US2580572A

US2580572A - Internal-combustion engine

Info

Publication number: US2580572A
Application number: US46020A
Authority: US
Inventors: Wallace A Mcmillan
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1948-08-25
Filing date: 1948-08-25
Publication date: 1952-01-01
Anticipated expiration: 1969-01-01

Description

2A SHEETS-SHEET 1 Filed Aug. 25, 1948 Jan. 1, 1952 Filed Aug. 25, 1948 WJZ.

W. A. MCMILLAN INTERNAL COMBUSTION ENGINE Patented Jan. l, 1952 INTERNAL-CUMBUSTION ENGINE Wallace A. McMillan, Glenham, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware i Application August 25,1948, Serial No. 46,020 4 This invention relates to an internal combustion engine ofthe reciprocating piston type operating with fuel injection. More particularly, the invention relates to an engine of this character wherein a single hydrocarbon oil serves as a medium for the lubricating system'of the engine and then as fuel for the fuel `injection system; and in a preferred embodiment illustrated. the single hydrocarbon oil serves in order as the cooling I medium, the lubricating medium and the fuel for the engine.

In the present stage of development of internal combustion engines of the'reciprocating piston type for automotive and aeronautical purposes, it is considered necessary to employ separate fuels. lubricants and cooling mediums which are tailormade to serve their respective purposes. In the majority of locations and under normal times, this presents no special problem, since sources of supply of the various mediums are readily availv able. In certain isolated localities. and particularly in abnormal times, such as encountered by the military inwar time, the supply of separate fuels, lubricating oils and cooling mediums for the internal combustion engines of mobile mi1i-V tary equipment has represented a serious problem. While there have been scattered proposals in the past tol employ an intermediate light oil, such as a kerosene, as both the lubricating medium and fuel of an engine, this has necessitated sacritice both in lubricating effectiveness and in combustion performance of the engine.

It is a principal object of the present invention to provide an internal combustion :engine of the fuel injection type which is capable of operating at high lubricating effectiveness and also at high combustion eiiiciency and power level on a single hydrocarbon oil medium. i

A further object of the invention is to provide an internal combustion engine of this type wherein the respective-functions of cooling, lubricating and combustion are satisfied in a highly efficient vmanner by a single hydrocarbon oil medium which flows in order from the cooling system to the lubricating system and thence to the fuel supply system of the engine.

Other objects and advantages of the present invention will be obvious from the following description, the attached drawing and the appended claims.

In accordance with the present invention, the high power level and eiiiciency'are attained by operating the engine on the Otto cycle at a relatively high compression ratio and on a relatively heavy hydrocarbon oil. of the character of gas oil 3 Claims. (Cl. 12S- 32) or even light lubricating oil, by utilizing the non# knocking combustion method and apparatus dis closed in the copending application of Everett M. Barber, Serial No. 10,598, iiled February 25, #1948, now Patent No. 2,484,009 dated October 11, 1949. In thisgoperation, fuel is injected into compressed swirling air within a localized portion of the combustion space during the latter part of the com pression stroke, the first increment of injected fue1 is spark-ignited as soon as combustible fuel vapor-air mixture is formed therefrom to establish a flame front'travelling counter to the swirling air, and the injection of fuel is continued into additional increments of the swirling compressed air immediately in advance of the travelling name front, so that additional combustible mixture is progressively formed and burned substantially as rapidly as formed to develop the power required on each cycle, while entirely preventing knock irrespective of the quality of the fuel employed or the compression ratio used. This permits operation on. the Otto cycle at relativelyl high compression ratios with a heavy oil or fuel, thereby securing the advantages of the Otto cycle efficiency and the higher power level due to the higher compression ratio, as well as supercharging. Further, in accordance with the present invention, this heavy hydrocarbon oil is rst supplied to the lubricating system of the engine where it is circulated therein to provide the normal lubricating requirements; and a portion of the circulating oil is continuously bled off to the fuel supply system from where it is forced by the usual fuel injection pump to the injection nozzles of the engine. In this manner, the medium in the lubricating system of the engine is rather rapidly consumed, so that any one quantity of oil does not remain in the lubricating system for suicient time to undergo objectionable oxidation or sludging.

As is well known, both motor oils and heavy duty engine oils employed in the present day automotive, aeronautical, or diesel driven power plants are of special additive type to withstand rigorous or heavy duty'lubricating conditions encountered over substantial periods of time. This means that a wide variety of lubricants must be supplied to meet the demands of the various mobile types of equipment, not to mention the different types of premium fuels required. The present invention obviates the necessity for supplying these various types of lubricants and fuels, and enables the mobile equipment to be operated satisfactorily at high power level with the supply of a single hydrocarbon oil-to the lubricating system and Ithe fuel system in series. Due to the fact that the oil in the lubricating system is rapidly consumed, even gas oils or non-inhibited light lubricating oils function very satisfactorily for the lubricating requirements of the engine.

The present invention also provides a further advantageous feature which is of benefit in mobile equipment operating under extremes of atmospheric temperatures or in desert service. This involves the use of the single hydrocarbon oil in series, flrst, in the cooling system of somewhat enlarged capacity to compensate for the lower heat conductivity of the oil in comparison to water or glycol, then in the lubricating system of the engine, and finally as the fuel in the injection system of the engine.

The invention is more particularly illustrated in the drawing wherein:

Fig. 1 is a side elevational view of the engine and appurtenances, with parts broken away and in section to illustrate the construction thereof;

Fig. 2 is a horizontal sectional view through one of the engine cylinders looking upwardly toward the cylinder head, together with a partial sectional view through a fuel pump cylinder supplying the fuel injection nozzle of said engine cylinder.

Referring to the drawings, the engine I is illustrated as of the four-cylinder Afour-cycle automotive type; but it is obvious that this is merely by way of example, and any suitable 7type of fuel injection engine adapted for aeronautical or other purposes can be utilized. Each' engine cylinder II (Fig. 2) is equipped with the customary cooling jacket I2. A conventional multicylinder fuel injection pump I3 is driven by cam shaft I4 (Fig. 2) interconnected in conventional manner with the engine crankshaft (not shown) to be driven at one-half engine speed for fourcycle`` operation in conventional manner. Each pumping cylinder of fuel pump I3 is provided with a plunger I5 operated by cam I6 carried by cam shaft I4. Fuel is supplied, to the pump by feed line IB which leads to a manifold formed in the pump block I9, the latter being interconnected with intake ports opening into each of the pump cylinders, the intake ports being under the control of the pump plungers I5 in conventional manner. On the pumping stroke of plunger I5 for a cooperating cylinder, fuel is forced through the'injection line 20 to the fuel injection nozzle 2I of a cooperating cylinder.

As shown more particularly in Fig. 2, each cylinder II is provided with an exhaust valve 22 and an air intake valve 23 equipped with a shroud 24 set tangentially of the disc-shaped combustion space 25, so that on the intake stroke of the piston (not shown) air is drawn into the cylinder I I in a manner to cause a high velocity air swirl within the combustion space 25 in the direction of the arrow 26. This air swirl is maintained during the succeeding compression stroke of the piston, such that the air swirl at the time of fuel injection may be about 6-8 times the R. P. M. of the engine.

The fuel pump I3 is coordinated with engine operation so as to initiate injection of fuel into combustion space 25 from nozzle 2I about 'I0-40 before top dead center of the compression stroke of the piston in the cooperating cylinder II. As shown, the nozzle 2| is mounted and constructed to inject a spray 28 tangentially of the combustion space in the direction of air swirl, so that 4 pressed air moving past the nozzle or one side of the combustion space is impregnated with fuel. Mounted in the periphery of cylinder II less than 90 of swirling movement, and preferably about 30, is a spark" plug I0 having electrodes II positioned to be contacted by the outer fringe of the flrst formed increment of fuel vapor-air mixture from spray 25 substantially as soon as formed. Each spark plug is connected by lead I2 in a conventional ignition circuit containing distributor 33 driven in synchronism with the engine in conventional manner, so as to produce a spark of igniting intensity at electrodes 3| about 4-12 crank angle degrees following the initiation of fuel injection, and at the time the first increment of injected fuel in combustible mixture form contacts the electrodes 3|. This initiates combustion and produces a flame front extending generally radially across the one side of the combustion space 25, said flame front travelling counter to the-direction of air swirl. Injection is continued from nozzle 2| in the spray form 28 on each cycle immediately in advance of the travelling flame front to delevop the power required, the succeeding increments of combustible fuel vapor-air mixture being thus formed immediately in advance of the travelling flame front and consumed by combustion substantially as rapidly as formed. For full power or load, it will be understood that injection continues on each cycle for a time equivalent to one complete rotation of the swirling air in combustion space 25, or for about -45 crank angle degrees depending upon the velocity of air swirl. For intermediate or lower loads, fuel injection is terminated earlier in the cycle, so that only a portion of the swirling air is impregnated and burned, it being understood that the localized segments of air which are impregnated are consumed by combustion before any substantial diffusion takes place, so that the localized segments are burned at substantially the fuel-air ratio at which they are impregnated. This provides the non-knocking -combustlon operation of the mentioned Barber ordinarily operated at a compression ratio of about 10:1, and with the timingset to produce the peak pressure rise of Otto cycle combustion slightly after top dead center.

Combustion, therefore, pendent of fuel quality, and any fuel which will properly vaporize and mix with the swirling air in the extremely short interval required for movement between the injection nozzle tip and the spark plug electrodes or the travelling flame front can be employed. Itv has been determined that a relatively heavy fuel within the gas oil range can be utilized in this engine without preheating. A lubricating oil within the conventional motor oil range can be utilized by preheating the fuel prior to injection to a temperature of the order of 20o-300 F., which can readily be accomplished by a conventional type of electrical heater mountedv on each of the injection lines 2l. This is not shown in the drawing, since ordinarily a heater is not required, as heat only a localized portion of the swirling comn rejection tothe oil will normally provide these is completely inde- 8 temperatures. A lubricating oil within the motor oil range can be utilized satisfactorily for starting and normal operations without preheating by mixing the same with a small proportion of a light hydrocarbon fuel', such as isopentane. Therefore, the present invention enables the selection as fuels for the engine of a wide variety of the heavier hydrocarbon oil fractions, in addition to the normal fuels of the gasoline and kerosene range. Where the single medium is employed for lubrication, as well as fuel, or for cooling, lubrication and fuel, it will be understood that a heavier hydrocarbon of at least the heavy kerosene range and which has lubricating properties, is selected. The control of the initiation of injection and duration of injection in accordance with load is obtained by rotation of the pump plungers Il through the throttle control (not shown) in conventional manner.

Referring again to Fig. 1, the cooling system of the engine I comprises radiator 3B having upper and lower headers 36 and 3l` with hose connections 3B and 3l, respectively. Lower hose connection 39 leads to the circulating pump 4I operated by the belt and pulley drive 4I from cam shaft I4.. the upper pulley of drive 4i also operating the cooling fan 42 in conventional manner. It will be understood that the circulating pump 40 forces the cooling medium which has passed through radiator $5 through the cooling jackets i2 and other circulating passages of the engine block and thence by hose connection I8 to the upper header 36 ofthe radiator. In accordance with the present invention, where a relatively heavy hydrocarbon oil having a high initial boiling point of the order of 250 Rand above is employed as the cooling medium, a closed cooling system without atmospheric connection or overflow can be used. The hydrocarbon oil for the multifunctional operation of the engine is supplied by gravity, or by suitable pump, from oil tank 44 through line 45 to the upper header 3B to maintain the cooling system at all times filled with the hydrocarbon oil. This offers the further advantage of insuring proper cooling of the engine without attention on the part of the operator and without refilling of the radiator, except as the normal fuel tank of the vehicle becomes exhausted. Furthermore, the use of a heavy hydrocarbon oil with a cooling system of the required increased cooling capacity offers the further advantage of satisfactory operation under extremes of low and high atmospheric temperatures without the necessity of changing from an anti-freeze to water cooling, and enables operation under severe conditions encountered in tropical heat or desert operation without serious overheating difficulties.

As further shown in Fig. 1, a bleed line 41 is connected in a drilled bore intersecting one of the circulating passages in the engine block for the cooling medium. This bleed line leads to and opens into the lower portion of the sump 48 of crankcase 49, and is under the control of valve 50 operated by float Si. Consequently, a portion of the hydrocarbon oil in the cooling circulating system is bled off into the crankcase to maintain the desired level of lubricating medium in the lubrication system of the engine. As this oil is bled off, make-up oil from tank 44, of course, flows by line 45 into the cooling system. The circulating lubricating system of the engine includes the conventional engine-driven oil pump 52 withdrawing oil by line 53 from sump 48 and I forcing the same through line 54 to oil ilter 5l, from where a portion returns by Icy-pass 58 to the sump. and another portion passes by pressure line 5l to the conventional oil circulating passages of the engine and thence returns to the crankcase in the usual manner. In accordance with the present invention, a portion of the oil supplied to pressure line 51 is continuously bled off by bleed line under the control of valve il to a fuel reservoir 6 I It will be understood that line i1 may be an open line or may also be provided with a valve 62, so that the rate of bleed to the fuel reservoir il can be accurately regulated or calibrated by manipulation of valve 60, or by both valves GU and 82. Consequently, a portion of the oil in the lubricating system is continuously removed to the fuel system during operation of the engine, with make-up oil for the lubricating system being supplied under the control of the float operated valve Il. Where a lighter hydrocarbon fuel, such as. for example, isopentane or -light aviation or motor gasoline, is to be mixed with the bled off oil, particularly where a lubricating oil is supplied to tank 44, a separate fuel tank B3 is provided and connected by line 64 under the control of valve 65 with the reservoir 6|, which then functions as a mixing tank. It will be understood that valves 65 and 6l or 86, 60 and B2 can be provided with suitable inter-connections with the throttle, so that the rate of bleed from thelubricating system to the fuel system, as well as the rate of supply of lighter fuel from tank 63, to the reservoir 8| can be in accordance with the load and fuel requirements of the engine; Or, in the alternative. valves G and 65 can be manipulated by a float control in reservoir 6I. It will be understood that valve `65A can be disconnected from the throttle interconnections, `and kept completely closed when theoil from tank 44' furnishes the entire fuelrequirements ofr the engine.

Thus, in the particular-.embodiment illustrated, `a single hydrocarbonoil furnishes the medium for cooling, `lubricating and fueling the engine. This provides notonlythe `advantages for operation `under extremescfjtemperature for the cooling on above, 'but also affords simiu ,Y llubricating system. Thus, a gas oil which `is consumed rapidly in the lubrieating system andfconsequently replaced with fresh oil, possesses adequate lubricating properties for even heavy duty service and under the extremes of temperature encountered. A lubricating system of the so-called` dry sump type, which contains a relatively small quantity of oil for a given enginesize, is particularly suitable for purposes of the present engine. While the present invention4 is of particular utility under exceptional or emergency conditions where the supply of a single medium for the mobile equipment is highly advantageous or necessary, its use is not limited to such exceptional operations.

Even where thereis no problem of supply, the present invention offers advantages particularly in connection with the `modification where the hydrocarbon oil is supplied first tothe lubricating system and then the fuelsystem. In such case, it will be understood that oil tank 44 is connected by line 45 directly to the iioat operatedvalve" lli in the line leading to sump 48, and the cooling system of the engine is entirely independent and of conventional character. Where water isreadily available, and the extremes of temperature are not encountered, this modification offers similar advantages from the standpoint ofsupply. But, in addition, the present invention enables the socalled heavy duty or additivetype of lubricants to accom:

7- b'eliminated and adequate lubrication. still secured. It is recognized that the oxidation of lubricating oils with the resultant formation of sludge, increase in neutralization number of the oil, and deposition of varnish or lacquer on the cylinder walls and pistons, together with serious bearing corrosion, involves a time factor. During the first few hours of engine operation under severe test conditions, the oxidation or deterioration of the oil is relatively slight. However, as the test is prolonged beyond this so-called induction period, and oxidation starts with increase'ln neutralization number, the rate of deterioration of the oil then progressively increases to a maximum. These test conditions, of course, involve operation which is equivalent to 500 to -1,000

miles of automotive service, for example, and thus represent the prolonged period of service of the lubricating oils as conventionally employed.

The present invention involves a new approach to the lubricant problem, and enables aturnover of the medium in the lubricating system in a relatively short period of time, equivalent, for example, to about -200 miles of operation. Consequently, the lubricant is replaced before substantial oxidation reactions set in under normal conditions of service. Moreover, by the use of specially refined gas oils which are more resistant to these oxidation reactions than the heavier lubricating oils, the lubricant is replaced in the system before any substantial oxidation and sludging occurs. The net result is that substantially the only type of impurity getting into the lubricating medium under these conditions is combustion soot resulting from blow-by; and the latter is readily removed by the conventional oil filter 55. Consequently, both the lubricant and fuel systems are maintained relatively free from impurities of the character of sludge; and the only requirement is for more frequent replacement of the oil filter 55 which is a simple and inexpensive matter.

While the use of the gas oil type of multifunctional medium is preferred for the present invention, the conventional types of lubricating oils are not excluded. As pointed out above, these can be employed alone as fuel; or a light hydrocarbon fuel can be blended with the lubricating oil prior 'to injection. Moreover, while the additive types of lubricants are normally not required, these can also be used where the additive is of such character as to avoid precipitation in the injection lines and nozzles, or where the additive is not precipitated by admixture with lighter fuels when the latter are employed. A very satisfactory type of multi-functional hydrocarbon oil for purposes of the present invention is a gas oil having a boiling range of about 40G-700 F.

Obviously many modifications and variations of the invention as above set forth may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. The method in the operation of an internal combustion engine of the reciprocating piston type Awhich comprises supplying a hydrocarbon oil having lubricating properties to the cooling system of the engine and circulating the same therein, bleeding off a portion of the circulating hydrocarbon oil in liquid state from the cooling system-and supplying it to the lubrication system of the engine and circulating the .same ina-the latter, bleeding'off a, portion of the circulating hydrocarbon oil in liquid'state from the said lubrication system and then injecting the bled off hydrocarbon oil into compressed air within the combustion space of a cylinder of said engine to provide for combustion therein to develop the power required, whereby the said hydrocarbon oil provides in order the cooling, lubricating and fuel requirements of the engine, and introducing fresh hydrocarbon oil into said cooling system to make up for that bled off. v

2. In an internal combustion engine of the reciprocating piston type, the combination with the crank case and circulating lubricatingsystem of said engine, of.a lubricating oil tank, means including a flow line for supplying lubricating oil from said tank to said crank case and to maintain a constant level of lubricating oil therein, an offtake from .said crankcase'below the. lubricating oil leveltherein, an oil pump having its suction side connected to said offtake, a vdivided line-connected to lthe pressure side .of said oil pump, a by-pass line also connected to the pressure side of said pump and leading to said crankcase to return excess lubricating oil directly to the latter, one portion of said divided line being connected to said engine circulating lubricating system, a mixing tank, the other portion of said divided line being a bleed line connected to said mixing tank through a control valve to supply lubricating oilto -the mixing tank, a fuel tank, a valve controlled line connecting ,said fuel tank with saidmixing tank to supply liquid tothe latter, a fuel pump, a fuel injectorfor said engine connected to the pressure side of said fuel pump, and a line connecting the suction side of said fuel pump with said mixing tank.

3. In an internal combustion engineof the reciprocating piston type, the combination with a circulating cooling lsystem for said engine, of a circulating lubricating system for said engine, a valve controlled bleed line for bleeding off a portion of the circulating medium in said cooling system in liquid state to said lubricating system, a fuel injection system for said engine, a valve controlled bleed line from said circulating lubricating systemto said fuel injection system. whereby the same medium passes in liquid state in order from said'cooling system to said vlubricating system and thence to said fuel injection system to serve as Vthe fuel in the latter, and an oil supply tank connected to said ycooling system to supply `make-up mediumto the latter.

WALLACE A. MCMILLAN.

REFERENCES CITE) The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 830,144 Frantz Sept. 4. 1906 1,480,402 Krollage Jan. 8, 1924 2,066,452 Bernard Jan. 5, 1937 2,319,858 Grow May 25. 1943 FOREIGN PATENTS Number Country Date 792,405 France Oct. 21, 1935