US2410946A - Fuel injection mechanism - Google Patents

Description

Nov. 12, 1946. L. E. JOHNSON FUEL INJECTION MECHANISM 4 Sheets-Sheet 1 Filed April 10. 1945 INVENTOR. 4 L/ayd E. Jab/7:0!) M 7 I 117' T QENEY.

Nov. 12, 1946. L. E. JO NSON 2,410,94

' FUEL INJECTION MECHANISM Fil'd April 10 1943 4 Sheets-Shet 4 I ,INVENTOR. L/ayd E. Jab/75017 ATTOENEYI Patented Nov. 12,

UNITED" STATES-* PATEN T OFFICE FUEL INJECTION MEcHAmsM Lloyd E. J ohnson,

Fon du Lac Township, Tazewell' County, Ill., assignor toCaterpillar Tractor Co.,

San Leandro',

Calif., a corporation of California Application April 10, 1943, Serial No. 482,577

My invention relates to fuel injection mechanism, and more particularly to a fuel injection nozzle of the outwardly opening valve type adapted for delivering timedinjections of liquid fuel, into an internal combustion engine.

2'Claims. (01. 251-145)" caused by friction or rubbing, partsj is ofsuch character asto enable the proper degree of com- Nozzles of this character may be employed ing of the nozzle valve to effect flow of fuel under pressure, into the engine.

For efiicient engine operation, particularly in a multiple cylinder engine with each cylinder of which is associated a fuel injection nozzle, it is extremely desirable that the individual'nozzles have a high frequency operation. In other words, the valve member in the nozzle should open in a minimum period of time fordischarge of fuel, and also close with a popping action to shut off fuel discharge from the nozzle in a minimum time period, to insure good atomization of the fuel when the nozzle opens, and proper metering of the fuel at all engine speeds from idling to full load speeds. Such action is particularly desirable in high speed engines in order to provide for proper fuel injection timing.

In order to obtain the desired high frequency nozzle, it is desirable to employ a high rate spring in association with the nozzle valve member, or, in other words, a still spring which serves to close the nozzle valve member upon termination of fuel injection and against which the valve moves when it is opened by fuel pressure. Also, it is desirable that the weight of the spring and the mechanism operated by the-spring be relatively light so as to minimize damping of the spring which might otherwise be caused by the inertia of relatively heavy parts, thereby allowing the spring to act fast in closing the valve.

My invention has as its objects, among others, the provision of an improved high frequency fuel injection nozzle of the outwardly opening valve type, designed to satisfy the above mentioned requirements, and which employs a stiff or high rate spring; is provided with a valve member having a floating mounting in the nozzle sothat' during movement thereof there can be no damping effect on the spring which might otherwise be pression to be placed on the spring so that all like nozzles may have like metering characteristics; is provided wit-h spring retainer means which cooperates in providing for proper compression on the spring, and which has a 1' guideless mounting in the nozzle to preclude damping effect on the, spring; .is well shielded against the entrance of dirt and other deleterious matter which might adversely affect proper nozzle operation; is providedwith means to enable'accurate control of the extent of opening. of the valve; and which is of relatively simple and economical construction. Other objects of my inventionwill become apparent from a perusal of the following. description thereof.

Referring to the, drawings:

Fig, 1 is a longitudinal sectional view of one form of nozzle mechanism of my invention,

adapted for employment in a type of compression ignition or Diesel engine in which it is now being embodied; a portion of the precombustion chamber ofsuch engine being also shown, in section. The scale of Fig, 1 is drawn to approximately three timesfull size.

Fig. 2 is an enlarged longitudinal sectional view of a valve assembly unit forming part of the nozzle structure illustrated in Fig. 1.

Fig. 3. is an enlarged horizontal section taken in a plane indicated by line 3-3 in Fig.1.

F 8. 4- is an enlarged horizontal section taken in a plane indicated by line 44 in Fig. 1.

Fig. 5 is an end view looking in the direction of arrow 5 in Fig. 2. I

Fig. 6 is a fragmentary horizontal sectional elevation taken in a plane indicated by line- 6-6 in Fig. 1.

Fig. 7 is a longitudinal sectional view of another form of nozzle mechanism adapted for employment in an engine wherein the valve may occupy less space, such as in the head of a spark ignition engine; aportion of the engine being also shown indicated by line llll in Fig.

in section. The scale of Fig. '7 is drawn to approximately three times full size.

Fig. 8 is a horizontal section taken in a 'plane indicated by line 8-8 in Fig. 7.

I F18. 9 is a fragmentary section taken in a plane indicated by line-98 in Fig. 8.

Fig. 10 is an enlarged longitudinal sectional view of avalve assembly: unit forming part of the nozzle structure illustrated in Fig. 7.

Fig.11 is a horizontal section 7taken in a plane associated with valve stem 4, spring abutment member 8, spring 3 compressed between retainer I and abutment member 8, and sleeve about abutment member 8. As can be noted from Fig. 2, spring 9 holds all the parts of this assembly together with the exception of sleeve II which fits around abutment member 8. In the. compression ignition engine in which such assembly is employed, there is suflicient space to provide a holder therefor of suificient thickness of metal to transfer heat away from the nozzle; this being desirable in a compression ignition engine because of the relatively high maximum operating temperatures in such an engine.

The holder includes an outer sleeve member l2, within recess l3 in compression ignition engine part |4 having external cooling fins l6. Preferably, sleeve I2 is of a metal of relatively high heat conductivity, such as aluminum, for the purpose of conducting heat away rapidly from the nozzle tip. Press fitted within the outer sleeve I2 is an inner sleeve member having conically surfaced externalshoulder l8 which seats against a complementary tapered internal shoulder in outer sleeve l2. Valve assembly unit ,A is clamped in position within inner sleeve l1; and to provide for strength to withstand the clamping stress, sleeve I1 is preferably made of steel. At the fuel discharge end of the injection mechanism, inner sleeve I1 is formed with an internal shoulder l9 on which is seated nozzle tip member 2| having peripheral shoulder 22 provided with a fiat seating face 23 resting on shoulder l9, and with an opposite fiat seating face 24 against which rests one side of seat 6 of valve assembly unit A.

Tip 2| fits with a light press fit within the aperture defined by internal shoulder l3, so as to be readily insertable in and removable from inner sleeve I1, and has an axially extending elongated fuel discharge passage or orifice 26, for the purpose of effecting a penetrating spray which is desirable in the injection of fuel oil into a compression ignition engine. Passage 26 communicates with a recess 21 formed in tip 2| to accommodate head 3 of the valve which is normally sealed against one side of seat 6 by spring 9. Upon injection of fuel by the pressure created by the fuel injection pump (not shown), the valve will open to allow discharge of fuel; the extent of opening of the valve being determined bythe depth of recess 21. Thus, tip 2| serves as a stop for determining the extent of outward opening of the valve. Preferably, the volume of recess 21 is at a. minimum with reference to the volume occupied. by head 3 to minimize the volume from which fuel might escape after injection, thus minimizing dribbling at the nozzle. In this connection, head 3 is provided with a cross slot 28 to allow flow of fuel into fuel discharge passage 26 when the valveopens.

In order to have the same fuel injection characteristics in all like fuel injection nozzles, it is desirable that the extent of opening of the valve be the same for all such like nozzles. In various production valve assembly units A, valve heads 3 may not all be of exactly the same axial thickness which may result from the usual dimensional differences which occur in commercial production, or the heads 3 might not all seat exactly at the same location on seats 6. Therefore, if nozzle tips 2| were employed having recesses 21 all designed to have the same depth, the extent of opening of the valve might vary among different nozzles. To insure that such extent of opening will be the same for all nozzles, I provide nozzle tips 2| having recesses 21 of varying depths; and

in assembling the nozzle, the proper nozzle tip is selected by testing to insure that the extent of opening of the valves will be the same in all assembled nozzles.

Means including the nozzle holder is provided for transmitting clamping pressure through sleeve ll of valve assembly A to clamp together seat 6 and nozzle tip 2| in the holder. In this connection, it is, to be noted that inner sleeve |1 ofthe holder is of less length than outer sleeve |2 of the holder, and'that sleeve ll of valve assembly A extends beyond end surface 29 of inner sleeve H. A plate 3| having central aperture 32 is supported on the end of valve assembly sleeve U adjacent surface 29, and transmits clamping pressure to sleeve I to hold the previously mentioned I parts together. Clamping pressure is imparted to plate 3| by sleeve 33 screwed in outer sleeve |2 of the holder; sleeve 33 and sleeve |2 being locked together by, means of L-shaped locking pin 34, one leg of which fits through apertures in these parts, and the other legIof which lies in a recess 36 formed in the outer surface of sleeve l2. At its outer end, sleeve 33 is-formed with a rightangle extension 31 having fuel flow passageway 38, and which is adapted for connection to the fuel line (not shown) leading to the fuel injection pump (not shown).

I preferably provide in sleeve 33 a fuel strainer 39 to remove any relatively coarse foreign particles that may be in the fuel. Any suitable strainer may be employed; the strainer illustrated comprising a cylindrically-shaped solid member having a plurality of axially extending spirally-shaped grooves 4| leading from one end of the member to the other, and which form complementary spirally-shaped fins 42, the edges of which fit with slight clearance with respect to the inside wall of sleeve 33. As can be observed from Fig. 6, each end of strainer 39 is formed with a pair of cross channels 43, the opposite ends of each of'which communicate with sets of the grooves 4|. However, the channels 43 at either end of the strainer communicate with different grooves than those at the opposite end. The end of the strainer adjacent valve assembly unit A engages plate 3| which overlaps the inside of sleeve 33, and consequently serves to seal off the grooves 4| at such end of the strainer, which do not communicatewith cross channels 43 atthat end.

. The opposite end of the strainer engages plate 46 having an aperture 41 for flow of fuel therethroughfrom passage 38; plate 45 and strainer 33 being held in position by apertured spring 43 in the form of a bowed ring of sheet metal. As with respect to plate 3|, plate 46 seals of! the grooves 4| which do not communicate with cross channels 43 at the end of the strainer covered by plate 46. Thus, fuel entering the ends of grooves 4| at the inlet end of the strainer cannot escape from the same groovesat the discharge end of the strainer, but must flow over fins 42 which will strain out part l4 to engine part.

foreign particles, and intothe" grooves which communicate with cross channels at the I strainer discharge end. The type of strainer described is quite efiicient for the straining of relatively viscous fuel oil such as is encountered I in compression ignitionengines' 'For clamping the nozzle on the ngine, I provide I a clearance space 65 bei shoulder 64 on the stem by 'msnsj'brsprmg 4 between the retainer and the stem. A conically 7 shapedhead '66 is formed adjacent shoulder 64 merely to enable gripping and centeringbf valve member 2'by a suitable tool" during manufacture thereof. Abutment'surface BJon theretainerds an externally threaded nut 49 having shoulder I adapted I I and which is adapted to be screwed into engine clamp the I I The seating (and of sleeVeIlZ is proto engage an end of'oute'r sleeve l2,

apply pressureagainst sleeve 12 and opposite endof sleeve 1 I2 against such I,

vided with a sonically-shaped seating surface 52 adapted to engage a complementary conicallyshaped surface on a shoulder 53 integral with engine part 14. Preferably, clearance space 54 is provided adjacent the discharge end of the I nozzle to provide insulation at .that pointj'and sleeve I 2 adjacent the discharge the portion of I provided with longitudinally sleeve33 in sleeve l2- against plate 3|, the parts will all be held in position. I I i Valve assembly unit A I of my inventionforms an important part thereof. 'With reference to Fig. 2, it is to be noted that the' entire. valve member 2 has a floating mounting in thenozzle, as it is'not piloted in any way. Stem 4 passes loosely or freely through an enlarged aperture 58 in seat 6, and through an enlarged aperture 53 in spring abutment spacer member 8. Also, re- 'tainer 1 is'not guided or pilotedin any way in sleeve ll. Thus, valve member 2 is" centered for the purpose of enabling I be. positioned in sleeve 33 which is insertable through aperture 51 in nut 49; and upon screwing zle constructions wherein 'afspring retainer is made flat, and sp rin'g 9 issqua'red off at its ends to seat accurately; against; abutment surface *61, as well as abutmentspacer affTo enable positioning of the retainer stem 4 may be inserted. The periphery "69 of the retainer .isfj'free I I thusproviding a guideless mounting therefor in the nozzle.

The guideless mounting of. the valve not only allows automatic centering thereof by the fuel j stream, as was previously explained, but also pre- I cludes damping effect on spring 9 which. would be caused if the spring were .to work against rub- 1 bing or'frictionallyengaging parts. Thu when the valve. after termination of-- the spring closes fuel injection, it only has, to move the weight of the valve and the'ret'ainer. This enhancesfast closing of the valve with a popping'action; Furthermore, opening of the'valve by fuel pressure is also made faster by the elimination of rubi parts, v I

With respect to prior. outwardly opening nozscrewed on a valve stem, I have found that such arrangement is not desirable becauseia retainer nut screwed on the stem must be employed in association with othermeans forlocking the 'nut. This creates extra weight, the inertia of which dampens the effect ofthe spring, thereby'impeding fast action in opening .andjclosmg of the in the position thereof during opening thereof solely by the fuel stream I fiow'ing through the nozzle; and as a result the peripheralo-rifice, which is formed when valve head 3 is moved away-from the seating" side 59 of seat 6 by fuel pressure, -will always be of the same width around'its' entireperiphery, thus insuringa uniform spray at all times. This might not otherwise be the case if the valve member 2 were guided or piloted in the nozzle because such arrangement might produce cit-centering of valve head 3 when it opens by fuel pressure.

To insure proper seatingof head 3 about its entire periphery, against seating side 59 of seat 5 when the nozzle is closed, seating surface 6| of I head 3 is formed to have the shape of a segment of ajsphere, and is adapted to engage along an.

edge 62 at an inner beveled part 63 in seating ment of valve stem 4 in the closed position of precludingdripping. at the nozzle. In this connection, it is to be observed that the peripheral I valve. Furthermore, it

' struction'. of my inventon. lies in I I of the removably mountedabutment orspacer member ,8 which is held by spring 9 against the I is relatively difficult with a retainer screwed on the stem to have )it hold its exactposition. at alltimes; and slightchange I causes variation in v the load imposed on the spring, which results in nonuniform spray characteristicsfamong various nozzles on an engine. Since the retainer of my invention isheld'f reely againstshoulder 64, spring 61 thereof will always be at a I abutment surface I I fixed position relative to valve stem'4."

Another important feature .of the nozzle c'onthe provision sideof seat 6 opposite tothat against which valve through spring 9,

"side 59. Thus, should there be slight misaline- I surface of head 3 throughout its entire path of movement during opening and closingv of the nozzle, has relatively wide clearance in recess 21 of nozzle tip 2|. the head cooperates ing thereof. I

With particular reference it is to be noted that it fits freely .or loosely about stem 4, and is 'held against a bevelled Such guideless mounting of in permitting accurate seatto springretainer 1,

operates with the I insuring that alllike nozzles head 3 seats whenthevalve is closed. n assembly of the parts of valve assemblyA, stem 4 is inserted through aperture 158 of seat 6 and Retainer 1 is then slipped over stem 4 and spring}! is held againstretainer abutment surface 61 by any suitable instrument. Abutment member 8, which is provided with an inwardly extending slot 1|, is-thenslipped over stem 4 between seat 6 and the end. ofthe spring 9 opposite that resting against retainer abut? ment surface 61. I provide abutment members 8 of various thicknesses; andbyv a suitable calibrating instrument, I measure the load on spring .9 resulting from theinsertionof various abutment members 8. By selecting an abutment member of the proper thickness, the same predetermined load maybe placed on spring 9 for all like--noz-' zles assembled. Thus, such arrangement .00

will have. uniform spray characteristics.

After assembly of the selected abutment memng provided about stemaboutjstem 4,,it is provided with an inwardly extending, slot 68. through which of .contact with sleeve l I,"

other features mentioned in ing pressureiohold her. 0, sleeve I I is then slipped over the periphery of the abutment member to center it properly. Thus sleeve I I not only serves to transmit clampthe nomle assembly together in the manner previously described, but also serves as airetaining her 0. In this connection, it is to be observed that theportion of sleeve II adjacent abutment member is provided with increased thickness at I2 to center the end of spring 0 adjacent abutment member'l.

. The embodiment of the invention illustrated in Figs. 7 through 13 isessentially the same as that previously described, insofar as the construction of valve assembly unit A? is concerned. Therefore suchunit will be described primarily with reference to the differences between it and the previously described valve assembly unit A. Unit 'A comprises valve member 02 including valve head 02 and stem 04, seat", spring retainer 01 mounted freely about stem 80 and thrust against shoulder 00 on stem 04 by spring 00, and

spring abutment spacer member-0| interposed between spring 08 and seat". Spring retainer 01 is provided with inwardly. extending slot 02 to enable the retainer to be slipped over stem 04; and abutment member 0| is formed wlth'a similar slot 50.

Abutment member 0 I is of ness to place a predetermined load on spring 00; and the'parts are assembled in the same way as in the previously described embodiment of the invention, a sleeve 04 being provided about abutment member 0| to maintain the'abutment member centered. In this connection, sleeve 0| is also provided with a portion of increased thickness 00 adjacent abutment 9| to serve as a centering means for spring 00.

As can valve assembly unitA, is contained in a holder 01 which is in theform of relatively soft ductile seamless metal tubing having its opposite ends 00' pressed or rolled over nozzle tip member 99 and a plate member III, respectively. The perlp eries of both nozzle tip member and plate member IOI are formed with tapered surfaces I00; and when the ends over'these end parts, the entire assembly will form a compact unit in which holder 91 serves as a tubular capsule providing a sealing envelope for the parts contained therein. Furthermore, nozzle tip 09, seat 00, sleeve 04, and plate IOI will be'rigidly clamped together by clamping pressure transmitted through sleeve 04. In this connection plate IOI, although it may be a separate member if so desired, is formed as an integral flange on strainer tube I02 which has apertures III to allow flow of fuel into the interior thereof, and a strainer I04 about the outside thereof which will be more fully described her'einafter.

The head of the nozzle valve of Figs. 7 through 13 is designed for injectionof volatile fuels, such as gasoline, into a spark ignition engine. In such engine, it is desirable that the fuel spray be more diffused than fuel oil injected into 9. Diesel engine. For thispurpose, valve head 83 which is contained in recess I06 in nozzle tip memebr 90, is so formed as to impart a swirling motion to the fuel for passage through discharge orifice or passage I01 in nozzle tip 80. With reference to Fig. 11, it will benoted that the side of head 03 adjacent orifice I01 is formed with a centrally disposed recess I00 in line with orifice I01, and with a plurality of inwardly extending passages I00 leading from the periphery of the head means for abutment mempredetermined thick-.

.6; the depth of recess I00 itrols the extent of opening of the valve.

sure that the valve will open to the same extent for'allv like nozzles manufactured in production, tips 00 are provided with recesses I00 of predetermined depth: and by selecting a tip having a proper depth recess, during assembly of a nozzle, the extent of opening of the valve may be made uniform for all nozzles as in the previously described modification.

Although any suitable strainer may be employecl about tube I02; in the embodiment of the be seen most clearly from Fig. 10, the

non-circular in cross section,

invention illustrated, I preferably employ as the strainer a spring coil III in which the individual coils .are relatively close together so as to strain out foreign particles that may be in the fuel. Tube I02, as canbe seen from Fig. 8 is and its corners II2 are formed with screw threads III in which coil III is screwed; coil III being spot welded to tube I02 at suitable points I to hold the coil fixedly in position. Preferably, the outer peripheral surface of the coil is ground flat as shown in Fig. 9, so as to eliminate any wide spaces between the interstices of the coil in which relatively wide particles might become caught, and thus clog the strainer. I

The construction thuslfar described provides a complete unit, as shown in Fig. 10, which may be mounted in the engine. If the strainer describedis not employed, the unit will be the same as that illustrated in Fig. 10 with an ordinary of holder 01 are engaged plate substituted for flange I0 I Fig. 7 illustrates a form of mounting means for the nozzle in an engine. Such mounting means will ofcourse vary with various engines, depending upon space and size limitations. The mounting means illustrated comprises an adapter sleeve I I6 screwed in head III of the engine, and

having intermediate cooling fins '8 located in space ,IH) in the engine head. Splines I2I are formed on adapter Iii to enables. suitable tool to be engaged therewith for screwing of adapter I it into head Iil. Internal threads are provided in adapter I I6 at the end opposite to that screwed 'in the engine head, into which an elongated clamping sleeve I23 may be screwed for clamping the nozzle in position. The tapered end parts I00 of the nozzle enable proper centering thereof when clamped in position.

To facilitate removal of the nozzle when sleeve I23 is unscrewed, I provide a sleeve I20 within clamping sleeve I23 and which has one end screwed onto a boss I20 integral with strainer tube I02, and the opposite end'provlded with a flange I2'l adapted to engage an internal shoulder I28 formed in sleevel23; the sleeve lubeing formed with apertures I20 to allow fuel which flows therethrough, to flow into sleeve I22'and through apertures I02 in strainer tube 102, to

the nozzle. Since flange I21 is engageable with shoulder I28, it will be apparent that upon unscrewing of clamping sleeve I23, the entire nozzle assembly will be removed from the engine when sleeve I20 is lifted oi! the engine. 'A notch I20 9 I is formed in flange I21 01' sleeve I24 toenable insertion of a Suitable tool for screwing such sleeve relative to boss I26 01 strainer tube I02 To prevent turning of sleeve I23, when the nozzle is clamped in position, an aperture I30 is provided therein for insertion oflocking wire that may be wound abouta suitable part of the engine.

A special fitting is provided for connection 01 fuel line I3I to the described nozzle mounting means, which enables proper connection of the fuel line irrespective of theangular position thereof with respect to the nozzle axis. With reference to Fig. 7, it is to be observed thatthe end of sleeve I23 opposite to the nozzle end, is provided with an inward taper I32 over which complementary tapered ring I33 is adapted to fit; ring I33 being formed with an internal annular fuel passage I34, and being provided with tubular part I36 into which fuel line I 3I is rigidly connected and sealed by suitable welding I37. Ring I33 is clamped in position by a cap screw I 38 screwed into clamping sleeve I23, and having a head I33 between which and ring I33 is interposed sealing gasket I4I. Cap screw I38 is provided with internal passage I42 communicating with apertures I43 in the wall thereof, to permit flow of fuel from passage I34 in ring I33. Apertures I44 in head I39 of the cap screw permit insertion of locking wire which may be wound about Dart I36 to hold cap screw I38 against turning.

From the preceding, it is seen that irrespective of the angular position of fuel line I3I, it

may be readily connected by the described con nection, to sleeve I23, and that because of the tapered flt at I 32 between the end of the sleeve and ring I33, the connection will be tightly maintained irrespective of engine vibration. It is to be noted that the tapered fit I32 is only at the end of sleeve I23 and the part of ring I33 adjacent suchend, and not with the entire ring. As a result, fuel line I3I does not have-to be bent to any considerable extent when it is desired to connect it with or disconnect it from sleeve I23.

I claim:

1. 'A fuel injection nozzle comprising an apertured valve seat, an apertured spring abutment member adjacent the seat, a. valve stem passing with clearance through the seat and abutment members and having a head On one end engageable with the seat, a spring retainer loosely connected with the opposite end of the valve stem, aspring interposed between said retainer and said abutment member to urge the ,valve head toward the seat, and a separate sleeve member embracing the abutment member and a portion of the spring to center them relative to the seat but free of contact with the retainer member and the greater portion of the spring whereby the valve stem is unguided with relation to the seat.

2. A fuel injection nozzle comprising a seat having an aperture therein, a valve member having a head adjacent one side of the seat and a stem. extending through the aperture, the stem having a guideless mounting in the nozzle, a shoulder on the stem, an abutment member removably positioned at the opposite side of the seat and through which the stem extends with clearance, spring retainer means about the stern adjacent the shoulder and having a guideless mounting in the nozzle and a free mounting relative to the stem and moveably engaged with the shoulder, spring means about the stem between the abutment member and the retainer means, and a sleeve about the abutment member and the spring means engaging the periphery of the abutment member for retaining the abutment member in position, the sleeve being separable from the seat and having a portion adjacent the abutment member for centering the spring means and the remainder of the sleeve being free of engagement with the sprin means.

E. JOHNSON.

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