US1938271A - Internal combustion engine - Google Patents

Description

Dec. 5, 1933. L. M. WOOLSON INTERNAL COMBUSTION ENGINE Filed April 2, 1930 Patented Dec. 5, 1933 UNITED STATES PATENT OFFICE INTERNAL COMBUSTION ENGINE Application April .2, 1930. Serial. No. 440,89!

31 Claims.

ihis invention relates to internal combustion engines and more particularly to a method of operating a Diesel engine and to mechanism for injecting liquid fuel into compressed air to form the combustion mixture.

In Diesel engines the combustion mixture is formed by the injection of atomized liquid fuel of relatively low volatility, and there is required a certain degree of fuel atomization and penetration thereby of the compressed air in order to insure combustion. This requirement is naturally more necessary when the fuel charge is of low volume, as when starting and idling, and because the pressure of the liquid fuel when injected into the compressed air must be at least such as to cause SllfiiClGIlt penetration or otherwise combustion will fail for lack of proper intermingling of the mixture constituents.

With fuel mechanisms which are actuated through mechanism driven in accordance with and by rotation of the crank shaft, the pressure developed behind the fuel charges varies in accordance with the crank shaft speed, and in all of such mechanisms of which I am aware the starting engine speed and usually the idling speed, at least during low temperature, are too low to produce the pressure in the injections whereby the fuel is atomized and penetrates the compressed air in a manner to insure combus- 30 tion. In order to overcome such difficulties, it has been proposed to apply heat to the cylinder structure and to the air and the fuel previously to mixing, and while such heat application is of some assistance, still it adds mechanism and cost and does not insure combustion. It is also well known that starting dimculties are in accordance with the temperature conditions, and that the application of heat without the proper atomization of the fuel and its penetration of the compressed 40 air charges does not insure easy starting even though the temperature is relatively high.

The starting mechanism which must be employed to rotate the crank shaft of a Diesel engine is necessarily so large as to be prohibitive if the 45 crank shaft is to be turned fast enough to operate the fuel injection mechanism in a manner which will develop a pressure behind the fuel charge necessary to insure combustion. As a result, it is the common practice to use a small starter which will rotate the crank shaft slowly and at the same time utilize auxiliary heat in some manner, but with such apparatus, starting difficulties are constantly prevalent. Of course, the powerful starter would overcome the starting difliculties above related, and there may be uses where the weight, cost and size of such a starter would make no difference, but with small boats, aeroplanes, and motor-propelled apparatus such a starter is highly impractical.

An object of this invention is to provide a fuel injection mechanism for Diesel engines in which atomization of the fuel and its penetration into compressed air will be suflicient to sustain combustion irrespective of the engine speed so that the fuel charge will be of a character such that it will ignite readily when the engine is turned over in starting.

Another object of my invention is to provide a method of operating a Diesel type of engine in which combustion will be assured when operating at low speed.

An object of this invention is to provide fuel injection mechanism for Diesel engines in which the liquid fuel charges are introduced at a pressure such that they will be adequately atomized and will penetrate the compressed air charges sufficiently to ignite during the compression stroke during any speed of engine operation or regulation of the fuel charge.

Another object of my invention is to provide an airless fuel injection device for Diesel engines which will be actuated to discharge the liquid fuel into compressed air charges at a pressure, when the engine is operating below a predetermined speed, which will support combustion.

Still another object of my invention is to provide a pressure fuel injection device for Diesel engines in which there are two actuating mechanisms for the pump plunger, one of which causes a faster stroke than the other and which is automatically brought into operative relation when the engine crank shaft is below a predetermined rotational speed.

Another object of my invention is to provide a pressure fuel injection device for Diesel engines in which a member is arranged to be actuated by either one of two independent cams driven at different speeds by the engine, the faster speed cam being effective only below a predetermined engine speed.

Another object of my invention is to provide a centrifugally controlled cam member which is associated with an engine in a manner such that it is effective to actuate a fuel injection device within a certain range of the engine speed.

A further object of my invention is to provide a radial engine with fuel injector actuating means in which two cam members operating at different speeds can individually be effective and which the compartment 14.

will shield the injector actuating means from the other under predetermined conditions.

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

Fig. 1 is a rear elevational view of a radial engine partially broken away to show the fuel injection mechanism;

Fig. 2 is a sectional view of the same taken on line 2-2 of Fig. 1;

Fig. 3 is a sectional view taken substantially line 33 of Fig. 2 illustrating one of the cam structures.

Referring now to the drawing by characters of reference, illustrates generally a nine cylinder radial Diesel type of engineoperating upon a four-stroke cycle and designed particularly for use as the power plant for an airship. There is a barrel type crank case 11 within which is arranged a transversely extending partition 12 which separates the connecting rod containing compartment 13 from the accessory mechanism compartment 14, and a rear end cover 15 closing Such rear cover is provided with a plurality of apertures 16 through which suitable securing means can be arranged to fasten the engine upon a suitable support.

The cylinders 17 are air-cooled and include an integral head 18 upon which is secured an auxiliary head 19. In order that air may be drawn into the cylinders for the fuel charge, and burnt gas expelled from the cylinders, I provide a single passage 20 through the heads of each cylinder which is in the form of a venturi extending tangentially of the inner wall of the cylinder and at an angle to the axis thereof. Such passages 20 are controlled by valves 21 which are each nor- ,mally seated by springs 22 and held open by rock levers 23 which are actuated by mechanisms ex tending through the housings 24 and terminating in rods 25.

The crank shaft 26 extends axially through the .crank case and includes a single throw portion 27 upon which is associated a connecting rod assembly of the type usually employed with radial engines, there being pistons 28 arranged to reciprocate in each of the cylinders and associated with the connecting rod assembly in the usual transversely extending fuel inlet ports 32.

manner.

Associated with each cylinder is an individual fuel injection device consisting generally of a nozzle portion A and a pump portion B preferably formed as a unit assembly and secured to the side of the cylinder by the studs, 29. The

pump sections of the injecting devices include a barrel 33 having an axially extending bore, in which a piston 31 is arranged to reciprocate, and The ports open into a housing formed by the attachment of a removable casing 33 around the barrel, such casings being in open communication with a fuel feeding manifold consisting of a plurality of sections 34. An overflow conduit-35 is connected to the uppermost fuel feeding device for quantity of fuel charge which will be injected through the nozzle into the compressed air in the associated cylinder, and the speed at which the plunger is operated will determine the pressure under which the fuel is injected into the compressed air charges in the cylinder. It will be seen that the degree to which the fuel penetrates the compressed air charges and the degree of atomization caused by passing through the nozzle valve (not shown) will vary in accordance with the pressure under which the fuel is injected into the cylinders by the plungers.

The fuel pump plungers 31 are operated by engine driven mechanism which I will now describe. Arranged Within each of the pump barrels is a guide member 36 to which the plunger is connected and a spring 37 is arranged within the barrel to normally exert pressure against the guide member 36 sumcient to cause its movement in a direction uncovering the inlet ports 32 when the cams permit, so that after each injection stroke such spring will move the piston into a retracted position uncovering the fuel inlet ports 32 and allowing replenishing of the fuel. A sleeve 38 extends through the crank case, adjacent each of the pump barrels, for the purpose of guiding plunger actuating rods 39, such rods engaging the guide 36 and being reciprocably mounted in the sleeves. Links .0 are associated with the rods 39 and also engage rock levers il, which are pivotally mounted upon shafts 42 extending transversely of the compartment 14 and secured in the walls 12 and 15. The rock levers are providedwith a curved face 43 with which the links engage and upon wh ch they can be simultaneously and equally adjusted longitudinally by turning the ring 44, as the links 45 are connected to pins 45 and are pivoted to the links 40. The ring has slots 46 therein through which studs 47 secured to the wall 12 extend to retain the ring in position. Suitable rack and pinion mechanism 48 is associated with the ring 44 to be operated by movement of the link 49 fixed to the shaft 50, the rotation of which will cause rotation of the ring. The curved faces 43 of the rocker members are related with the fuel pump actuating mechanism so that upon adjustment of the links e0 longitudinally of the rock levers, the effective stroke of the plungers will be varied upon actuation of the rock levers. As shown in Fig. 1, the links 40 are related with the rock levers so that there will be a maximum piston stroke after closing the fuel inlet ports 32 under which circumstance the maximum quantity of fuel is delivered, but when the link 40 is adjusted toward the heel of the face 43, then the link stroke becomes slower and shorter, so that less fuel will be introduced into the cylinders. When the links 40 are at the right end of the rock levers illustrated, then the pump stroke is not sufiicient to close the inlet ports and consequently the cylinders will not receive any liquid fuel. I

Fixed to the crank shaft adjacent the partition wall 12 is a cam hub structur consisting of members 51 and 52 which are secured together by the bolts 53, there being a recess formed between such members and extending through a portion of the periphery thereof for the reception of a pivoted arm 54 which is provided with a hub carried upon the bolt 55 which extends through cam hub sections 51 and 52. The cam section 52 is provided with an elongated hub which is keyed to the crank shaft and upon which a cam 56 is rotatably mounted, such cam being pro- R. P. M.

vided with four lobes 57 for actuating rock levers 58 with which the valve actuating rods 25 are associated. The rock levers 58 are mounted parallel with the rock levers 41 and on the shafts 42. Four lobes 59 are also arranged'on the cam 52 to actuate the rock levers 41, such lobes being in a plane intermediate the lobes 57 and the other cam hub. The cam 56 is provided with an internal gear 60 which is rotated through reduction gears 61, 62 and 63 driven by the crank shaft, and the cam 56 is thus driven preferably at one-eighth crank shaft speed and in a direction reverse to that in which the crank shaft is rotating. 7 I

As heretofore stated, the arm 54 is pivoted upon the bolt 55 and is arranged to rock within a recess between the sections 51 and 52, there being a peripheral opening through which the lobe portion 64 can extend. The interior end of the arm 54 is in the form of a weight 65 and such end of arm is anchored to the casing 51 by the coil spring 66. The coil spring, just mentioned, normally holds the cam member 54 in the position shown in Fig. 3 but the tension thereof, which can be adjusted as desired, must be overcome by centrifugal force when the crank shaft is rotating in order to move the lobe 64 into an ineffective position inwardly of the recess as shown in dotted lines in Fig. 3. With the en-' gine illustrated, 1400 R. P. M. is calculated to sustain flight of an airship, and consequently I arrange the spring tension so that centrifugal force will move the cam lobe 64 out of operating position when the crank shaft is rotating above 1400 It will be seen that the rock levers 41 are provided with an extended portion 6'7 so that they can be actuated by either the single lobe 64, or by the lobes 59 on the cam 56. When the engin is operating below 1400 R. P. M., the cam lobe 64 will actuate the rock levers and as this cam is rotating at crankshaft speed, the injection strokes transmitted to the plungers 31 will be several times faster than the stroke which would be transmitted by the cams 59 which are rotated at an eight to one speed reduction from the crank shaft. When the engine is idling or being started, there Will be a fast pump plunger stroke which will cause the fuel to be injected at a much higher pressure than if the lobes 59 were causing the actuation, and thus when idling or starting, the pressure under which the fuel is injected is always sufficient to cause a fine degree of atomization and a penetration of the air changes by the fuel charges such that the fuel intermingles and vaporizes in substantially the same manner as when operating under load thus permitting ease of starting and aiding in eflicient idling operation.

When the engine is operating at an R. P. M.

'of more than 1400, the cam lobe 64 moves inwardly and is in an inoperative position, whereupon the cam lobes 59 serve to cause the injection strokes of the pump plungers, and at such speed the rate of rotation of the cam 56 will be sufficient to cause a plunger movement fast enough to result in a pressure on the fuel which will cause the desired atomizationofthe fuel and its penetration into the compressed air charges.

Having two cams rotating at different speeds for operating the fuel injection mechanisms, it is necessary that provisions be made to cause one of the cams to be ineffective while the-other is effective, and this I havearranged for automatically. As before related,the cam lobe-64 is automatically effective or ineffective in accordance with a predetermined speed; the spring 66 causing the lobe to move into effective relation below a predetermined crank shaft R. P. M. and centrifugal force causing the lobe to move within the cam hub and become ineffective above a predetermined R. P. M. With such structure, therefore, it is still necessary that provision be made for causing the lobes 59 to be ineffective when the lobe 64 is effective, and this is accomplished automatically also through the relation and form of the cam lobes and their relation with the rock levers 41 together with the timing of the cams relatively. The cam 56 rotates in a reverse direction to that of the crank shaft and at one eighth its speed while the other cam rotates with the crank shaf, and therefore the single lobe rotates eight times as fast as the lobes 59 and in a reverse direction. Upon each two revolutions of the crank shaft, the cam 56 will be rotated a quarter turn and the lobes 59 will, when effective, have actuated each of the rocker levers once in the cylinder sequence of 1'3-5 79-2-4-68. The lobe 64 rotates eight times as fast as the cam 56, and is fixed on the crank shaft so that it will lift the rocker levers just in advance of the lobes 59, the timing permitting this, and the lobes 59 will therefore pass under the rocker levers ineffectively. The lands of the lobes 59 are made long so that the rocker levers will ride thereon after they have been raised by the lobe 64 until such lobe again passes thereunder, and in this manner the lobes 59 serve to allow the lobe 64 to actuate only every other rocker lever in every revolution.

The cam lobe construction and arrangement is such, however, that the rocker levers are allowed to ride onthe base circle of the cam 56 between injection strokes in order to allow the pumps and nozzles to fill with oil to replace the 115 evacuated charge. I also provide the cam lobe end of the arm 54 with a gradually rising face 150 in order that stresses upon the pump mechanism caused by the shock of the contact of the lobe with the rocker levers 41 will be'reduced 130120 a minimum. It will be readily understood that the first part of the plunger injection stroke is ineffective so that the gradual movement over a longer crank shaft angle, as caused by the face 150, will in no way affect the desired fast plunger injection stroke after the ports 32 are closed.

The device herein described will automatically maintain a predetermined minimum fuel atomization and penetration thereof into the compressed air charges, even though the pressure 131] inducing, mechanism is operated by the engine and also irrespective of the regulation of the fuelvolume injected. In this manner a Diesel engine can be readily started because the fuel mixtures will always be in a properly vaporized 135 and intermingled relation. It will be understood that other mechanism can be utilized to cause the minimum fuel pressure set forth, and that the invention is not limited to the mechanism or the type of fuel injection device illustrated.

When it is desired to start the engine,'an inertia or other conventional form of starter (not shown) is applied to the crank shaft jaw 151 so that the crank shaft is slowly rotated. Under such circumstances air will be drawn into the 145 cylinderand compressed, the cam 64 will actuate the injection mechanism and cause a liquid fuel injection into the compressed air, the compres-- sion of the air with the-fuel therein is continued and then there is a power stroke after which the 15's charge or burnt gases will be expelled. It will be understood that such cycles occur in the cylinders in the order above mentioned. The cam 64 continues to actuate the fuel injection mechanisms until centrifugal force retracts it, at which engine speed the slower speed cam will promote the requisite atomization of the fuel and its penetration into the compressed air charges to sustain combustion. Thus at any engine speed, the fuel is injected with suflicient force by engine operated mechanism to insure a requisite atomization and penetration to insure combustion, it being understood of course that several rotations of the crank shaft by the starter may be required depending on the surrounding temperature.

While I have herein described in some detail a specific embodiment of my invention, what I deem to be new and advantageous and may specifically claim, I do not desire it to be understood that my invention is limited to the exact details of the construction, as it will be apparent that changes may be made therein without departing from the spirit or scope of myv invention.

What I claim is:

1. In an engine, a liquid fuel injection device including pressure producingmeans, mechanism for actuating the pressure producing means, a pair of engine operated cams rotated at different speeds and associated to actuate the mechanism, and means actuated by centrifugal force for moving the faster cam into ineffective position above a predetermined engine speed.

2. In an engine, a liquid fuel injection device including pressure producing means, mechanism for operating the means, and a pair of independent cam means rotated at different speeds by the engine in regular paths for actuating the mechanism, one cam means having a shiftable lobe, said lobe shielding the other cam means from engagement with the mechanism when in effective position and being ineffective while the'other is effective.

3. In an engine, a liquid fuel injection device including a plunger, mechanism connected to cause reciprocation of the plunger, and a pair of engine driven cams, each of said cams being associated with the mechanism to individually cause complete injection strokes of the plunger, one of said cams having a pivoted lobe effective to operate said mechanism in a predetermined engine speed range, the other of said cams being effective to operate said mechanism only in an engine speed range in which the cam having the pivoted lobe is inefiective. r

4. In an engine, a liquid fuel injection device including a plunger, mechanism connected to cause reciprocation of the plunger, and a pair of engine driven cams associated to individually actuate the mechanism and cause complete injection strokes of the plunger, only one of said cams being effective in each of two complementary portiens of the engine speed range.

5. In an engine, a liquid fuel injection device including pressure producing means, mechanism connected to cause reciprocation of the pressure producing means, a pair of cams arranged to individually actuate the mechanism to cause complete injection periods, and engine driven means rotating said cams at different speeds, one of said cams, when effective, actuating said mechanism and preventing the mechanism being operated by the other cam.

6. In an engine, a liquid fuel injection device. including a plunger, mechanism connected to cause reciprocation of the plunger, and a pair of engine operated cams arranged to individually actuate the mechanism and cause complete injection strokes of the plunger, said cams being operated in a timed relation so that when one is effective the other is shielded thereby from actuating the mechanism.

7 '1. In an engine, a liquid fuel injection device including a plunger, mechanism connected to causereciprocation of the plunger, a pair of rotated cams arrangedto individually actuate the mechanism to cause complete injection strokes of the plunger, and engine driven means for rotating the cams in opposite directions and at different speeds. I

8..In an engine, a liquid fuel injection device including pressure producing means, mechanism connected to cause injection periods, a pair of rotatable cams arranged to individually actuate the mechanism and cause complete injections from the device, and engine driven means for rotating the cams at different speeds, the faster rotating cam being effective only during a low speed range of the engine and being timed relative to the other cam during such speed range to maintain the mechanism out of. position to be actuated by the slower speed cam.

9. In an engine, a liquid fuel injection device including an injection producing plunger, mechanism associated to reciprocate the plunger, and individual engine driven actuating means each associated with the mechanism to individually cause complete plunger injection strokes, said means being operable automatically to change the speed of the plunger stroke relative to the engine speed. a

10. In an engine, a liquid fuel injection device including a plunger, mechanism associated to reciprocate the plunger, and a pair of independent engine driven means for individually actuating the mechanism to cause complete injection strokes of the plunger, one of said pair of means operating at a faster speed than the other means.

11. In an engine, a liquid fuel injection device including a plunger, mechanism associated to reciprocate the plunger, and a pair of independent means driven at relatively different speeds by the engine, each of said means being associated to individually and completely actuate the mechanism, only one of the means shielding the slower driven means from engagement with the device at a time and the faster driven means being effective in the slower speed range of the engine.

12. In an engine, a liquid fuel injection device including a plunger, mechanism associated to reciprocate the plunger, a pair of independent means driven at relatively different speeds by the engine associated to individually and completely actuate the mechanism, only one of the means being effective at a time, and automatic means for placing the faster driven means in effective relation with the mechanism during the slower speed range of the engine.

13. In an engine, a liquid fuel injection device including a plunger, mechanism associated to reciprocate the plunger, a pair of means driven at relatively different speeds by the engine, each of said pair of means being associated to independently and completely actuate the mechanism and arranged to be effective only one at a time, and 145 means responsive to centrifugal force for controlling the efiective and ineffective relation of one of said means.

14. In an engine, a liquid fuel injection device including a plunger, mechanism associated to re- 1 .50

ciprocate the plunger, an engine'driven cam for actuating the mechanism to cause complete plunger injection strokes while the engine is performing work, and automatically effective engine driven means associated with the mechanism to cause complete plunger injection strokes at a higher speed when the engine is idling than that which would be caused by the cam at similar engine speed.

15. In an engine, a liquid fuel injection device including a plunger, mechanism associated to reciprocate the plunger to apply pressure upon charges injected thereby, engine operated means for operating said'mechanism to produce complete high pressure plunger strokes, and another engine actuated and controlled means for operating said mechanism while the engine is idling to produce complete plunger injection strokes of a higher pressure than that which would be produced by the first mentioned means under similar engine operating conditions.

16. In a Diesel engine, a liquid fuel inject on device including mechanism associated to project fuel charges into compressed air, and separate engine operated and controlled means each associated to actuate said mechanism, said separate means individually projecting complete fuel charges different distances at any given engine speed into the air charges, the means inducing the greater penetration of the air by the fuel charges relative to the engine speed being effective only below a predetermined engine speed.

17. In an engine, a liquid fuel injection device including a plunger, mechanism associated to reciprocate the plunger, a cam operated by the engine at crank shaft speed for actuating the mechanism to individually cause complete plunger injection strokes, and another cam operated by the engine at a speed which is a fraction of crank shaft speed to individually cause complete plunger injection strokes, the faster operating cam being effective only below a predetermined R. P. M.

18. In an engine, a liquid fuel injection device including a plunger, a pivoted lever having an extended contact boss, actuating mechanism intermediate the plunger and lever, a pair of cams for individually directly contacting with the lever boss to cause complete plunger injection strokes, said cams being driven by the engine at different speeds and effective one at a time.

19. In an engine, a liquid fuel injection device including mechanism for causing fuel injection periods, a pair of cams effective one at a time and rotated at different speeds and in opposite directions to individually actuate the mechanism to cause complete fuel injections, and individual means driven by the engine for rotating said cams, the lobe arrangement of said cams being formed and timed in their rotation so that the effective cam will lift the mechanism and hold it out of the path of the other cam.

20. In an engine, a liquid fuel injection device including a plunger, mechanism connected to cause reciprocation of the plunger, a pair of separate cams engageable with the mechanism to individually cause complete plunger injection strokes, and means driven from the engine rotat ing the cams at different speeds, said cams being timed so that one cam engages the mechanism ahead of the other and holds it lifted until the actuating portion of such other mechanism passes thereunder.

21. In an engine, a liquid fuel injection device including a plunger, mechanism connected to cause reciprocation of the plunger when actuated,

a pair of independent cams for operatingthe mechanism to individually cause complete fuel injection plunger strokes, only one of said cams being effective at a time, means for rotating one of the cams at engine speed, and means for rotating the other cam at several times less than engine speed.

22. In a Diesel engine, a plurality of radially disposed cylinders, a plurality of devices cachincluding a plunger associated to project liquid fuel charges directlyinto the cylinders, radially disposed plunger reciprocating mechanisms, and a pair of parallel cams cooperating one at a time with the mechanisms to cause complete plunger injection stroke and means driven by the engine for rotating said cams at different speeds.

23. In a Dieselengine, a, plurality of radially disposed cylinders, a liquid fuel injection device including a plunger associated with each cylinder to move fuel charges at a high pressure therein, radially disposed mechanisms for reciprocating the plungers, a pair of engine rotated cams individually arranged to actuate the radial mechanisms to cause complete injection strokes of the plungers, one of said cams having a single lobe and the other cam having plural lobes, said cams being in operative relation one at a time and the speed of rotation of the single lobe cam being a multiple of the rotation of the other cam and effective only below a predetermined engine speed.

24. In a Diesel engine, a plurality of radially disposed cylinders, a liquid fuel injection device including a plun er associated with each cylinder to move fuel therein, means for adjusting the plunger stroke to control the fuel quantity in the charges, radially disposed mechanism for reciprocating the plungers, and a pair of separate rotatable cams for actuating the mechanisms to individually cause complete plunger strokes, said cams being driven at different speeds and effective only one at a time.

25. In an internal combustion engine, a pressure device for injecting liquid fuel into compressed charges of air in the engine, a pair of cams individually effective one at a time for completely actuating said injection device, said cams being driven by the engine at relatively different speeds, and means operative to place either cam in effective actuating relation with the injection device.

26. In an internal combustion engine, a pressure device for injecting liquid fuel into compressed charges of air in the engine, a pair of cams individually efiective one at a time for completely actuating said injection device, said cams being driven by the engine at relatively different speeds, and automatic means operative to place one of the cams into effective and ineffective actuating relation with the injection device.

27. In an internal combustion engine, a pressure device for injecting liquid fuel into compressed charges of air in the engine, a pair of cams individually effective one at a time for completely actuating said injection device, said cams in the compression stroke, and means operative to place either of said cams in efiective actuating relation with the injection device.

29. In an internal combustion engine, a pressure device for injecting liquid fuel into compressed charges of air in the engine, a pair of engine driven cams individually effective one at a. time to completely actuate said injection device, said cams being timed differently in the compression cycle, and automatic means selectively controlling the cam relation as to effectiveness in actuating the injection device.

30. In an engine, a liquid fuel injection device including a plunger, mechanism connected to actuate the plunger, a single lobe cam for actuating the mechanism to cause plunger injection strokes, means driven from the engine for rotating the single lobe cam, a multiple lobe cam for actuating the mechanism to cause complete plunger injection strokes, and means driven from the engine for rotating the multiple lobe cam, said single lobe cam being operated at a multiple speed relative to that at which the other cam is rotated.

31. In an engine, a liquid fuel injection device including a pressure producing means, mechanism for actuating the pressure producing means including a pair of cam means driven from an engine part at different speeds relatively and angularly disposed so that one normally leads and masks the other from actuating the mechanism, and means for moving the leading cam means into an ineffective position unmasking the other cam means.

LIONEL M. WOOLSON.

Images