US3740172A

US3740172A - Reciprocating fuel pumps

Info

Publication number: US3740172A
Application number: US00153460A
Authority: US
Inventors: O Ulbing
Original assignee: Borg Warner Corp
Current assignee: TILLOTSON Ltd (TILLOSTSON") A CORP OF IRELAND
Priority date: 1971-06-01
Filing date: 1971-06-01
Publication date: 1973-06-19
Anticipated expiration: 1990-06-19

Abstract

Improved system for supplying fuel and oil to two-cycle internal combustion engines including a simple and reliable fuel-oil injector pump which mixes the fluids in a desired ratio from separate tanks. Means for automatically shutting off fuel flow upon loss of oil are provided. Crankcase scavenging pressure assists oil pumping. The injector pump continuously circulates fuel through the fuel tank to avoid vapor lock. Several arrangements for properly correlating the injector pumping rate with engine air flow are disclosed. An improved injection nozzle utilizing an elastomeric band is disclosed. A system for supplying dual cylinders from the same injector pump is disclosed.

Description

United States Patent 1 1 Ulbing 4] RECIPROCATING FUEL PUMPS 75 Inventor: Otmar M. Ulbing,.Lisle, NY.

[73] Assignee: Borg-Warner Corporation, Chicago,

Ill.

[22] Filed: June 1, 1971 [21] Appl. No.1 153,460

Related US. Application Data [63] Continuation of Ser. No. 786,233, Dec. 23, 1968,

abandoned.

[52] US. Cl. 417/469, 417/496, 417/497,

[51] Int. Cl. F04b 7/04 [58] Field of Search..... 417/490494, 496, 499,498

[56] References Cited 1 UNITED STATES PATENTS 1,854,009 I 4/1932 Wilkinson 417/498 1,917,169 7/1933 Ulgers et al.... 417/490 2,551,053 5/1951 Rogers 417/565 2,576,451 11/1951 Dickson et a1 417/498 June 19, 1973 2,740,667 4/1956 Dickson et a1 417/494 2,676,544 4/1954 Schauer 417/490 2,890,657 6/1959 May et a1..... 417/494 2,969,738 l/196l Ulbing 417/494 Primary ExizminerWilliam L. Freeh Attorney-Richard G. Stephens [57] ABSTRACT Improved system for supplying fuel and oil to two-cycle internal combustion engines including a simple and re liable fuel-oil injector pump which mixes the fluids in a desired ratio from separate tanks. Means for automatically shutting off fuel flow upon loss of oil are provided Crankcase scavenging pressure assists oil pumping. The injector pump continuously circulates fuel through the fuel tank to avoid vapor lock. Several arrangements for properly correlating the injector pump-' ing rate with engine air flow are disclosed. An improved injection nozzle utilizing an elastomeric band is disclosed. A system for supplying dual cylinders from the same injector pump is disclosed.

24 Claims, 18 Drawing Figures Patented June 19; 1973 10 Sheets-Sheet 4 MM M W Patented June 19, 1973 10 Sheets-Sheet 5 Patented June 19, 1973 10 Sheets-Sheet 6 Patented June 19, 1973 3,740,172

10 Sheets-Sheet 7 FIG. 3c

FIG. 3e

Patented June 19, 1973 -10 Sheets-Sheet 8 Patented Jam-19, 1913 3,740,172

10 Sheets-Sheet 9 Patented June 19, 1973 10 Sheets-Sheet 10 Am OE RECIPROCATING FUEL PUMPS This application is a continuation of my prior copending application Ser. No. 786,233 filed Dec. 23, 1968 and now abandoned.

This invention relates to two-cycle gasoline engines, to fuel and lubrication injection and control systems for the same, and various features of the invention have application to other types of engines and even various nonengine applications.

A wide variety of machines, such as snowmobiles, motorcycles and various other devices utilize two-cycle gasoline engines, ordinarily because of the lower cost per horsepower and lesser weight per horsepower of such engines, and their lower cost is the primary reason why two-cycle engines are preferred to four-cycle engines in many such applications. Despite their mentioned advantages, two-cycle engines have not met with favor in a number of applications due to the necessity of providing a gasoline-oil mixture in order to insure lubrication of the engine crankcase bearings and the cylinder walls. Providing a mixture of gasoline and oil in the proper ratio is troublesome and time-consuming, and many two-cycle engines have been ruined because the ratio of the mixture has been wrong. While the calculation of proper amounts of oil and proper amounts of fuel to provide a desired ratio involves only elementary mathematics and a modicum of care, experience has shown that in the ordinary applications of many two-cycle engines the mistakes of unskilled or careless persons result in improper ratios frequently being used, often to the detriment of the engine. It is one object of ing high heat conditions. Another object of the invention is to provide an improved fuel-oil injection system which insures better starting of a two-cycle engine in cold weather when oil viscosity may be rather high.

While a number of two-cycle engine systems utilizing carburetion have been deemed satisfactory for constant load or other specific load-applications, they have been disadvantageous in not being controllable over a very wide range of speeds. It is a further object of the invention to provide a two-cycle engine system which can run smoothly, under varying load conditions, over a greater range of speeds. The present invention also allows a two-cycle engine to provide higher power output at a given speed, both at low and high speeds, and allows the engine to accelerate and decelerate without the delay which accompanies some carburetion systhe present invention to provide a two-cycle engine system in which oil and gasoline may be supplied to two respective tanks with no pre-mixing being required and in which means are provided to automatically mix the oil and gasoline in the proper ratio as they are used, so that no pre-mixing is required, and so that the proper mixture or ratio is always provided, no matter whether the engine is running fast or slow. In some applications different mixture ratios are desirable at different engine speed and load conditions, and it is another object of the invention to provide a system in which mixture ratio may be arranged to vary automatically with the flow rate of the fuel-oil mixture supplied to the engine.

Cost is a major factor in many of the applications for which two-cycle engines are utilized, and most, if not all, prior two-cycle engines have utilized carburetors rather than fuel injection systems, due to the high cost and complexity of prior fuel injection systems. However, carburetors have a number of disadvantages which are overcome by the present invention. For example, carburetors are difficult to adjust, even by skilled mechanics sometimes, and they frequently require re-adjustment. It is another object of the present invention to provide a fuel-oil injection system for twocycle engines which requires no complex adjustment procedureand which does not require periodic readjustment. Carburetors also become clogged frequently, due tothe small passages necessarily included in them and the low pressures which they develop, and one object of the present invention is to provide a fuel-oil injection system for a two-cycle engine which is less susceptible to clogging. Carburetion systems frequently are plagued by vapor lock problems, and a further object of the invention is to provide a fuel-oil injection system which overcomes vapor lock problems, which otherwise often occur in two-cycle engine systems durterns.

In ordinary two-cycle engine systems involving carburetion, little or no fuel-oil mixture is supplied to the engine intake manifold, and hence little or not engine lubrication is provided, unless the carburetor throttle plate is open, i.e., unless the accelerator pedal is depressed, for example, in a snowmobile, even though the snowmobile may be traveling at ahigh speed and the engine turning at a high speed, with the result that many two-cycle engines have been ruined for lack of lubrication when a snowmobile, for example, coasts down a long, steep hill with the engine running slowly and braking the snowmobile. Most two-cycle engines can operate in such an overrunning condition for only perhaps 60 to seconds without seriously damaging the engine. It is another important object of the invention toprovide a two-cycle engine system wherein suc operation is automatically prevented.

If a two-cycle engine is operated for any substantial length of time without lubrication, it rapidly will be damaged, as just mentioned. If premixing of gasoline and oil is to be avoided and gasoline and oil are installed in separate tanks without the need for measuring precise amounts of each, and if the gasoline and oil are automatically dispensed from the two tanks with theproper ratio, it will be apparent that one tank well may become emptied before the other, and that if the oil supply became depleted before the gasoline supply, continued running of the engine might seriously damage the engine. Thus it is another important object of the invention to provide a two-cycle fuel-oil injection system in which the engine will be automatically shut off if the oil supply fails while the engine is running, so that damage to the engine will not result. The invention also includes a novel, inexpensive and reliable injection nozzle assembly which efficiently atomizes the mixture supplied by the injector of the invention. Attending each of the aforementioned objects is the very important object of providing a fuel injection system for a two-cycle engine which is inexpensive, compact, and reliable, having no delicate parts whichare subject to failure or misadjustment. Further objects of the inven tion are to provide a fuel injection pump wherein lesser pressures are built up across .the pump piston for a given pumping flow rate so that less precise pistoncyclinder tolerance is required, and a pump in which delivery per stroke is substantially independent of pump speed, supply pressure, and check valve loading.'

Two-cylinder two-cycle engines often utilize two carburetors rather than a single carburetor inorder to provide greater power output. If one carburetor fails such engines frequently continue to run on one cylinder, and the lack of lubrication then experienced by the cylinder fed by the failed carburetor may cause considerable damage. It is another object of the invention to provide a fuel-oil injection system for a two-cylinder two-cycle engine which prevents the possibility of such damage.

Other objects of the invention will in part be obvious and will, inpart, appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is a side view of a two-cycle engine showing portions of a system constructed in accordance with the present invention.

FIG. 2 is a cross-section view of one form of fuel-oil injector pump constructed in accordance with the present invention, with additional parts of a fuel and oil control system shown schematically.

FIG. 2a is a view taken at lines 2-2 in FIG. 2.

FIG. 2b is a view taken at lines 3in FIG. 2 with plug 64b removed.

FIG. 2c is a diagrammatic view useful in illustrating the operation of the pump of FIGS. 2, 2a and 2b.

FIG. 3 is a cross-section view taken at lines 44 in FIG. 3b through a further form of fuel-oil injection pump.

.FIG. 3a is a view taken at lines 55 in FIG. 3 with piston 161 and springs 133 and 162 removed.

FIG. 3b is a view taken at lines 66 in FIG. 3a.

FIG. 30 is a view taken at lines 77 in FIG. 3.

FIG. 3d ia view taken at lines 8-8 in FIG. 3.

FIG. 3e shows a portion of an injector pump of the type shown in FIGS. 3 and 3a-3d connected to be controlled by control apparatus illustrated schematically.

FIG. 4 is a side view of the engine showing one manner in which the injector pump of the present invention may be arranged to be operated from the cranksahft (or other shaft) of an engine.

FIG. 5a is a front view of the air intake duct of the engine system of FIG. 1.

FIG. 5b is a side view of the air intake duct of the engine system of FIG. 1.

FIG. 6 is a side view of a portion of the system of FIG. 1 illustrating the atomizing injector nozzle of the present invention.

FIG. 6a is an enlarged isometric view of a port of the nozzle assembly of FIG. 6.

FIG. 6b is a view taken at lines 99 in FIG. 6.

FIG. 7 is'a view partially cutaway illustrating use of an injector pump to supply both cylinders of a dual cylinder two-cycle engine.

Referring now to FIG. 1, a known type of two-cycle engine 10 is shown as including an externally-finned cylinder 11 having a single piston (not shown) inside, spark plug 13 and crankcase 14. FIG. 1 is drawn to resemblethe basic structure of a Series SA 290 Model 297-68 engine, (Ser. No. 5529098) manufactured by Sachs GmbH in Germany and commercially available in the United States. Engine 10 is provided with an air intake duct or chamber 15 which communicates directly with the input duct (not shown in FIG. 1)

through which fuel (and oil) are admitted to the crankcase of engine 10. Intake chamber 15 (or manifold in the case of multicylinder engines) includes an open end to admit air and includes an adjustable throttle plate (not shown in FIG. 1), the adjustment of which controls the air flow through passage 15. The throttle plate corresponds in one basic principle to the throttle plate used to choke ordinary carbureted engines. A

fuel-mixture injection nozzle assembly 18 includes a nozzle which extends into intake chamber 15. A fueloil mixture is supplied to the nozzle of assembly 18 via tubing 18a from injector pump 12. Various preferred details of the nozzle 18 assembly will be further explained in connection with FIG. 6. Engine 10 is a common type of two-cycle engine of the crankcasescavenged type, having a hermetically-sealed crankcase in which the pressure changes as the piston rises and descends. It will become apparent as the. description proceeds that the invention is applicable as well to two-cycle engines of the type which use a separate scavenging fan or pump. Furthermore, while engine 10 is shown as a type wherein gasoline and oil are applied as a mixture to an intake chamber, it will become apparent that many aspects of the invention are applicable as well to two-cycle engines of the autolube" type wherein oil is not mixed with the gasoline prior to its introduction into the engine, but instead pumped through suitable conduits to specific bearing or other desired lubrication points within the engine.

FIGS. 2, 2a and 2b illustrate one form of injector pump constructed in accordance with the present invention, and FIG. 2c is a porting diagram useful in illustrating the operation of that fuel injector, which utilizes a number of the principles of the pump illustrated in my prior US. Pat. No. 2,969,738. The fuel injector comprises a central casting or housing 20 preferably of aluminum having a rear head 21 and a front head 22 bolted thereto, with suitable gaskets 21a and 21b therebetween. Four mounting

holes

20f, 20f (FIG. 2) are provided through casting 20 to mount the injector pump on the'engine crankcase. Three mounting

holes

20g, 20g (FIG. 2b) are provided to bolt each head to central casting 20. Shaft 23 driven by the engine crankshaft through pulley 24 and a timing belt 25 (FIG. 1) is journalled in casting 20 and extends through oil seal 26 (FIG. 2a) in one wall of housing 20 and carries eccentric cam 27 which is disposed within hollow chamber 28. A domed circular cup 23a (FIG. 2a) pressfitted into one side of casting 20 closes the side of the casting and axiallylocates shaft 23. Casting 20 also includes a longitudinally-extending bore 29 which extends into chamber 28. Generally cylindrical sleeve 29a is prefitted into place in bore 29, and piston 30 is situated within sleeve 29a, which is provided with a plurality of ports, as will be described. Control rod 31 is rotatably journalled in rear head 21 and secured against axial movement by means of

snap rings

32a, 32b which engage circumferential slots in rod 31. U-shaped return spring means 33 interconnects piston 30 and control rod 31, the forked ends of spring 33 engaging

pins

34 and 35 which' extend through respective ends of rod 31 and piston 30. As the engine crankshaft rotates pulley 24 and shaft 23, eccentric cam 27 will be seen to urge piston 30 rightwardly against the force of spring means 33 during a portion of each revolution of cam 27, and the spring means will return piston 30 leftwardly during another portion of each revolution, and hence piston will reciprocate back and forth a predetermined distance within bore 29 during each cam revolution. has much as control rod 31 is rotatably journalled in head 21 and piston 30 is rotatable within bore 29, angular rotation of control rod 31 will be seen to act through spring means 33 to similarly angularly rotate piston 30.

Cylindrical sleeve 29a has a plurality of ports 34-37 and piston 30 is provided with a plurality of

external grooves

38, 39 which extend partially around the periphery of piston 30, and hence angular rotation of piston 30 about longitudinal axis x--x by means of control rod 31 serves to angularly

position grooves

38, 39 with respect to ports 3436. Ports 34-37 are each shown as comprising a slot which extends partially around sleeve 290, with each slot having a uniform width measured in the axial direction of sleeve 29a. Oil intake port 34 in sleeve 29a connects to hollow chamber 28 through passage 41, an piston 30. slot milled in sleeve 29a. Oil outlet port 35 connects through passage 42a to check valve 50 situated within passage 42b, which extends to mixing chamber 43 provided within front head 22. A ball 42c plugs the end of passage 42a. Fuel (gasoline) intake port 36 connects via passage 44, a longitudinally-extending slot milled in sleeve 29a, to fuel inlet chamber 64 and thence via fuel supply lines a, 45b

to fuel tank 46, and fuel outlet port 37 connects via

passages

47a, 47b and check valve 51 to mixing chamber 43.

Each of the

grooves

38, 39 on piston 30 comprises a V-shaped groove milled on the periphery of cylindrical piston 30, with the depth of each V-groove equal to ap proximately half the diameter of piston 30, so that the apices of each V-groove are spaced apart approximately 180 degrees from each other around piston 30. Piston 30 is shown rotated 90 degrees from its ordinary operating range of positions in order to afford a better view of V-

grooves

38 and 39. Ports 34-37 in sleeve 29a are each shown extending perpendicularly to axis x-x. The relationship of V-groove 38 to oil intake and

outlet ports

34 and 35, and the similar relationship of V- groove 39 to fuel intake and

outlet ports

36 and 37, are better illustrated by the geometric diagram of FIG. 2c wherein the outside surface of piston 30 and the inside surface of sleeve 29a are shown developed, or unrolled, and superimposed on each other. The use of a v-shaped milling tool having straight sides will be recognized to provide grooves on cylindrical sleeve 29a of the nature shown at 38 and 39 in FIG. 20.

FIG. 2c illustrates in solid lines a condition where pis ton 30 is at its leftward limit of travel and where piston 30 has been rotated by control rod 31 to an angular position to provide a minimum or a very low pumping rate. V-groove 38 will be seen to communicate with or substantially register with oil intake port 34, and V- groove 39 to substantially register with fuel intake port 36, while oil outlet port 35 and fuel outlet port 37 will be seen to be blocked. Rightward travel of piston 30 in FIG. 2 is represented by rightward movement of V-

grooves

38 and 39 relative to ports 34-37 in FIG. 2c. As piston 30 moves rightwardly in FIG. 2c, V-groove 38 will be seen to register less and less with port 34, and nearer and nearer toward a position where it will register with port 35. The shape of groove 38 and the loca tions of

ports

34 and 35 are established so that groove 38, over its entire stroke, will communicate with at least one or the other of

ports

34, 35, and at all angular positions of piston 30, groove 38 will communicate with both

ports

34 and 35 during a certain portion of each stroke.

With piston 30 in the angular position shown in solid lines in FIG. 20, it will be seen that groove 38 will register with port 34 during most of the piston stroke (the total length of which is indicated by distance s in FIG. 20) and will register with port 35 only during a very small terminal portion of the rightward stroke. If piston 30 is rotated within bore 29, however, such as to a me dium position indicated by groove 38 in dashed lines at 38a in FIG. 30, it will be seen that groove 38 will be cut off from inlet port 34 earlier during the rightward stroke and will register with outlet port 35 during a substantial portion of the stroke. If piston 30 is further rotated within bore 29, so that groove 38 can be represented at 38b in FIG. 20, it will be seen that groov 38 will cutoff from inlet port 34 and communicate with outlet port 35 very early during the rightward stroke. Thus by angularly positioning piston 30 within bore 29 by means of control rod 31, one may control the relative times during a stroke during which the two

ports

34 and 35 communicate with movable piston groove 38. Groove 39 operates relative to

ports

36 and 37 in precisely the same way that groove 38 operates relative to

ports

34 and 35. Inasmuch as

grooves

38 and 39 are fixedly spaced relative to each other on piston 30, and inasmuch as ports 34-37 are all fixedly spaced relative to each other in bore 29, it will be seen that the opening and closing of inlet and outlet ports are permanently synchronized with each other, need no adjustment and cannot get out of adjustment.

Referring back now to FIG. 2, it will be seen that piston 30 includes a central longitudinal bore 55 and a hollowed-out right end portion 56 which communicates with the portion of bore 29 on the righthand side of piston 30, to provide chamber 60. Oil piston 61 fits within bore 55 and inner coil spring 62 urges oil piston 61 rightwardly from piston 30. Chamber is shown as in-cluding a valve seat 63 against which end 61a of piston 61 is seated by the force of spring 62 to close off chamber 60 from chamber 64. In many embodiments of the invention valve 61a-63 may be omitted, and piston 61 may, if desired, be rigidly affixed to the right end of chamber 60, and then inner coil spring 62 is not re: quired. Even if no valve or passage is provided at 64, I prefer however, not to rigidly affix the right end of piston 61, and to allow spring 62 to urge piston 61 rightwardly against the closed right end of chamber 60, as allowing piston 61 to float rather than permanently affixing it to chamber 60 obviates precision alignmen problems.

To understand the operation of the fuel injector of FIG. 2, first as-sume with piston 30 at its left limit of travel that chamber 28, passage 41, oil intake port 34,

V-groove 38 and chamber 65 (the portion of bore 55 to the left of piston 61) are all filled with oil. As eccentric cam 27 urges piston 30 rightwardly, piston 61 will be seen to expel oil out from chamber 65, and since V groove 38 initially registers only with inlet port 34, oil initially will be pumped back through port 34 into chamber 28. The rightward excursion of piston 30 will be seen to provide a suction in chamber 28, thereby accelerating the oil flow from port 34 to chamber 28.

port 34 will be closed, so that oil will be expelled only through oil outlet port 35, past check valve 50 to mixing chamber 43. The times during the rightward stroke during which port 35 is opened and port 34 is closed are determined, it will be recalled, by the angular position of piston30.

With fuel supply line 45a connected to fuel inlet port 36, and with V-groove 39 communicating with chamber 60, it will be seen that fuel will be ex-pelled from chamber 60 back through groove 39 toward the fuel supply tank 46 during an initial portion of the rightward stroke of piston 30, and then expelled through fuel outlet port 37 past check valve 51 to mixing chamber 43 during aterminal portion of the rightward stroke. Because of the fixed relationship shown between

grooves

38, 39 and ports 34-37, return pumping of oil back through inlet port 34 will occur for the same portion of the stroke during which fuel is pumped back into supply line 44, and forward pumping of oil past check valve 50 will occur throughout the same portion of the stroke that fuel is pumped past check valve 51, and by rotation of piston 30 by control rod 31, the relative amounts of return pumping and forward pumping which occur on a given stroke can be controlled for both fluids. Inasmuch as oil outlet port 35 and fuel outlet port 37 are opened for the same portion of each rightward stroke of piston 30, it will be seen that the relative amounts of the two fluids which are pumped during each rightward stroke depends solely upon the ratio of the effective areas of the two pistons, the effective area A of oil piston 61 being 11-11 where d is the diameter of piston 61, and the effective area A, of fuel piston 30 being 1r(d -d where d is the diameter of piston 30 or bore 29. If A, is arranged to be times A for example, it will be seen that 25 times as much fuel as oil will be pumped on a given rightward stroke. With the relative amounts of fuel and oil fixed by the relative effective piston areas, it will be seen that a mixture having a desired fuel-oil ratio always will be obtained, irrespective of the amounts of each fluid pumped during a given stroke.

It will be apparent at this point that by proper spacing of the ports and the V-grooves one may provide one extreme angular position of piston which will result in

inlet ports

34 and 36 being cutoff and

outlet ports

35 and 37 being opened very near the beginning of the rightward stroke, thereby to provide maximum pumping, and one may provide another extreme angular position which will result in

inlet ports

34 and 36 being cutoff and

outlet ports

35 and 37 being opened at or near the end of the rightward stroke, so that little or no fluids will be pumped. It is important, however, that all angular positions of piston 30 provide at least some slight overlap between the opening of the outlet ports and the closure of the inlet ports, in order that blockage of fluid not damage the injector. While FIGS. 2 and 2c illustrate a pump valving arrangement wherein V- grooves have been provided on piston 30, to provide openings having an edge which varies in longitudinal position as a function of piston angular position, and wherein the cylindrical sleeve has straight slots, each having an edge which does not vary in longitudinal position as a function of its angular position it will become apparent that equivalent valving may be provided with other combinations of shapes of grooves and slots. For example, it will be apparent that equivalent operation may be effected through a simple reversal of parts, providing piston grooves of unvarying width and sleeve slots having edges whose longitudinal positions vary with angular position. Also, it will become apparent upon reflection that it is unecessary that either a port or its cooperating groove have an edge which does not vary longitudinally with angular position, and that both may vary, though at different rates, to provide equivalent overall operation. The specific valving system described in detail is preferred, however, inasmuch as it may be provided accurately and inexpensively using only simple machining operations. Both

grooves

38 and 39 may be milled simultaneously on piston 30 using a pair of spaced V-shaped milling cutters, and pairs of ports may be milled simultaneously in sleeve 29a using straight-sided milling cutters.

In the specific porting system shown both inlet ports open and close at the same time and both outlet ports open and close at the same time, irrespective of the angular position of piston 30 in sleeve 29a. It is possible, however, to vary the relationship between the ports and grooves so that the time at which the fuel inlet port closes and the time at which the fuel outlet port opens are not always the same times at which the oil inlet port closes and the oil outlet port opens, but rather vary relative to each other in accordance with the angular position of piston 30. For example, if the fuel inlet and outlet ports are given a slight axial cant, as indicated in FIG. 20 at 36a and 37a, while

oil ports

34 and 35 have no such cant, it will be seen that the fuel system will switch from return pumping to forward pumping earlier during each pumping stroke than when the oil system switches, with the amount by which fuel forward pumping precedes oil forward pumping varying with the angular position of piston 30, so that fuel ports of the nature shown at 36a and 37a will automatically provide a thinner mixture (i.e., greater ratio of fuel to oil) as the pump flow rate increases. Canting the fuel ports in an opposite direction would provide a richer mixture as pump flow rate increases. Provision of a thinner mixture as flow rate increases obviously may be provided by giving oil ports 34 and 35 a counterclockwise cant instead of giving

fuel ports

36 and 37 the clockwise cant shown at 36a and 37a, and provision of a clockwise cant at

ports

34 and 35 would provide a richer mixture at greater flow rates. It should be apparent at this point that both the oil ports and fuel ports may be canted, in either the same or opposite directions, and that the relative angular relationship between them will determine the sense and the amount by which the mixture ratio changes as the flow rate varies, and it will also be apparent that equivalent operation may be effected by suitably shaping the piston grooves instead of or in addition to canting the ports. It is not necessary that canted pairs of ports always utilize straight-sided ports, and if desired canted curved ports may be provided in order that mixture ratio vary with pump flow rate in a desired non-linear manner. Irrespective of whether pump 12 provides a fixed mixture at all flow rates or a ratio which varies with pump flow rate, it will be appreciated that the ratio at a given rate is inherently built into the piston-cylinder port geometry and cannot get out of adjustment.

A number of prior art pumps using angularlyadjustable pistons for variable metering of a fluid provide only an inlet port, rather than both inlet and outlet ports, so that their pump chambers are in constant communication with their outlet check valves, and forward pumping past their check valves occurs as te inlet port is closed off to prevent return flow. If the fluid supply has positive pressure, it will be seen that the check valve in such prior systems must be loaded to at least the same pressure in order to prevent forward pumping prior to complete closure of the inlet port. And even if the fluid supply is not pressurized, it should be understood that the pressure in the prior art pump chambers necessarily builds up prior to complete closure of their inlet ports, in amounts dependent upon the pump speed and the amount of restriction to return flow between the pump chamber and the fluid supply, with the amount of restriction increasing from a basic amount to complete blockage as the inlet port is gradually closed off. If forward pumping is not to occur prior to complete closure of the inlet port, the check valve must be loaded to the highest such pressure which may occur prior to inlet port closure. The heavier check valve loading necessarily results in higher pressures in the pump chamber, thereby requiring a more precise piston-cylinder fit. [the pump of the present invention forward-pumping cannot occur prior to opening of an outlet port, irrespective of whether the supply is pressurized, and hence the instant at which forward pumpig begins during a pumping stroke remains substantially independent of pump speed and outlet check valve loading.

Chamber 2 8 in FIG. 2 is connected to oil supply tank 75 through a check valve 68. As piston 30 starts leftwardly on its return stroke, the pressure in chamber 28 will be seen to increase positively and to tend to continue to increase during further return travle, to a maximum value determined by the setting of check valve 68. Simultaneously, upon the return of piston 30, oil outlet check valve 50 prevents reverse flow of oil from mixing chamber 43, and hence an increasing partial vacuum will be built up at port 35 and within chamber 65 and V-groove 38. When piston 30 has returned sufficiently far for V-groove 38 to register with inlet port 34, it will be seen that the positive pressure in chamber 28 and the partial vacuum in V-groove 38 and chamber 65 will both act cumulatively, to force oil from chamber 28 through port 34 to fill chamber 65 very quickly during the latter portion of the return stroke. Similarly fuel inlet port 36 connects to supply tank 46 through check valve 74, and as fuel is pumped toward tank 46 during the initial portion of the rightward stroke of piston 30, a positive pressue approaching the loading of check valve 74 will build up in line 45a between port 36 and check valve 74. The initial portion ofthe return stroke also creates a partial vacuum at port 37 and in chamber 60 and V-groove 39, and when V-groove 39 registers with port 36 near the end of the return stroke,- the combination of the positive pressure and partial vacuum result in quick filling of chamber 60. Chambers 65 and 60 must be filled very rapidly, during a small portion of he injector cycle when the engine is running fast with an appreciable load, and the combination of pressure and vacuum which serves to fill them rapidly is an important feature of the invention.

Mixing chamber 43 in head 22 by means of a threaded connection at 43a via tubing 180 (FIG. 1) to an injection nozzle in assembly 18 which extends into the intake duct of the engine. In applying the invention to autolube type two-cycle engines, it will be apparent that the two passages leading from

check valves

50 and 51 should not lead to a mixing chamber, but instead that the fuel passage alone should lead to the injection nozzle and the oilpassage'should leadto the lubrication points in the engine.

FIG. 2 an optional modification is illustrated wherein a ball checkvalve 76 is shown interconnecting chamber and chamber 60, and if such a check valve is provided, oil outlet port 35, passage 42a and check valve 50 may be eliminated. During the rightward piston stroke with such an arrangement, it will be seen that oil pressure will build up in chamber 65 as soon as oil inlet port 34 is cut off, and the oil will] pass through check valve 76 and be mixed with the fuel in chamber 60, and a fuel-oil mixture will be pumped out of chamber 60 during each stroke.

In FIG. I the fuel line from fuel 46 is connected to chamber 64 with which valve 61a-63 also communicates. It will be seen that the vacuum created in chamber 60 during the return stroke produces a differential pressure across valve 61a-63 which may be arranged, by selection of the valve 61a area, to overcome spring 62 and urge piston 61 leftwardly during each return stroke, so that chamber 60 may be filled from chamber 64 via valve 61a-63 as well as through port 36. This additional means for quickly filling chamber 60 is wholly unnecessary in most applications of the invention, however. The use of valve6la-63 does provide a useful safety feature, however. In FIG. 2 the fuel pressure in chamber 60 will be seen to act on piston rod 61 tending to move it leftwardly against a combined force applied to piston 61 by spring 62 and the oil pressure in chamber 65, and during normal operation the righward pressures on piston 61 maintain its valving end 61a tightly seated on valve seat 63. If the oil supply in tank should run out, however, the loss of oil pressure in chamber 65 lessens the rightward. force on piston 61, whereupon the fuel pressure in chamber 60 overcomes the force of spring 62, moving valve end 61a off of valve seat 63. Fuel in chamber 60 than will be expelled through valve 6ll63 into chamber 64 rather than being pumped out through port 37, and hence the en gine will stall. Valve 61a-63 may connect to a conduit which merely spills the gasoline on the ground, if desired, but preferably it is connected as shown to return to chamber 64.

In order to insure the transfer of low viscosity oil from tank 75 to the injector during; cold weather, a substantial scavenging pressure (e.g. 10-15 psig) from the engine crankcase is applied via check valve 77 to oil tank 75, which is closed with a pressure-type cap. Oil tank 75 connects to oil chamber 28 of the injector through a lightly-loaded check valve 69 which allows easy flow of oil to chamber 28 during the pumping stroke of injector piston 30, but shunt-connected oppositely-oriented check valve 68 allows pressure to build up in chamber 28 during a portion of the return stroke. It may be noted that the creation of such pressure in chamber 28 during the return stroke does require the use of a stronger return spring at 33.

With positive pressure applied to the oil supply in the manner mentioned, a safety interlock" of the same nature as that described in connection with valve 61a-63 may be provided without the use of such a valve. With the oiltank 75 so pressurized, as soon as all the oil is used up air under pressure will be seen to be applied to

chambers

28 and 65, and the fit of piston 61 in bore 55, even though quite adequate for pumping oil, may be such that the pressurized air will seep past the sides of piston 61 into chamber 60, where the air, which is under pressure, will displace the fuel, which is at atmospheric or a very low pressure, and shut off the engine, thereby preventing damage when the oil supply becomes entirely depleted.

FIGS. 3 and 3a through 311 illustrate a modified form of injector much like that of FIG. 2, but with certain differences which will be pointed out. Parts in FIGS. 3, 3a-3d generally similar to corresponding parts of FIG.

2 are given similar numbers with a 1 prefix, e.g., piston 30 in FIG. 2 corresponds to piston 130 in FIG. 3. As best seen in FIGS. 3 and 3d, pulley 124 driven from the crankshaft rotates shaft 123 which carries cam 127. Cam 127 reciprocates tappet 81, which is carried in bushing 82 with an O-ring seal 83a. The right end of tappet 81 bears against the left end of piston 130, which reciprocates within sleeve 129a. A spring 133, only a portion of which is shown, is inserted between head 122 and a right-end face of piston 130 and operates to return piston 130. A lower gear sector 83 (FIGS. 3 and 3c) pinned to piston 130 is engaged by upper gear sector 84 pinned to control shaft 131, so that rotation of shaft 131 angularly positions piston 130. Upper gear sector 84 is axially wider than lower gear sector 83 so that the gears remain enmeshed as sector 83 reciprocates with piston 130. Oil is supplied to chamber 128 via a pipe connection made at 128a on the side of casting 120. Oil and fuel inlet ports are provided in sleeve 129a at 134 and 136, and oil and fuel outlet ports are shown at 135 and 137. Oil piston 161 is urged rightwardly against head 122 by inner coil spring 162. Holes drilled in main (Part 120 at 142a and 147a connect the outlet ports with longitudinallyextending passages in which

check valves

150 and 151 are situated, and plugs 142e, 1476 close the ends of passages 142 and 147a. Check

valves

150 and 151 at the outlet side of the injector are shown as comprising elastomeric or rubber duckbill valves of a known type (Part No. VA 3178 of Material VL422 M2 sold by Vernay Laboratories, Yellow Springs, Ohio), and each such valve connects with mixing chamber 143 provided in head 122.

Fuel chamber 164 in the device of FIG. 3 is shown provided with two connections 1450 and 145d (FIG. 3b) to the fuel tank 146 through two further duckbill check valves 90 and 91 (FIG. 3a) oriented in opposite directions. If the injector pumping capacity is substantially greater than that required to run the engine at full speed under full load, a substantial amount of fuel will oscillate in and out of fuel chamber 164 as piston 130 reciprocates and the pressure in fuel chamber 164 rises and falls. This oscillation is rectified by duckbill valves 90 and 91, so that fuel is continuously drawn from fuel tank 146 into fuel chamber 164 and continuously pumped from fuel chamber 164 out to fuel tank 146. The fuel tank acts as a heat sink, so that the continuous circulation of fuel keeps the fuel cool at the injector and prevents the vapor lock which plagues many carburetor systems. It will be apparent at this point that a pair of oppositely-oriented check valves (not shown) also could be provided, if desired, to similarly connect oil chamber 128 to provide continuous circulation of oil to and'from the oil tank.

FIG. 4 shows a modified mounting arrangement in which a portion of the injector extends within an engine crankcase 114. The mounting arrangement shown in FIG. 4 was developed for use with a commerciallyavailable .ILO two-cycle engine Model TYT-L372L (Ser. No. 37220305). Cam 227 carried eccentrically on the engine crankshaft 223 is surrounded by a nonrotatable porous bronze or oilite ring 85, which does not rotate, but which will be seen to be reciprocated with a planetary motion as shaft 223 rotates eccentric cam 227. A hemispherical depression in ring is engaged by the hemispherical end of tappet 181, which is urged into engagement with ring 85 by the piston return spring (not shown in FIG. 4). Through use of ring 85 it will be seen thatmuch less sliding motion results between tappet 181 and ring 85 than would result if tappet 181 directly engaged cam 227, and hence much less wear occurs and any need to periodically adjust the length of tappet 181 or compensate for a change in the length thereof is obviated. An oil hole 86 in the injector opens into the engine crankcase and a passageway leading therefrom carries oil to lubricate tappet 181. Aside from the described manner in which its tappet is arranged to be reciprocated by the engine, the injector pump of FIG. 4 otherwise corresponds with the pump of FIG. 3. While cam 227 in FIG. 4 must be circular in order to use ring 85, it is important to note that

cams

27 and 127 in FIGS. 2 and 3 need not be circular, and can include various other shapes to provide desired reciprocating motion of the pistons which they drive.

FIGS. 5a and 5b illustrate the air intake duct and throttle plate arrangement of one embodiment of the invention, and FIG. 6 illustrates the manner in which injection nozzle assembly 18 extends into the engine intake duct. Air intake 15 includes a flange 15a which bolts to the engine adjacent the engine cylinder inlet port. A conventional circular throttle plate is rotatably mounted on shaft 96 which extends through duct 15, and shaft 96 is connected by any suitable arrangement to be rotated by the vehicle accelerator pedal or throttle control, to open throttle plate 95 when the engine is to be accelerated. Shaft 97 rigidly affixed to duct 15 and extending parallel to throttle-plate shaft 96 carries pivot arm 98 and arm 99. Spring 100 affixed to duct urges arm 98 clockwise as viewed in FIG. 5b, so that cam follower roller 101 carried on arm 98 is urged against the periphery of rotatable throttle cam 102. As the accelerator pedal is depressed, throttleplate shaft 96 and cam 102 are rotated counterclockwise as viewed in FIG. 5b, thereby rotating arm 98 counterclockwise as the throttle plate unblocks the air intake duct. The lower end of arm 98 connects, by means of an adjustable turnbuckle 103 to crank arm 104, and rightward movement of the lower end of arm 98 rotates the control rod of the fuel injector, rotating piston 30 of FIG. 2 (or piston of FIG. 3) so as to increase the amount of fuel-oil mixture pumped during each stroke. A wire 105 connected to arm 99 leads to an engine choke control 96, a simple frictionpositioned knob. Pulling on control serves to rotate arm 98 counterclockwise about shaft 97, withdrawing cam follower roller 101 from cam 102, so that a large amount of fuel-oil mixture may be supplied to the engine while the throttle plate remains almost closed, thereby providing a rich mixture desirable for starting a cold engine.

An alternative form of injector control suitable for use in various industrial engine applications wherein rapid acceleration is not as important as economy is shown in schematic form in FIG. 3e connected to the injector of the type shown in FIG. 3, to provide an arrangement wherein the injector is controlled indirectly rather than directly with the throttle plate opening. The engine crankcase scavenging pressure is applied via check valve 106 and needle valve or orifice 107 to diaphragm 108, and a bleed to atmosphere is provided through needle valve or orifice 109 from the diaphragm chamber. The scavenging pressure in the engine crankcase varies with throttle position and is a fairly accurate indication of the mass flow of air through the engine. The pressure applied to diaphragm 108 will be seen to be proportional to peak scavenging pressure. The diaphragm is mechanically connected through crank arm 204 to rotate the injector control shaft 131 against the force applied to crank arm 204 by spring 110, the pressure of the spring being adjustable by rotating threaded shaft 111 relative to fixed nut 112. Adjustment of spring 1 varies the richness of the air-oil-fuel mixture applied to the engine.

The mixing chamber of the injector connects through tubing 18a, which is preferably very short, to the injector nozzle assembly best seen in FIGS. 6 and 6a. The injector nozzle assembly comprises a tube 215 having a flared end which seats within an internal ring-shaped recess 216 provided in the same type of duckbill check valve 218 as those previously mentioned. A generally cylindrical insert 217 preferably formed of solid hard nylon or the like extends forwardly out through the front end of the elastomeric duckbill valve for a distance of about one-sixteenth inch, and when utilizing a Vernay Laboratories Model VA 3 l 78 duckbill valve of the type mentioned, a nylon insert having a diameter of seven sixty-fourths inch has proven satisfactory. One insert suitable for use with that model valve had dimensions shown in FIG. 6a as a through e of five thirtyseconds, one-sixteenth, seven sixty-fourths, fifteen thirty-seconds and one thirty-seconds inch, respectively. A portion of the insert within the valve is tapered down rearwardly to allow the mixture to completely surround the insert back from the exit end of the valve, and an enlarged tip 217a on the rear end of the insert also engages ring recess 216 to hold the insert securely within the valve. It will be apparent that the rear end of insert 217 may be held in place by provision of suitable locking means on the end of tube 215 ifdesired. The essential feature of the nozzle assembly is the provision in a flexible body having a fluid passageway of a central body having a substantially circular crosssection, so that the flexible body grips it on all sides with substantially uniform pressure, over substantially uniform area around the central body. The mixture pumped by the injector completely surrounds insert 217 up to where the mouth of flexible valve 218 is stretched around the cylindrical insert. Because valve 218 is flexible and stretched around an insert which is circular in cross-section, it will be seen that the pressure with which the resilient valve grips the cylindrical insert will tend to be uniform all the way around the insert, so that flow of the fuel-oil mixture will tend to occur evenly all the way around the valve, thereby providing a thin ring-shaped spray" pattern. It will be noted that the spray pattern will remain ringshaped irrespective of the flow rate out of the nozzle assembly. Experience has shown that the provision of such a pattern results in very effective atomization of the mixture. The front end portion of the cylindrical insert gripped by the mouth of the duckbill valve need not be truly cylindrical, but also may taper (preferably enlarging outwardly). It is highly desirable, however, that that portion of the insert always be circular in cross-section.

The injection nozzle assembly will be seen to be extremely inexpensive, and reliable. Those skilled in the art will readily recognize that a variety of different elastomeric materials may be utilized to provide injection nozzles, it being important, of course, that any such materials not be adversely affected by exposure to oil or gasoline. The diameter of the insert may be varied when different elastomeric materials are used, of

course, to provide a desired tension of the valve mouth around the cylindrical insert, and hence to provide a desired pressure drop at the nozzle. While the tension around the ring-shaped nozzle mouth ordinarily will need no adjustment, it will be apparent that an adjustable nozzle may be made by provision of a taper on the nylon insert and provision of adjusting means whereby the insert may be moved axially relative to the flexible encircling body. It will also be apparent that use of the new nozzle assembly is in no way restricted to twocycle fuel-oil atomization, but may be used in a wide variety of other applications, with many different fluids. Also, it will be apparent that the various other features of the invention do not require the specific nozzle assembly shown and that numerous other types of nozzles may be utilized.

FIG. 7 illustrates an intake duct or manifold utilized with a two-cylinder two-cycle engine wherein cylinders C-1 and C-2 operate out of phase, so that only one cylinder is aspirating at a given time. The injector nozzle 118 extends downwardly at a slant into the top of a Y- shaped duct 315 and points toward apex 315a of the duct. Each arm of the Y-shaped duct leads to the input port associated with a respective cylinder, and the common leg of the duct includes a throttle plate a similar to plate 95 of FIG. 6 which controls air flow. The injector pump (not shown) which feeds nozzle 118 is arranged to operate at twice the speed of a singlecylinder arrangement by halving the timing pulley diameter or by providing two eccentric lobes on cam 27, for example. Running out of fuel or oil will be seen to disable both cylinders and stop the two-cylinder engine, obviating the damage which often occurs in dual carburetor two-cylinder two-cycle engines if one carburetor becomes clogged or otherwise fails.

While I prefer to provide two separate tanks for fuel and oil to avoid requirement for proper pre-mixing of the two fluids, it will be apparent :at this point that simplified versions of the injector pump having a single V- groove and single inlet and outlet ports and a single outlet check valve may be provided to pump a premixed mixture of fuel and oil from a single tank to an injection nozzle.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the above constructions without departing from the scope of the invention, it is intended that all matter containedin the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

The embodiments of the invention in which an exclusive property or prilege is claimed are defined as follows:

1. A fluid pump, comprising, ll'll combination: means defining a cylindrical bore having an inlet port and an outlet port axially spaced from each other; a rotatablyadjustable piston adapted to reciprocate within said bore to decrease the size of a chamber formed by said piston and said bore during a pumping stroke involving relative motion between said piston and said bore for a predetermined distance in a first direction and to increase the size of said chamber during a return stroke involving relative motion over said predetermined distance in an opposite direction, said piston having a passage adapted to connect said chamber in a sequence of three successively different porting conditions during a pumping stroke throughout said predetermined distance, said sequence consisting of a first porting condition during an initial portion of said pumping stroke in which said chamber is connected with said inlet port and not connected to said outlet port, a second porting condition during an intermediate portion of said pumping stroke in which said chamber is connected with both said ports, being connected decreasingly with said inlet port and increasingly with said outlet port, and a third porting condition during a terminal portion of said pumping stroke in which said chamber is connected with said outlet port and not connected to said inlet port, whereby delivery of fluid from said outlet port may begin during said second porting condition, continue throughout said third porting condition, and further continue for an initial portion of said return stroke, the rotation of said piston being operable to adjust the points during a pumping stroke at which said passage changes from a given one of said porting conditions to a succeeding one of said porting conditions.

2. A fluid pump, comprising, in combination: means defining a cylindrical bore having an inlet port and an outlet port axially spaced from each other; a rotatablyadjustable piston adapted to reciprocate within said bore commences, decrease the size of a chamber formed by said piston and said bore during a pumping stroke involving relative motion between said piston and said bore in a first direction and to increase the size of said chamber during a return stroke involving relative motion in an opposite direction, said piston having a passage adapted to connect said chamber in a sequence of successively different porting conditions with only said inlet port during an initial portion of said pumping stroke, decreasingly with said inlet port and increasingly with said outlet portduring an intermediate portion of said pumping stroke during which delivery of fluid through said outlet port commences, and with only said outlet port during a following terminal portion of said pumping stroke, the rotation of said piston being operable to adjust the points during said pumping stroke at which said passage changes from each one of said portingconditions to a succeeding one of said porting conditions, whereby delivery of fluid through said outlet port begins at a point determined by the rotary adjustment of said piston and terminates at a piston position substantially independent of said rotary adjustment of said piston.

3. A fluid pump, comprising, in combination: means defining a cylindrical bore having an inlet port and an outlet port axially spaced from each other; a rotatablyadjustable piston adapted to reciprocate within said bore to decrease the size of a chamber formed by said piston and said bore during a pumping stroke involving relative motion between said piston and said bore in a first direction and to increase the size of said chamber during a return stroke involving relative motion in an opposite direction, said piston having a passage adapted to connect said chamber in a sequence of successively different porting conditions with only said inlet port during an initial portion of a pumping stroke and a terminal portion of a return stroke whereby fluid is expelled from said chamber through said outlet port during said initial portion of said pumping stroke, with both said ports during intermediate portions of said pumping stroke and said return stroke, and with only said outlet port during a terminal portion of said pumping stroke and an initial portion of said return stroke whereby fluid is expelled from said chamber through said outlet port during said terminal portion of said pumping stroke, the rotation of said piston being operable to adjust the points during said strokes at which said passage changes from each one of said porting conditions to a succeeding one of said porting conditions.

4. A pump according to claim 3 wherein, with a given rotary adjustment of said piston, said initial portion of said pumping stroke embraces the same range of piston movement as said terminal portion of said return stroke.

5. A pump according to claim 3 wherein, with a given rotary adjustment of said piston, said intermediate portions of said pumping and return strokes embrace the same range of piston movement.

6. A pump according to claim 3 wherein, with a given rotary adjustment of said piston, said terminal portion of said pumping stroke embraces the same range of piston movement as said initial portion of said return stroke.

7. A pump according to claim 3 having a first fluid supply source connected to said inlet port; and an assembly including a second bore and a second piston adapted to decrease and increase the size of a second chamber during said pumping and return strokes, respectively, second inlet and second outlet ports, said assembly having a passage adapted to connect said second chamber under said successively different porting conditions with only said second inlet port, both said second inlet port and said second outlet port, and with only said second outlet port during said pumping stroke, the rotation of said piston carried within said cylindrical bore being operable to adjust the points during said pumping stroke at which said passage of said second piston changes from a given one of said porting conditions to a succeeding one of said porting conditions; and a second fluid supply source connected to said second inlet port.

8. A pump according to claim 7 having check valve means interconnecting said cylindrical bore and said second bore.

9. A pump according to claim 7 having a third chamber; said outlet port of said cylindrical bore being connected to said third chamber through first check valve means and said second outlet port being connecte d to said third chamber through second check valve means, whereby fluids pumped from said first and second fluid supply sources are mixed in said third chamber.

10. A pump according to claim 7 wherein said first piston has an effective area n times as great as the area of said second piston, whereby the amount of fluid pumped from said first fluid supply source is n times the amount of fluid pumped from said second fluid supply source.

11. A pump according to claim 7 in which said second bore is located within said piston and said second inlet and outlet ports are spaced along said cylindrical bore.

12. A pump according to claim 7 having valve means operable to spill fluid from said chamber formed by said piston and cylindrical bore; and means responsive to the pressure in said second bore for controlling said valve means.

13. A pump according to claim 7 having a greater pressure at said second fluid supply source than at said first fluid supply source, whereby depletion of fluid at said second supply source results in admission of a gas or air to said cylindrical bore to displace the fluid therein and stop the pumping of the fluid supplied from said first fluid supply source.

14. A pump according to claim 7 wherein said rotation of the piston within said cylindrical bore is operabie to vary the amounts of fluid pumped from said first and second supply sources during a pumping stroke while maintaining constant the ratio between said amounts. 15. A pump according to claim 3 having check valve means connected to said outlet port, whereby fluid may flow from said chamber through said outlet port and said check valve means only while said passage of said piston is connected with both said ports or with only said outlet port, and whereby suction will be built up in said chamber during a portion of said return stroke.

16. A pump according to claim 3 having check valve means connected to said inlet port, whereby fluid may flow from said chamber through said inlet port and said check valve means only while said passage of said pistori is connected with both said ports or with only said inlet port, whereby fluid will be expelled from said chamber through said inlet port past said check valve during said initial portion of a pumping stroke.

A pump according to claim 3 having a second fluid chamber connected to said inlet port; a fluid supply source, and first and second oppositely-oriented check valve means each connected between said second fluid chamber and said fluid supply source, said first check valve means being operable upon increase in pressure in said second chamber during a return stroke of said piston to return fluid from said second chamber toward said supply source, and said second check valve means being operable upon decrease of pressure in said second chamber during a pumping stroke to admit fluid from said supply source toward said second chamber, whereby reciprocation of said piston causes circulation of fluid between said second chamber and supply source 1 8. In a fluid pump having piston means adapted to reciprocate within a cylindrical bore having an inlet port and outlet means, said piston means having a passageway adapted to communicate with said inlet port during one portion of a pumping stroke in which fluid is eitpelle'd from said bore through said inlet port and adapted not to communicate with said inlet port during a second portion of said pumping stroke during which fluid is expelled from said bore through said outlet means, said piston means being angularly adjustable within said cylindrical bore to adjust the relative lengths of said two portions of said pumping stroke and thereby to adjust the amount of fluid pumped through said outlet means during a pumping stroke, the combination of means defining a chamber communicating with said piston means so that said piston means expands said chamber during said one portion of said pumping stroke, said chamber being connected to communicate with said inlet port, whereby expansion of said chamber during said one portion of said pumping stroke creates a suction in said chamber to aid the expulsion of fluid from said bore through said inlet port to said chamber during said one portion of said pumping stroke.

19. A fluid pump, comprising, :in combination: a cylindrical bore having an inlet port and an outlet port axially spaced from each other; a rotatably-adjustable piston means adapted to reciprocate within said bore to decrease the size of a first chamber formed by said bore and said piston means during a pumping stroke and to increase the size of said chamber during a return stroke, said piston means having a passage adapted to connect said first chamber to said outlet port during one portion of a return stroke and to connect said first chamber to said inlet port during another portion of a return stroke; means defining a second chamber adapted to be increased in size by said piston means during said pumping stroke and to be decreased in size during return stroke; returnstroke; a fluid supply source; first and second check valve means; said second chamber being connected to said fluid supply source through said first check valve means, said second chamber being connected to said inlet port, and said outlet port being connected to said second check valve means, whereby motion of said piston means dur ing said one portion of said return stroke creates a pressure within said second chamber and a suction between said inlet port and said second check valve means, said pressure and suction acting cumulatively during said another portion of said return stroke to force fluid from said second chamber through said inlet port into said first chamber.

20. A fluid pump, comprising, in combination: a first piston-cylinder assembly having a. first bore, a first piston adapted to reciprocate within said bore to vary the size of a first chamber formed by said first piston and first bore during pumping and return strokes of fixed length in opposite directions of said first piston relative to said first bore, a first inlet port and a first outlet port, and a first passage reciprocable relative to said first inlet and outlet ports to connect said first chamber sequentially to said first inlet port and said first outlet port; a second piston-cylinder assembly having a second bore, a second piston adapted to reciprocate within said bore in synchronism with the reciprocation of said first piston within said first bore to vary the size of a second chamber formed by said second piston and said second bore, a second inlet port and a second out let port, and a second passage reciprocable relative to said second inlet and outlet ports: to connect said second chamber sequentially to said second inlet port and second outlet port; means for connecting a first fluid supply source to said first inlet port; means for connecting a second fluid supply source to said second inlet port; and means for rotating said first passage relative to said first inlet port and said first outlet port and rotating said second passage relative to said second inlet port and said second outlet port to vary the points during said pumping and return strokes at which said first passage connects to said first inlet port and said first outlet port and at which said second passage connects to said second inlet port and said second outlet port, thereby to vary the amounts of fluids pumped from said first and second-supply sources.

Claims

1. A fluid pump, comprising, in combination: means definiNg a cylindrical bore having an inlet port and an outlet port axially spaced from each other; a rotatably-adjustable piston adapted to reciprocate within said bore to decrease the size of a chamber formed by said piston and said bore during a pumping stroke involving relative motion between said piston and said bore for a predetermined distance in a first direction and to increase the size of said chamber during a return stroke involving relative motion over said predetermined distance in an opposite direction, said piston having a passage adapted to connect said chamber in a sequence of three successively different porting conditions during a pumping stroke throughout said predetermined distance, said sequence consisting of a first porting condition during an initial portion of said pumping stroke in which said chamber is connected with said inlet port and not connected to said outlet port, a second porting condition during an intermediate portion of said pumping stroke in which said chamber is connected with both said ports, being connected decreasingly with said inlet port and increasingly with said outlet port, and a third porting condition during a terminal portion of said pumping stroke in which said chamber is connected with said outlet port and not connected to said inlet port, whereby delivery of fluid from said outlet port may begin during said second porting condition, continue throughout said third porting condition, and further continue for an initial portion of said return stroke, the rotation of said piston being operable to adjust the points during a pumping stroke at which said passage changes from a given one of said porting conditions to a succeeding one of said porting conditions.

2. A fluid pump, comprising, in combination: means defining a cylindrical bore having an inlet port and an outlet port axially spaced from each other; a rotatably-adjustable piston adapted to reciprocate within said bore commences, decrease the size of a chamber formed by said piston and said bore during a pumping stroke involving relative motion between said piston and said bore in a first direction and to increase the size of said chamber during a return stroke involving relative motion in an opposite direction, said piston having a passage adapted to connect said chamber in a sequence of successively different porting conditions with only said inlet port during an initial portion of said pumping stroke, decreasingly with said inlet port and increasingly with said outlet port during an intermediate portion of said pumping stroke during which delivery of fluid through said outlet port commences, and with only said outlet port during a following terminal portion of said pumping stroke, the rotation of said piston being operable to adjust the points during said pumping stroke at which said passage changes from each one of said portingconditions to a succeeding one of said porting conditions, whereby delivery of fluid through said outlet port begins at a point determined by the rotary adjustment of said piston and terminates at a piston position substantially independent of said rotary adjustment of said piston.

3. A fluid pump, comprising, in combination: means defining a cylindrical bore having an inlet port and an outlet port axially spaced from each other; a rotatably-adjustable piston adapted to reciprocate within said bore to decrease the size of a chamber formed by said piston and said bore during a pumping stroke involving relative motion between said piston and said bore in a first direction and to increase the size of said chamber during a return stroke involving relative motion in an opposite direction, said piston having a passage adapted to connect said chamber in a sequence of successively different porting conditions with only said inlet port during an initial portion of a pumping stroke and a terminal portion of a return stroke whereby fluid is expelled from said chamber through said outlet port during said initial portion of said pumping stroke, with both said portS during intermediate portions of said pumping stroke and said return stroke, and with only said outlet port during a terminal portion of said pumping stroke and an initial portion of said return stroke whereby fluid is expelled from said chamber through said outlet port during said terminal portion of said pumping stroke, the rotation of said piston being operable to adjust the points during said strokes at which said passage changes from each one of said porting conditions to a succeeding one of said porting conditions.

14. A pump according to claim 7 wherein said rotation of the piston within said cylindrical bore is operable to vary the amounts of fluid pumped from said first and second supply sources during a pumping stroke while maintaining constant the ratio between said amounts.

15. A pump according to claim 3 having check valve means connected to said outlet port, whereby fluid may flow frOm said chamber through said outlet port and said check valve means only while said passage of said piston is connected with both said ports or with only said outlet port, and whereby suction will be built up in said chamber during a portion of said return stroke.

16. A pump according to claim 3 having check valve means connected to said inlet port, whereby fluid may flow from said chamber through said inlet port and said check valve means only while said passage of said piston is connected with both said ports or with only said inlet port, whereby fluid will be expelled from said chamber through said inlet port past said check valve during said initial portion of a pumping stroke. A pump according to claim 3 having a second fluid chamber connected to said inlet port; a fluid supply source, and first and second oppositely-oriented check valve means each connected between said second fluid chamber and said fluid supply source, said first check valve means being operable upon increase in pressure in said second chamber during a return stroke of said piston to return fluid from said second chamber toward said supply source, and said second check valve means being operable upon decrease of pressure in said second chamber during a pumping stroke to admit fluid from said supply source toward said second chamber, whereby reciprocation of said piston causes circulation of fluid between said second chamber and supply source

18. In a fluid pump having piston means adapted to reciprocate within a cylindrical bore having an inlet port and outlet means, said piston means having a passageway adapted to communicate with said inlet port during one portion of a pumping stroke in which fluid is expelled from said bore through said inlet port and adapted not to communicate with said inlet port during a second portion of said pumping stroke during which fluid is expelled from said bore through said outlet means, said piston means being angularly adjustable within said cylindrical bore to adjust the relative lengths of said two portions of said pumping stroke and thereby to adjust the amount of fluid pumped through said outlet means during a pumping stroke, the combination of means defining a chamber communicating with said piston means so that said piston means expands said chamber during said one portion of said pumping stroke, said chamber being connected to communicate with said inlet port, whereby expansion of said chamber during said one portion of said pumping stroke creates a suction in said chamber to aid the expulsion of fluid from said bore through said inlet port to said chamber during said one portion of said pumping stroke.

19. A fluid pump, comprising, in combination: a cylindrical bore having an inlet port and an outlet port axially spaced from each other; a rotatably-adjustable piston means adapted to reciprocate within said bore to decrease the size of a first chamber formed by said bore and said piston means during a pumping stroke and to increase the size of said chamber during a return stroke, said piston means having a passage adapted to connect said first chamber to said outlet port during one portion of a return stroke and to connect said first chamber to said inlet port during another portion of a return stroke; means defining a second chamber adapted to be increased in size by said piston means during said pumping stroke and to be decreased in size during return stroke; returnstroke; a fluid supply source; first and second check valve means; said second chamber being connected to said fluid supply source through said first check valve means, said second chamber being connected to said inlet port, and said outlet port being connected to said second check valve means, whereby motion of said piston means during said one portion of said return stroke creates a pressure within said second chamber and a suction between said inlet port and said second check valve means, said pressure and suction acting cumulatively during said another portion of said return stroke to fOrce fluid from said second chamber through said inlet port into said first chamber.

20. A fluid pump, comprising, in combination: a first piston-cylinder assembly having a first bore, a first piston adapted to reciprocate within said bore to vary the size of a first chamber formed by said first piston and first bore during pumping and return strokes of fixed length in opposite directions of said first piston relative to said first bore, a first inlet port and a first outlet port, and a first passage reciprocable relative to said first inlet and outlet ports to connect said first chamber sequentially to said first inlet port and said first outlet port; a second piston-cylinder assembly having a second bore, a second piston adapted to reciprocate within said bore in synchronism with the reciprocation of said first piston within said first bore to vary the size of a second chamber formed by said second piston and said second bore, a second inlet port and a second outlet port, and a second passage reciprocable relative to said second inlet and outlet ports to connect said second chamber sequentially to said second inlet port and second outlet port; means for connecting a first fluid supply source to said first inlet port; means for connecting a second fluid supply source to said second inlet port; and means for rotating said first passage relative to said first inlet port and said first outlet port and rotating said second passage relative to said second inlet port and said second outlet port to vary the points during said pumping and return strokes at which said first passage connects to said first inlet port and said first outlet port and at which said second passage connects to said second inlet port and said second outlet port, thereby to vary the amounts of fluids pumped from said first and second-supply sources.

21. A pump according to claim 20 in which the angular positional relationship of said first passage relative to said first inlet port and first outlet port differs from the angular positional relationship of said second passage relative to said second inlet port and second outlet port, whereby rotation of said passages relative to said ports varies the ratio between the amounts of the fluids pumped from said first and second fluid supply.

22. A pump according to claim 20 in which said first and second outlet ports are connected through first and second check valve means, respectively, to a mixing chamber.

23. A fluid pump, comprising, in combination: first cylinder means having a first bore; first piston means adapted to reciprocate within said first bore and vary the size of a first chamber formed by said first piston and said first bore; second cylinder means defining a cylindrical second bore, said first cylinder means having a cylindrical cross-section and being adapted to reciprocate as a piston within said second cylinder means to vary the size of a second chamber, said second cylinder means including a first inlet port and a first outlet port axially spaced from each other along said second cylinder means, said first cylinder means having a first passage adapted to connect said first chamber sequentially with said first inlet and outlet ports, said second cylinder means including a second input port and a second outlet port, said first cylinder means having a second passage adapted to connect said second chamber sequentially with said second inlet and outlet ports.

24. A pump according to claim 23 having means for reciprocating said first cylinder means through a fixed distance relative to said first piston and said second cylinder means; and means for rotating said first cylinder means relative to said second cylinder means to vary the proportionate parts of said distance at which said first and second passages connect with inlet ports and outlet ports.