US3387790A

US3387790A - Fuel injection nozzle

Info

Publication number: US3387790A
Application number: US633666A
Authority: US
Inventors: Luca Frank De
Original assignee: American Bosch Arma Corp
Current assignee: Ambac International Corp
Priority date: 1967-04-11
Filing date: 1967-04-11
Publication date: 1968-06-11
Anticipated expiration: 1985-06-11

Description

3 Sheets-Sheet 1 Filed April 11, 1967 FIGZ.

F'IGI.

INVENTOR: FRANK DE LUCA ATTYS.

June 11, 1968 F. DE LUCA 3,387,790

FUEL INJECTION NOZZLE FRANK DE LUCA ATTYS.

June 11, 1968 DE 3,387,790

FUEL INJECTION NOZZLE Filed April 11, 1967 I5 Sheets-Sheet 3 ATTYS.

United States Patent T 3,387,790 FUEL INJECTION NOZZLE Frank De Luca, Thompsonville, Conn., assignor to American Bosch Arma Corporation, Springfield, Mass, a corporation of New York Continuation-impart of abandoned application Ser. No. 561,489, June 29, 1966. This application Apr. 11, 1967, Ser. No. 633,666

11 Claims. (Cl. 239-453) ABSTRACT OF THE DISCLOSURE A fuel injection nozzle assembly comprising a holder, a nozzle mounted at one axial end of the holder having a bore defining a fuel chamber and a valve member mounted for axial movement in the bore of the nozzle. The assembly further includes a plug threadedly mounted in the holder and a stem spaced from the plug to adjust valve lift and spring biasing means in the holder for normally seating the valve in a closed position. The stem and valve have axially extending bores therein so that fuel from the inlet in the holder passes through to the fuel chamber surrounding the valve at the lower end of the nozzle. The tail section of the valve has a pair of angled fuel passageways which connect with the fuel chamber and the axial bore in the tail section of the valve.

This is a continuation-in-part of my prior application Ser. No. 561,489, filed June 29, 1966, for Fuel Injection Nozzle, now abandoned.

The present invention relates to improvements in fuel injection nozzles.

Some of these fuel injection nozzle assemblies conventionally comprise an elongated holder and a nozzle mounted at one end of the holder, the entire assembly being mounted in an elongated bore in the engine cylinder head to supply fuel to the cylinders of the engine.

In these assemblies, one end of the holder is provided with an inlet adapted to be connected to a suitable fuel supply source and an axial passage is provided in the holder which communicates with a fuel passageway in the nozzle to direct fuel to an annulus in the axial end face of the nozzle confronting the holder. From the annulus, fuel passes through two or more fuel ducts in the nozzle to an enlarged annular sump surrounding a valve member mounted for axial movement in an axial bore in the nozzle. By this arrangement, fuel pressure build up in the sump raises the valve against the bias of a spring in the holder to permit the fuel to pass through spray orifices in the outer free end of the nozzle tip.

Several disadvantages or drawbacks are noted in the conventional type of fuel injection nozzle assembly discussed above. For example, it has been found that it is diflicult to reduce the size of these assemblies in terms of cross sectional dimension by reason of the separate axial passage for the fuel, the axial bore for the valve element and chamber for the valve actuating spring. Nozzle assemblies of reduced cross section are desirable to permit more space in the engine cylinder head for larger valves and thus improve the volumetric efficiency of the engine. Furthermore, since these assemblies are comparatively small in size, the construction thereof is difiicult due to the precision drilling required to form these fuel passageways or ducts and other internal bores or chambers in the holder and nozzle.

Moreover, the sump tends to trap dirt and foreign particles and is diflicult to clean thoroughly. Also, the sump, annulus and seat provide an excess parasitic or dead fuel volume which makes it difficult to control fuel injection characteristics. Additionally, in engines employing Patented June 11, 1968 the sump-type fuel injection nozzle fuel consumption is high and the engine tends to smoke. Further it has been found that various moving parts of the assembly are extremely sensitive and that conventional spring mountings for the valve element produce side thrusts on the valve member causing sticking and hanging up of the valve. Furthermore, in the conventional fuel injection nozzle assemblies discussed above, flow of fuel is turbulent which again may result in valve sticking and may produce cavitation or erosion.

In accordance with the present invention the fuel passageways or the like in the various elements of the entire assembly are located axially and centrally thereof to permit the entire assembly to be made of a much smaller cross section. More specifically, the fuel injection nozzle assembly of the present invention includes a holder and a nozzle tip mounted at one end of the holder. A tubular plug is mounted in the end of the holder remote from the nozzle, the inner end of which is spaced a predetermined distance from the valve assembly in the closed position of the valve to define a gap controlling valve lift.

The nozzle comprises the usual body portion and an elongated tip or shank, the body portion having a bore in which the valve element slides and a lower bore section defining a fuel chamber. The valve assembly includes an elongated hollow tubular stem mounted in a socket in the tail section of the valve head which is guided adjacent its upper end in the axial bore in the holder. A biasing spring mounted in a spring chamber in the holder ci cumscribes the stem and serves its normal function to bias the valve assembly to a closed position. The head of the valve is of a streamlined configuration and is connected to the tail section by a reduced neck portion. By this arrangement, fuel enters the fuel injection nozzle assembly through the central opening in the plug, fiows through the hollow stem and into the fuel chamber through diametrically opposed angled connecting passages in the tail section of the valve. The head of the valve serves as a venturi in the fuel chamher so that flow through the fuel chamber is laminar. This assembly is comprised of comparatively few parts so that it is easy and economical to make. Furthermore, the valve assembly is guided on either side of the actuating spring to minimize thrust.

With the foregoing in mind, an object of the present invention is to provide a fuel injection nozzle assembly of substantially smaller dimensions particularly in cross section thereby permitting more space in the engine cylinder head for larger valves and thus improve the volumetric efficiency of the engine.

Another object of the present invention is to provide a new and improved fuel injection nozzle assembly with axial high pressure fuel passages for ease of machining and reduction of fuel volume.

Still another object of the present invention is to provide a hollow valve of relatively short length with reduced inertia which facilitates high speed operation.

A still further object of the present invention is to provide a novel fuel injection nozzle assembly wherein the valve is guided at both ends and the actuating spring is positioned between the terminal ends of the valve so as to make the valve less susceptible to side thrust effects from the actuating spring.

Another object of the present invention is to provide a fuel injection nozzle assembly including a valve characterized by novel features of construction and arrangement wherein side thrusts are minimized to insure more reliable functioning of the valve and flow through the assembly is laminar to minimize erosion and cavitation.

A further object of the present invention is to provide a separate fitted assembly of valve and nozzle tip which can be readily serviced or replaced.

These and other objects of the present invention and the various features and details of the operation and construction thereof are hereinafter more fully set forth with reference to the accompanying drawings, wherein:

FIG. 1 is a side elevational view of a fuel injection nozzle assembly in accordance with the present invention;

FIG. 2 is an enlarged sectional view through the assembly showing the same mounted in an opening in an engine cylinder head;

FIG. 3 is an enlarged sectional view similar to FIG. 2 of another embodiment of fuel injection nozzle assembly in accordance with the present invention;

FIG. 4 is an enlarged fragmentary sectional view of the lower terminal end of the assembly with the valve in a closed position;

FIG. 5 is a fragmentary view similar to FIG. 4 showing the valve in an open position;

FIG. 6 is a sectional view similar to FIGS. 2 and 3 of still another embodiment of fuel injection nozzle assembly in accordance with the present invention; and

FIG. 7 is an enlarged sectional view of the lower stem section.

Referring now to the drawings and particularly to FIG. 2 thereof, the fuel injection nozzle assembly includes a nozzle holder 10, a fuel injection nozzle 12 mounted at the lower axial end of the holder by means of a cap nut 14 for axial movement and a valve assembly 15 mounted in the nozzle. The fuel injection nozzle as sembly is adapted to be mounted in an elongated stepped opening 16 in the cylinder head 18 to deliver fuel to the combustion chamber thereof.

The holder 10 is an elongated generally cylindrical member having a fuel inlet 22 at its outer axial end and an axially extending upper bore section 24 which is enlarged adjacent the lower end of the holder as at 25 to define a spring chamber C. An externally threaded plug 26 is mounted in the upper bore section 24 of the holder, the plug 26 having an axially extending central passage 28 through which fuel passes from the inlet 22. The plug is movable axially in the upper bore section 24 to selectively vary the gap or spacing G between the inner axial end face of the plug 26 and the upper end of the valve assembly to adjust the valve lift. In the present instance the holder is provided with a radial port 27 which communicates with the spring chamber C and serves as a leak-0d bypass for fuel leaking into the spring chamber. The leak-off bypass may be connected back to the main fuel supply if desired and in order to seal the entire assembly there is provided an O-ring 29 surrounding the holder above the leak-off bypass.

The nozzle 12 comprises a generally cylindrical body portion 30 and an elongated shank 32 of reduced cross section depending from the body portion. The body portion 30 has an axial bore 34 therein for the valve and a lower bore section 36 of slightly enlarged cross section to define a fuel chamber F. In the present instance a nozzle spray tip 40 is mounted in the lower terminal end of the nozzle which may be press fitted into the enlarged open.- ing in the free end of the nozzle shank, sealed with epoxy resin and spun over for mechanical fastening. The spray tip insert 40 has a conical seat 42 against which the valve seats and a plurality of spray orifices 44 in the outer terminal end of the nose section 46 of the tip through which fuel is delivered to the engine cylinder.

The valve assembly comprises a streamlined head portion 50 having a conical tip 51., a tail section 52 merging with the head portion in a reduced neck section 54 and an elongated tubular stem 56 mounted in a socket-like opening 58 in the tail section. The stem 56 has an axially extending central fuel channel 62 which at its lower end communicates with a pair of diametrically Opposed outwardly diverging outlet holes 66 in the neck of the valve. The stem 56 is secured at its inner end in the socket 58 by means of an epoxy resin type agent and in the seated position of the valve, the opposite outer axial end face 0f the stem 56 is spaced from the lower terminal end of the threaded member 26 to provide a gap G determining the valve lift. In the present instance, the head portion 50 has a double conical tapered tip which engages the valve seat in the closed position of the valve and the sidewall of the insert is also tapered to provide an inwardly converging forward section to the fuel chamber conforming generally to the tip.

The valve member is normally biased to the closed position by means of a compression spring 72 in the spring chamber C which abuts the lower end of the chamher at one end and seats on the flange 74 of a collar abutting the tail section of the valve.

In the normal operation of the fuel injection nozzle.

assembly of the present invention, the spring force of the compression spring 72 and the pressure of the fuel acting on the axial end face of the stem 56 normally maintain the valve member in a closed position where the conical tip 51 engages the valve seat 42. Now when the fuel pressure builds up to a predetermined amount, the valve memer is raised upwardly against the bias of the compression spring 72 due to the area differential between the valve seat diameter D and the stem diameter D In the present instance, the particular arrangement of the assembly permits the opening and closing of the valve to be controlled very accurately. For example, valve opening pressure P is equal to 4F, W valve closing pressure P is equal to 4F 1 3 and compression spring force F is equal to i era es-wan Now assuming a valve opening pressure of 3,000 p.s.i., a valve diameter D of 0.236, a seat diameter D of 0.118 and a stem diameter D of 0.0986", the spring force F is 75.6 lbs., and the closing pressure P required is 2090 p.s.i. This contrasts with conventional assemblies where the spring load required would be about p.s.i. By the present arrangement, the fuel pressure acting on the area D of the stem reduces the spring load required over conventional ducted nozzles. Further by the present arrangement, by varying the diameter D of the stem, different spring loading and pressure differences may be obtained between the opening and closing pressures.

There is illustrated in FIGS. 3, 4 and 5, another embodiment of fuel injection nozzle in accordance with the present invention. This assembly is generally similar in overall configuration and construction to the embodiment illustrated above and includes a nozzle holder 100, a fuel injection nozzle 112 mounted at the lower end of the holder by means of a cap nut 114 and a valve assembly 115 mounted in the nozzle.

The nozzle holder 100 has a fuel inlet 122 at its upper axial end and an axially extending upper bore section 124 terminating in an enlarged lower section 125 defining a spring chamber C. A threaded plug 126 is mounted in the upper bore section 124 and has a central passage 128 through which fuel passes from the inlet 122.

In the present instance the nozzle 112 is an integral assembly comprising a generally cylindrical body portion 130 and an elongated shank 132 of slightly reduced cross section, the body and shank having

axial bore sections

134 and 136 respectively, the bore section 136 being of slightly enlarged cross section and defining a fuel chamber F. The lower end of the fuel chamber is provided with adjacent

conical wall sections

137 and 139, the lower conical wall section 139 defining a valve seat and merging with a discharge opening 141 in the lower axial end of the nozzle shank.

The valve member 115 comprises a streamlined head portion 150 having a tail section 152 merging with the head portion in a reduced neck section 154 and an elongated hollow tubular stem 156 mounted in a socket-like opening 158 in the tail section, the stem 156 having an axially extending central fuel channel 162 communicating at its lower end with a pair of diametrically opposed cutwardly diverging outlet holes 166 in the neck of the valve. The outer axial end face of the stem 156 in the seated section of the valve is spaced from the lower terminal end of the plug 126 to provide a gap G determining the valve lift. The valve is normally biased to the closed position by means of a compression spring 173 in the spring chamber C which abuts the lower end of the chamber at one end and seats on the flange 175 of a collar abutting the tail section of the valve.

In the present instance the assembly is a poppet type assembly and to this end the tip of the head portion 150 has a double conical tapered tip 170 which engages the valve seat in the closed position of the valve and a pintle 172 projecting from the tip through the discharge opening 141 in the nozzle shank. As best illustrated in FIGS. 4 and 5, the pintle 172 has a profiled sidewall 174 consisting of an upper frusto conical wall section 176, a lower frusto conical wall section 178, which merges with the upper section in a rounded or gently curved neck 180 of narrow width. The upper wall section in the present instance is inclined at a greater angle relative to a plane through the neck 130 perpendicular to the axis of the valve. By this construction when the valve lifts off of its seat as shown in FIG. 5 and the high pressure fuel follows the matching contours of the conical tip and seat of the valve and nozzle shank respectively, the fuel discharges in a wide conical spray. Further by virtue of the short distance between the seat 139 and the straight sided portion of the discharge opening 141, the flow of fuel is directed inwardly toward the profile portion of the pintle and then reversed as shown to issue a wide spray up to 180.

Further, in the operation of the valve due to the particular configuration of the fuel ducts and passageways and the streamlined configuration of the valve head, flow through the fuel injection nozzle assembly may be de scribed as laminar thereby minimizing erosion and cavitation.

Moreover, by elimination of the annulus and sump, areas that tend to trap dirt and foreign particles which are dilficult to clean are eliminated. By the present arrangement, fuel injection characteristics may be controlled more accurately by minimizing parasitic or dead fuel volume. Also by the particular spring mounting between the extreme ends of the valve member, deleterious side thrust due to the spring are minimized and accordingly, the valve has less tendency to stick or hang up. Lastly, the assembly of the present invention is extremely economical to manufacture and with this design reduction of the nozzle diameter and miniaturization are possible.

There is illustrated in FIG. 6 still another embodiment of fuel injection nozzle in accordance with the present invention. This assembly is generally similar in overall construction to the previous embodiment and includes a nozzle holder 200, a fuel injection nozzle 212 positioned at the lower end of the holder by means of a cap nut 214 and a valve assembly 215 mounted interiorly of the nozzle and adapted for axial movement therein between an open position and a closed position.

The holder 2% is an elongated generally cylindrical member having a fuel inlet 222 at its outer axial end and an axially extending upper bore section 224 which is enlarged adjacent the lower end of the holder as at 225 to define a spring chamber C".

An externally threaded plug 226 is mounted in the upper bore section 224 of the holder, the plug 226 having an axially extending central passage 228 through which fuel passes from the inlet 222. The plug is movable axially in the upper bore section 224 to selectively vary the gap or spacing G between the inner axial end face of the plug 226 and the upper end of the valve assembly to adjust the valve lift. In the present instance the holder is provided with a radial port 227 which communicates with the spring chamber C and serves as a leakotf bypass for fuel leaking into the spring chamber. The leakoff bypass may be connected back to the main fuel supply if desired.

The nozzle 212 comprises a generally cylindrical body portion 230 and an elongated shank 232 of reduced cross section depending from the body portion. The body portion 230 has an axial bore 234 therein for the valve and a lower bore section 236 of slightly enlarged cross section to define a fuel chamber F". The lower terminal end of the nozzle body portion 230 has a conical seat 252 against which the valve seats and a plurality of spray orifices 243 in the tip of the nozzle shank 237 through which fuel is delivered to an engine cylinder.

The valve assembly comprises a streamlined head portion 250 having a conical tip 251, and a tail section 252 merging with the conical tip in a reduced neck section 254. The tail section has a central axial bore 253 which at its lower end merges with a pair of diametrically opposed, outwardly diverging outlet holes 266 in the neck of the valve. As illustrated, the head portion 250 has a double conical tapered tip which engages the valve seat in the closed position of the valve and the interior sidewall of the valve body adjacent the tip is also tapered to provide an inwardly converging forward section to the fuel chamber F" conforming generally to the tip.

In the present instance, the valve assembly includes an elongated tubular stern assembly 256 comprising an upper section 256:: and a lower section 256b, the upper stem section 256a being mounted in the central passageway in the holder having its upper end spaced from the plug 226 to provide a gap or spacing G determining the valve lift. The stem sections as illustrated are elongated hollow tubular members having axial bores 255a and 2551) which communicate with the central opening in the plug 226 and the bore in the tail section to permit flow of fuel from i the source to the fuel chamber F. As in the previously described embodiments, the plug 226 is adjustable axially so that the valve lift may be selectively varied. The lower stern section 25612 has tapered conical terminal ends 257 and 259 which nest in conical seats 261 in the upper stern section 256a and a conical seat 263 in the axial end face of the tail section of the valve. The coil spring 272 in the spring chamber C" at one end engages shims 267 mounted in the upper end of the spring chamber and at its opposite end engages a radial flange 269 on the lower end of the sleeve 271, the sleeve 271 having an inwardly directed flange 273 overlying the enlarged lower end 275 of the upper stem section 2560.

In the normal operation of the fuel injection nozzle assembly described above, the spring forces of the compression spring 272 and the pressure of the fuel acting on the axial end face of the upper stem assembly 2560 normally maintain the valve member in a closed position wherein the conical tip 251 engages the valve seat 252. Now when the fuel pressure builds up to a predetermined amount, the valve member is raised upwardly against the bias of the compression spring due to the area of differential of the valve seat diameter D; and the stem diameter D In the present instance the two-piece stern assembly 256a and 2561: provides flexibility and eliminates excessive side thrusts on the valve. Further, in order to eliminate leakage of high pressure fuel at the junclure of the lower stem section 25Gb with the upper stem section and valve, the mating angular surfaces have a different angle of taper so that the parts seat on the ouside diameter. Preferably the included angle A on the ends of the lower stem section 25611 is greater than the counter-sink angle on the seats in the upper stern section and valve. For ex- 7 ample, if the included angle A is 90, then the countersink angles B for the seat in the tail section and the seat on the lower end of the stem aszembly are between 80-S5.

While particular embodiments of the present invention have been illustrated and described herein, it is not intended to limit the invention and changes and modifications may be made therein within the scope of the following claims.

I claim:

1. A fuel injection nozzle assembly comprising an elongated holder, a nozzle mounted at one axial end of the holder, means defining a first axial bore in the nozzle defining a fuel chamber, valve member means mounted for axial movement in said bore between open and closed positions, a fuel inlet in the axial end of said holder opposite said one axial end, means defining a second axial bore in said holder communicating with said inlet, said valve member including an elongated stem engaging in said second axial bore, said stem having a central fuel passage communicating at its inner end with a pair of angled fuel passageways in said valve member which in turn communicates with said fuel chamber.

2. A fuel injection nozzle assembly as claimed in claim 1 including a plug mounted in said second axial bore having its inner end normally spaced from an axial end of said stem providing a gap determining valve lift.

3. A fuel injection nozzle as claimed in claim 2 wherein said plug is movable axially in said bore whereby the gap may be varied selectively to vary valve lift.

4. A fuel injection nozzle assembly as claimed in claim 1 including an enlarged lower bore section in said one end of the holder defining a spring chamber and including a spring in said chamber circumscribing said stem.

5. A fuel injection nozzle assembly as claimed in claim 1, wherein said valve member has a streamlined head portion including a conical tip, a tail section merging with the head portion in a reduced neck section.

6. A fuel injection nozzle assembly as claimed in claim 1 including a tip insert mounted in the axial bore in the free end of said nozzle.

7. In a fuel injection nozzle assembly including a holder having a fuel inlet, a nozzle having a first axial bore defining a fuel chamber, a discharge opening in one axial end of the nozzle and a valve seat adjacent the discharge opening, valve member means mounted in said fuel chamber having a streamlined head portion including a conical tapered tip, a pintle projecting from the tip, said pintle consisting of an upper frusto-conical wall section, a lower frusto conical wall section which merges with the upper wall section in a rounded neck of reduced cross section, means defining a second axial bore in said holder communicating with said inlet, said valve member including an elongated stem engaging in said second axial bore, said stem having a central fuel passage communicating at one end with said inlet and at said opposite end with said fuel passage in said valve member which in turn communicates with said fuel chamber, said valve member adapted for axial movement in said first axial bore between a closed position wherein the tip engages the nozzle seat and an open position wherein the tip is spaced from the seat whereby fuel discharges in a wide conical spray.

8. A fuel injection nozzle assembly comprising an elongated holder, a nozzle mounted at one axial end of the holder, means defining a first axial bore in the nozzle defining a fuel chamber, valve member means mounted for axial movement in said bore between open and closed positions, a fuel inlet in the axial end of said holder opposite said one axial end, means defining a second axial bore in said holder communicating with said inlet, said valve member including an elongated stem engaging in said second axial bore, said stem having a central fuel passage communicating at one end with said inlet and at its opposite end with a fuel passage in said valve memher which in turn communicates with said fuel chamber.

9. A fuel injection nozzle assembly as claimed in claim 8 wherein said stem comprises an upper stem section engaging in said second axial bore and a lower stem section at one end engaging the upper stem section and at its opposite end engaging the upper axial end face of the valve member.

10. A fuel injection nozzle assembly as claimed in claim 9 wherein said lower stem section has tapered conical terminal ends which engage in conical seats in the upper stem section and valve member respectively.

11. A fuel injection nozzle assembly as claimed in claim 10 wherein the angle of taper at the terminal ends of the lower stem section is greater than the included angle of said conical seats.

References Cited UNITED STATES PATENTS 3,224,684 12/1965 Roosa 239533 3,244,377 4/1966 Roosa 239-533 3,255,974 6/1966 Roosa 239-533 FOREIGN PATENTS 1,121,065 4/ 1956 France.

592,519 2/ 1934 Germany.

617,795 2/1949 Great Britain.

746,785 3/1956 Great Britain.

EVERETT W. KIRBY, Primary Examiner.