US1938274A - Internal combustion engine - Google Patents

Description

1933. 1.. M. WOOLSON INTERNAL COMBUSTION ENGINE Filed July 21, 1930 2 Sheets-Sheet 1 3 1W0 LIUNEI'L h Nana 501v, DEGEHSED Brfizs EkEc'UTRIx EMMH F NUDLBUN.

Dec. 5, 1933. L. M. WOOLSON INTERNAL COMBUSTION ENGINE .Filed July 21, 1930 2 Sheets-Sheet 2 35' Z8 Z9 1 a az n 4 1K 7 a mmm 9 J w s a E0 0& w a N 8 Z 9 W5 3 4 3 w 5 i: 5 55M M L E m L m u M Patented Dec. 5, 1933 UNITED STATES PATENT OFFICE field Village, Mich., assignor to Packard Motor Car Company, Detroit, Mich., a corporation of Michigan Application July 21, 1930. Serial No. 469,327

11 Claims.

This invention relates to internal combustion engines and more particularly to engines of the compression-ignition type in which fuel is injected into the combustion chamber through mechanism actuated by an engine part.

The invention has to do more particularly with the starting of engines in which liquid fuel is injected into the compressed air charges at a pressure developed in accordance with the engine speed. With this type of engine, the degree of fuel atomization and the pressure at which the fuel is injected becomes less as the speed of the engine is reduced and, therefore, the fuel is not injected into the compressed air in the combustion chambers under a pressure or in an atomized condition conducive to the formation of a mixture which will result in quick starting when the crank shaft is being turned slowly by a source of internal power.

An object of the invention is to regulate the timing, the pressure and the atomization of liquid fuel charges injected into compressed air charges in the cylinders of a compression-ignition engine in a manner to promote the formation of a mixture which will readily ignite under compression while the engine is being turned over in the starting.

Another object of the invention is to provide an internal combustion engine of the compressionignition type in which the timing of the fuel injection and the pressure produced upon the injected fuel charges is automatically increased beyond the pressure developed by the mechanism, operating the fuel injection devices when the engine is running under its own power, during cranking of the engine.

A further object of the invention is to provide an automatic control for regulating the actuation of the fuel injection devices of a compression-ignition engine so that, during cranking, the fuel charges will be injected into the combustion spaces when the compressed air charges are substantially at their highest compression and under a pressure such that there is sufiicient penetration of the air charges by the fuel charges to result in a homogeneous mixture which is thoroughly intermingled in a short space of time.

Still another object of the invention is to provide an automatic control which is actuated during the application of a starter to an engine of the compression-ignition type to bring into effective relation a faster moving fuel pump actuating cam mechanism and at a later time in the compression stroke of the engine pistons than the time-at which the injection takes place when the engine is operating under its own power.

These and other objects .of the invention will appear from the following description taken in connection with the-drawings, which form a part 0 of this specification and in which: I

Fig. 1 is a rear elevational view of a radial engine partially broken away and partially in section to show a fuel injection device and the actuating mechanism therefor, the cams being in a relation with the slowercam in effective position;

Fig. 2 is an elevational view showing the fuel injection mechanism, actuating cams arranged with the faster cam in effective position;

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 1;

Fig. 4 is a sectional view taken on the line 4-4 ofFig.3; a

Fig. 5 is a sectionalviewof one of the nozzle portions of afuel injection device.

Referring now to the drawings by characters. of reference, 10 representsgenerally the crank case of a compression-ignition type of internal combustion engine from which nine air-cooled cylinders 11 extend radially, the cylinders being secured underi compression around the wall of the crank case by compression rings, one of which is indicatedat 12. The cylinders are formed with an integral dome 13 and secured upon each of the domes is a head 14. Each of the associated heads and domes are formed with a single Venturi passage 15 leading into the interior of the associated cylindensuch passages serving as both the air inlet and the exhaust outlet for the combustion chambers which are between the cylinder domes and the pistons 16. In order to control the passages 15, there is provided with each a valve 17 which is normally closed by a plurality of springs 18 and opened by conventional engine actuated mechanism including a push rod 19 which extends into the crank case.

A diaphragm, or internal wall 20 is secured within the crank case and is formed with a central opening in which is arranged a bearing 21 for supporting the rear end of the crank shaft 22, the crank shaft projecting axially through the crank case. Arranged in a relation substantially parallel to the diaphragm is a detachable rear wall 23 which closes the open end of the crank case, and detachably secured to the rear wall is a starting device, indicated generally at 24, which is preferably of the inertia type as illustrated in .Patent No. 1,739,469, issued December 10, 1929, to R. P. Lansing. Such start- 0 ing device is arranged with a manually operable axially reciprocable jaw 25 which projects into the crank case in alignment with the rear end of the crank shaft, so that it can be moved into a cranking relation. y, n v

The engine illustrated. is of the compressionignitiomor Diesel type,whichoper'ate's on a'"fourstroke cycle, air charges being drawn into the cylinders through the passages 15 upon the suc,-

tion strokes of the pistons, during which time the valves 1'7 are mechanically held open; The valves are next closed and the compression strokes then occur, and during the "compressipn strokes, charges of fuel oil are injected under aihlghpressure at any engine speed:and;gillall}atomizedcondition into the air charges being compressed,

such that the mixture thereof with the compressed air will form a cliarge"-of-a character producing quick combustion. There 'associ-. ated with each cylinder a fuel injection device which consists generally of. a nozzle portion 26 and a pump portion 27, the nozzlesportions being secured rigidly. tothe cylinders and arranged to project through the walls thereof so that the fuel charges can be injected directly into 1 the interior of the cylinders.

Each nozzle consists of a panel 28 having a detachable end.29 extending throughithe associated' cylinder wall: and formed with-.a conical outletopening in' which the. -valve--' head- =30sis arranged. The valve stem-31 is arranged to'be moved into engagement with the stop member.

32=by a spring 33 and'such stopfmembenis adjusted to prevent the valve from-entirely closing. The barrel 28 is formed with a downwardly ex-- tending. neck portion which isprovided with-a passage 34 leading to the hollow chamberimtha barrel through which the valve rodextends.

Such nozzle neck is screwed into the 1350f the associated pumpunit' and bears against a spacer 36 which"maintain's.=thezpump'barrel 3'? in position within .the casing '35, there being av pair of spring-pressed valves's38 associated with.-

the'spacer and the barreltopreventliquidrfuel returning to the pumpstructure from the nozzle structure. A plunger -39 is arranged to reciprocate within the pump-barrel andra fuelinlet manifold 40 communicates with all 'of'irthe'pumps, there being a union 41 in the manifold structure associated with each of the barrels, and ports 42-extend through the casing and the barrel to establish communication between the fuel feeding manifold and the interior of the barrel. Such ports are controlled by the position of the .plunger so that when a plunger uncovers the-ports 42,

liquid fuel is moved into the pump barrel and nozzle, under a low pressure from the source of supply (not shown), completely filling the chambered' portions therein. The pump plunger-s are moved in their injection strokes by adjustable mechanism, which will be hereinafter described, and during such movement they close the ports 42, their stroke after closing such ports determining the quantity of fuel whichis displaced from the nozzle into the cylinders.

It will be seen that the speed .of the plunger movement determines the degree of pressure under which the fuel charge. is forced past the' nozzle valve head. The effective stroke of the plungers will force fuel past the'valves 31 and from the nozzles in a manner such that the fuel" charges are directed into the cylinders in a conical-spray. The air inlet passages are formed and arranged so that they cause rotation of the air in the cylinders and such rotation continuesduring the following compression stroke of the piston, the fuel charges being sprayed into such compressed rotating air charges.

The degree of fuel atomization and the extent of the pressure at which it is injected determines thedegree of theiintermingling of the oil with the air and, therefore, it is necessary that there be sufficient atomized fuel penetration of the air to .cause a uniform distribution if eflicient engine operation is to result. It is also necessary that the atomizationiand penetration of the air by the This invention has to docparticularly with ng mechanism for injectingfuel oilzin' an atomized condition and ;at a. sufiicienttpressure to cause an,

intermingling with the compressedair in-;the.j

cylinders such that ignition ;will readily result from; compression; whenthe crank .shaft is being slowly turnedthrough the application of-astarting;device,@.f1 q.this end, I utilize the regular fuelg iniec inss 'eh n s ;f rt no a run operation of .the ,engine andprovide an auxiliary actuatingmechanism therefor which is-elfective only. during the application of the starting-mechanism to the crank shaft. This-auxiliary actuat-.

ing mechanism is :made effective.-automaticallythrough application of the starting device and is placed in ineffective; relationv when the starting device is released. carrying out such inventlQIL-I'DIQPQSQ that-the liquidfuel charges will be injected, during the. turning .of the crank shaft by thestart gidevice -ata pressure which will cause v the 5 fuel .to penetrate substantially to the center of thecylinder land-in a finely atomized condition so that one rotation of the compressed air. inithe cylinder will cause a uniform distribution therein of the atomized liquid fuel.

Under normalrunningoperation, crank shaft actuated mechanism is provided for causing the pump plungers to move in theininjection strokes,

and such mechanismis returned to a position uncovering the ports 42-by means of the coil spring '43. A..fuel plungerpush rod 44 extends through the crank case and has. associated therewith arod 45 which is ,pivotally connected with a link 45 carried bya regulating ring 47 rotatably mounted Within the crank case. The ring 47 can be actuatedthrough the association ofa tooth segment 48 with a.rack49 which isfixed to the ring,'the segment being rotated by means of the shaft 50 whichis in-turn actuated-through suitable mechanism connected with the lever 51. As-

sociated with each of the levers 45 is a slipper or rock lever, as shown at 52, 53 and 54, each being carried by a shaft 55 supported by the diaphragm and therear casing cover 23. The free ends of the slippers areformed with a curved groove in which the'associated rod 45 'is adjustably posi tioned by rotation of the ring 4'7: and the connecting links 46, so that uponmovement of the rods 45, lengthwise of-ithe slippers, the effective stroke of the pump plun'gers can be simultaneously varied.

Arranged interiorly of the pivoted slippers 53, for" actuating the same to cause an injection stroke=0f the pump plungers, is a cam 56 which is provided with four lobes 57, 58, 59 and 60. A cam 56"is' also provided with a plurality of lobes 61 arranged in a parallel plane with the lobes 57, 58, 59 and 60 and at the rear thereof for actuating the slippers 62, one of which is pivotally mounted upon each of the shafts, and one of the rods 19 is associated with each of the slippers 62. Upon rotation of the cam 56 the lobes 61 will cause movement of the valve operating mechanisms to open the ports 15 in desired timed relation with the engine cycle.

A cam 63 is mounted upon the rear end of the crank shaft and is provided with an extended hub 64 which is keyed to the crank shaft as indicated at 65, a suitable bearing ring 66 being arranged intermediate such cam hub and the bearing-21. Looking at the engine from the rear end, the crank shaft and the cam 63 rotate as an integral unit in a clockwise direction.

The cam 56 is driven through mechanism associated with the crank shaft. The hub of the cam 56 telescopes the hub 64 of the cam 63 and is rotatably mounted thereupon. Arranged within a bore 67 formed in the rear end of the crank shaft is a drivensleeve 68 having a helical gear 69 formed on the outer end thereof. The inner periphery of such sleeve 68 is splined to the crank shaft as indicated by the numeral 70 while the inner portion of the sleeve is formed along its entire wall with a helical spline 71. Telescoped within the driven sleeve 68 is a starter jaw 72 which is formed on its periphery with a helical spline 73 which meshes with the helical spline in the interior of the helical spline 71. Extending axially'through the bore 67 and screwed into the rear crank arm is a pin 74 upon the rear end of which is screwed a retainer sleeve 75 which bears against a ring 76 for retaining the starter jaw axially in a definite relation to the crank shaft, such ring 76 engaging an inwardly extending shoulder 77 extending from the starter jaw. Within the bore 67 is arranged a compressed coil spring 78 which bears at one end against the crank cheek and at the other end against the driven sleeve 68, the tension of such sleeve being sufficient to normally retain the driven sleeve in its rearmost position. Upon a shaft 79 carried by the rear wall of the crank case is fixed a helical gear 80 and a spur gear 81, the spur gear being arranged to mesh with an internal gear 82 formed on the cam 56. Such train of gearing is preferably arranged to drive the cam 56 from the crank shaft in an anti-clockwise direction and at oneeighth the speed thereof.

In Figs. 1 and 3 the cams 56 and 63 are shown in their desired relation when the engine is operating under its own power. In such position the lobes, for actuating the slippers of the fuel injection mechanism, are related to the crank shaft so that they are effective in a range extending between forty and twenty degrees before the pistons reach the top of their air compression strokes, the degree in the range at which the lobes cause actuation of the associated slippers is controlled by the adjustment of the ring 47. When in such relation the lobes 57, 58, 59 and 60 are of such length that they raise the slippers prior to the movement of the single lobe on the cam 63 thereunder and hold the slippers in raised position so that the lobe of the faster cam will pass thereunder without effecting operation of the slippers. The cam 63 is preferably fixed to the crank shaft so that in its rotation the lobe thereon will cause actuation of the slippers of the fuel pump actuating mechanisms approximately ten degrees before the pistons reach the top of their air compression strokes. Under such conditions the spring 78 exerts sufllcient force against the driven sleeve 68 to maintain it in its rearmost position and when in such. position the cam 56 is effective to cause actuationof fuel-injection devices. 7

' Rotation of the crank shaft imparts rotation to the sleeve 68 through the spline connection 70 and consequently rotation of the helical gears 69 and 80 and the gears 81 and 82 cause rotation'of the cam 56 from the crank shaft.

When the engine is to be started the inertia starter'34 is energized-and the jaw 25' is moved axially into engagement with the starter jaw 72. The first rotation of the starter jaw 72 upon the application of the inertia starter thereto, due to the helically splined relation with the driven sleeve and its splined relation with the crank shaft, will cause a forward axial movement of the driven sleeve 68. Forward movement of the driven sleeve will cause the helical teeth of the gear 69 formed thereon, to rotate the gear 80 and through the train of gears extending therefrom to the cam 56 will impart a similar rotation thereto. This forward movement of the driven sleeve is sufficient to cause a rotation of the cam 56 in an angular relation to the crank shaft such that the lobes for actuating the fuel mechanism slippers will be moved to a point where they would engage the slippers later than the time at which the slippers are engaged and actuated by the lobe on the cam 63, and preferably the cam 56 is thus rotated to a position where the fuel mechanism actuating lobes thereon would engage the slippers approximately at the time the pistons reach the top of their compression strokes. When the sleeve 68 has been moved to its rearmost position through the rotation of the starter jaw, continued rotation thereof by the inertia starter-will cause rotation of the crank shaft andall of the driving mechanism as an integral unit, it being understood that the driven sleeve 68 is moved forwardly against the tension of the spring 78 so that upon release or an over-running of the starter jaw 25 by the starter jaw 72, the spring will return the gear driving mechanism to its rearmost position as shown in Figs. 1 and 3. In Fig. 2 the cams 63 and 56 are illustrated in the position they assume when the starter has been applied to the starter jaw and the cam 63 in effective position. When the cam 63 is in effective position it will raise the slippers in advance of the lobes on the cam 56 and the single lobe thereon is of sufficient length to maintain the slippers which have been actuated to cause an injection stroke in an elevated position until such time as the actuating portion of the lobes of the cam 56 have passed beneath the same. It will be seen, therefore, that when the cam 63 is effective to cause fuel injection strokes it will shield or mask the lobes on the cam 56 and vice-versa. This masking relation of the cams is due to the length of the lobes and to the relation and speed of operation thereof, it being understood that upon every two revolutions of the crank sliaft there will be one actuation of each of the fuel injection devices.

As the cam 63 is moving eight times as fast as the cam 56 there will be a material pressure developed behind the fuel charges being injected through the nozzle even though the cams are beingrotatedirelatively slowly by the applicationofthe starter. It will be seen that the cam 63 .is automatically madeeffective through the association of the starter with the mechanism for 6 driving the cam'i56 and that the spring 68 automatically. returns the camv 56 to effective position upon releaseof the starter, it will be understood, howeven that this movement could be performedmanually if desired.

10- The pressure developed behind the fuel'upom the injection strokes of the pumps when a the cam- 63 is. effective will cause a :fine. atomization of :and. pressure behind the fuel charges. injected, suflicient uto. penetrate substantially midway of the air rotating within the cylindersso that upon one:revolution rof compressed air-inthe cylindersrtheatomized fuel'will be uniformlydistributed and form a homogeneous mixture which will ignite readily under the pressure developed within the combustion chambers, and in this manner starting of a compression-ignition.engine -is ma-- terially assisted. :-.Under normal temperature conditions, this form of: injection requires-only a few rotations of thecrank' shaft to "cause-the, and-even under =coldtemperature conditions the addition- [engine to operate under its own power,

ofa; glow. plug or the heating of the air charges drawn into'the'cylinders' is all that is required: to result ineasy starting of the engine with this ao imannerof injecting-the fuel upon starting, :It'

will also be seen that the fuel charges are delivered at substantially" the: highest point of com&

pression of the "air-charges, when-the cam -63 is'inefiective position, so that the-greatest-heatski'i'developed isutilized. at the proper'timeto cause ignition" and thus assist'in easy starting, an economy of operation. I

-.-While thereis hereindescribed in'some detail a'ispecific embodiment of: the invention, 'whichis OLE deemed tobe-new andadvantageousand may be specifically claimed,- :it is not desired to be understood-that the invention is limited-to the exact details of-the construction-as it will lie-apparent that changes may be: made therein without de- 'i'partingfromthe spirit or-scope of the invention.-

What I- claim-is:

"-1.'In;an internal combustion engine of 'the' compression-ignition type in which fuel and-air charges are introduced separately into-the com-'- 50. ibustion spaces, a device for injecting atomized liquid'fuel charges under pressure into a combustion space, a crank shaft, a cam rotatably associated Withthe crank shaft for actuating the fuelinjection device, an axially movable sleeve fiaiarranged to rotate with the crank shaft, said sleeve having a gear portion formed with helical 'teeth, reduction gearing intermediate the sleeve and the cam including a helical gear mesh-' ing with the helical teeth of the sleeve, and'a 6G i'starting jaw associated with the sleeve to initially cause axial movement and then rotation of the said sleeve having a gear portion formed'with helical teethyreduction gearing intermediate the sleeve and the cam including a helical gear meshing with the helical teeth of the sleeve, a startingjaw associated to initially move the-sleeveaxi- M ally and then rotate it when cranked, and ,means for normally. maintaining the sleevein one-ex: treme. axial position and opposing axial-move ment' thereof by the starter jaw.

3.1m an internal combustion engine of the compression ignition type in which fuel and air charges are introduced separately into the combustion spaces,-a devicefor injecting atomized liquid fuel charges .under pressure into a combustion space, a crank shaft, a camrotatably associated with thecrank shaft for actuating the fuel injection device, an axially movable sleeve -ar.- ranged to rotate with the crank shaft, said-sleeve having a gear portion formed with helical teeth, reduction gearing intermediate the sleeve:.and the cam including a helical gear meshing with the helical teeth of the sleeve, a,-startine Jaw associated with the sleeve to initially cause axial movement and then rotation thereof when cranked, andra coil spring for .normallyamaintaining the sleeve :in one extremeiaxial position and opposing axial movement thereof imp-the starter jaw. a

4. In an internal hombustiongnginexof -:the compressiondgnition type ;in v which a fuel andair charges are introduced separate'ryf intogthe room,- bllSlJiOIl FSDELCGS, ya rdevice for, injecting"; atomized liquid fuehcharges under. pressureinto-a com-. bustion space, .a-crank shaft-havinga'hollow-zend provided". interiorly with 'diametric; vsaxiall-y extending. grooves, acam rotatably associated with the crankshaft for actuating the. fuel injection device, a sleeve-extendinginto the hollow-'endrllo of the crankshaft, said sleeve'being provided with splines seated in the groovesinthe crank shaft; and with helical gear teeth,-=reduction.gearing connecting the sleeve with the cam, said reduction gearing including ahelical gear meshing. with thesleeve;teeth,-:andmeans initially moving the sleeve axially :and then rotating it \when cranking the-:engine starting, said gearing being rotated aby the axial movement of :thesleeve to retardzthe cam-timing.

:5. In an internal-combustion :engine :of the compression-ignition type in-cwhich fuel and sair charges are introduced separately into the com bustion spaces, a device for injecting atomized liquid fuel charges under pressure into acombus-.: tion space, a crank shaft having a hollow end, -a rotatable cam through which the crank shaft extends axially, said cam being arranged to -actuate the fuel injection device, arod extending'through the hollow end of the crank shaft'and'secured in fixed relation thereto, a sleeve extending intothe hollow end of the crank shaft and splinedto rotate with the crank shaft but in an axially adjustable relation therewith, said sleeve being formed with hehcal teeth, a-reduction gearing between the sleeve and the cam," said reduction gearing including a helical gear meshing-with the helical teeth of the sleeve, a starting jaw telescoping within the sleeve and meshing helically therewith, and means associated with the rod and the starting jaw for fixing the'starting jaw in an axial relation with the crank shaft.

6. In an internal comloustionengine of the compression-ignition type in which fueland air charges are introduced separately into the combustion spaces, a-device for injecting atomized liquid fuel charges under pressure into a combustion space, acrank shaft having a hollow end, a rotatable cam through which the crank shaft extends axially,..said.cam. being arranged to etc-.1150

tuate the fuel injection device, a rod extending through the hollow end of the crank shaft and secured in fixed relation thereto, a sleeve extending into the hollow end of the crank shaft and splined to rotate with the crank shaft but in an axially adjustable relation therewith, said sleeve being formed with helical teeth, a reduction gearing including a helical gear meshing with the helical teeth of the sleeve, a starting jaw telescoping within the sleeve and meshing helically therewith, and said starting jaw having an inwardly extending flange, a retaining washer keyed to the rod and engaging the flange of the starting jaw, and a nut threaded upon the rod for securing the retainer in a definite position.

'7. In an injection type of internal combustion engine, a crank shaft, a plunger type of fuel injection device, a pair of adjacent parallel cams, mechanism for operating the injection device in operative engagement with both of said cams, one of said cams being keyed to the crank shaft and the other cam being rotatably mounted relative thereto, said cams being normally timed so that the rotatable cam leads and shields the mechanism from actuation by the fixed cam, a sleeve fixed to the crank shaft and movable a limited extent axially thereof, said sleeve having helical teeth thereon, reduction gearing between the rotatable cam and the sleeve including a helical gear meshing with the helical sleeve teeth, a jaw helically threaded to the sleeve, a starter device adapted to engage the jaw, and means normally urging the sleeve in a direction toward the starter, rotation of the jaw by the starter initially moving the sleeve axially away from its normal position before rotating the crank shaft to rotate the reduction gearing and retard the rotatably mounted cam so that the fixed cam will lead and shield the mechanism from actuation by the rotatable earn.

8. In an internal combustion engine of the compression-ignition type in which fuel and air charges are introduced separately into the combustion space, a device for injecting atomized liquid fuel charges under pressure into the combustion space, a crank shaft, a cam for actuating the fuel injection device, a sleeve member arranged to rotate with the crank shaft and axially movable a limited extent relative thereto, said sleeve member having helical teeth thereon, reduction gearing in driving relation between the sleeve and the cam, said reduction gearing including a helical gear meshing with the helical teeth on the sleeve member, and means for reciprocating said sleeve axially of the crank shaft including a spring and a starting jaw, said starting jaw being rotata-bly mounted on the crank shaft and helically splined to the sleeve member, cranking of the jaw to start the engine moving the sleeve member axially and changing the cam position angularly, said spring being arranged to oppose axial movement of the sleeve' induced by the rotation of the starting jaw.

9. In an internal combustion engine of the compression-ignition type in which fuel and air charges are introduced separately into a combustion space, a device for injecting atomized liquid fuel charges under pressure into the combustion space, a crank shaft, a cam rotatably associated with the crank shaft for actuating the fuel injection device, a sleeve member arranged to rotate with the crank shaft and associated therewith to be moved axially a limited extent, said sleeve member having helical teeth thereon, reduction gearing in driving relation between the sleeve and the cam, said reduction gearing including a helical gear meshing with the helical teeth on the sleeve member, rotatable means in driving relation with the sleeve member, the rotation of said means moving said sleeve axially in one direction and changing the position of the cam angularly on the crank shaft, and spring means opposing such axial movement of the sleeve mmber, said spring means normally maintaining said sleeve member in one extreme position of its axial movement.

10. In an injection type of internal combustion engine, a crank shaft, a plunger type of fuel injection device, a pair of parallel cams, mechanism for actuating the injection device arranged in operative engagement with both of said cams, one of said cams being fixed to the crank shaft and the other of said cams being rotatably mounted relative thereto, said cams being normally timed so that the rotatable cam leads and shields the mechanism from actuation by the fixed cam, a sleeve fixed to rotate with the crank shaft and movable a limited extent axially thereof, said sleeve having helical teeth thereon, reduction gearing between the rotatable cam and the sleeve including a helical gear meshing with the helical teeth of the sleeve, rotatable means having helical threads engaging with the sleeve, and a spring carried by the crank shaft and associated with the sleeve opposing axial movement thereof induced by rotation of said means, the rotation of said means moving the sleeve axially of the crank shaft and thereby rotating the reduction gearing and changing the angular position of the associated cam whereby the fixed cam will lead and shield the mechanism from actuation by the rotatably mounted cam.

11. In an internal combustion engine of the compression-ignition type in which fuel and air charges are introduced separately into the combustion space, a device for injecting atomized liquid fuel charges under pressure into the combustion space, a crank shaft, a cam rotatably associated with the crank shaft for actuating the fuel injection device, a sleeve arranged to rotate with the crank shaft and axially movable a limited extent relative thereto, said sleeve having a gear portion formed with helical teeth, reduction gearing intermediate the sleeve and the cam including a helical gear meshing with the helical teeth of the sleeve, resilient means urging said sleeve in one direction, and means including a starter device for moving the sleeve axially of the crank shaft, axial movement of the sleeve changing the timing of the cam.

EMMA F. WOOLSON, Executrix of the Estate of Lionel M. Woolson,

Deceased.

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