US2575955A - Fuel injection pump - Google Patents

Description

1951 J. w. HATCH FUEL INJECTION PUMP Filed July 10, 1947 Tzg.L-1"1g- 13 b. I1g 4 INVENTOR.

2 M m W4 J m Patented Nov. 20, 1951 UNITED STATES PATET OFFICE FUEL INJECTION PUMP James W. Hatch, Los Angeles, Calif.

Application July 10, 1947, Serial No. 759,954

8 Claims. 1

The invention presented herein is concerned with fuel injection in internal combustion engines and particularly relates to pump-type fuel injectors.

This application is a continuation, in part, of my application entitled Fuel Injection Pump," Serial No. 513,882, filed December 11, 1943, now abandoned.

Previously, such injectors when utilized with liquid fuels, and particularly with such volatile liquids as gasoline, inescapably operated on their intake stroke to agitate the gasoline while naturally reducing the pressure thereupon. The inevitable result was to transform the intaken fuel into a frothy mixture of fuel vapor, liquid fuel and air- The quantity of fuel drawn into the chamber of previously proposed fuel injection pumps consequently varied depending upon the amount of fuel vapor and air presentin the intaken mixture. As the quantity of fuel taken in during the intake stroke of the plunger varied such pumps were not capable of constantly de-. livering equal fuel charges to the combustion chamber of the internal combustion engine with which they were used.

This successive distribution of unequal charges to a given engine cylinder eventually resulted in overheating of the cylinder, and the simultaneous delivery in one cycle of. unequal charges to the various cylinders effectuated uneven power impulses from the various cylinders, with resultant excessive vibration and irregularity of operation. Even more serious is the fact that this overheating, uneven firing, and vibration materially reduced the thermodynamic efficiency and the brake horsepower of the engine.

This problem has been a vexatious, one and has been sought to be solved by providing means formetering the fuel supplied to the pump at the intake stroke. The means heretofore proposed for metering the charge supplied the pump have been complicated and difiicult to maintain. They have not been entirely successful for they too agitated the fuel while varying the pressure thereon so that the fuel charge supplied the pump was again compressible to varying and undeterminable degrees.

The present invention conceives of a method and a means for enabling fuel injectors to pump an invariably equal amount of highly voltatile fuel at a constant pressure into each of the cylinf ders of an internal combustion engine on each or the engine cycles. predicated upon drawing into the chamber of the pump such a quantum of fuel in mixed-phase Generically, the invention is condition as to insure the presence in the chamber, after reduction of the mixed-phase condition of the fuel to a liquid-phase, of a quantity of liq uid fuel in excess of a preselected quantity desired to be injected; reducing the fuel inthe mixed- -phase condition to a liquid fuel by com,- pression; eliminatingfrom the pump chamber the fuel in excess of the preselected quantity to be injected while retaining the fuel under compression; and thereafter ejecting under :a higher compression the remaining fuel fromthe pump chamber.

The now preferred embodiment of the fuel injection pump of the present invention comprises a compression chamber in which a plunger isreciprocatably mounted. The chamber is formed with an intake port located adjacent the one end of the stroke or path of movement of the plunger and adjacent the opposite end of the stroke of the plunger with an ejection port normally closed by a pressureresponsive means. A relief port also normally closed by a pressure responsive means is disposedintermediate the intake and ejection ports. l In carrying out the method of the present'in vention the quantum of fuel in mixed-phase condition is drawn into the chamber as the plunger reaches the end of its intake stroke and uncovers the intake port. As the plunger begins its com pression stroke the intake port is closed and the fuel in mixed-phase condition is subjectedflto progressively increasing pressure until a' pressure is reached at which the fuel in the mixedphase condition is reduced to a liquid-phase.

The relief port is so spaced from the intake port that the reduction of the fuel in the mixed-phase condition will have been brought about before the plunger reaches the point in its compression stroke at which the same will close the relief port. The pressure responsive means normally closing the relief port is set to open at a pressure slightly in excess of the fuel mixture-liquifying pressure and will open subsequent to the reduction of the fuel in the mixed-phase condition to permit elimination of the quantity of liquid fuel in excess of that quantity remaining in'the cham: her after the plunger has reached aposition in its compression stroke at which therelief port will be closed by the plunger. The means normally closing the ejection port is operated to open the port by the attainment lof a predetermined pressure within the chamber greater than that pressure at which the relief port is opened. 'Ihereis thus nodanger thatthe 3. ejection port will open prior to the elimination of the excess fuel by way of the relief port.

The pressure at which the ejection port will open is brought about by movement of the plunger in its compression stroke beyond its position of travel at which the relief port will be closed by the same. When the predetermined pressure is reached by compression of the now liquid fuel the ejection. portis opened and the liquid. fuel is forced under-pressure into the combustion chamher.

The plunger is formed with control means which will upon rotation of the plunger var the position of the plunger during its compression stroke at which the same will close the. relief port. I

As the position at which the plunger will close the relief port during the compressionsstroke thereof can be varied the quantity of fuelremaining in the chamber;v at the time the relief port isclosed can consequently also be Vaiied. Thus the injection pump of the present invention provides means for ejecting at each compression stroke a preselected, invariably equal quantity of highly volatile fuel at constant pressure. *Otherfeatures and advantages of the present invention will be apparent from the following detailed description thereof taken in connection with the accompanyingflrawing; in Y which:

Figure l is a fragmentary longitudinal section, partly inelevation, of a fuel injection pump incorporating my invention showing the intake port open and the positionof the plunger at the beginning of its compression stroke;

Figure2 is aview similar to'Figure l but showing the plunger; as having closed the intake port and progressively; increasing the, pressure on the intaken fuel mixture;

-'Figure-3 is also. a view similar tog-Figure 1 but showin the relief'port open withthe plunger approaching the position in its compression stroke at which the relief port will be closed;

Figure-dis a: longitudinal section showingthe plunger at a position after'the relief port has been closed and the ejection port 1 has been opened; 1 j

fi ur isa View m a o. ieu eag u Sh li 't p sit qn ofth rlun er at the comp e q o el i o th ue 1 iE u 6 i a s ciicntaken a 1Q l l ,0 F u 1 an lijigureq is a fragmentary. longitudinal section, partly in elevation, ofa modified form ofthe fuel inj t mp f h r se invention- The now preferred embodiment of the fuel injectionpump of the present invention, referring now to the accompanying drawing and more particularly toFigure 1 thereof, comprises a" housing Hlincluding a compression chamber H in which a plunger l2is mounted for reciprocatorymotion through some conventionaldriving means. This means may comprise a driven shaft l3 carrying a cam l-I against whichthe lower end of the plungeriis normally urged by a spring l5 surroundingtljie pl nger 121 between the lower surface of the hou in 9.and. a circular shoulder [6 carried by the lower end of the plunger.

-".lhe housing l0 is provided with anintalge port I1 adapted to' be connected by a suitable conduit, not shown, to a source. of fuel such as theconventional fuel tank. A booster pump may be inorporet int t j ondu l a in to. t t k port'if found desirable. The inner wall of the iqas n h if me w t .ani u a ie o 1. whichintersects the intake port I"! as shown, the

port shown at 25 is normally closed by a ball 28 held across the port by a spring 27 seating on a .-c0llar..or the like suitably anchored to the wall of thehhousing. The port 25 is the relief port through which the excess fuel may be eliminated just prior to therejection cycle of the pump. The

intake port I! and the relief port 25 constitute passage means communicating with the fuel supply.

In the operation of. the pump hereindisclosed,

- as the plunger: I2 moves downwardly in the housing 10a partialvacuum isncreated above-.the plunger so that when the plunger movesdownwardlyipast:theintakeport l7 thefuel :Within the line adjacent the port is suddenl subjected tomb-atmospheric pressure .andthe. quantity. of fuel drawn into the housing, because of the partialwacuum therein,. takes admixed vapor. and liquid: phase. condition. "The: fuelin this. mixedphase. condition is highly compressible. to, varying and incalculable degrees.

The camz M is so formed that the. plunger remains in an arrested positionwith the intake port open for a time sufficient to permitthe chamber l I to. completely fill with the. mixed-phase fuel. The quantity. of fuel. in the mixed-phase. condi tion drawnintoand filling the-chamber is sufficientto insure a quantity of liquid fuel, after reduction; of the inixedrphase condition. of the uel intakent La l quid mhas in. excess p the preselected quantityto be ejected.

As the cam urges 111E116 plunger upwardly. .the latter first ,closesgtheiintake port. and. as it. continues to move upwardly, progressively. increases the 1-pressure.-.on .,the fuel mixture held by the chamber. :At some pressure, dependent upon: the type..of:fuel,a.the=.amount of :free :air and 'fuel vapor presentsin the. indrawn: mixture, as wellas the temperature: of. the ..same,- the fuel mixture willreturn to.-the:liquidphase. The springZT-is of. such.=a rate as:.to hold the ball- 26 in port-closingposition until this pressure has been reached. The intake port is so spaced from the relief port that the pressure a at which the fuel mixture is reduced to a liquidwill'bereached under all expected; normal operating conditions before the plunger-hasmoved upwardly a distance sufficient to close the relief port.

Continued upward --movement of the plunger after the indrawnfuel mixture has been liquefied results in anincreased pressure on the liquid fuel now held by the chamber and, at some predetermined pressure the ,ball 26 .will he moved back against theactio'n of the s rin 21 and thus .Th sprin 23 is tronger than. sprmgm so that the ball 22 is held against'the ejection port 19 as the liquid fuel is -forc ed outwardly through the reliefport vAfter the relief port is closed by, the plunger,however, continued upyvard movement of the latter increases the pressureon the liquid fuel to overcome the resistance of the spring, and the liquidfuel is ejected through theportl9. i I

As the liquid fuel is substantially incomprese sible the port I9 is opened almost simultaneously with the closing of the relief port. Thus it can be said that the quantity. of fuel ejected by the pump of the present inventionis substantially that remaining in the chamber at the time the plunger closes the relief port. ,The time the relief port is closed by the plunger in the compression or ejection cycle of the fuel pump herein shown can be varied so that the quantity of fuel remaining in the chamber at the instant of closure of the relief port orthe quantity to be ejected can also bevaried.

This control may be accomplished by various means but in the now preferred embodiment of the invention, this control is brought about by forming the outer cylindrical surface of the head portion of the plunger witha downwardly spiralling shoulder 28. It will be seen that by rotating the plungerfl various portions of the shoulder 28 will effect closing of the relief port. Thus if the plungeris' rotated so that the lowermost portion of the shoulder effects closureof the port the top face of the plunger will have moved a considerable distance beyond 'the port before the latter is closed. On the other hand, if the plungeris rotated to a position in which the uppermost portion of the shoulder effects the closing, the top face of the plunger will be substantially in alignment with the top of the port when the latter is closed. It is clear that in the first example, a smaller quantity of fuel will remain in the chamberwhen the relief port is closed than in the example last given.

Although the plunger can be rotated by a number of means it is now preferred to form the lower end of the plunger with" peripherally arranged spur-teeth 29 which engage the teeth of arack3l mounted for longitudinal movement.

Some means not shown, can be provided for selectively moving the rack to bring about the desired rotation of the plunger.

. It should now be seen that the fuel injection pump of the present invention is capable of ejecting a predetermined accurately, controlled quantity of liquid fuel at each injection stroke thereof. This ejection is accomplished without the employ of complicated and intricate :means of metering the fuel to the end that the service life of the pump herein disclosed is extremely long In order to quickly terminate, the ,ejection period, the plunger may be provided, at a distance from its upper endface equal to the dis tance between the intake port l1.and thewall 2| of the casing, with a peripheral groove 32 connected by a diametrical bore 33 and an axial bore 34 to the upper face of the plunger. It

will now be seen that when the plunger has moved to a position in which the upper face thereof is substantially contacting the inner face of the wall 2| the groove 32 is substantially registering with the groove 18 and the interior of the chamber is vented to the ambient atmosphere. This obviously results in a sudden decrease of the chamber pressure whereupon the spring 23 quickly moves the ball 22 to its portclosingposition, Anywfuel remaining in the upper end of the chamber,will,, of course pe forced out of the chamber through the inter:- connecting bores 33 and 34 and grooves '32 and I8 back through port ll into the supply system. There is shown in Figure 7, a modified form of the means for varying the closure of the re,- lief, port. In this form of the invention the plunger formed with an angularly disposed end surface 35. The surface may be machined, cast or otherwise formed on the plunger, and functions to control the time of closing of the relief port as does the spiral shoulder 28' of the preferred form of the pump of the present invention. t

Although the now preferred embodiments of the present invention have been shown and described herein, it is to be understood that the same are not to be limited thereto for the present invention is susceptible to changes in form and detail within the scope of the appended claims.

I claim:

1. In an injection pump for internal combustion engines: a compression chamber having an intake port, a relief port and an ejection port; pressure responsive means engaging both said relief and ejection ports; and a plunger in said chamber having relief passages, and a control member; said control memberbeing constructed and adapted to close said relief port and maintain closure of said relief port throughout the ejection period of said plunger stroke, said relief passages being constructed and adapted to establish communication of said chamber and said intake port at a predetermined point in the compression stroke of said plunger to terminate the ejection period, said pressure responsive means engaging said relief port being adapted to operate at a lower pressure than said pressure responsive means engaging said ejection port.

2. A pump for injecting liquid fuel, from a mixed-phase volatile source, into an internal combustion engine cylinder, including: a com pression chamber containing a single piston-like plunger reciprocative therein; an intake port in the lower portion of the chamber for inducting mixed-phase volatile fuel; an ejection port in the upper portion of said chamber; a relief port located along the path of travel of said plunger above said intake port a distance proportional to the conventional amount of vapor-phase in the mixed-phase fuel; pressure-responsive means engaging said relief port and engaging said ejection port, the former being adapted to operate at a lower biasing pressure than the latter, and said plunger including port-obturating means adapted to close said relief port and maintain it closed during the whole of the injection part of the plunger stroke; said plunger including relief-means adapted to establish communication of the upper part of said compression chamber with said intake port at a predetermined part ofthe injection stroke so as to abruptly terminate the injection of fuel. r

3. A pump for injecting fuel into a combustion cylinder of an internal combustion engine, comprising: a compression chamber having a volatile fuel intake port; a plunger reciprocative in said chamber; an ejection port spaced from said intake port; pressure-responsive means normally closing said ejection port, said means opening said port upon the attainment within said cham ber of a predetermined pressure; a relief port in awall of said chamber intermediate said intake port and said ejection port; pressure-responsive means normally closing said relief port, said last azm'gess "named pressure respensive means opening said relief port -'at 'a" preselected pressure which is less tharrsaid predetermined pressure; and means for -reciprccating said plunger whereby a *fuel and air -mixture is drawn into --saidchamber during the intake "stroke-of said plunger and reduced to a liquid during-the compression-stroke of said plunger, the portion 'of said liquid in excess ofthe quantity which will remain in said chamber at the time said *relief port-is closed b'y said plunger "being "ejected through -*sa-id relief port wh'en'theipressureon-saidliquid equals-said pre-selected pressure,- the remainder of said liquid beingejected through said ejection iport during the "compression "stroke of -tsaid plunger when "the predetermined -pressure is attained withinsai'dchamber. V

' 4'. A pump "for injecting 'volatile fuel into a combustion cylinder of an internal combustion engine, comprising: "a compression "chamber having a fuel intake port; aplunger reciprocating insaid chamber; ran ejection port spaced "from said intake port; pressure-responsive 'means normally closing said ejection'portpsaid means opening said 'port upon 'the attainment within said chamber of a predetermined pressure; a single "relief port in "a wall of said chamber 'intermediate said intake :port and "said ejection port; pressure-responsive means normally closing saidrelief port, saidlastnamedpressure responsive means'opening said relief port upon the attainmentwithin said-chamberof a pre-selected pressure which is less-than said predetermined pressure; and means for reciprocatin said plunger wherebya fuel and air-mixtureis drawn into said'chamber during the intake stroke of saidplunger and reduced to a liquid on travel of'the plunger between said intake'port andsaicl relief port before the'attainment-of said preselected 'pressure 1 during the compression stroke of said plunger,-a portion of-said liquid fuel-being ejected throughsaid relief port prior to the closure of said relief port'by said plunger when the pressure onsaidliquidequals said pre-selec'ted pressure, the remainder of said liquid being ejected through said ejection port during the remainder of the compression stroke of said plunger when the predetermined pressure is :attamed-within said chamber. r

5. A pump for injecting volatile fuel into Ea combustion cylinder of an internal combustion engine, comprising: a compression chamber having a fuelintake port; a plunger reciprocating in said chamber; an "ejection port spaced from *said'intake'port; pressure-responsivemeans nor- 'mally closing saidcjection port; said means opening said port upon the attainment within :said a chamber of'a-predetermined pressure; a single relief port in a Wall of said chamber intermediate said intake-port and said ejection port; :pres-sureresponsive means .normally closing said relief port, said last named pressure-responsive means opening said relief port upon the :attainment within said chamber of a pre-selected pressure which is less than said predetermined pressure;

and means for reciprocating sa'idplunger .where- -by a fuel and "air mixture containing.:a.aquantum of fuel in excess of that-quantity to 'b'e'injected into said combustion cylinder isdrawn-into said chamber during the'intake stroke of said. plunger and reduced to a liquid between said intake port and said relief port during the compression stroke of "said plungerythe portionof said liquid in excessof that portion WhiChWill remain after said relief port is closed "being ejected through said "relief orter-1on0 the iclosu'r'e of said is lief' vport *by *said =plunger when the pressure -*on said liquid equal =said -pre-'-selected pressure, the remainder ofsaid liquid being ejected through said =ejection' p-ort "during the remainder -"of the compress-ion stroke of said plunger when the predetermined pressure "is attained within said chamber. g

*6. ii-pump for injecting liquid ful' into -an=internal combustionieng'ine comprising: a compression chamber having a fuel intake port at" the lower -end itherecf =-adapted 'to be connected to a source of liquid-fuel; a plunger reciprocative in said chamber betweena positionadjacentthe upper 'end thereof *to -one spaced below said -intake port; movement-o'f said plunger downwardly in said chamber creating 'a partial vacuum therein wherebyfuel is drawn into said chamber through said intake port in a mixed vapor 'anfd liquid-phaseconditionrarelif port spacedabove said intake port; pressure responsive-means normally "closing 1 said relief "portand operative 'under a predeterminedpressure 'toopen said relief port; an 'ejection'port at theupper endof said chamber; andpressure "responsive 'means "normally "closing "said "ejection port "and operative under-"a predeterminedpressure higher than said first named predetermined pressure for "opening said ejection-port; movementof said plunger upwardly in said chamber from its position below said intakeport-closingthe same and-thereafter progressively increasing the pressure ;on said fuel confinedwithin said chamberto-re'duce the fuel "to 'a liquid, that portion of said liquid fuel in excess of the quantity confined 'within said chamberbetween theejection'port and said-re- 'liefportbeingejectedthrough the latter as the pressure :of said -fuel exceeds 'said first "named "predetermmed pressure, the "remainder of said liquid fuel being "ejected through said ejection port during the remainder or the compression "strokep'f'said plunger when'rthe second'predeterminedYpressure "isattained within :said 7 chamber.

" 7. hpumpffor "injecting la preselected .quantity of liquid fuel into a combustion cylinder 'of an internal combustion "engine, comprising: a ."comptess'ion chamber having "a 'fuel intake port to 'b'e'connected to'a'source of volatile fuel "aplunger reciprocative in said chamber between alternate positions adjacent opposite ends of said compression "chamber, "said intake port in tone of "said alternate positions of the plunger communicating 'said "chamber with said source, movement of said plunger toward said *last mentioned position 'creating -'a "partial vacuum in said chamber 'so that'as said plunger moves "in said position a 'fuel m'ixture in a vapor and liquid phase and containing a quantum of'fuel in excess of said preselected quantity "is drawn into said chamber through said in'take port; means, including a relief port, for communicating said chamber with said-source; =pressure responsive meansnoranally-closing sai'd communicating means and operati-ve upon a'predetermined pressure within said chamber to open the same to communicate said chamber with :said source, 'said chamber tiens closing said intake apart andprogressively increasing the pressure on said fuel mixture to reduce the same to the liquid phase condition, the pressure responsive means closing said communicating means opening upon the attainment within said chamber of a pressure equal to said first predetermined pressure whereby said liquid fuel in excess of the preselected quantity is returned to said source, continued movement of said plunger closing said relief port whereby the preselected quantity of fuel is ejected through said ejection port when the second predetermined pressure is attained within said chamber.

8. A pump for injecting a completely liquid charge of fuel of a predetermined quantity into an internal combustion engine comprising: a pump chamber having a movable wall for expansion and contraction of the chamber, said chamber having an ejection port; passage means for communication between said chamber and a fuel supply; means to move said wall for expansion and contraction of said chamber by a volume difference in excess of the volume of said pre-determined quantity of fuel, expansion of said chamber creating a partial vacuum therein whereby fuel in excess of said quantity is drawn into said chamber from said passage means in a mixed vapor and liquid phase condition; means to close said passage means for an initial portion of the compression movement of said wall and then to open the passage means, whereby said fuel drawn into the chamber is raised to an intermediate pressure to reduce the fuel to liquid and then the excess portion of the liquid is returned to the passage means; means responsive directly to movement of said wall to close said passage means at a later point in the compression movement of the wall to cut off the return flow of the liquid fuel; and pressureresponsive means normally closing said ejection port and operative to open under higher pressure than said intermediate pressure.

JAMES W. HATCH.

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

UNITED STATES PATENTS Number Name Date 1,883,980 Lang Oct. 25, 1932 1,993,759 Stockmeyer Mar. 12, 1935 FOREIGN PATENTS Number Country Date 665,885 Germany 1938

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