US3044404A - Self-regulating reciprocating pumps, in particular for the injection of fuel into internal combustion engines - Google Patents

Description

United States Patent 3,@l4,0i SEiJF-PEGULATNG Pmi/WS, EN PARTICUL n FR THE BelsttCiN @E FUEL INT@ llNTERNA CMBUSEEN ENGHES Pierre Etienne Bessire, 55 Blvd. Commandant Charcot, Neniliy-sur-Seine, France Filed Nov. 2t?, Het?, Ser. No. 72,2il Claims priority, application France Dec. l, i959 '7 Ciaims. (Si. 163-421) The present invention relates to self-regulating reciprocating pumps, in particular for the injection of fuel into internal combustion engines, the self-regulating effect being obtained by means of a regulating element, hereinafter called shuttle, which, during the delivery stroke of the pump piston and under the driving eiect of a power liquid acting against a return force, performs its own outward stroke during which or at the end of which it opens a discharge conduit so as to stop the delivery of the pump, this shuttle element being braked during its return stroke due to the provision of a throttled passage through which it must `force at least a portion of the liquid which previously has produced the outward stroke of said shuttle. The self-regulating effect is due to the so-called liquid abutment phenomenon which starts occurring when the pump is working at a speed above a predetermined value, the speed of the pump being proportional to that of the internal combustion engine fed by the pump. This liquid abutment effect causes a shortening of the stroke of the shuttle element and therefore advances the time of opening of the discharge conduit Aby a value which is the more important as the speed increases above said predetermined value, this predetermined value being the lower as the section of the throttled passage is itself smaller.

The object of this invention is to provide a pump of this kind which is better adapted to meet the requirements of practice than those known up to now.

The invention consists mainly, in a pump where the liquid serving to operate the shuttle element is delivered by anauxiliary pump the piston of which consists of an enlarged portion of the piston of the main pump and the feed conduit of which is controlled by the edge of said auxiliary piston, in providing in the side Wall of the auxiliary pump piston a groove or a fiat surface forming a passage extending axially from said control edge and ensuring a communication of restricted cross-section Vbetween the auxiliary pump cylinder and its feed conduit for axial positions of said auxiliary piston where said control edge has already moved beyond the level of the upper point of the feed conduit opening, this groove or flat surface reducing, when the pump is flowing at relatively low speeds, the amount of liquid delivered by the auxiliary pump, which causes a delayed opening of the discharge conduit and consequently an increase of the delivery flow rate of the main pump.

Another feature of this invention relates to the case where the shuttle element is rotatable about its axis so that it can be brought into a position corresponding to an increased oW rate `delivery of the pump, where it opens a discharge conduit for the driving liquid serving to operate said shuttle element, this last mentioned conduit having a reduced cross-section, and this feature consists in having this discharge conduit controlled in accordance with the position of the member which adjusts the cross-section of the throttled passage serving to brake the return movement of the shuttle element, the control of the last mentioned discharge conduit being such that it is closed for the positions of said member for which the cross-section of the throttled passage is relatively large, that is to say for positions thereof corresponding to in- 2 Y termediate and high speeds of the enginev fed with fuel fro-m the pump. i Y

Preferred embodiments of the present invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example and in which:

FIG. 1 shows, diagrammatically and in vertical section, a fuel injection pump made according to an ern- -bodiment of the invention, the portion of the cross-section that is located on the right hand side of middle line A-A being angularly offset ywith respect to the portion located on the left hand side of this middle line.

FlGS. 2, 3 and 4 illustrate, for three different angular positions of the shuttle element, the cooperation of said element with the pump discharge conduit.

The pump includes a main cylinder'l in which is provided a cylindrical bore 2 in which is slidably mounted a reciproca-ble piston 3.

This piston is driven through means not shown by the drawings, for instance by means of a cam, to have, in the cylinder, axial movements between an `outer dead center position (shown by IFIG. l) `and aninner dead center position, the outer dead center position being the lowest position of the piston and the inner dead center position Ibeing the top position of said piston.

ln view of the fact that the piston, in the pump shown by way of example, also acts as a distributor valve for feeding fuel successively to a plurality of injectors, this piston is further driven in rotation about its axis through means which are not shown, whereby the movement of the piston is a comb-ined reciprocating axial movement and rotating movement.

A feed conduit 4 opens in the chamber 2 of cylinder 1. A plurality of ydelivery conduits 5 startfrom said chamber, a check-valve 6 being provided in each-of said delivery conduits. v l t The `working chamber of the pump, that is to say the space located above piston 3 inside cylinder 1, is placed, during every delivery stroke, into communication with one of the delivery conduits 5. For this purpose, I provide in piston 3 a groove 7 which extends longitudinally over a given length from its end surface. Furthermore, in order to feed liquid to the working chamber during the downward strokes of piston 3, this chamber is placed in communication with feed conduit 4 through an axial conduit S one of the ends of which opens into the end surface of piston 3, whereas, at its other end, it opens into a transverse channel 9 also provided in piston 3, this last mentioned channel connnunicating, through a groove lil, with a number of axial grooves 11 (in the side wall of piston 3) equal to the number of injectors to be fed during a complete rotation of piston-3 about its axls. t,

`Control of the suction of the pump and-of-its delivery is ensured by the rotation of piston 3 which closesV feed conduit lV and establishes communication between' the working chamber and one of the delivery conduits 5 during every delivery stroke and also communication b etween the vfeed conduit 4 and said working chamberduring every suction stroke. l v

In order to obtain a self-regulation of the iiow'rate of the pump during every delivery stroke of pistone1 l make use of a regulating element-called shuttle ,which is movable in a cylinder 13 and controlsa discharge conduit consisting of two portions 14a and Mb, portion 14m connecting the working chamber "2 of cylinder l with the inside of cylinder 13, whereas portion Mb connects cylinder 13 with the outside. Y v

The shuttle is driven during its outward stroke (that is Yto-say its upward stroke in the embodiment 'shown by the drawing) by a driving liquidtwhich is delivered-in a pulsatory manner and in. synchronism with the delivery strokes of piston 3, under shuttle 12, by an auxiliary pump including a piston 15, consisting of an enlarged portion of piston 3, and a cylinder 16 in which said piston 15 is Working. This cylinder 16 is. provided with a delivery conduit` 17 which connects it, with the intermediate of al check-valve 18, with the lower end of cylinder i3, and also'withca feed conduit 1.9 which is controlled by auxiliary piston 15. Furthermore,A cylinder 16-is connected to the lower end of cylinder 13 through another conduit 2d, the inside of a cylinder 21. andV a conduit 22, the orilice through which conduit'Ztl opens into cylinder 21 being -throttled at 23, the. cross-section of this throttled passage being. variable under the effect of a slide valve 24 the position of which is` adjustable for instance by means of a screw 25. Y

The outward (upward) stroke of shuttle 12, due to the delivery of driving liquid from the auxiliary pump takes place against the action of a return spring 26 which urges shuttle 12 towards its position of rest, which is that where shuttlel-Z is-applied against an abutment 27.

The outward stroke of shuttle 12 stops-when the lower surfacelthereof clears a dischargepconduit 2 3.

It-will be understood'that, during every delivery Vstroke ofthepiston'unit-3-15,piston,element 15, after having separated feed conduit 19 fromv the inside or working chamber-of cylinder! 16, delivers liquid under shuttle 12 vso asto produce the upward stroke thereof at the same time as piston 3 ismoving upwardly, on its delivery stroke. When shuttle 1,2 places the two portions 14a and 14b of the discharge conduit into communication with each other, piston3 ceases to deliver fuel through one of conduits 5 .toward the corresponding injector, but fuel is discharged to the outside through discharge conduit 14a, 14b. When v the piston unit 3-15 starts on its downward strokes, shuttle 12 also starts moving downwardly toward abutment 2 7. However, the delivery downward stroke ofthe shuttle'is `braked by the fact that it must force liquid present under itV into cylinder 13 past throttledl passage 23, the iow of liquid through conduit 17 being of course prevented by check-yalvel., Due to Vthis braking action, there is a given value of the speed-of reciprocation of piston 'unit'V 3-,15l above which the shuttle has not yet reached, its position ofjrest when said piston unit again deliveringrliquid tothe space under the shuttle and com-pels it to move back in theupward direction.v In other wordsthe so-called liquid abutment phenomenon starts occurring whenthe speedY is above said predetermined value. The stroke of the shuttle necessary to open dischargeconduit 14a, 14b thereforebecomesshorter and shorter as., the speed of reciprocation of piston unit 3-15 increases abovesaid predetermined value.

In, order to obtain anincrease of the ow rate delivery of the pump when it is working at low speeds, I provide, accordingrto thelpresent invention, in the auxiliary piston element 15, a dat surfaceY or groove 29 which extends longitudinally in thedownward direction from the edge 15a of said piston element 15, and Ipgive this groove a relatively small cross-section. Owing tothisarrrangement, a communication stillexists between the inside Aor working chamber of cylinder 16 and feed conduit 19' after the Yedge 15a yhas-movedabove the level of the upper point of conduit 19. c c

For small loads of the engine, the upwardy stroke of shuttle 12 can therefore begin only 4when the lower. end of groove 29 has ,reached the level of the top point of feed conduit 19. This delay, whichis thus brought` to the beginning of theupward movement of shuttle 12, causes adelay-of theopening-of the discharge, conduit A114,11,and'therefore increases the delivery'ilow rate of .the

pump. When the speed of the' piston increases,` and be-V fore these-.called liquid abutment phenomenon` has occurred, the resistance opposedby groove 29 to the iiow of liquid (due to thesrnall cross-section o f Vthis groove) has Y for its elect to start the upward movement of shuttle 12 before the lower end of groove 29 has reached the top point of theV opening of Ifeed conduit 19. Consequently, lfor speeds :above a given value, the fact that the auxiliary pump has its piston provided with such a groove is practically without effect and there is no longer any increase of the delivery flow rate of the pump.

According to another feature of the invention, the opening of liquid feed conduit 19 into the auxiliary cylinder 16 is in the form of an annular groove 30 extending substantially in a plane perpendicular to the axis of this cylinder. The fact of replacing the mere hole through which the feed conduit generally opens into the cylinder` by a groove the section area of whichV is of course much greater than that of such a hole permits of reducing the height of its :free section that is necessary when piston 15 is in. its lower dead center position, and therefore the length of the stroke of said piston, without impairing the lling of its cylinder. This reduction of the axial movement of the piston is particularly important when the closing of the feed conduit 4 ofthe main pump takes place, not by an axial movement of piston 3 but by its rotation.

If, as is the caseV for the pump shown by PIG. l, piston 3 also acts as a distributor valve rotating about its axis, the provision of groove 30 further permits of using a single flat surface or groove 29 instead of being comF pelled to provide'a number of such grooves 29 equal to the number of delivery conduits 5.

The drawings also show another arrangement for obtaining an increased delivery iiow rate of the pump at low speeds thereof, in the case lwhere shuttle 12 is rotatable about its axis through means not shown and which act upon the end 31 of square cross-section of said shuttle 12. For this purpose, when shuttle 12 is in the angular position it occupies when it is desired to obtain such an i increase of the delivery dow rate of the pump, it opens a discharge conduit 32 comprising at least one throttled por-tion. Furthermore, theV .opening or closing of this conduit 32 is controlled through member Sid-which serves to adjust the cross-section area of throttled passage 2.3, preferably directly by it, and this in such manner that conduit 32 is closed by member 24 when said member occupies positions where the cross-section of throttled passage 23 is relatively-large, that is to say corresponding'to intermediate and high speeds of the engine fed with fuel from the pump. For this purpose, member 24 is provided with an extension carrying, at its end, a piston 33 provided with a groove 34. This piston and its groove are disposed in such manner that when control member 24 gives` throttled passage 23 a relatively large crosssection (as shown by FIG. 1'), piston 33 closes conduit 32 but that, when member 24 is in a position where the cross-section area of throttled Vpassage 23 is very small, groove 34 is brought opposite conduit 32 and thus opens it.

As for the means which, for a given angular position of shuttle 12, connect conduit 32 with the lower end of cylinder 13', they consist of a longitudinal groove 35 provided in the side wall of the lower portion'of shuttle 12. Advautage'ously, this groove 35 is given a sufiiciently small cross-section to enable it to play the part of the Vthrottled passage that is to be provided in conduit 32.

The operation ofthe pump is as follows.

When member 24 occupiesra positionV such that it considerably reduces the cross-section of'throttlcd' passage 23, that is to say a position corresponding to low speeds of the engine fed with fuel from the pump and when shuttle 12 Vis brought-into the angular-,position where groove 35 opens discharge conduit 32, such shuttle 12 is not liftedas Along as the pump is running at low speeds, in View of -the fact that practically the Whole of the liquid then delivered by piston 15 can, escape through conduit 32. AThe increase of delivery ow rate is therefore maxi-Y mum since Yshuttle 12 never opens discharge conduit portion 14b. When the speed increases a little, the shuttle starts being'lifted from its abutment 27, but this lifting @gaat movement is braked due to the fact that a portion of the liquid delivered by piston can still escape through conduit 32. The amount of liquid which thus escapes through conduit 32. however becomes negligible when the speed further increases, and this due to the resistance opposed eby groove 35 to the flow of the liquid therethrough. The increase of delivery flow rate then disappears.

Closing of conduit 32 by member 24 when said member gives throttied passage 23 relatively large cross-scctions, that is =to say when this member occupies positions corresponding to higher speeds of the pump, has for its object to prevent the driver from using the increased delivery flow rate (which is to be used only for starting the engine fed by the pump) when said engine is to deliver its maximum power, which is for instance the case if a vehicle driven by said engine is to climb a hill.

Rotation of shuttle l2 about its axis not only has for its object to place groove 35 into and out of action, but also to vary the length of the stroke of shuttle i2 from its position of rest necessary to open discharge conduit ida, ldb. For this purpose, shuttle i2 is provided with an inclined edge 36 to cooperate with the opening of discharge conduit portion ll-ib. At one of the ends of this inclined edge there is provided a longitudinal groove 37 which, when it is located opposite discharge conduit portion Mb, constantly keeps this discharge conduit portion ltdb in communication with cylinder 13 into which opens the other portion ida of the discharge conduit, and this whatever be the axial position of shuttle i2. In this case, the engine is stopped.

Preferably, the angular position of groove 3S for which said groove is in action is located between the position for which groove 37 is opposite the opening of Mb (stopping position) and the position for which the lower end of inclined edge portion 35 is opposite the opening of Mb (full load position).

FIGS. 2, 3 and 4 show three angular positions of shuttle l?. (the portion comprising inclined edge portion 35 and groove 37 being shown in developed View) with respect to the opening of discharge conduit portion 14h.

FiG. 2 corresponds to running on no load, groove 37 cooperating with discharge conduit portion ldb and keeping it constantly open.

FIG. 3 corresponds to an intermediate load, where shuttle l2 is to have a stroke equal to a from its position of rest to open discharge conduit portion Mb. lt is in such a position of the shuttle that groove 35 is located opposite conduit 32, so that this position is also that corresponding to an increase of the delivery flow rate at low speeds of the pump (starting of the engine).

Finally, FiG. 4 corresponds to -full load conditions, where shuttle 12 must have a stroke equal to b from its position of rest to open discharge conduit portion db. lt will be seen that b is greater than a.

Due to this disposition of groove 35 with respect to inclined edge portion 36, l obtain that if the shuttle is not brought into full load position after the engine has been started, the amount of fuel that is injected to lower than the full load amount as soon as the driver, by acting upon member 24, opens throttled passage 2.3 and thus closes conduit 32.

yin a general manner, while I have, in the above description, disclosed what I deem to be practical and ethcient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What l claim is:

l. A self-regulating reciprocating action liquid pump which comprises, in combination, a main cylinder, a main piston reciprocable in said cylinder so as to limit therewith a working chamber of variable volume, a discharge conduit leading out from said `working chamber to the outside, a shuttle slide valve mounted to control liquid ilow through said discharge conduit, means forming a cylindrical housing arranged to accommodate said shuttle slide valve slidable therein, an auxiliary cylinder, an auxiliary piston slidable in said auxiliary cylinder so as to limit therewith an auxiliary working chamber of variable volume, said auxiliary piston being operatively connected with said main piston to move in synchronism therewith, liquid feed conduit means opening into said auxiliary chamber side wall, whereby the communication between said auxiliary Working chamber and said liquid feed conduit means is controlled by the movement of one edge of said auxiliary piston along said side wall, conduit means connecting said :auxiliary working chamber with one end of said shuttle valve housing to move said shuttle valve in one direction to produce the outward strokes thereof during lthe delivery strokes of said pistons, for which the respective volumes of said working chambers are reduced, spring means operatively connected with said shuttle valve for urging it in the opposed direction with respect to said housing for the return strokes of said shuttle valve, conduit means in communication with said end of said housing during said return strokes for the outiiow of liquid from said end of said housing, means forming a throttled portion in said last mentioned conduit means, said auxiliary piston being provided with a passage of restricted crosssection extending from the end face of said auxiliary piston that comprises said edge thereof to a portion of the side wall of said auxiliary piston that is in communication, during the beginning of every delivery stroke of said auxiliary piston, with the opening of said liquid feed conduit means into said auxiliary cylinder, whereby, at low speeds of movement of said pistons, said auxiliary piston starts deiivering liquid to said end of said housing only when said auxiliary piston has moved, on its delivery stroke, to the position where said portion of its side wall is no longer in communication with said liquid feed conduit means opening so that Said passage no longer places said auxiliary working chamber in communication with said liquid feed conduit means.

2. A pump according to claim 1 in which said passage consists of a groove in the side wall of said auxiliary piston extending from said edge to a distance thereof.

3. A pump according to claim 1 in which said liquid feed conduit means opening is an annular groove formed in the wall of said auxiliary cylinder about the axis thereof.

4. A self-regulating reciprocating action liquid pump which comprises, in combination, a main cylinder, a main piston reciproca-.ble in said cylinder so as to limit therewith a working chamber of variable volume, a discharge conduit leading out from said working chamber to the outside, a shuttle piston functioning as a slide valve mounted to control liquid ow through said discharge conduit, means forming a cylindrical housing arranged to accommodate said shuttle piston slidable therein, an auxiliary cylinder, an auxiliary piston slidable in said auxiliary cylinder so as to limit therewith an auxiliary working chamber of variable volume, said auxiliary piston being voperatively connected with said main piston to move in synchronism therewith, liquid feed conduit means opening into said auxiliary chamber side wall, whereby the communication between said auxiliary working chamber and said liquid feed conduit means is controlled by the movement of one edge of said auxiliary piston along said side wall, conduit means connecting said auxiliary working chamber with one end of said shuttle piston housing to move said shuttle piston in one direction to produce the outward strokes thereof during the delivery strokes of said main and auxiliary pistons, for which the respective Volumes of said working chambers are reduced, means operative at least during the return strokes of said pistons for exerting a limited thrust on said shuttle piston to urge it in the direction to produce the return strokes thereof, conduit means in communication with said end of said housing during said return strokes yfor the outflow of liquid from said end of said housing, throttling means in said last mentioned conduit means, acontrol member forradjusting said throttling means, said shuttle piston being,rotatableYinV said cylindrical housing, a discharge conduit Vof restrictedV cross-section area for the liquid fed from said auxiliaryfworlting chamber to said end of said cylindrical casing, saidv last mentioned discharge conduit extending from the side wall of said cylindrical casing end to the outside, the side wall of said shuttle piston being providedy with a passage extending from the end face of said shuttle piston in. contact with said liquid to a distance from said end face for connecting, for a given angular position of said shuttle piston, said cylindrical casing end with said lastmentioned discharge conduit, and valve means operatively connected with said control member for closing said last mentioneddischarge conduit when said control member is in a position where said throttling means are. relatively open and opening said last mentioned -discharge conduit when said control member is in a position where said throttling means are relatively closed. v

5. A pump according to claim 4 in which said shuttle piston is rotatable in said casing between two end pos-itions, said `valve member being arranged so that, in one of said positions it constantly opens said first mentioned discharge conduit, and in the other of said two postions it opens said lirst mentioned discharge conduit for minimum time periods, the angular position 4of said shuttle piston for which said passage in the side wall thereof connects said cylindrical casing end with said second mentioned discharge conduit being located between said two end positions.

6. A self-regulating reciprocating action liquid pump which comprises, in combination, a main cylinder, a

an auxiliary piston slidable inV said auxiliary cylinder so as to limit therewith an auxiliary working chamber of variable volume, said auxiliary piston being operatively connected with said main piston to move in synchronism therewith, liquid feed conduit means opening into said auxiliary chamber side wall, whereby the communication between said auxiliary working chamber and said liquid feed conduit mean-s is controlled by the movement of one edge of said auxiliary piston along said side wall, conduit means connecting said auriliary working chamber with one end of said shuttle valve housing to move said shuttle valve -in one direction to produce the outward strokes thereof during the delivery strokes of said pistons, for which the respective volumes of said working chambersv are reduced, means operative at least during the return strokes of said pistons for exerting a limited thrust on said shuttle member to urge it in the direction to produce the return strokes thereof, Vconduit means in cornmunication with said end of said housing during said return strokes for the outlow of liquid from said end of said housing, means forming a throttled portion in said last mentioned conduit means, at least one of the cooperating surfaces of said auxiliary piston and said auxiliary cylinder being provided with a passage of restricted crosssection extending longitudinally to form, at the beginning of every delivery stroke of said auxiliary piston, a communication between said auxiliary chamber and the opening of said liquid feed conduit means into said auxiliary cylinder, whereby, at -low speeds of movement of said pistons, said auxiliary piston starts delivering liquid to said end of said housing only when said auxiliary piston has moved on its delivery stroke, to the position where said passage no longer places said auxiliary working chamber in communication with said liquid feed conduit means.

7. A pump according to claim 6 in which said two pistons are in line, and rigid, with each other, the auxiliary piston being of greater diameter than the main piston.

No references cited.

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