US1839791A - Combustible mixture supply for internal combustion engines - Google Patents

Description

Jan. 5, 1932, G. R. LAWRENCE 1,839,791

COMBUSTIBLE MXTURE SUPPLY FOR INTERNALCOMBUSTION ENGINES Filed July 2, '1928 5 sheets-sheet 1 DAQ- Jan. 5, 1932. G. R. LAWRENCE `COMBUSTIBLE MIXTVURE SUPPLY FOR INTERNAL GOMBUSTION ENGINES Filed July 2, 1928 3 Sheets-Sheet v2,

Jan. 5, 1932. G. R. LAWRENCE COMBUSTIBLE MIXTURE SUPPLY FOR INTERI/JAL COMBUSTION ENGINES Filed July 2, 1928 3 Sheets-Sheet 3 Patented dan. 5, 1932.

narran stares GEORGE E. LAWRENCE, OF CHICAGO,v ILLINOIS i COMBUSTIBLE MIXTURE SUPPLY FOR INTERNAL COMBUSTION ENGINES iippiiceaifm` fried July a,

This invention has to do with certain improvements in means for supplying. combustible mixture to internal combustionengines, and also has reference to the mode of operation thereof. Briefly stated the invention relates to the foregoingV featuresas applied to internal combustion engines generally. The structure and mode ofl operation herein disclosed are particularly intended for use with tvvo stroke cycle engines; and more particularly the features of the invention have been devised for use in connection With that type of engine illustrated and described in Letters Patent of the United States No. 1,160,419 which was issued to me on November 1G, 1915. lnasmuch as, however!7 the features of the present invention may be advantageously used in connection with many other forms of engines, both tivo and four stroke cycle, l Wish it understood Atliat l do iiot intend to limit the usefulness or scope ol my invention to engines of the type particularly illustrated and described in the said earlier patent, except as l may do so in the claims. y

The present invention relates primarily to improvements in the means for introducing the individualized charges of fuel into the different cylinders together with the relationship which such means bears to the general construction and operation of the engine as a Whole, as Well as to the construction and mode of operation of the fuel pumping device per se7 andif considered as anindependent element. y

The main feature of the present invention relates to the provision of an improved construction and arrangement of fuel pump for delivering the fuel charges'to the Working cylinders of the engine under the most advantageous conditions. More particularly the invention has to do With improvements in fuel pumps for engines of the general type already referred to herein; but it Will present-ly appear that numerous features of the invention may also be advantageously used in connection With fuel pumps for other purposes.

One ofthe features of the invention relates to a provision of a fuel charge forming 192s. serial no. assess.

pump of a construction such that the same delivers to the Working cylinders of the engines charges composed ofthe fuel, togeth With a volume of air which is generally smaller than-the air contained Within the Working cylinder of the engine. The air charges deliveredby the fuel pump are` constant volumeybeing uniform througho tlie' range of load conditions; but the indivi ual charges of fuel taken into the constant of ut volume charges of air are varied accordingly to the load requirements of theengine.

which the air is admittedy to the fuel pum As this air line is closed the flow ofy air through it decreases and the suctioninf creases with a consequent increase vof the amount of fuel drawn into the pump cylinder at each stroke; and a contrary action will takey place with an increased amount throttle opening. The fuel pump itself is constructed that just before the completion `of its intake stroke, an air port or ports are uncovered by the pump piston` allowing fiA sudden inru'sh of additional air Which oins the air charge previously drawn into the pump cylinder and insuresa full charge combustible mixture at atmospheric pressure. This ycharge is then introduced into the working cylinder of the engine as already n explained.

It is very difhcult to meter minute quantities of liquid fuel suoli as gasoline with high degree of accuracy; and a relative small variation in the amount of liquid so metered will produce a very appreciable per-y centage of error in the metering action. On

the contrary it is possible to meter the rel tively larger charges of air and vapor with the desireddegree of accuracy; and the same amount-of variation in themetering of this relatively-large body of air vvill produce on a very small fraction of the error in percentage which represented by a similar vari tion of amount When applied to the relative small charge of liquid fuel itself.

I have thereforeprovided an arrangement such that the metering is a metering of a relatively large body of air and vapor and not a metering of a small quantity of liquid; thus making it possible to secure a very accurate control of the fuel charge forming operations.

More particularly, I have provided a fuel charge forming device comprising a pump driven in synchronism with the movements of the working pistonswhose cylinders it supplies. This fuel pump is in effect an air pump, the primary source of air supply thereto being through a passage which can be controlled by a suitable valve such as a throttle valve. 'lhe primary supply of air flowing through this passage to the fuel pump will aspirate and carry with it into said fuel pump the charges of liquid fuel. These charges are then taken into the fuel pump together with the primary air therefor, so that this fuel pump handles a rich mixture of air and fuel.

This mixture, together with a certain amount of secondary air, is then delivered by the fuel pump to the working cylinders of the engine.

The fuel pump itself is sov arranged that the primary charges of air and fuel are drawn into the pump cylinder on the suction stroke of the pump piston, and necessarily under a degree of vacuum dependent on numerous factors. One of these factors is the amount of closure of the throttle valve which controls the primary air. As this valve is opened and closed to control the engine, greater or lesser quantities of primary air are allowed to be drawn into the pump cylinder during its suction stroke.

The aspirating effect of the charges of air drawn into the pump cylinder will depend upon the amount Aof such air drawn in at each suction stroke of the pump; and I have provided an arrangement whereby the fuel is drawn into this primary air by reason of its aspirating effect and therefore approximately inverse in proportion to the amount of primary air being used.

Since the pump operations areof a pulsating nature, the primary air charges are also of a pulsating nature and this is also true of the fuel charges. Since both the air and fuel are delivered to the pump or the intake there- Vof through passages it follows that the inertia eect of the flow through said passage will be aggravated as the rate of the pulsations increases. I have provided an arrangement whereby the effect of this pulsating condition will be minimized. v VFurthermore since the fuel is a liquid and therefore substantially non-compressible,

` whereas the air is highly compressible and eX- pansible, it follows that the effect of the pulsations on the column of liquid flowing Lthrough, the supply passage will Vbe very differentfrom'its effect on the column of air flowing through the primary air supply pas-- sage.

This result- I accom jlish b allowing the introduction into the fuel pump cylinder, of a suflicient amountof air Just before the completion of the suction stroke to restore the pressure to atmospheric. rlhis insures the presence of a full charge of air within the pump cylinder, together with the metered amount of fuel drawn in with th'e primary air. rIhis full volume of mixture is then delivered to the working'cylinder of the engine.

In connection with the foregoing, this supplemental or secondary air for the fuel pump is drawn into the cylinder thereof from a space around the top side of the pump piston. Consequently any seepage which may have previously'taken place past the pump piston is restored to the working side of the pump and delivered into the working cylinder on the'next succeeding pump delivery stroke. As a consequence the loss and error so occasioned by seepage, is practically eliminated and the accuracy of operation correspondingly improved.

Another feature of the invention relates to the provision of an arrangement whereby the fuel nozzles can be adjusted by the operator to the desired conditions so as to insure correct operation with fixed nozzle adjustments, the control of the fuel supply operation being proportioned to regulation of the flow of primary air.

A further feature of the invention relates to the provision of an arangement whereby any leakage of burnt gases from the working cylinder backwardly cannot have any appreciable eect upon the operation of the system, and cannot seriously impair either-its operation or its efficiency.

A further feature of the invention relates to the provision of an arrangement whereby any leak in the intake valve of the fuel pump will simply result in a leakage of mixtur back to atmospheric and will not effect the amount of fuel taken into the pump on the next succeeding cycle.

A further feature of the invention relates to the provision of a fuel pumping device which also serves largely the function of a. supercharger, that is, it delivers the fuel together with a portion of the air into the cylinders under a certain amount of compression, thereby increasing the quantity of combustible introduced into each working cylinder per working stroke.

A further feature of the invention relates to the provision of a fuel pump in conjunction with a plurality of individual working cylinders of the engine, said pump being so timed in its operations with respect to the working piston `movements that it delivers charges of fuel to the different working cylinders in sequence and takes care of the requirements of all of the working cylinders for which it is intended. lvloreparticularly it is an object in this connection to combine each fuel pump with two of the Working cylinders of a two stroke cycle engine, timing the operations of said pump at double engine speed so that the fuel pump may serve to deliver to the two cylinders in alternation. rlhis result is further accomplished by combining the lfuel pump with two working cylinders whose crank throws are set in opposion or 180 apart. Y

A'further object accomplished bythe foregoing is that the speed of operation ,of the fuel pump isdoubled so that the duration of the injection cycles is correspondingly reduced and the operation improved.

A further feature in conjunction with the foregoing is a provision of a valve larrangement of very simple form forinsuring the delivery of fuel to the two cylinders 1n alternation this result being made possible by reason of the fact that during the injection movement of the pump one working cylinder of the pair is under pressure and the other working cylinder of the pair is under exhaust so that the pressure in one of the working cylinders is very high while the other is practically at atmospheric pressure. rl`he fuel pump will automatically select its delivery of combustible into the working cylinder of low pressure, which is of course the one which should receive the charge. j

A further feature of the invention is the w provision of a multiple cylinder engine with its cylinders working in pairs in opposition to each other, together with a fuel pump for each of said pairs working in opposition, so that any particular pair of cylinders and the I corresponding fuel pump may be thrown out of commission as a pair or unit and without throwing the engine as a whole out of balance except so far as torque impulses are concerned. Furthermore, the throwing of certain cylinders of the engine out of commission will not impair the operation of the remaining cylinders and fuel pump. It is further a feat-ure of the invention to provide av needle valve in conjunction with each fuel pump, for controlling the supply of liquid fuel thereto, to-

Other objects of the invention are to provide devices for the foregoing purposes which are extremely simple and rugged in construction, built up from relatively few parts of simple form and which can be readily of the working cylinders together with the i' main air valve thereof, of a two stroke cycle engine of the general type described in my aforesaid Patent No. 1,160,419, having applied thereto a fuel supply pump construction embodying the features of the present invention;

Fig. 2 shows a vertical elevation' of the fuel pumping mechanism, partially in section, and may be considered as being taken substantially on the line 2 2 of Fig. 1, lookin g in the i direction of the arrows but on enlarged scale;

F ig. 3 shows a horizontal section on the line 3 3 of Fig.1 looking in the direction of the arrows but on enlarged scale; and may also be considered as being a section on the line 3 3 of Fig. 2 locking in the direction of the arrows on same scale; y

Fig. t shows a side elevation of one of the fuel pumps, partly in section; and

Fig. 5 shows a fragmentary vertical sectionon the line 5 5 of Fig. 3 looking in the direction of the arrows.

In the drawings I have shown a single element or unit comprising two cylinders numbered and 11 .respectively the same comprising a single twok cylinder unit. This unit may be individually considered or itmay be considered as one unit of a multiple cylinder engine of more than two cylinders.

yEach of the cylinders is provided with the usual piston 12 and the two pistons-of each unit are connected to the opposing throws 13 and 14 of the crank shaft 15. rIhese throws being inopposition, insure movements of the two pistons in opposition.

Along the upper portion of the cylinder structure there is placed a rotary air inlet valve 16, the same being rotatably mounted within a cylindrical casing 1701i the upper end of the structure. This valve 16 is driven at crankshaft speed andis connected to a gear 18 and the valve is drivingly connected to the crank shaft 15 on a 1 to 1 ratio. Consequently the valve 16 makes onerevclution for each crank shaft revolution. n

The valve 16 is provided with an air inlet port 19 yin line with the upper'end each cylinder; and air under ay suitable pressure supply is delivered to theinterior ofthe valve `16 by anysuitable source of compremed air supply in accordance with'certain of the principles disclosed ni my aforesaid Patent No.

' 1,160,419. rlhe valve 16 is so timed that it closes after the piston commences its upward or compression stroke; and this timing is varied so as to trap in the cylinder an amount of air to be compressed, the amount of such air being in proportion to the power to be developed. For a full power stroke the valve loses just alter the exhaust ports have closed to seal the cylinder, thus trapping a Stull charge of air; .for a. less'than full power stroke the valve 16 does not close until somewhat later, allowing some air to be expelled back trom the cylinder so that less than a full charge of air is trapped and compressed.

The cylinders illustrated are for convenience shown as being air cooled torwhich purpo-se theyare provided with fins 20, but, manifestly, as far as the present invention is concerned, the cylinders might be jacketed and cooled by a selected circulating medium. l liround the belt ot each cylinder at point adjacent tothe lower-most piston movement there is located an exhaust or scavenging. passage 21, which communicates with the interior of the cylinder by a series ot ports 22. rllhese ports are so placed that they are uncovered as the piston approaches its lower limit of movement to thereby insure proper scavenging and'discharge of the spent gases.

rlhe rotation ot the air inlet valve 16 is so timed that the uncovering of the port 19 takes place shortly after 'the exhaust ports 22 are uncovered by the piston movement, and the port 19 is orn surticient angular length for the varying requirements of the operations. As a consequence the inrushing fresh charge of air materially assists the scavenging operation by positively displacing the spent gases downwardly through the ports 22.

Means (not shown) are provided tor va.n rying the angular position or timing of the inlet valve 16 with respect to the crank shaft 15, in accordance with the Vlundainental disclosures ot my aforesaid Letters Patent No. 1,160,419 .and as already mentioned. herein. ln this way it is possible to regulate tht;` charge of air Vwhich will be trapped in the cylinder, and in accordance with the momentary power requirements of the operation.

l will now describe my improved fuel charge forming and pumping. device for delive-ring the charges of fuel into the cylinder in proper quantity and timing and under Vproper conditions to insure the most perfect operating results.

For each pair4 of cylinders 10 and 11 l provide a single fuel pump 23. This pump comprises a cylinder 24, open at its top end, and within which reciproca-tes the piston 25. This pistonv is provided with an upwardly reaching connecting rod 26, which is driven by a pump crank shaft 27y through'the medium of a crank 28 as illustrated in Fig'. 1. The crank shaft 27 is in turn driven by a pinion 29 which meshes with the gear 18, the pinion being of one-half size so as to rotate at double speed as compared with gea-r 18 and therefore at double the speed of the main crank Vshaft 15. 1t thus follows that the pump piston 25 makes a complete up and down'reciprocation tor each down stroke oi the two pistons of the pair ot working cylinders which are served by said pump.

ln the ease of a tour cylinder engine two of the pumps 23 are provided, one. for each pair of cylinders, these being the pumps 30 and 31 oi"- Fig. 2. ln such case both ot said pumps may be supplied with air by a common T connection 32, the inlet leg 38 of which is provided with a butterfly valve 34 under the control of the operator. At the inlet side of aid butterfly valve the inlet connection 33 is )rovided with a tubular or cylinder chamber 5 w'thin which is placed a plunger 36 havng the stein 37, said plunger being normally raised by a spring 36 into the uppermost poe sition illustrated in Fig. 2. rit this point Ythe -ilunffer 36 strikes against a cross iece 39 by means ot which its upward movement is limited.

The chamber 35 is provided with a series of inlet ports 40 immediately below the position of the plunger 36, and upon the existence oi an unusually heavy suction beneath the plunger it will be drawn down against the spring 38y and thereby partially close the ports 40, thus reducing the .rate of air inlet.

|lhe ports 40 are, however, never closed completely.

From the T connection 32 the air supply lines 41 and 42 lead to the two pumps 30 and B1 respectively; and the form of these air supply lines will be explained more in detail presently.

ln the floor of each of the pump cylinders there is located a .[itting 43 having at its up per end valve seat which receives the poppet valve 44 having the downwardly depending stem 45. A light spring 46 normally draws the valve stem down and thereby seats the valve. T he fitting 43 has a series of vertical passages 47 through which the charges of air and fuel are drawn upward past the valve into the cylinder. The passages 47 communicate at their lower ends with a small chamber 48 immediately beneath the fitting 43, and the air drawn through the connection 41 or 42 as the case may be enters the chamber 46 through a passage 49 in a right angle direction.

immediately adjacent to the point of entry of the passage 49 with the chamber 48 there is a small fuel port 50, the same being on the bottom side ot the passage 49, and being controlled by a needle valve 51. rEhis needle valve is in turn provided with a finger piece 52 at its lower end whereby its setting can be adjusted. The usual packing 53 may be provided around the needle valve or the stem 52. rIhe fuel is supplied to each of the needle valves 51 by a connection 54, and a float cham-V .into the pump in an intermittent manner there will necessarily be a certain amountof resistance to the delivery of the individual impulses of fuel due to inertia.. In order to reduce thel effect of this inertia in the fuel supply line as much as possible I have pro; vided a small chamber 57 (see Fig. 4) in close proximity to each of the needle valves and connected to the needle valve by a short pasi sage 58, the upper end ofeach of the said chambers being sealed. As a consequence the.

momentary demands for liquid fuelwill be supplied from the chamber 57 corresponding to the impulses, and there will be a more or less continuous and-uninterrupted supply ofV fuel through the connection 54. Thus'the inertia effect on the liquid' fuel line will be greatly reduced. l y v Around the wall of the cylinder 24 there are located a series of air ports 59, the same being located at such an elevation that they will just be fully uncovered at the upper limit of the plunger stroke. Until the piston 25 reaches a sufficient elevation to uncover the ports 59 there will be developed a suction within the cylinder which will draw in a partial charge of air through the connection 49; and at the same time the necessary amount of liquid fuel will also be drawn in and mixed with said air above the position of the needle valve and during the movement through the passages 47. This small charge of air and fuel will be extremely rich, much richer than in fact should be used in the cylinder of the engine, and as has already been explained the predominating portion of the air necessary for the proper explosive mixture in the cyl# inder is supplied independently and through the main air supply valve 16. f

As soon as the piston 25 reaches a sufficient elevation to uncover'the ports 59 the suction beneath the piston will he broken and the valve 44 will seat. At the same time air or vapors will rush into the cylinder through theL ports 59 to equalize the pressure below the piston. Immediately thereafter the piston on its down stroke will close the ports 59 and co-mmence to deliver the charge thus trapped.

There is a delivery port 60 reaching backwardly from the lower end of the cylinder 24 and branching into a pair of branches 61 and 62 (see Figs. 3 and 5). The ends of these branches areplugged by the blocks 63 as shown at Fig. 5. Reaching upwardly from the two branches -61 and 62 are the passages 64 yand 65 which lead -into chambers 66 and 67 corresponding to the two working cylinders 10 and 11. The ball check valves 68 and 69 placed between the passages 64 and 65 and the chambers 66 and 67 respectively, prevent any backward movement from the respective working cylinders.y The upper ends of the chambers 66 and 67 are blocked by the blocks 70. l

Reaching sidewise from'the chambers 66 and 67 are the passages 71 and 72 which lead into the working cylinders at positions close to the upper or compression ends thereof. If desired, spray heads 7 3 and 74 may be placed at the discharge ends of the passages 71 and 72, said spray heads being provided with relatively small spray openings 75 so as to create a turbulent condition within the cylinder with consequent increase in the firing speed. A

Itwill be understood that the operations ofthe pistons 25 are so timed with 'respect to the movements of the working pistons 12 that the admission of the fuell charge into the working cylinder takes place after the scavenging has been completed and just be'- fore the valve 19 closes. As a consequence the gas pressure existing in the working cylinder which is 'receiving the charge is only slightly above atmospheric or in some cases may be slightly below atmospheric. At this time the gas pressure existing in the other working cylindery of the pair is very high since the piston of such working cylinder is at its upper or compressed-position. The check valves 68 and v69 serve to `prevent any back flow from the working cylinders to the fuel pump; and due to the presence of said check valves the fuel pump will always select and deliver its charge to the working cylinder which is ready to receive it.

Under rapid operation the inertia of the liquid fuel coming to the fuel pumps may seriously affect the siphoning action 'of the fuel delivered through the small ports 50 under control of the needle yvalves 51 and consequently excessive quantities of air may be` drawn in. In order to equalize the conditions ofair supply to' the fuel pump as much as possible at all speeds, I prefer to establish a relatively long air column ineach of the air connections 41 and 42 at a position close to the delivery end of such connection leading into the passage 49 of the pump. As

butterfly valve 34 at a givensetting, the air for the pump will be drawn in past said butterfly valve and through the tube 76 or 77 as the case may be, past the orifice (the liquid fuel standing somewhat below the same ydue to control of the float chamber and will be drawn past the valve 4ta into the pump cylinder 24. Bue to the rapid up moveyment'ofthe piston 25 there will eXist a partial vacuum within the cylinder, and the eX- tent thereof will be somewhat determined by the amount of opening` of the throttle valve 34. Manifest-ly the amount of fuel which` `der. The fuel charge will however have been talren into the cylinder prior to the inrush of air.

'(As the speed of the engine is increased the plunger 36 will be drawn down so as to partially close the ports 40.) This action will result in a further resistance to the flow of air past the throttle valve, which resistance will be increased as the mot-or speed increases. The plunger 36 never moves down low enough to completely close the ports 40, such result being insured by proper design of the spring 38,`the turns of which will close up before the plunger 36 can completely close the ports40. f

The inertia effect due to the pulsating nature of the column of air flowing through the pipe 7 6 is necessarily affected by the fact that the air column is highly' compressible and expansible instead of being non-compressible as in the case of a solid or liquid. The

action of the valve 36 will largely serve to offset the compressible or expansible nature of the air column and will serve in connection with the long air columns 7 6 and 77 to so regulate the intermittent air supplies through the pipe 7 6 that the proportions of air delivered through the pipe 76 and fuel delivered through the orifice 50 will be vsubstantially constant through a wide range of op-4 erating rates at any setting of throttle valve opening.

As the fuel pump vpistons 25 move down on the rworking strokes there may be a slight seepage of mixture upward past said pistons Y and delivering out of the upper ends of the cylinders 2li. Such seepage will be extremely small. Nevertheless,` in order'to avoid any loss of fuel due to this cause I have provided an arrangement whereby such seepage will be trapped and returned to the interior of the cylinder 24:. For this purpose I have provided a shell 7 8 surrounding the uper portion of each of the cylindersY 24 and having its upper end 7 9 flanged over and turned inwardly a suiiicient distance to establish a relatively small central opening 80 for the accommodation of the pump connecting rod 26. This shell 78 establishes an annular passage 31 leading from the upper end of the cylinder and piston downwardly into communication with the inlet air ports 59 already referred to. As a consequence the charges of air drawn inwardly through the ports 59 are received in the first instance from a position around the connecting rod 26 and around the upper end of the piston itself, so that any vapors seeping up past the piston will be trapped and drawn down and restored into the cylinder on the neXt suction stroke of the piston. v

While I have herein shown and described only a single embodiment of the features of my invention, still I do not intend to limit myself thereto, except as I may do so in the claims;

I claim:

l. Fuel supply means for an internal combustion engine comprising in combination means for pumping intermittently in harmony with the working piston movements of the engine, means for delivering primary air charges of size variable under control of the operator, and corresponding charges of fuel, to said pumping means, and connections for the delivery of secondary air supply charges to said pumping means to supplement said primary air charges and establish full volume charges, substantially as described.

2. Fuel supply means for an internal com- -bustion engine comprising in combination means for intermittently formingcombustible charges comprising primary air charges of variable size under control of the operator, m-eans for admitting thereto fuel charges in inverse proportion thereto, and means for admitting thereto secondary air charges to supplement said primary air charges to establish full volume charges for delivery to the working cylinder of the engine, substantially as described.

3. Fuel supply means for an internal combustion engine comprising means for intermittently drawing primary air charges through a suitable connection under control of the operator and for drawing fuel charges with said primary air charges and in proportion thereto, connections for supplementing said prima-ry air charges with secondary air charges to establish full volume charges after the fuel charges have been drawn in, and connections for the delivery of all of said charges to the working cylinders of the en gine7 substantially as described.

4. Fuel supply means for internal combustion engine comprising in combination a reciprocating pump, connections for the supply of primary air charges to said pump and of volume under control of the operator, and for the supply of corresponding charges of fuel into the pump together with said primary air charges, connections for the supply of secondary air charges to said pump to supplement said primary air charges, and connections for the delivery of all of said charges to the working cylinders of the engine, substantially as described.

5. Fuel supply means for an internal com bustion engine comprising in combination a reciprocating pump, connections for the delivery of charges of primary air and fuel to said pump intermittently, means for varying the amount of air in said air charges, connections for the delivery of secondary air charges to said pump after the supply of said primary charges of air and fuel, to supplement the same and establish full charges in the pump cylinder, and connections for the delivery of full charges to the working cylinders of the engine, substantially as described.

6. Fuel supply means for an interna-l combustion engine comprising in combination a reciprocating air pump, a connection for the supply of primary air and fuel to said pump, means for varying the amount of air taken into said pump at each stroke according to the requirements of engine operation, connections for the admission of secondary air charges to said pump to insure full charges of air for delivery to the working cylinders of the engine, and suitable connections from the pump cylinder for the delivery of said air charges and fuel to the working cylinder of the engine, substantially as described.

7. Fuel supply means for an internal combustion engine comprising in combination a reciprocating air pump including a cylinder and a piston working therein, an inlet connection to the lower end of the cylinder, primary air supply and fuel connections to said inlet connection, a check valve in said connection for retaining the charge against back flow therethrough, a secondary air port extending through the upper portion of the cylinder, .said secondary air port being normally covered and sealed by the piston and uncovered by the piston at the upper limit of movement'thereof to admit a secondary air charge into the cylinder to establish the full volume of air within the cylinder at the upper limit of piston stroke, together with a suitable delivery connection from the cylinder to the working cylinder of the engine, substantially as described.

8. A method of forming and supplying fuel charges for the operation of an internal combustion engine which consists in intermittently drawing primary air charges of variable amount under control of the operator, aspirating fuel charges into said primary air charges and in inverse proportion thereto, thereafter drawing secondary air charges into said primary charges in quantities sufficient to establish complete charges of definite size, and thereafter delivering said complete charges into the working cylinder of the engine, substantially as described.

9. A method of forming and supplying fuel charges for the operation of an internal combustion engine which consists in drawing intermittent primary charges of air of variable size under control of the operator, and simultaneously drawing fuel charges thereinto in proportion to said primary air charges, and thereafter delivering said primary charges of air and fuel, together with supplemental air charges, into the working cylinder of the engine, substantially as de-v scribed.

10. A fuel pump for the purpose specified comprising in combination a cylinder, a piston working therein, a mixture inlet valve in the floor of the cylinder, a chamber beneath said valve, an air supply connection leading into said chamber, a fuel port leading into the air supply connection adjacent to the chamber, a fuel supply/*passage leading to said port, means for delivering fuel to said passage and an expansion chamber in close proximity .to the position of said port and having its lower portion in communication with the fuel supply connection, the uppe1 portion of said expansion chamber being sealed in air tight fashion substantially as described. v

il. A fuel pump for the purpose specified comprising in combination a cylinder, a piston working therein, a mixture inlet valve in the floor of the cylinder, a chamber immediately beneath the said valve, an air supply connection leading into said chamber, a fuel supply port in the lower part of the air supply connection adjacent to said chamber, a needle valve controlling said fuel supply port, a connection for the delivery of fuel to said port in regulated elevation and a sealed chamber adjacent to the needle valve and in connection with the fuel supply at a point below the fuel supply port, substantially as described.

GEORGE R. LAWRENCE.

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