US2596360A - Fuel pump - Google Patents

Description

May 13, 1952 R. s. BLAKEWAY FUEL PUMP Filed Aug. 6, 1948 Patented May 13, 1952 UNITED STATES PATENT GFFICE FUEL PUMP Richard Stanley Blakeway, Victoria, New South Wales, Australia 7 Claims.

This invention relates to airless or solid injection means or apparatus for spontaneous ignition constant pressure internal combustion engines, of the type comprising a fuel pump and motive means directly coupled with the fuel pump and operable by compression pressure in an engine cylinder to actuate the fuel pump for injecting fuel in a regulatable solid charge or volume into the engine cylinder.

In accordance with established practice, an engine fitted with injection apparatus of the type specified, is governed by Varying the volume of fuel injected. The volume of fuel injected upon each operation of the fuel may be controlled by variation of the point or position in the operative stroke of the ram or plunger at which fuel ceases to be injected or alternatively, commences to be injected.

In order to thus regulate the quantity injected, the ram may be -arranged for rotation relatively to the piston of the motive means and provided with a port or groove having an inclined face or edge which registers earlier or later, according to the rotated position of the ram, with a fuel release port or the fuel supply or charging port,

Alternatively, the volume of fuel injected may be regulated by adjustably shutting off communication between the cylinder of the motive means and the engine cylinder, so that operation of the former terminates earlier or later and the volume of fuel injected is accordingly less or greater.

The volume injected may also be varied by changing the effective capacity of the fuel pump chamber, so that more or less fuel is discharged while the stroke of pump plunger remains substantially constant.

In thus controlling the volume of injection, the fuel pump may be fitted with two plungers one of which comprises a control plunger and is movable by hand or governor so as to approach or recede from the other which comprises the operative plunger and is actuated by the motive means.

Now the principal objective of this invention is the provision of injection means orapparatus of the type specified, which is of generally simplied construction and easier to assemble and dismantle than the forms hitherto developed, and is, moreover, efficient in operation, and adjustably controllable for fuel injection responsive to variations of engine load.

The facility with which the injection means or apparatus according to this invention Amay pair, and readily reassembled is of material importance in the general maintenance and running of engines.

In achieving the above-stated principal objective and in the broadest concept of the invention, there is provided an injection means or apparatus of the type specified, having in the fuel pump a control plunger opposed to and separated from the operative plunger by a space comprising the fuel chamber, the operative plunger responsive to action of the motive means controlling the filling or charging with and ejection of fuel from the fuel chamber for injection, and the control plunger being adjustably movable relatively to the operative plunger to vary the volume of injection and comprise a stop variably limiting the stroke of the operative plunger.

The initial volume of fuel in the fuel chamber, i. e. the volume at the commencement of each stroke of the operative plunger, is constant, but the stroke of the latter is terminated earlier or later by engagement with the adjustable control plunger, so that the quantity of fuel displaced and injected by successive strokes of the operative plunger comprises a greater or less proportion of the constant initial volume responsive to changes of engine load.

Further objects of the invention are to provide free movement for the control plunger unopposed by pressure, so that a governor may adjust the control plunger to Vary the quantity of fuel injected in response to changes of engine load, to provide means for absorbing shock upon completion of injection, and to incorporate in the motive means a device to facilitate engine starting and slow running.

In order that the control plunger may be freely moved by a governor, the former is contained in the pump bore or cylinder and is pressure-balanced i. e. the pressures upon the opposite ends are equalized by the provision of a passage interconnecting the fuel chamber at one end of the control plunger with the portion of the pump cylinder at the opposite end of said plunger.

An important function achieved by the operation of the motive piston, is the increase in clearance volume space which lowers the compression pressure, i. e. decreases the compression ratio. Such decrease in compression ratio lowers the temperature of compression below the necessary ignition temperature, but this lowering of temperature is compensated by heating of the fuel arising from sudden impact of the pump yaeeefeco 3 plunger thereon and the friction resulting from the high velocity of the fuel through the nozzle jets and through the dense compressed air.

The heating thus produced and the heat of compression raises the temperature to the ignition point, notwithstanding the reduction in compression pressure.

The injection: apparatus according to the invention, may therefore be used effectively on engines of small size operating at relatively low compression pressures, and such engines are resultantly operated on a spontaneous ignition constant pressure cycle.

4l V member 21 are provided with apertures 32 oppositely located at equal distances from the common axis of the casing 5 and body member, and studs Yor boltsV (not shown) passed through the aperreceive an axial extension 35 of the piston 22.

The invention will be better understood from the description of the exemplary practical injection apparatus illustrated in the accompanying drawings, wherein: V

Fig. 1 is a longitudinal section of the injection apparatus.

Fig. 2 is a planviewon theline II-II of Fig. 1.

Fig. 3 lis a longitudinal section on the line rrr-1110i Fig. 2. ,y A V l Fig. 4 is a fragmentary sectional detail on a larger scale. y

'In these drawings, thenumeral A5I designates a cylindrical. casing, of which the exterior portion, indicated by (Lis appropriately dimensioned to fitmwithin a fuel supply aperture 1 in thecinbustionhead 8 of a cylinder 9 of an internal cblrhustio engine Y.he cylindrical casing is formed Withan en- Vlargement lll and is axially step-bored. The bore isrof maximum diameter at l I within the enlargementVv l a'n d,of least diameter at I2 Within the portion 5 with intermediate bore diameters at VAt the :termination of g the minimum bore I2, there is an internal flange I5, which is axially bored and recessed at I 6 to form a seating l1 for an externally flanged vbushing I8 having an axial orice I9 which ared o r tapered at each end,V the taper indicated by comprising a valve seat as presently explained. Formed oblique'ly Ain lthe bushing i3 is a port or passage 2l of relatively small v'diameter which forms a by-pass between the interioro'f the en ine cy1inder 9 andthe interior of the bore l2 ofthe casing 5 'fora purpose hereinafter described.

Slidabl'y tting the bore portion i2 is a piston 22 formed With a entral projection or boss 23 which is tapered at 24 to` form a. valve vfor engagement Ywith the correspondingly tapered valve vs ea'tZIl, see Fig. 3.

The extensions 33 and 35 comprise respectively the barrel and plunger of the fuel injection pump hereinafter more fully described.

Slidably tting the bore portion ['13 is a cylinf drical sleeve 35 having an internal flange 31 upon Which .is seated one end of a helical spring 38, the 'opposite end of which bears upon the piston 22 and urges the valve 24 thereon into engagement with the valve seat 20 to shut on communication between the cylinder 9 and the interior o the bore l2. Y

Extending coaxially from the bore to the end of the body member 21, is a bore 39 of somewhat greater diameter in which is'tted a liner 40 which comprises an extension of vthe pump barrel 33 and projects from the end of the body member and is threaded for engagement by a manually adjustable nut M. An integral flange a and screws 45h secure the liner 40 to the body member 21. In contact movable upon the liner @il and secured to thrust V rods 43 which extend through longitudinal holes partially closes the latter, so that an annular passageindicated by 26, is kformed betweenthe extension 25 and the interior of the bushing I3.

'Ijhe annular passage -26 connects the interior of the cylinder 9 and bore l2 upon the valve -24 being displaced'froin theseat 20, see Fig. 1,

'but is closedb'y the valve 24 upon engagement with thesea't 20 as shown in lig. 3. `The bore Ilv of the casing 5 isinternally V threaded to receive a correspondingly screwed closure-or body member 21, the outer surface of which has the same external diameterasthe enlargement l0, so thatthe former has a shoulder tion i3 and thereby disposer. the vbody member 'a'ceurat'eiy in epaxiaiaiigiimeiii with uit casing '5. V

`Lugsh30 and -3| formed integrally with the body 44 in the body member 21 into contact with the sleeve 36. V

It will be apparent that by adjustment of the n ut 4I, the thrust rods 43 may be slidably moved in the holes 44 to adjust the compression or nor- V mal energising or the spring 33 to thereby vary the closing pressure of the valve V24 on the valve seat 20,'and resultantly determine the compression pressure in the engine cylinder at which the valve 24 will open, as hereinafter described. Locking of the nut 'di upon adjustment, is effected by a pin 45 engageable with one or more ramp slots 46 in the collar 42. f

Through the plunger 35, piston 22 and extension 25 vis an axial bore 41 which terminates at the closed end 43 of the extension 25, and in the bore 41 is closely ntted a capillary-tube 9 having a nne bore 50. f

' The end of the capillary tube "i9 is reduced in diameter at 5l to form an annular space 52 and the inner side o'f the closed end 48 is separated from the end ofthe capillary tube by a space or gap indicated by 53.

'I he extension 25 is tapered at 5G and through this tapered part is drilled a multiple vnumber o f small spray apertures through Whichfuel `is sprayed into the engine cylinder 9, the extension 25 accordingly, comprising the fuel'injectio'n nozale. V

Slidably fitted in the liner VvSil is a control plunger 55 which is reciprocal in the former and has an axial bore 51 extending between the ophesite ends thereof. l In order that the control plunger 55 may be adjustably reciprocated in the liner 4 0, lthe former has at or about the mid-length, a peripheral lslot 58, with which iseng'ageda tongue 59 on a crosswith the nur il is a @ouai u axially Y t Y and a link 65 controlled manually or by a governor is connected to the screw 6|, so as to actuate the crosshead 6I) and thereby `move the control plunger 56 in the liner 46 in response to variations of load, as hereinafter described.

The space between the ends of the pump plunger 35 and the control plunger 56 comprises a fuel chamber 66 into which extends a cushioning block 61 carried by the control plunger 56.

The cushioning block 61 has a shank 66 which slidably fits an enlargement 69 of the axial bore 51 and is retained therein by a transverse pin 10 which extends through a slot 1I in the shank 68. Bearing upon the end of the shank 68 and seated upon the end of the enlarged bore 69 is a spring 12 which normally retains the inner end of the slot 1I in engagement with the pin 10 and the cushioning block extended from the control plunger 56. In the shank 68 are ports 13--14 whereby communication is established between the axial bore 51 and the fuel chamber 66.

`The end of the pump plunger 35 is bored and threaded toV receive a plug having a central aperture 'I6 which is closable by a spring-influenced check valve 11 positioned in a passage 18 continuous with the capillary bore 5D.

Extending through a vertically disposed aperture 19 in the lug 3I` is a ltering device comprising a cylindrical plug 80 having a threaded head 8| to which is connected a fuel supply tube (not shown). The plug 8l] projects from the opposite side of the lug 3| and is threaded to receive `a removable cap 82 which by a sealing pad 83 closes a bore 84 extending through the plug to a constriction 85 forming a shoulder 86 against which a ltering sleeve 81 is normally maintained by a spring 88.

The sleeve 81 has ends 89 fitting the bore 84, and between the ends 89 there is a reduced portion 96 forming with the surrounding bore 84 an annular space 9|. In the opposite ends of the sleeve 81 are axially drilled holes 92 which by small radial apertures 93 are connected with the annular space 9|. In passing through the filtering sleeve 81, impurities and any contained water are extracted from the fuel and gravitate to the lower end of the plug 80 for removal upon withdrawal of the cap 82.

A hole 94 in the plug 89 is aligned with a port 95 in the lug 3| which connects with a longitudinal passage 96 in the body member 21. The passage 96 has a terminal port 91 which connects with the bore 34 of the pump barrel 33 and is opened by the plunger as the valve 24 moves into contact with the valve seat 29, see Fig 3.

Upon the terminal port 91 being thus opened, fuel from the fuel line which is maintained at a required charging pressure, passes through the sleeve valve 61 by way of the axial holes 92, radial apertures 93, annular space 9|, hole 94, port 95 and passage 96 to and through the terminal port 91 into the lfuel chamber 66 which is accordingly charged with liquid fuel.

Furthermore, the liquid fuel passes through the 'ports 13-14 in the shank 68 into and through the bore 51 and fills the portion of the liner 49 or extension of the pump barrel above the control plunger 56, the liner 46 being closed by a screw 98 and packing washer 99.

In operation, and assuming the fuel chamber 66, bore 51, and said portion of the liner 46 to 'be thus filled with liquid fuel, and the valve 24 to be closing the annular passage 26, the engine is initially rotated to impel the piston inwardly into the cylinder on the compression stroke of the cycle Vof operations.

During the compression stroke and in accordance with the operative cycle of spontaneous ignition constant pressure engines, air is conipressed in the engine cylinder, and as the pressure rises, compressed air passages through the by-pass port 2| into the cylinder I2, so that the pressure therein increases but at a relatively slow rate consequent upon the small area of the bypass 2|. l

The compression pressure in rising bears upon an area of the piston 22 equivalent to the full cross-sectional area of the axial orifice I9 of the bushing I8, and as the engine piston approaches the end of the compression stroke, the compression pressure acting upon this arca, together with the pressure in the cylinder I2 acting upon the annular part of the piston 22 surrounding the boss 23, is suicient to displace the valve 24 from the seat 20 against the resistance of the spring 38.

Thereupon the compression pressure acts upon the full area of the piston 22 which together with the pump plunger 35 is rapidly moved and thrust against the spring 38 which is accordingly compressed and further energized.

In the rapid movement in the pump barrel 33, the plunger 35 firstly, closes the fuel inlet 9'1 and then ejects the fuel charge in the fuel chamber 66 through aperture 16 past the valve 11 into the capillary bore 56 and thence into the injection nozzle 25 from which the fuel is sprayed through the apertures 55 into the engine cylinder, wherein the fuel is spontaneously ignited and burnt in the compressed air to impart the initial impulse to the engine.

The brief injection period terminates upon engagement of the marginal edge of the aperture 1'6 with the cushioning block 61, whereupon the delivery of fuel into the engine cylinder ceases.

Upon injection of fuel ceasing as described, the piston 22 and plunger 35 are brought to rest Without shock by the back pressure generated in the fuel remaining in the fuel chamber 65, bore 51 and the upper portion of liner IIB. When the marginal edge of the aperture 16 of the outwardly rising plunger 35 engages 'with the cushioning block 61 the latter is impelled in an upward direction under restraint by the transverse pin 10 in the slot 1I of the shank 68, the spring 12 and the pressure of the fuel remaining in the ports 13 and 14, the bore 51 of the control plunger 56 and the upper portion of the liner 40. The back pressure of the fuelthus arising at the termination of injection and which the cushioning block 51 and its related Vmembers are designed to induce, has the effect of bringing piston 22 and plunger 35 to rest without shock, due in the applicants belief, to the slight compressibility of the fuel, dilation of the metal parts and the increased fuel pressure which balance out the compression pressure.

In the starting of the engine as above described, and to some extent in slow running, a portion of the air undergoing compression passes through the by-pass port 2| and the compression pressure in increasing acts upon the whole `area of the piston 22 which is accordingly operated earlier during the compression stroke than would be the case if the by-pass port were omitted and the compression pressure acted only upon the area of the piston equivalent to the crosssectional area of the axial orifice I9 of the bush ing I8.

Accordingly, it Will be appreciated vthat in starting or running at much reducedispeeds, the by-pass port 2l by admitting lcompressed arinto the annular space surrounding theboss 2`3 v obviates the factors Whichreduce compressionpressure and arising from heat losses consequent upon the lower rate ,of compression, and @thc longer period of time forpiston blow by, Aand Vleakages through inlet and eXhauStWalif-'esj lall of which Aby .simultaneousvaction yWould render the operation of the motive means too late", Ysuspend'the operation altogether, if thearea below the valve 24 alone was `exposed to increasing compression pressure.

As the engine accelerates, the by-,pass .port 2l, resultantly of its' restricted cross-sectional area, becomes ldecreasingly effective until, upon the engine attaining the normal running speed jthe by-pass port `beconlr-:s almostY ineiective and the compressionpressure acts vonly upon .thegarea ,of the piston :22 equivalent `to the area Aor ,the

' orice I9. Y

The area or diameter of the by-passportzl Y ber 66, the bore; 5'! of the control-plungen.and

the portion of the bore oitheliner `lll)above-the control plunger, is constantgat .they-commencement of Yeach stroke of Y the lpumppl 1.1 r,ig er,notwithstanding the v axial position Yof 1 lthe control plunger 56, as it Willebe evidentthatareduction in capacity ofthe fuelr chamber 6 6 is. compenisated by anV equalinoreasein capacity ofithe jportionof the .bore above thelvcorltrolgplungeri.

The vstroke of the pump Vplunger 3531s. limited by contact with the vcontrol plunger 55and the latter resultantly of the action of thezgovernor in response to changesof loajdispositioned,nearer to ori further from the initial; position: of the-forfmer, at the. commencement of each stroke.

Consequentlyv the Ystrokeofthe pump ,plunger I 35: is varied and ,at;each injection; expels va-proportionally greater. or less volume of ,the constant .total pump capacity from-'the fuel. chamberg.

As Ythe pressureson theends of control plunger xare balanced, as a consequencev of the axial bore 51 through Whichfuel is freetov flowzin either direction, Vthe resistance.opposingthe governor is slightso. that sensitivegoverning .ofthe engine vis achieved.

Upon the pistonl22 being operated during :the A compression stroke :of the engine y,as ydescribed, the volume. of the; clearance space of: the engine cylinder .is increasedby connection with. the interior. of the motive .cylinder I2.

Resultantly, the compression ratio is decreased and the compression pressure is, accordingly, lowered, so that theftemperature ofthe .compressed v airin :the engine cylinder,wouldbelessgthan vthe minimum required for ignition, i. e.;1000 Fahrenheit, were it .not for. otheriagctorsvvhich counteract'the fall of temperature.

Factors which contribute.to-increaseJtheftemperature to the ignition point .are 'the-f sudden impact ofthe .purnpplungeit upon the fuel/Which in the applicants belief generates heat .-in the latter, and the `friction arising from lthe high velocityof the `fuel 'in' passingv througlif'thefjet ories and through theV dense comiiessled ailljl which' itY is, ,believed generates heat ein 'the fuer The accumulative lheating 'eie'cts from .those causesand engine compression' have been lfound to raise .the ytemperature `to the ignition `poi'r'it`,' so thatlth'e apparatus described herein'may be used efficiently' 'on engines '.ofrsm'all size operating a't relatively .low compression" pressures," both at starting yand in normal 'runningand permitssuch engines to befoperated ona spontaneous ignition constant pressure lcycle.

"Althoughlthe,improvedinjection' apparatus has been described with particular reference lto'iconstant pressure engines voperating on` 'relativfely heavy fuels, such `as ndiesel oilfit Willbe ,appreelated that the lapparatus may `be utili'zedvith lilieadva'ntagesfor constant volume engines operating -on lightI vand volatile Yliquid fuels .or spirits. such as petrol, benzine, alcohol, kerosene y,and ,the like. .j In order to overcome thelubrication dicultes apt ,to be vlenco,untered in injection apparatus yvhensuch light fuels-are used, the .liner may be made of material havingself-lubricatinglcharacteristics Such es a Suiiablrlasiia Oil Qr'srphiteimpregnated metals, powdered l metals, ,orthe likejanld `operative 4parts such as the plunger and barrel, and the Y control plunger may befs'leeved or lined-With such I'naterialsfu 1. `In a pressure operatedliquid injection appa.- ratus, a vpump cylinder,` a plunger vrec'ip,rocab'le in the'.pump cylinder, an axially adjustablelstop member inthepurnp cylinder to variablyliniit Y the stroke of the plungen'an axially Vdisposed .ratus, a". pump cylinder, a .pump plungleri V opposite endsjof, ,said piungie'ni andga ah/' member resiliently mounted ,011" ,the Cori J discharge duct in the plunger, means for-hydraulically balancing: the stop memberaglainst liquid pressure, and valvular vmeans carried. bythe stop ,plunger to engage the pump plunger and ,the,axiallzlischargecluetlf 3. `VIn a pressure operatedliquid injection appacylinder, acontrol plungerin the cylinderopp to and axially adjustableftoflimit.the stro eA f the pumpplunger,an faxial discharge duct inthe pmnp'plun'ger, .a pressure. equalizi'ngl duct .extending longitudinally through thecon'trl pluri hydraulically balancethe liquidpress',

plunger to engage the pump plungerand ebt the axial dischargeduct. Y

4. In apressure operated liquid injection apparatus, a pump cylinder, a. power cylinder incaaxial alignment-With the Vpump cylinder, apiston in the-power cylinder operable byincreasing''uid `pressure in said-cylindeija plungeryin the pump cylinder operatively connected with the piston,

a control. plunger in thepump cylinder opposed to the pumpzplungenmeansfor laxially' adjusting discharge. .ductinthecontrol plunger, and avalve resiliently mounted on the control plunger to engage the pump plunger and obturate the longitudinal discharge duct.

5. A pressure operated liquid injection apparatus comprising a pump cylinder, a power cylinder, a piston in the power cylinder operable by increasing fluid pressure in said cylinder, a plunger in the pump cylinder operatively connected with the piston, an admission port in the end of the power cylinder closable by a portion of the piston having a primary area exposed to the increasing fluid pressure through said port, a secondary area of the piston to which the fluid pressure is additionally applied upon initial movement of the piston responsive to action of the increasing fluid pressure on the primary area, a chamber between the secondary area of the piston and the end of the cylinder, and a by-pass through which the duid is fed at reduced rate to the chamber to effect a, gradual increase of pressure on the secondary area simultaneously with the direct increase of pressure on the primary area through the admission port.

6. A pressure operated liquid injection apparatus, comprising a pump cylinder, a power cylinder in coaxial alignment with the pump cylinder, a piston in the power cylinder operable by increasing fluid pressure in said cylinder, a plunger in the pump cylinder operatively connected with the piston, an admission port for fluid under increasing pressure in the end of the power cylinder, an extension of the piston, a valve seating disposed about the admission port, a valve on the extension of the piston engageable with the seating, an annular chamber disposed about said eX- tension, resilient means urging said valve upon the seating and opposing operative stroke movement of the piston and plunger, a control plunger in the pump cylinder opposed to the pump plunger, means for axially adjusting the control plunger to variably limit the operative stroke of the plunger and piston, a longitudinal discharge duct for liquid extending axially through the plunger, the piston and said extension of the piston, a pressure edualizing duct extending axially through the pump plunger. means for equalizing the liquid pressures on opposite ends of the control plunger, and valvular means carried by the control plunger to engage the pump plunger and obturate the longitudinal discharge duct.

7. A pressure operated liquid injection apparatus as claimed in claim 6, wherein the uid under increasing pressure is applied through the admission port directly to a primary area of the piston and through a by-pass port at reduced rate into the annular chamber to act at a diminished pressure upon a secondary area of the piston.

RICHARD STANLEY BLAKEVJAY.

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

UNITED STATES PATENTS Number Name Date 1,622,266 Ake Mar. 29, 192'! FOREIGN PATENTS Number Country Date 45,872 France Oct. 30, 1935 (Addition to No. '799,95l) 405,980 Great Britain Feb, i2, 1934 537,857 Germany Nov. 1G, 1933

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