US2503186A - Fuel injector for diesel engines - Google Patents

Description

April 4, 1950 J. a. ZIEGLER FUEL INJECTOR FOR DIESEL ENGINES Filed Oct. 22.

Jose/w 5. Z/zame.

IN VHV TOR.

Patented Apr. 4, 1950 -UNITED STATES PATENT OFFICE v 2,503,186 FUEL INJECTOR FOR DIESEL ENGINES Joseph B. Ziegler, South Bend, Ind.

Application October 22, 1948, Serial No. 56,085

Claims. 1

This invention relates to improvements in fuel injectors for Diesel engines.

The primary objects of the invention are to provide an injector by means of which fuel may be injected to a Diesel engine during a large porameter portion 26 from which projects inwardly tion of each cycle of operation of the engine,

wherein the pressure of the fuel required for feeding the same is held at a low value compared to the pressure at which fuel is conventionally injected into a Diesel engine, wherein the construction avoids the necessity of injecting fuel into an engine cylinder against high cylinder pressure therein, wherein the necessity for anexpensive fuel metering pump is avoided and a simple low pressure fuel pump may be employed, and wherein novel cooling action of the injector is provided.

Other objects will be apparent from the following specification.

In the drawing:

Fig. 1 is an axial sectional view of one embodiment of the injector.

Fig. 2 is an enlarged fragmentary view illustrating one position of the injector. Fig. 3 is a view similar to Fig. 2 illustrating a second position of the injector. Fig. 4 is an axial sectional view of a modified embodiment of the invention.

Fig. 5 is a sectional view of the injector taken on line 55 of Fig. 4.

Referring to the drawing, and particularly to lflgs. l to 3 thereof which illustrate one embodiment of the invention, the numberal l8 designates the head of a cylinder of an internal combustion engine within which a piston (not sh own) reciprocates in a manner well understood in the art. The head III has a bore therein adapted to receive the injector, which bore preferably has a tapered mouth parts I2, an oppositely tapered socket portion l4, and an internally screwthreaded outer portion l6.

Within the bore of the cylinder head as described is mounted an injector including a nozzle having a cylindrical body portion l8 screwthreaded in the portion l6 of the bore, and a tapered portion having a snug pressed fit within the tapered portion l4 of the bore. The outer end of the nozzle projects from the outer surface of the cylinder head l0 and has an enlarged flange 22 of suitable configuration to facilitate its insertion into the bore by the use of wrenches or other tools.

An elongated valve stem 24 extends centrally or axially through the nozzle, being preferably provided at its inner end with a reduced dia portion 28 having a snug sealing and sliding fit within the bore of the tip portion of the nozzle. An enlarged flange 30 is formed at the inner end of the valve stem and is adapted to bear against the end surface of the nozzle tip. The valve stem 24 is slidable within an elongated tubular guide 32 having a circumferential flange 34 formed intermediate its ends. A ring 36 bears upon and is supported by a shoulder 38 formed in the interior of the nozzle, and the circumferential flange 34 bears against the said ring. A sleeve 40 is screw-threaded into the cylindrical portion l8 of the nozzle and is provided with an external flange 42 at its outer end adapted for application of a tool, such as a wrench, thereto. The sleeve 48 has an inwardly projecting circumferential flange 44 adapted to bear upon the flange 84 of the guide 32. A coil spring 46 encircles the upper ends of the valve stem 24 and the valve guide 32, with its lower end portion fitting within the retainer 40 and bearing against the internal shoulder or flange 44 thereof. The upper end of the valve stem 24 mounts a head 48 and a sleeve guide member 50 provided with a circumferential flange 52 intermediate its ends. The upper end of the coil spring 24 fits around the lower portion of the sleeve guide 50 and bears against the flange 52.

The cylinder head has a fuel intake passage 54 formed therein and a sleeve 56 is screw-threaded in said passage to a position bearing against a shoulder between said portion 54 and a reduced portion 58 of the passage. A spherical valve element 6!! is mounted in and free to shift lengthwise in the passage portion 58 which is provided with a reduced terminal portion 62. The shoulder between the passage portions 58 and 62 is preferably ridged at 64 to form a stop for the sphere 68 which prevents its closing the passage portion 62. The passage portion 62 communicates with the tapered portion l4 of the bore adjacent the lower or inner portion thereof, and a circumferential groove 66 is formed in the tapered portion 28 of the nozzle and registers with the passage portion 62. One or more small bores 68 are formed in the tip portion of the nozzle, communicating at one end with the groove 66 and at its opposite end with the outer or tip transverse surface of the nozzle. A second restricted bore or group of bores 10 is formed in the nozzle, communicating at one end with the groove 66 and at its opposite end with the inner surface of the tapered portion 20 of the nozzle spaced inwardly from the portion engaged by the valve part 28.

The engine will be provided with a suitable valve operating cam shaft in the manner well understood in the art, and the valve head 48 will be positioned to be engaged by a, cam upon said shaft for the purpose of longitudinally shifting said valve stem 24 against the action of the spring 46. The movement of the valve stem for valve operating purposes will occur in properly timed relation, as is understood in the art, and two of the open positions of the valve are illustrated in Figs. 2 and 3. The fuel passage 54 will be connected with a source of fuel, as by means of a low pressure fuel pump. The engine will also be provided with means for intake and exhaust of air, as is alsowell understood in the art.

The parts are illustrated in Fig. 1 in the position occupied during the compression stroke of the engine. Note that the valve head 28, 30 seals the end of the nozzle but that fuel may be supplied through the passage 54, the bore of the sleeve 56, the passage 58 around the spherical valve 60, the passage 62, the groove 68 and the passage 10. The closed position of the valve head 28, 30 seals the interior of the nozzle against the pressure existing within the engine cylinder, and, consequently, the flow of fuel into the interior of the nozzle through the passage mentioned above may occur at a pressure much lower than normal injection pressures in Diesel engines.

The cam for actuating the valve will be so arranged that until the compression within the cylinder has reached a predetermined value incident to the compression stroke of the piston, for example, a value in the neighborhood of 100 pounds per square inch, the valve will be actuated to a slightly or partly open position, as illustrated in Fig. 2. The cracking of the valve in the Fig. 2 position permits air under pressure to pass from the cylinder through the bore 68, the groove 66 and the bore I into the interior cavity of the nozzle. This air mixes with the fuel in the groove 68 and in the interior of the nozzle. At the same time the pressure of the air so discharged from the cylinder into the groove 66 acts against the valve element 60 to shift the same in the portion 58 of the fuel passage to a position bearing against the inner end of the sleeve 56 and sealing the bore of said sleeve when air pressure exceeds fuel pressure. The valve 28, is then closed, i. e. when pressure reaches approximately l00 pounds, and the compression stroke of the piston of the engine continues until a predetermined time shortly before the connecting rod (not shown) which is connected with said piston reaches dead center. The engine cam engaging the head 48 will be of such contour that at this time the valve is reopened to the position shown in Fig. 3. The time of reopening of the valve will be correlated ,with the stroke of the piston so that, when the valve is open to the Fig. 3 position, the air within the cylinder will have been compressed to an extent generating heat sufficient to ignite the charge contained within the injector nozzle and pre-combustion will occur within the nozzle. The pre-ignition will occur by the time the piston has reached dead center, and the pre-igniti0n will force airfuel mixture from the injector body into the cylinder around the reduced portion 26 of the valve stem, thereby causing ignition within the cylinder itself to generate the power required for the power stroke of the engine. As soon as the power stroke and the subsequent exhaust of the products of combustion from the cylinder has been ing fit within the sleeve 84.

I the feeding of fuel through a large part of each cycle of the engine. Also, the feeding of the fuel can occur against substantial atmospheric pressure; hence the fuel can be supplied at a much lower pressure than is conventionally utilized in fuel injectors for Diesel engines and at the same time assure the feeding of an adequate amount of fuel for proper engine operation.

A modified embodiment of the invention is illustrated in Figsmi and 5, wherein the head I0 of the engine cylinder has a substantially cylindrical bore terminating at its inner end in a conical enlarged portion 82. A cylindrical sleeve 84 is screw-threaded or otherwise secured within the bore and preferably terminates at a point adjacent to the junction of portions 80, 82 of the bore. The cylindrical member 84 has an enlarged externally projecting flange 86 at its upper end positioned outwardly of the head If! and an annular sealing gasket 88 is interposed between said head I0 and flange 86. The lower portion of the sleeve is preferably provided with a tapered surface 90 forming a valve seat. A circumferential groove 92 is formed in the external surface of the sleeve 84, and one or more passages 94 open at the tapered surface 80 communicating with said groove. One or more additional passages 98 communicate with the groove 92 and are open at the inner face of the sleeve 84 in spaced relation above the tapered surface 90 of said sleeve.

The head I0 is provided with a fuel passage of substantially the same construction hereinabove defined, including a reduced terminal portion 58, an enlarged elongated portion I00 receiving a ball valve I02, and a sleeve I04.

A valve stem I06 is positioned coaxially of the sleeve 84 and extends through a central aperture in a closure plate I08 mounted upon and spanning the upper end of the sleeve 84. A coil spring III) encircles the valve stem I06 and bears at its opposite end upon a head (not shown) mounted upon the upper or free end of the valve stem. The valve stem mounts a valve plunger I I2 whose upper portion is cylindrical and has a snug slid One or more circumferential grooves are formed in the inner or upper part of the valve I I2 and receive sealing rings II4, such as conventional piston rings. The intermediate portion I I6 of the valve plunger is formed of reduced dimension. The inner or lower portion of the valve plunger includes a cylindrical portion II8 adapted to have a. snug sliding fit in the end of the sleeve 84 and an enlarged conical portion I20 adapted to seat against the conical valve seat 80. The parts are so proportioned and arranged that the cylindrical portion II8 terminates outwardly of or below the mouth of the aperture or apertures 86 when the conical portion I20 is fully seated upon the seat 90.

The head I0 is provided with a valve insert I22 seated in a tapered opening communicating with the bore 80 intermediate the end thereof. The valve seat has a tapered or frusto conical outer surface which fits snugly within the tapered 8 of the head I8. and the insert extends through this opening. The valve insert has a bore I28 extending for a part only of the length thereof and is provided with a valve seat I88 at its inner end. A lateral aperture I82 is formed in the insert in communication with the bore I28. The outer end of the insert has a reduced bore portion I84 which'slidably receives and guides a valve stem I 38 mounting a valvehead I88 adapted to bear against the valve seat I88. An air intake passage I48 is formed in the head, and the lateral opening I32 of the insert communicates therewith. Acoil spring I 42 encircles the outer end of the valve stem I88 and bears against a head (not shown) for the purpose of normally urging the valve I38 to seated position. The head of the valve I88 is preferably of a diameter slightly less than the diameter of the insert at its smallest or inner end. The insert is so positioned and of such size that it communicates with the interior of the cylinder or sleeve 84 intermediate the portions 2 and H8 of the valve and is spaced therefrom a distance greater than the full travel of the valve plunger between its fully open and fully closed positions.

This device possesses the same advantages and can be used in the same manner as described above. Observe that when the valve I 28 is seated against the valve seat 90, the supply of fuel under low pressure through the fuel intake ports 98 and I past the ball valve I02 is permitted. The valve may be opened partially, as illustrated in Fig. 4, to permit the flow of compressed air from the cylinder to the port 84, the groove 92 and the port 96, to the space within the sleeve 84 between the head portions H2 and H8 of the valve plunger. Any pressure existing within this sleeve between the two valve plungers acts equally in opposite directions so that the spring I III of the valveis not subjected to any load incident to the mixing of fuel and air in the chamber around the reduced portion II 8 of the plunger. That pressure will tend to act against the valve head I38 to urge it to sealed position. While the valve is in this cracked position, the portion 8 of the valve maintains itssealing fit within the inner or lower end of the sleeve 84 to prevent direct communication between the interior of the sleeve and the engine cylinder. Closing of the valve permits continued supply .of fuel if the pressure within the chamber around the stem portion I I8 does not exceed the pressure at which the fuel is supplied. Full opening of the valve to a position at which the plunger part H8 is clear of the sleeve 84 may be obtained by a proper throw or movement of the valve stem 8 at the commencement of and during the power stroke and during the air intake stroke or portion thereof.

The primary advantage of this device, over and above that shown in Fig. l, is that the same provides a large chamber for receiving air and also permits a fast fiow of air from that chamber into the engine cylinder upon ignition at the beginning of the ignition or working stroke. A further advantage is the fact that the forces acting upon the valve by reason of the equal size of the valve portions H2, H8 are equal. Cooling of the injector is also facilitated by reason of the flow of intake air into the cylinder through said injector. It will be understood that suitable I means (not shown), such as timing cams, will It will be understood that any suitable means.

embodiments of the invention illustrated. This means may take any form found suitable and will serve the purpose commonly served by the accelerator or fuel control element for the control of speed of a conventional internal combustion engine, as is well understood in the art. While the preferred embodiments of the invention have been illustrated and described herein, it will be understood that changes may be made in the construction within the scope of the appended claims without departing from the spirit of the invention.

I claim: 1. In aDiesel engine, an engine cylinder including a wall having an opening therethrough and a fuel passage communicating with said opening adjacent to its inner end, a check valve I in said fuel passage, a nozzle mounted in said opening, a valve including a head in said cylinder adapted to seal the inner end of said nozzle and a valve stem projecting through and outwardly from said nozzle, and means sealing the outer end of said nozzle to define-an auxiliary combustion chamber therein, said nozzle having a groove in its outer surface communicating with said fuel passage, and a pair of passages communicating with said groove, one of said passages communicating with said auxiliary combustion chamber and the other opening at the end surface of said nozzle and adapted to communicate with the interior of said cylinder, said 35' valve normally seating against the end surface of said nozzle to seal said last named passage.

2. In a Diesel engine, an engine cylinder including a wall-having an opening therethrough and a fuel passage communicatin with said opening, a check valve in said passage, a hollow member seated in said opening to define an auxiliary combustion chamber and having an aperture and a valve seat surrounding said aperture, and a valve normally engaging said seat to seal said aperture and including a stem having a snug sliding fit in said aperture, said chamber having a recess in its outer surface communicating with said fuel passage, and. a pair of passages branching from said recess and respectively open at said valve seat to communicate with said cylinder and at an inner surface of said member spaced from said aperture to communicate with said auxiliary chamber.

3. In a Diesel engine, an engine cylinder including a wall having an opening therethrough and a fuel passage communicating with said opening, a check valve in said passage, a hollow member fitting. in said opening to define an auxiliary combustion chamber and having an aperture surrounded by a valve seat, a valve having a head normally engaging said seat and a Oil portion having a snug fit in said aperture, said hollow member having a pair of passages each communicating at one end with said fuel passage, one of said last named passages opening at said valve seat for communication with said cylinder and the other opening into said auxiliary.

hollow chamber defining member are of mating tapered contour and said fuel passage communicates with the tapered portion of said wall opening and said last named passages are formed in the tip portion of the tapered end of said hollow member. 6. The construction defined in claim 3, wherein said valve includes a stem having a portion adjacent to said head of smaller cross-sectional size than said aperture and a portion projecting from said member, a valve guide carried by said member and receiving said stem, said stem projecting through and externally of said auxiliary chamber, a coil spring encircling the outer portion of said stem and bearing against said member, and a spring abutment mounted on the outer end of said'stem.

7. In a Diesel engine, an engine cylinder ineluding a wall having an opening therethrough and a pair of spaced passages communicating with said opening for supplying fuel and air, respectively, a check valve in said fuel passage, a hollow member seated in said openin to define an auxiliary combustion chamber, said member having a valve seat open at said cylinder and a second valve seat communicating with said air passage, a pair of valves each normally engaging a valve seat, said hollow member having a pair of ports each communicating with said fuel passage, one port opening at the valve seat communicating with said cylinder and the other port communicating with said auxiliary combustion chamber. a

8. In a Diesel engine, an engine cylinder ineluding a wall having an opening therein and spaced passages for fuel and air communicating with said opening, a cylindrical sleeve fitting in said opening to define an auxiliary combustion chamber and having a valve seat at its and open at said cylinder, a valve plunger shiftable in said' sleeve and including a valve portion at its end adapted to engage said valve seat and a reduced portion normally positioned within said sleeve, said sleeve having ports in communication with said fuel passage and open respectively at said valve seat and at the interior of said sleeve spaced from the valve portion of said plunger for communication with said auxiliary chamber, said sleeve also having a port registering with said air passage and positioned opposite the reduced portion of said plunger in all positions of the plunger, and a valve closing said last named port.

9. The construction defined in claim a wherein said plunger includes a portion spaced outwardly from said last named valve to define the outer end of. said auxiliary chamber, and an annular seal encircling said last named portion.

10. The construction defined in claim 8, and an insert fitting in and having a passage forming a part of said air passage, said insert projecting into said sleeve, said insert mounting said last named valve whereby said valve and insert form a preassembled unit.

JOSEPH B. ZIEGLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,451,384 Whyte Apr. 10, 1923 1,813,781 Thomas et a1 July 7, 1931

Images