chamber and having a valve stem guided in said passage, the free end portion of said stem being formed with an annular groove in communication with said internal chamber and movable into and out of communication with said second chamber and defining a head projecting into said second chamber, a plurality of restricted helical grooves formed in the periphery of said head and estab discharge orifice and an outlet chamber opening to and tapered toward said orifice, means in said body defining a central chamber and a guide bore connecting said chambers, a springseated valve for controlling the supply of fuel from said inlet to said central chamber and opening in the direction of fuel flow, a stem on said valve guided in said 'bore and having a head movable with a close sliding fit from said bore progressively into said outlet chamber, a plurality of restricted grooves formed in and opening along the periphery of said head and being helically inclined, means defining a primary fiow restriction when said valve is in proximity to closed position and creating a difierential pressure upon fuel rfiow to impart an initial transient valve opening assistance, said inclined grooves constituting a second fiow restriction effective after said primary restriction and creating a difierentiai pressure upon fuel flow to impart a second valve opening assistance, and means defining a third fiow restriction eflective after said second restriction and creating a differential pressure upon fuel flow to impart a valve opening assistance as said valve continues movement toward full open position.

12. In a fuel injection nozzle, in combination, a casing having fuel inlet means and a restricted discharge orifice, spring-seated valve means con trolling the supply of fuel from said inlet means and having a relatively small valve area exposed when seated to the inlet pressure and a relatively large lifting area exposed to the inlet pressure upon initial opening of said valve means, and fiow restriction means independent of the flow area through said valve means located in the fiow path to said orifice and operable to provide a differential pressure acting on said lifting area, said restriction means in the opening movement of said valve means directing said fuel to said orifice first centrifugally and then non-centrifugally to vary the coefficient of discharge.

13. In a fuel injection nozzle, in combination, a body having a chamber with a fuel inlet, valve means for controlling the supply of fuel to said inlet, a. head movable with said valve means and slidable with a close fit progressively into and out of said inlet, said head being constructed to coact with said inlet to define a restricted flow passage along said head variable in effect in accordance with the position of said head in said inlet and arranged to direct the fuel centrifug-ally about said chamber, and a. plurality of peripherally spaced bores formed in said body and extending transversely of said head and being intersected tangentially by said chamber, each of said bores having an axial discharge or!- fice with a conical inlet, whereby the swirling fuel in said chamber is caused to enter and swirl in said bores and to discharge from said orifices in a centrifugal spray.

14. In a fuel injection nozzle, in combination, a body having a chamber with a fuel inlet; valve means for controlling the supply of fuel to said inlet, a head movable with said valve means and slidable with a close fit progressively into and out of said inlet, said head being constructed to coact with said inlet to define a restricted fiow passage along said head variable in effect in accordance with the position of said head in said inlet and arranged to directthe fuel centrifugally about said chamber, and a bore formed in said body and extending transversely of said head and being intersected tangentially by said chamber, said bore having an axial discharge orifice, whereby the swirling fuel in said chamber is caused to enter and swirl in said bore and to discharge from said orifice in a centrifugal spray.

15. In a fuel injection nozzle, in combination, a body having a fuel chamber with a fuel inlet and with a fixed restricted injection orifice discharging therefrom, said chamber being tapered toward said orifice, valve means for controlling the supply of fuel to said inlet, a. head movable with said valve means and slidable with a close fit in said inlet for movement progressively from said inlet into saidchamber as said valve means opens and movable from said chamber into-said inlet as said valve closes, said head and said inlet being formed to define a restricted flow passage along said head setting up a resistance to

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