US2438251A - Engine fuel supply means - Google Patents

Description

March 23, 1948. T. PEDERSEN ENGINE FUEL SUPPLY MEANS Filed Jan. 22,' 1945 INvs/vron; 7h65 PEDERSEN CRANK ANGLE M Fuel. PRESSURE ATTQRNEY Patented Mar. 23., 1948 ENGINE FU'EL SUPPLYZMEAN S Tage Pedersen, Beloit, Wis., assignor to Fairbanks, Morse-85 Co., Chicago, Ill., a corporation l of Illinois Application January 22,1945, Serial No. 574,010

3 Claims. (Cl. 103-41) This invention relates to improvements in fuel I supply means for internal combustionengines, and has particular reference to improved and greatly simplified fuel injecting mechanism for engines of reversible, solid fuel injection type.

The principal object of the invention is to provide for embodiment; in engines of the character indicated, improved and simplified fuel injecting mechanism including a single-cam operated fuel pump of plunger type, which is operable equally in either direction of engine rotation, to deliver fuel under pressure and in regulated quantity, for cylinder injection, and where the improvements attained are such as toavoid any necessity for angular shift of the pump cam or other adjustments of the mechanism, in order to accommodate a change in the direction of engine rotation.

Another object resides in the provision as a part of the improved mechanism, of a plunger fuel pump of constant stroke character, embodying control means affording a variable beginning of fuel-pressure delivery by the pump, and pressure-delivery cutoff or release at a predetermined constant point in the plunger delivery stroke, Wherebythe timing of cylinder fuel injection relative to the engine piston compression stroke, and the quantity of fuel injected, may be closely controlled.

AA further object is to provide in operative association with a fuel pump of the character indicated, adapted for fuel-delivery cut-off lor're-l lease before the pump plunger attains the end of its delivery stroke, a .pressure-operated control device operable responsively to fuel delivery from the pump, to open a fuel line Ibetween the pump and an injection valve at the engine cylinder, and to close the line upon 4delivery release at the pump, wherein the control device is effective to cause a re-opening of the cylinder injection Ivalve, whereby there is prevented undesirable secondary injection or fuel dribble at the injection Valve.

Further objects and' advantages afforded b the .present improvements, -will appear readily from the following description of a preferred embodiment of the invention as exemplified in the accmpanying drawing, wherein:

Fig. 1 is a vie-W in sectional elevation, of an engine cylinder and fuel injecting mechanism therefor, the latter embodying the improvements effected by the present invention, and being shown in somewhat enlarged section and in elevation as to the pump operating cam, for the sake of clarity of disclosure, the view also including in diagrammatic elevation, an" engine operated governor control for the fuel pump, and

Fig. 2 illustrates graphically, the fuel pressures obtaining in the fuel injecting cycle.

The presently improved fuel injecting mechanism by preference is of unit character, and is `applicable inparticular, to single or multi-cylinder, reversible, engines. of the-tWo-cycle, solid fuel injection type. In the instance of engines having more than one cylinder, each cylinder preferably will have an injecting unit individual thereto, while .regulation of the units to effect injection timing and fuel quantity control, may and preferably will be attained by means common to the several units and connected to an engine operated device, such as a governor responsive to engine speed and loading.

Referring now to Fig. 1 of the drawing by appropriate reference characters,` the injecting mechanism is illustrated in application to an engine of the character indicated, being shown in association with a cylinder assembly thereof, indicated generally by the numeral I0. Although illustrated in part only, the assembly includes an engine frame or block II supporting a cylinder liner I2 and a cylinder head member I4. Disposed for reciprocation in the liner I2, is a piston I5 which is operatively connected through a connecting rod I6, with the crank- I8 of the engine crankshaft I 9. The block and cylinder liner are suitably apertured to provide scavenging air inlet and exhaust ports 20 and 22 respectively, located so as to be controlled by the piston I5, such being a common arrangement in two-cycle engines. Arranged centrally in the cylinder head member I4, is a Ifuel injection valve 23 of a solid injection type. as of the spring loaded,

Vneedle valve character shown,- -wherein the neeplunger 35, but that by reason of pump delivery 'release at a constant point in the plunger delivery stroke, varying the beginning of pump delivery also determines in direct proportion, the

quantity of fuel delivered by the pump.

Any suitable means may be employed to effectrangular adjustment of the pump plunger, as to Fuel pump 3| which as shown, is of a camdriven plunger typeis comprised of a pump housing orframe assembly generally indicated by the numeral 32, providing a cylinder 34 within which reclprocates a pump plunger 35. The lower end 35 of the plunger engages a cam-follower guide 38 which is slidably supported by a portion 39 of the engine frame. Carried by guide 38 is a cam-follower or roller element 40 which rides upon the operating surface of a cam 42 on the engine camshaft 43, the; latter being driven by suitable means (not shown) from the crankshaft I9. A spring 44 serves to maintain the plunger and guide 38 in engagement, and to assure retention of roller 40 in contact with the cam, whereby to afford positive plunger reciprocation by the cam. As shown, the cam 42 provides a -single cam-projection 46 formed to have adjacent symmetrical operating faces 41 and 48 merging in a rounded t'ip or cam-peak 50. In consequence of the particular shape, the plunger attain the foregoing result. As presently illustrated, a rotatable sleeve 64 longitudinally splined Y r to the shank portion 66 ofthe pump plunger 35 so as to permit plunger reciprocation relative to the sleeve, is retained in the pump housing assembly against displacement longitudinally thereof, and when rotated, willV produce a corresponding rotation of the plunger. Rotation of the sleeve 54 may be effected manually, or by preference and as is. usual in fuel systems of this character, by

automatic means, as an engine governor responl on the sleeve64. Thus asthe governor responds will have a constant stroke and of the same extent in either direction of vcam rotation, this being attained for a purpose which lwill appear presently.

The upper section of the pump cylinder 34 constitutes a pump chamber 5|, and arranged in a wall portion of the cylinder is a fuel passage 52 vterminating in a fuel port 54 opening to the cylinder in the zone of chamber 5|. Fuel is conducted to the passage 52 from a suitable source (not shown), through conduit 55. Controlling communication of the port 54 and pumping chamber 5|, is a control device at the head end 56 of the plunger 35, the device preferably being formed as an integral part of the plunger head, and comprising a head recess 58 defining an angulate control edge 59, and an annular-recess lili y therebelow defining a control edge 62 normal to the plunger axis. The recesses 58 and 60 are at all times open to each other through a connecting recess 63 directed longitudinally of the plunger, as shown. Thus it will readily appear from Fig. lthat through angular or rotary displacement of the plunger 35, the angular or generally spiral control edge 59 will serve in the upstroke or fuel delivery stroke of the plunger, to cover or close port 54 atan earlier or later point in said plunger stroke.' whereby the beginning of fuel pressure delivery A,by the pump, may be thus varied as desired.

The control edge 62 on the other hand, being normal to the plunger axis, will open the port 54 always at the same point in each delivery stroke of the plunger, and will thus establish direct communication between the port and the pumping chamber 5|, through recess 60, passage 63 and recess 58. When the port is so opened,

to changing engine speed or loading, it will effect through the operating connection described, a corresponding rotation of the fuel pump plunger 35 to relate the plunger control edge 59 to the port 54 so as to determine an earlier or later beginning of pump delivery 4and the quantity of fuel delivered, whereby to adapt the fuel injection to changes in the engine speedor loading.

VA feature ofimportance to the present improvements, is found in the location of the fuel V'I'he recess Vand control hence releasefurther pump Vdelivery inthe manner described, during the delivery stroke of the plunger and .before the latter attains the end of its stroke The arrangement'as herein provided is such that opening of vport 54 by control edge 62, to release pump delivery, occurs during the plunger delivery stroke and, considering for example, clockwise rotation of the camas viewed in Fig. 1, as thecam peak 50 approaches the follower-roller 40. More particularly, initial port opening is attained when .the cam and roller are engaged on the relativelystraight-portion 41 of the cam projection, at about the point of merger between the straight portion and the rounded,

. locity lift of the plunger by the straight portion 41 of the cam projection, to assure the desired high degree'of fuel atomization throughout the injection period, and effects a release ofpump delivery just before the rounded cam peak 50 is lbrought to bear on the roller 40, when the rate of plunger lift rapidly decreases to zero.

The cam-actuated fuel pump mechanism of the character now described, is effective equally in either direction ofv enginerrotation, without requiring angular displacement adjustment ofthe Y, cam or otheradjustment of the mechanism in order to condition the injecting mechanism for one or the other direction. of engine rotation., This ,is afforded by the described symmetrical formation of the cam,-and further, by the relative operative positions of the cam and engine piston. As shown in Fig. l, the cam is positioned on the camshaft, so that its peak 50 will fengage the roller 40 to dispose the pump plunger 85 at the end f its lift or upstroke, when the engine piston I is at inner dead center. As a result, crankshaft rotation in either direction, will effect the same cycle of pump operation.

Referring briefly to the pump cycle and considering the same first upon clockwise or forward crankshaft and camshaft rotation (Fig. 1), during the period of roller engagement on the cam surface 14 of uniform radius, the pump plunger will remain stationary, as at outer dead center of its reciprocable movement, when the plunger control end 56 will .be below the port 54. At this time, fuel delivered through supply pipe 55, and entering through port 54, nils the pumping chamber 5|. brought to bear upon the follower-roller 40, the plunger will be thereby displaced upwardly in the pump cylinder, effecting first a closure `of port 54 as the plunger control edge 59 passes thereover, and thence pressure-discharge of fuel from chamber 5I and through the fuel line 30 to Now as the cam surface 41 is the injection valve 23, `for cylinder injection. -f

During this phase of pump operation, the engine pistonl I5 is on its upward or compression stroke, approaching inner dead center position. Initial cylinder injection of fuel however, is regulated in accordance with the dictates of engine speed and loading as hereinbefore describe-d, so as to occur at a time earlier or later in the approach of the piston|5 to its inner dead center position, this being attained through angular positioning of the pump-plunger by the engine-responsive governor, to dispose the angulate plunger'control edge 59 relative to port 54 for closing 4the port earlier or later in the 4plunger upstroke.

At a predetermined constant point in the plunger upstroke, occurring when the cam point X engages the roller 40, the plunger control edge 52 will uncover the port 54 to the plunger recess 60, and thereby release further pump fuel-pressure delivery. The plunger then continues to the end of its stroke, as effected by the rounded campeak 50 acting on roller 40, and thereafter is returned to the opposite dead-center position under f the influence of plunger-return spring 44, as the thereof as viewed in Fig. 1, will result in the same cycle of pump operation, the cam surface '48 now becoming effective to produce the plunger delivery stroke, with pump cutoi.atcam-point Y. As will be observed, the point Y occupies the same relation with respect to cam surface 48, as does the point X with respect to cam surface 41. Thus as will now appear, in either forward or reverse engine rotation, the present improvementsl afford the same control as to .timing of initial fuel in'- jection and quantity of fuel injected.

A further element of the present invention vis found in an improved fuel control device indicated generally at 80, arranged in the fuel deliv# ery line and preferably, mounted on and forming a part of the fuel pump assembly. 'I'he device as will hereinafter appear, is adapted for coaction with the fuel pump such as to open the fuel line 30 in response to pump fuel pressure delivery, and in response to cessation of pump delivery, not only to close line 30, -but to effect a predetermined reduction in the volume of fuel remaining in the line, so as .to preclude secondary fuel injection or fuel dribble at the cylinder in- Jection valve 23. i

The device 80' in its `presently preferred embodiment as sh'own, comprises casing sections 8| yand 82 sealed by packing 84 at the telescoped ends thereof, the sections being held together and in assembly to the pump frame 82 by suitable means not here illustrated. Casing section 8| provides a central longitudinal bore 85 opening at its lower end to the pump chamber 5| and affording a bevelled valve seat 88 atits upper open end. Slidably received in bore 85 is a combined valve and control member 88 formed to provide a valve head 89 at the upper` end, adapted for seating on valve seat 86, and a guide section 90 at the opposite end, of spider-like character providing longitudinal arms or vanes 82 closely slidably engaging th'e walls of the bore 85 along their longitudinal margins.' structurally interconnecting the valve head 89 and guide 98 is a centrally located stem 93 of predetermined, reduced diameter. The stem supports or has 'formed integrally thereof,

a circular flange 84 adapted for close sliding contact at its periphery, with the walls of the valve bore 85. Flange 94 is spaced longitudinally from the innerfends of the guide vanes 92, and fromthe valve head 89 to a predetermined extent, so as to define with' the valve head and interconnecting portion of the stem, an annular recess 96 of a predetermined capacity.

The control member 88 when .fully received in `the casing bore 85 to seat the valve head 89` on within the coils of spring 91, is a stop member |0| of tube-like form, supported at one end in the casing head portion I 00, and which may be adjustable axially ofv the casing. The inner free end |02 of stop- I 0| serves as an abutment for the valve head 89 to limit-the maximum opening movement of the control device 80. The bore |04 of stop member |0| communicates with the interio'r of casing 82 through ports |05, and with axial ing section l82.

passage |06 in the casing head |00, the latter passage opening directly to the. fuel line 480, as shown.

Describing now the operation of device 80, as pump 3l starts pressure-delivery of fuel from pumping chamber 5|, the advancing fuel under pressure, will lift member 88 against the loading i of spring 91,- displacing'the same to an extent suiiicient` to dispose the flange element 94up- Wardly beyond the valve seat 86, thereby fully opening the' valve bore 85 to theinterior of cas- Thus fuel then under high delivery' pressure from pump 3|, may pass into casing 82,'through ports |05 and bore |04 of stop member |'0|, casing paage |05, and fuel line 30 to injection .valve 23, for cylinder injection. W/hen pump-delivery ceases, as upon opening of pump port 54. by the plunger control edge 62, the valve spring 9"( then acts immediately to return the control member 8 8 to its closed position, as

to seat valve head 89 on valve seat 86. At such.

time and because of the relatively'rapid closing movement of member 88, there is retained in line 38 and in casing 82, a column of' fuel under a certain .residual pressure. Moreover, at the instant of closure of member 88, the column is under displacement in the direction of thepump, so, when cut olf, there results a reverse pressure-wave through the column toward the injection valve. If in a'fuel line of this character, the volume of fuel comprising the trapped column, is sulllciently large, the resulting reflected pressure-Wave may reach a pressure suflicient to produce secondary injection or fuel dribble at the injection'valve, with consequences quite detrimental to proper and efficient engine operation. In the present system, the control device 88 functions with ref lar recess 96 open only to casing 82, receives a i portion of the fuel in the trapped column, and is completely filled at the instant the valve head engages valve seat 86. Thus as the valve closes, there is removed from the fuel column a certain volume thereof as predetermined according to the capacity of recess 96, so as to result in a corresponding decrease in the volume of fuel remaining in casing 82 and line 38. As a result, the volume of trapped fuel is so v reduced upon fullvclosure of member 88,'that' the maximum presparting from the spirit and intended scope of the invention, as defined by the appended claims.

I claim: Y

1. In a fuel pump assembly for an internal combustion engine. a plunger type fuel pump including a fuel delivery passage extending therefrom, said pump comprising a pump cylinder in communication with said delivery passage and having a fuel inlet port, a plunger reciprocable in the cylinder, means for rotating the plunger to control the angular position thereof in the cylinder, port-control means movable with said plunger and adapted to close said inlet port at a time in the fuel delivery stroke of the plunger determined by the angular position of the latter as controlled by said plunger rotating means, said port-control means further being adapted for opening said port to the pump cylinder during the delivery stroke of the plunger andl before the latter attains the end. of its delivery stroke, and a control valve in said fuel delivery passage adjacent said pump cylinder` displaceable from a -closed position in response to fuel-pressure delivery by the pump, whereby to open said passage to the pump cylinder, said valve including means for receiving a portion of the fuel in said passage and retaining such fuel portion. in isolationvfrom the pump cylinder and from the passage beyond the valve, in the closedrposition of said valve.

2. In a fuel pump assembly for an internal combustion engine, a plunger type fuel pump including a fuel delivery passage extending therefrom,

' said pump comprising a pump cylinder in comsure developed bythe reflected pressure wave in the fuel column, will be less than the minimum fuel pressure required to open the injection valve 23. Hence, secondary injection or fuel dribble at the injection valve is thus precluded.

This result is illustrated graphically in Fig. 2, wherein the curve A represents the fuel pressure in the delivery line between the fuel pump and engine cylinder, as plotted against. degrees of crank angle. The horizontal line B represents the minimum pressure necessary to effect opening of the injection valve 23. As there shown, the fuel pressure increases rather abruptly upon pump pressure delivery, and continues at high injection pressure during the cylinder injection pericd, until the pump ceases pressure delivery, when the fuel pressure drops suddenly. The portion C of pressure curve A, indicates the rise and fall of the secondary, reflected pressure wave occurring in the trapped fuel column following full closure of the member 88 of control device 88. It will be observed that the high point of this pressure wave approaches but does not reach the minimum opening pressure of the injection valve, this because the volume vof the trapped fuel is so reduced as to preclude a greater pressurel rise.

A further feature of the presently improved control device 88 is found in the retention in recess 96, of the volume of fuel removed from the column in casing 82 and line 38 when the member 88 fully closes the line. Thus, upon the succeeding pressure delivery from pump chamber 5I,

. the fuel in recess 96 is returned to the fuel column ahead of the incoming fresh fuel from the pump, whereby to afford a full column of fuel in casing 82 and line 38 to the chamber 26 of injection valve 23 as the member 88 opens the line to pressure delivery from the pump.

Having now described the invention in a preferred embodiment thereof, it is to be understood that certain alterations in or modification of parts and their arrangement, may be made Without demunication with said delivery passage and having a fuel inlet port,A a plunger reciprocable in the cylinder, means for rotating the plunger to control the angular position thereof in the cylinder, port-control means movable with said plunger and adapted toclose said inietport at a time in the fuel delivery stroke of the plunger determined by the angular position of the latter as controlled by said plunger rotating means, said port-control means further being adapted for opening said port to the pump cylinder during the delivery stroke of the plunger at a predetermined point before the end-of the delivery stroke, and a control valve in said fuel delivery passage adjacent said pump cylinder, displaceable from a closed position in response to fuel-pressure delivery by the pump, whereby to open said passage to theY pump cylinder, said 'valve including means forming a chamber for receiving a portion of the fuel in said passage and retaining suchY fuel portion in isolation from the pump cylinder and from theT passage beyond the Valve, in the closed position of said valve.

3. In a fuel pump assembly for an internal combustion engine, a plunger type fuel pump including afuel delivery passage extending therefrom, said pump comprising a pump cylinder in communication with said delivery passage and having a fuel inlet port, a plunger reciprocable in the cylinder, means for rotating the plunger to control the angular position thereof in the cylinder, port-control means on the plunger adapted fo`r closing said inlet port at a time in the fuel delivery stroke of the plunger determined by the angular position of the latter as controlled by said plunger rotating means, said port-control means further being adapted for opening said port to the pump cylinder vbefore the end of the plunger delivery stroke and. at the same point in each del livery stroke independently of the-angular position of the plunger in the cylinder, and a control valve in the delivery passage adjacent the pump cylinder. including means normally biasing the valve to a passage-closing position, said valve be ing displaceable from said passage-closing position in response to fuel-pressure delivery `by the Dump, to open the passage to the pump cylinder, 5 and said valve further providing a chamber for f receiving a portion oi' the fuel in the passage and effective in the closed position of the valve, to isolate the fuel portion received in the chamber, from the pump cylinder and from the delivery 10 passage beyond the valve.

TAGE PEDERSEN.

REFERENCES CITED The following references are of record in the 15 file of this patent:v

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