US2911958A - Engine fuel system - Google Patents

Description

Nov. 10, 1959 E. F. GRIEP 2,911,958

ENGINE FUEL SYSTEM Filed Oct. 12, 1956 INJECTORS "I INJECTORS I l l 4 m i P g g; v 15 24 1 a2 ACCUMULATOR X21 U K T DISTILLATE RESIDUUM m; l 112* Ii] |i| If] {/24 I m i INJECTORS I LTJ Q i] ACCUMULATOR INVENTOR ELZER F. GR/EP BY :2

ATTORNEYS United States Patent ENGINE FUEL SYSTEM Elmer F. Griep, Berkeley, Calif., assignor, by niesne assignments, to California Research Corporation, San Francisco, Calif., a corporation of Delaware Application October 12, 1956, Serial No. 615,539

6 Claims. (Cl. 123-30) This invention relates to a fuel supply system for an internal combustion engine of the compression-ignition type that is being selectively operated upon one or both of two dissimilar liquid fuels, and particularly refers to a method and apparatus for sequestering a predetermined quantity of the fuel from the supply system and for rapidly transferring the fuel supply to a desired fuel source upon a predetermined change of operating conditions of the engine, and for returning the said sequestered fuel quantity to the supply system for consumption in said engine when the original operating conditions are restored.

An example of a fuel system to which the invention is particularly adapted is described in US. Patent No. 2,758,579 to P. L. Pinotti, which is characterized by a circulating header system that is selectively supplied by two dissimilar fuels, either singly or in predeterminable proportions, depending upon speed or load conditions of the engine. One fuel is desirably a distillate for operation at idle or low load conditions, and therother is a residual or heavy fuel which may be added to the distillate or supplant it entirely at high load conditions or when the engine can assimilate it readily. The particular fuel, or mixture of fuels, in that system is continuously circulated in the header until it is introduced by the injectors into the engine cylinder.

It has been found that sudden change in engine load, for example, a rapid reduction from high load to idle, as may occur in a railway diesel engine that is directed onto a siding immediately after ascending a long grade or after operating at high speed, will leave a quantity of a heavy fuel mixture or only heavy residual fuel in the fuel supply system immediately adjacent the injectors, for example, in the circulating header of PatentNo. 2,758,579, that is relatively unsuited to the low load or engine idling condition. The engine, meanwhile, will require such a low rate of fuel consumption under these circumstances that this quantity of fuel, even if it is a fraction of a gallon, will require a relatively long time to be consumed. Under such conditions, undesirable results, such as smoking, carbon deposits on injectors, or sparking, may subsequently occur.

It is an object of this invention to provide a method and apparatus for rapidly sequestering a predetermined quantity of fuel from a fuel system, particularly of the type just described, at the time the load on the engine is reduced to idle or a low output, so that the moredesirable fuel for the last-named condition will reach the injectors promptly and operate the engine at its optimum condition. Thereafter, when the higher load or speed is to be resumed, this sequestered quantity will be controllably returned to the fuel supply system, or circulating header, and blended withthe fuel therein to be consumed without adversely affecting the engine operations. Desirably, but not necessarily, the functioning ofv the sequestering means is interconnected with the engine throttle or the load-governing mechanism. In any specific 2,911,958 I Patented Nov. 10, 1959 installation, the most advantageous arrangement and mode of operation will be apparent to one skilled in this art.

Another object is to provide a method and apparatus of the type just described that is simple to operate and construct and is adapted to existing installations of engine fuel systems without extensive modifications.

These and other objects and advantages will be further apparent from the following description and the attached drawing, which forms, a part of this specification and illustrates diagrammatically simple examples of the invention as applied to a circulating header internal combustion engine fuel system and to a non-return fuel system, each selectively supplied from two dissimilar fuel sources.

In the drawing, Figure 1 is a diagrammatic plan view illustrating an example of the invention as applied to a circulating header type system as may be employed on an electromotive (General Motors) diesel engine.

Figure 2 is a fragmentary diagrammatic plan view of part of the arrangement of Figure 1, which illustrates a non-return or non-circulating header for supplying fuel to the engine injectors of the type used on Baldwin and American Locomotive Company engines.

Figure 3 is an enlarged, fragmentary, diagrammatic view of one form of mixing or proportioning valve that will introduce only one fuel or a mixture of two fuels, depending on the engine throttle setting.

Referring to Figure 1 of the drawing, reference numeral 10 designates generally in outline an engine, in this case an internal combustion engine of the compressionignition type, fitted with the usual banks of fuel injectors 11. The inlets of injectors 11 are connected in parallel to an inlet conduit 12 and their outlets communicate with an outlet conduit 13. A circulating pump 14 is connected between conduits 12 and 13 by means such as connecting conduit 15 to provide what may be termed a circulating fuel header. As is customary in these injectors, fuel oil supplied thereto through their inlets and not actually utilized or injected into the respective engine cylinders, flows to the outlet, so that, with the arrangement just described, there is a finite body or quantity of liquid fuel, the amount dependent upon the dimensions of the system, which fills that system and circulates to and through the several injectors.

' To supply dissimilar liquid fuels to the system just described, a pair of storage tanks 16 and 17 are provided, respectively, for distillate and residual fuel oil. Each is connected through its pump 18 and 19 and appropriate piping to a mixing point, which may be a selecting or proportioning valve 20, the operating means of which is suitably connected as shown by dotted line 21 to the throttle or governor 22 of the engine. Valve 20 is arranged to supply either fuel alone to the system or to mix them in any desired proportion. Figure 3 illustrates a form of three-way valve 20 that, in the position shown, will admit only distillate fuel from tank 16 to circulating header 15, as just described. When it is rotated clockwise through about it admits only residual fuel from tank 17. At intermediate positions, it varies the proportions by the respective port openings of the rotor 200 in a manner well known in the fluid control art. Alternatively, each pump may be suitably individually controlled by the governor or throttled to supply the desired fuel quantity, in which case the valve 20 could be a simple T or other means adapted to constitute a point of introduction of the fuel to the engine supply system. The outlet of valve 20 is connected to the inlet conduit 12 of the circulating header. The specific construction and arrangement of the engine throttle 22 and proportioning valve 20, as well as the usual filters, heaters, pressure regulators and the like, are not a part of this invention and, hence, need no discussion'in this specification. Reference is made to US. Patent No. 2,758,579 for a typical illustration of such details. 7

In order to provide a method and means for rapidly withdrawing and sequestering the liquid contents of the circulating header and injector system, an accumulator chamber 23 is connected to conduit between outlet conduit 13 and the inlet to' circulating pump 14 by means of a short conduit 24. Accumulator 23 is a simple cylindrical container fitted with a; sliding piston 25 or other displ'aceable means, such as a flexible diaphragm, for accumulating liquid in the left end 26 under the influence of a pressure differential or a resilient means, such as a spring. The opposite end 27 of accumulator 23 is suitably connected to a three-way valve 28 arranged to vent 27 to atmosphere through line 29, for example, when the accumulator is intended to withdraw a quantity of liquid fuel from the circulating fuel system 12, 13, and 15 under the pressure existing therein by virtue of pumps 1'8'or' 19 D'esirably, valve 28 is connected through a time delay mechanism, generally designated 30, to the engine throttle valve or load governor 22 by appropriate means designated by the dotted line 31. This is so constructed and arranged that Whenever the engine throttle or governor 2 is actuated to reduce the fuel supply to the engine from high load to'an idle or low load condition, accumulator 23 functions as just described to rapidly withdraw a predetermined quantity of the'liquid fuel from the'circulating header and sequester it until such a' time as is appropriate to return it to the header, as will be explained below. In practice, this quantity ma 'ra'nge from about 100% to 200% of the total capacity of the circulatingsys'te'm and injectors. V In the usualcase, when the load on the engine is rapidly reduced to idle or low condition, it is desirable to supply only distillate fuel until the high load or speed condition is resumed. The cooperation of throttle 22 with valve 20 provides such a supply, as that valve normally is'effec tive, either alone or in cooperation with conventional accessories, to prevent pump'19 from adding residuum to the circulating header during this condition; L

After the low load or idling condition is past and high or full'load engine operation is to'be rcsurnedythr'ottle 22 is adjusted to govern the supply of distillate and, if d esircd, residual fuelto the 'circulating header in cooperation with valve 20 and-pumps 18 aiid 1 9. Tirnedelay mechanism 30 is adjusted to allow a reasonabletinieperiod to elapse, so'that it is assured that high load conditionswill continue, whereupon it'furictions to actuatevalve 23: to permit air or gas'under suitable pressure froin al supply line 32 to enter end 27 of accumulator 23 and returnpis ton 25 to its initial pQSiti n at the extreme left end of the accumulator. This displaces the sequestered" liquid fuel from end 26 of the accumulator and returns it to the circulating fuel system 12, 13, and 15 undercoriditions where its compositiomwhich may be preponderantly'or entirely residuum, will not adversely affect the engine operation. p p i Referringnow to Figure 2, which illustrates the application of the invention to a non-return or noncirculating type fuel supply system, reference numeral 1d designates generally and in outline the engine, on which is mounted a plurality of injectors 111 which'receiv'e fuel from a conduit 112 supplied'from a' propo'rtio'ning valve or mixing point 120'and introduce it into the engine cylinders. Conduit 112 fomts the fuel supply system and'contains thefinite quantity of liquid fuel already mentioned. To supply the two dissimilarliquid fuels to point 120, pumps 118 and 119 are provided, each with a suitable tank (not shown) corresponding to 18 and 19 of Figure l;

Accumulator chamber 123is connected to conduit 112 by short conduit 124, and its function, construction, mode of operation, and control by the engine throttle or load governor are otherwise identical with the arrangement of Figure 1. Accordingly, repetition of the descriptions al- .4 readygiven for .theseelements is deemed to be unnecessary for an understanding of the invention.

In conclusion, it will be appreciated that this invention comprehends broadly the provision of a method and means for withdrawing and sequestering a predetermined quantity of liquid fuel from the fuel supply system of an internal combustion engine, which may be included in a circulating body .61- headei: system, or in a supply conduit system, undcr a phangein load or operating conditions of. the' eii e; for example, low load or idle, that the said fuel characteristics would impair the operation of engine and, thereafter, when the load or operating conditions are appropriate, returning the said withdrawn sequesteredquantity to the system for consumption in the engine; During the time interval when such an action has taken place, it is comprehended that a more suitable fuel would be supplied to the engine under the'load' conditions existing.

Although a simple embodiment has been illustrated and described with particular referenceto an arrangement of a circulating header for acompression-ignition engine, exemplified by ,Patent No. ,2,758,579,.and an alternative non-circulating arrangement, it will be apparent that the invention is not so. limited and that numerous changes could" be made without departing from its essential features. Accordingly, all such changes andmodifications that come within the scope of the appended claims are intendedto be'embraced' thereby.

I claim:

1'. In a method of operatingla'. compression-ignition engine on' a mixture of two dissimilar liquid fuels in predeterminable proportions, said mixture being conti'nuously circulated in a conduit or the like in communication with the fuel injection system ofvsaid engine, the stepsof withdrawing the contents of said conduit into a confined chamber to permit said conduit to fill with substantiallyonly one of said'fuels when the load on said ngine'is reduced, supplying said one fuel to said conduit during saidredu'ced load period, and subsequently returning said withdrawn portion to said circulating conduit when the load on'said engine is increased.

2; Ina method of operating a compression-ignition engine on a mixture of two dissimilar liquid fuels in predeterminable' proportions, said mixture being continuously suppliedto a conduit or the like in communication with the fuel injection" system of said engine, the step of withdrawing the contents of said conduit into a confined chamber to. permit said conduit to fill with substantially only one'of said'fliels when the fuel supply to said engine is r'ed uced, supplying" said one fuel to said conduit during said reduced'fuel supply period, andsubs'equently returning said withdrawn'portidn to said conduit when the fuel supply tosaid engine is increased. I I

3'. In a method of selectively operating an internal combustienen'gine on one or both of two dissimilar liquid'fuel's'in' predeterniinable proportions, and in which a finite" quantity of said'fiiel' is maintained in a closed systern betweena pointofintroduction and at least one point of utilization, the steps of sequestering aprcdetermino quantity of said'fuelfroin'said system whenthe loadon said'engine: is reduced'so'that substantially only one of said fuels'utilized in'sa'id engine, supplying substantially only said one fuel to saidfclosed system during said'reduccdlt'ia'dperid, and subsequently returning said seq'tiestered quantitytosaid'system when the load on said engine is increased; A p I 4. In" a method of operating an internal combustion engine aecording'to claim 3,"the added step of delaying the returnof' saidsequcstered quantity tosaid system for a predetermined period of time after the load on said engine'is increased. I

5. In afuel system for'supplying amixture of two dissir'nilar liquid fuels to a. compression-ignition engine including a;he'ader chamber communicating with the injector system of said engine, means for supplying said mixture thereto, means for circulating said mixture through said chamber, and means for controlling the rate of fuel supply to said engine; the combination comprising an accumulator for withdrawing the mixture Within said chamber, means for supplying substantially only one of said fuels to said header chamber to circulate therein, and means responsive to the fuel supply control means of said engine for actuating said accumulator and said lastnamed fuel supply means.

6. In a fuel system for supplying a mixture of two dissimilar fuels to a compression-ignition engine inciuding means tor maintaining a finite quantity of said fuel under pressure in a confined system between a point of intro duction into said system and at least one point of utilization in said engine, and means for regulating the rate of fuel supply to said engine, the combination comprising an accumulator responsive to said regulating means for sequestering said finite fuel quantity, means for supplying thereafter substantially only one of said fuels to said confined system, and means responsive to said regulating means for discharging the sequestered fuel from said 0 accumulator into said confined system.

No references cited.

Images