US3003422A - Reciprocating pumps including an auxiliary piston, in particular for the injection of fuel into internal combustion engines - Google Patents

Description

P. E. BESSIERE S INC Oct. 10, 1961 3,003,422 N, IN

RECIPROCATING PUMP LUDING AN AUXILIARY PISTO PARTICULAR FOR THE INJECTION OF FUEL INTO INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 1 Filed March 18, 1959 Oct. 10, 1961 P E BESSIERE 3,003,422

RECIPROCATING PUMPS INCLUDING AN AUXILIARY PISTON, IN PARTICULAR FOR THE INJECTION OF FUEL INTO INTERNAL COMBUSTION ENGINES Filed March 18, 1959 2 Sheets-Sheet 2 /NVE N TOR BY ATmRl Ex United States Patent '0 3,063,422 RECIPROCATHN'G PUMP INCLUDING AN AUX- ILIARY PISTON, 1N PARTICULAR FOR THE IN- JECTIUN F FUEL INTO INTERNAL COMBUS- TIQN ENGINES Pierre Etienne Bessiere, 55 Blvd. Commandant Charcot,

. Neniliy-sur-Seine, France Filed Mar. 18, 1959, Ser. No. 800,198 Claims priority, application France Mar. 24, 1958 4 Claims. (Cl. 103-41) The present invention is concerned with a reciprocating pump including an auxiliary piston which will be hereinafter called shuttle and which is moved, against the action of a return force, during the delivery stroke of the main pump piston, by at least a portion of the liquid delivered by said main piston during said delivery stroke, Whereas the auxiliary piston is braked during its return stroke, which takes place independently of the return movement of the main piston under the effect of said return force, this braking being obtained by means of a throttled portion provided in a conduit through which must flow the liquid driven by the auxiliary piston during said return stroke. In this way I obtain that, for speeds of operation of the main piston above a given value, said main piston begins a delivery stroke before the auxiliary piston has finish-ed its return stroke, which shortens said return stroke and serves to reduce the amount of liquid delivered by the pump to the outside.

I have already described, in prior patents, pumps working on these principles. In these pumps there is provided, in the conduit including the throttled portion above referred to, a valve element having in particular the form of a slide valve which closes said conduit during the delivery stroke of the main piston and opens it only during the return stroke thereof and also during the period for which the main piston stops at the end of its suction stroke before starting on a new delivery stroke.

The object of the present invention is to simplify the construction of such pumps.

For this purpose, according to this invention, I make use, as valve elements for controlling said conduit, of the main piston of the pump.

Other features of this invention will become apparent in the course of the following detailed description thereof, with reference to the appended drawings given merely by way of example and in which:

FIGS. 1 and 2 are diagrammatic axial sectional views of two pumps made according to two different embodiments of the invention.

FIG. 3 is a section on the line III-III of FIG. 2.

FIG. 4 is a developed view of a portion of the surface of the main piston of the pump of FIG. 2.

FIG. 5 shows a third embodiment of the pump according to the present invention.

In the following description, it will be supposed that the invention is applied to the construction of a fuel injection pump for an internal combustion engine, and in particular a diesel engine.

The pump includes a main piston 1 having a reciprocating movement in a cylinder 2 provided in the body 3 of the pump. Piston 1 is driven, at a speed proportional to that of the engine on which the pump is fitted, through suitable means constituted for instance by a rotating cam.

In the body 3 of the pump, there is further provided an auxiliary cylinder'4 in which moves an auxiliary piston (or shuttle) 5, this auxiliary piston dividing the auxiliary cylinder 4 into two chambers 4a and 4b.

A feed conduit 6 opens into the main cylinder 2 at 6a, this feed conduit being supplied with fuel from a suitable transfer pump. This port 6a is located at a point of the wall of cylinder 2 such that it is cleared by piston 1 when said piston is in its lower dead center position (position shown by FIGS 1 and 2). i

The main cylinder 2 communicates with the chamber 4a of auxiliary cylinder 4 through a passage 7 provided with a check valve 8 which permits liquid to flow only from cylinder 2 toward cylinder 4. Furthermore, chambers 4a and 4b are connected together by a conduit 9 including a throttled portion 10, preferably adjustable by means of a screw 11. The delivery conduit 12 of the pump starts from the chamber 4b of auxiliary cylinder 4, and a check valve 13 is provided in said delivery conduit 12 in the portion thereof close to chamber 412. Thus, during the delivery stroke of piston 5, fuel is fed from chamber 4b to the injector or injectors to be fed by the pump.

There is further provided, in chamber 4b, a return spring 14 which urges auxiliary piston 5 toward the position of rest thereof where the under face of said piston rests upon a shoulder 15 provided at the lower end of cylinder 4. A discharge conduit 16 opens into auxiliary cylinder 4 at some distance above shoulder 15, so that when said discharge conduit 16 is cleared by auxiliary piston 5, the delivery stroke of this piston is immediateley stopped.

The liquid delivered by piston 1 through passage 7 into chamber 4a must push auxiliary piston 5 upwardly and therefore must not escape during this delivery stroke from chamber 4a through conduit 9. This conduit 9 must therefore be closed during the delivery strokes of piston 1. For this purpose, according to my invention, cylinder 2 is interposed across said conduit 9 and the main piston 1 is used as valve means for closing conduit 9 during the whole delivery stroke of piston 1, whereas conduit 9 is opened, in the embodiment of FIG. 1, by means of a groove 17 provided in piston 1 at a place such that this groove connects together the sections of conduit 9 located, respectively, upstream and downstream of cylinder 2 when piston 1 is in its lower dead center position.

In view of the fact that, in the construction illustrated by FIG. 1, conduit 9 is opened only when piston 1 is inits lower dead center position, the means for driving piston 1 must be arranged in such manner that said piston stops for a relatively long time in this position, which can be obtained for instance by giving a suitable profile to the cam which drives piston 1. This profile is such that it ensures a quick return stroke of piston l. and remains then a relatively long time in its lower dead center position.

The operation of the pump shown by FIG. 1 is as follows:

Piston 1 closes, at the beginning of its upward (delivery) stroke, conduits 6 and 9 and then delivers fuel, present in cylinder 2, into the chamber 401 of auxiliary cylinder 4. This causes auxiliary piston 5 to move upwardly in said cylinder 4. The movement of auxiliary piston 5 stops when it clears discharge conduit 16. During its upward movement, piston 5 delivers fuel present in chamber 4b, past check valve 13, into delivery conduit 12. The amount of fuel thus delivered into conduit 12 on every delivery stroke of the pump is propor-- tional to the length of the upward stroke of auxiliary piston 5. Piston 1, after it has reached its upper dead center position, starts back on its downward stroke. However, due to the closing of conduit 9, auxiliary piston 5 remains in its upper position until the main piston 1' ciently long time in its lower dead center position, where it .opens conduit 9, to enable auxiliary piston 5, despite the braking of its movement by throttled passage 10, to reach shoulder 15 before piston 1 starts back upon its next upward stroke. However, when the speed exceeds a given value, piston 5 has not yet reached shoulder when piston 1 starts back upon a new-upward stroke; Saidauxilitary piston is thus stopped and againpushed back upwardly after a shortened downward stroke. The amount of fuel which, after this shortened stroke, is delivered through conduit 12, is thus correspondingly reduced. The speed from which this reduction of the flow rate is produced may be varied by acting upon screw 11 the position of which determines the cross-sectional area of throttled passage 10. I thus obtain an all speeds self-regulation.

In the embodiment which has been described, selfregulation depends upon the ratio of the time for which main piston 1 is stopped in its lower dead center position to the time taken by auxiliary piston 5 to accomplish its maximum downward stroke between its upper position, which is determinw by the position of conduit 16 with respect to cylinder 4, and its lower position, which is determined by shoulder 15.

in the embodiment shown by FIG. 2, self-regulation depends upon the ratio of the Whole of the time elapsing between the beginning of the downward stroke of main piston 1 and the beginning of its next upward stroke ,to the tme taken by auxiliary piston .5 to accomplish its maximum downward stroke. In this embodiment, there is provided in piston l, in addition to groovel'l, at least one pair of helical grooves 18 diametrally opposed to one another. The upper ends of said grooves open into groove 17 and their length,-in'the direction parallel to the axis ofpiston 1, is equal to thelength of stroke of this piston. Advantageously, the lower ends of these grooves are .connected together by a second groove .19 provided also in the periphery of piston 1. Furthermore, piston 1 is given, in addition to .its axial reciprocating movement, a rotation movement in the direction of arrow 1 at a speed, chosen, in relation 'to .its axial speed andin accordance with theinclination a of helical grooves 18, so that, during the upward stroke of piston 1, the communication between the two sectionsof conduit 9 located on opposite sides of cylinder 2 is cut off by the portions of the surfaces of piston 1 located between said grooves (see the developed view of FIG, 4 where the relative path of the port 9a of conduit 9 is shown in dotted lines), whereas, during the downward stroke .of-piston 1, this communication is restored, first by means of'groove 19 and then through the grooves 18 located opposite the ports 9a, 9b of the respective sections of conduit 9, and also by the grooves which connect together said helical grooves, the axial speed of piston 1 during its downward stroke being chosen so as to maintain this communication during the whole of the downward movement of said piston.

In the embodiment shown by FIG. 4, four helical grooves 18, located at 90 to each other,.have been provided. This single piston pump is intended to feed fuel to the respective cylinders of a four-cylinder engine.

The operation of the pump of FIG. 2 is quite analogous to that of the pump of FIG. 1 with the only difference that in this case, for the self-regulation action, the'whole of the time elapsing between the beginning of the downward movement and the beginning of the next upward movement of the main piston 1 enters into account.

The pump shown by FIG. 5 corresponds essentially to that shown by BIG. 1 with the difference that, according to FIG. 5, the crossvsectional area of the throttled pascage is .utcmatically variable in accordance with the speed of the engine on which the pump is .mounted, this cross-sectional area decreasing automatically when this speed increases.

In order to vary the cross-sectional area, I make vuse of an arrangement which can ,he .used separately and which consists in arranging a portion of conduit 9, for instance portion 90, in the form of a cylindrical housing in which moves a slide valve 20 preferably actuated by a hydraulic speed governor, this slide valve 20 being capable ,of varyingthe cross-sectional area of the throttled passageilflaprovided in conduit 9, this slide valve including alongitudinal groove or channel 21 through which flows the liquid which is to pass through conduit 9, after it has passed through throttled passage 10a. Preferably, the lower end of longitudinal groove 21 opens into an annular groove 22 having a conical bottom 23 and also formed in slide valve 26*. The throttled passage 10a is in the space left between this conical bottom 23 and the port through which the section 9:! of conduit 9 opens into the slide valve housing 9c. The cross-sectional area .of this throttled passage thus depends upon the position of slide valve 20 in said housing 9c. In order to ensure, for all positions of slide valve 2d, the communication between groove 21 and the section 9e which connects casing 9:: with chamber 4b, there .is further provided, in slide valve 20, a secondannular groove 2d into which opens the upper end of groove 21. In order to prevent a rotation movement of slide valve 20, which might bring groove 21 opposite the section 9d of conduit 9, there is provided a projection 25 engaged .in a longitudinal groove 26 provided in the periphery of slide valve 20.

In order to move slide valve 29 longitudinally in its casing 91:: and thus to vary the cross-sectional area of throttled passage 10a, I make use of ahydraulic governor such as shown by FIG. 5. This governor includes ,a continuous flow pump .27, such as a gear pump, driven at a speed which constitutes the controlling factor for the displacement of slide valve 20. This speed, .in the case :of a fuel injection pump, is the speed of the engine on which the pump is mounted. This pump draws liquid from a tank 28, whichmay be the fuel tank of the engine, and the delivery of pump 27 is connected, through a conduit 29, with the lower end of casing 90. Furthermore, ,I provide on the delivery of this pump a throttled passage .30 located in a conduit 31 for returning the liquid delivered by pump 27 to tank 28. The crosssectional area of this throttled passage 30 is adjustable by a slide valve 32 which, on the other hand, is placed under control of the action of the delivery pressure .of pump 27 applied to this slide valve through a conduit 33, andfurthermore under the action of a return spring 3.4, the whole being arranged in such manner that the cross-sectional area of throttled passage 30 increases when the delivery pressure of pump 27 increases.

Slide valve 20 is further subjected to the action of an opposing spring 35 the compression of which is adjustable, for instance by means of a screw 36.

When the speed of pump 27 increases, the pressure fed-through conduit 29 to the under face of slide valve 20 also increases and this slide valve moves in the direction which causes the cross-sectional area of throttled passage 10a to decrease. On the contrary, when the speed of pump 27 decreases, the cross-sectional area of throttled passage 10a increases.

The variation of the cross-sectional area of throttled passage 30 in the manner above indicated has for its effect that the increases and reductions, as a function of the speedofpump .27, ,of the delivery pressure acting upon slide valve 20 take place at a slower rate than if the cross-sectional area of throttled passage 30 were fixed. It is the fineness of the adjustment effect of the governor that remains the same within a wide range of speeds.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efiicient 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 scopenftheaccompanying claims.

What I claim is:

1. For use with an internal combustion engine, a reciprocating action fuel pump which comprises, in combination, a pump cylinder, a pump piston adapted to cooperate with said cylinder mounted for reciprocating displacement therein so as to limit therewith a variable working space, the movements of said piston in said cylinder in the direction for which the volume of said Working space is reduced being called delivery strokes, fuel inlet means opening into said pump cylinder, a fuel delivery means adapted to be fed during the delivery strokes of said piston with fuel supplied from said pump cylinder, a casing rigid with said cylinder provided with a discharge port opening to the outside, a shuttle member adapted to control said discharge port, the feed of fuel to said delivery means being stopped during every delivery stroke of said piston when said shuttle member has cleared said discharge port, said shuttle member fitting movably in said casing so as to limit with the inner wall thereof a variable volume chamber, the movements of said shuttle member in said casing in the direction for which the volume of said chamber is increased being called outward strokes, return means interposed between said casing and said shuttle member for urging said member to move in said casing in the opposed direction, the movements of said shuttle member in said last mentioned direction being called return strokes, a passage in said casing extending from said cylinder working space to said casing variable volume chamber, valve means in said passage operative by liquid pressure variations in said cylinder working space for opening said passage during the delivery strokes of said piston and otherwise closing it, a conduit starting from said casing variable volume chamber for the outflow of liquid from said chamber during the return strokes of said shuttle member, said conduit including a throttled portion for braking said shuttle return strokes, and valve means in said conduit constituted by a portion of said pump piston for closing said conduit during the delivery strokes of said pump piston and opening said conduit temporarily during at least portions of the timeintervals between said delivery strokes, said throttled portion being arranged to produce a braking action such that, for speeds of operation of the pump above a predetermined value, the return strokes of said shuttle member are the shorter as the speed of operation of the pump is higher.

2. A pump according to claim 1 in whichsaid piston is mounted for reciprocating axial displacement in said cylinder, said conduit including two separate sections opening into said cylinder at two different points of the cylindrical wall thereof, respectively, said piston being provided with a passage therein arranged to connect said two points together when said piston is in the position corresponding to the end of its suction stroke, the portion of said piston which carries said last mentioned passage constituting said valve means in said conduit.

3. A pump according to claim 1 in which said piston is mounted for reciprocating and rotating displacement in said cylinder, said conduit including two separate sections opening into said cylinder at two different points of the cylindrical wall thereof, respectively, said piston being provided at least with one helical groove in its periphery arranged to connect said points together during the suction strokes of said piston while leaving them out of communication during the delivery strokes of said 4. For use with an internal combustion engine, a reciprocating action fuel pump which comprises, in combination, a pump cylinder, a pump piston adapted to cooperate with said cylinder mounted for reciprocating displacement therein so as to limit therewith a variable working space, the movements of said piston in said cylinder in the direction for which the volume of said working space is reduced being called delivery strokes, fuel inlet means opening into said pump cylinder, a fuel delivery means adapted to be fed during the delivery strokes of said piston with fuel supplied from said pump cylinder, a casing rigid with said cylinder provided with a discharge port opening to the outside, a shuttle memberadapted to control said discharge port, the feed of fuel to said delivery means being stopped during every I delivery stroke of said piston when said shuttle member piston, the portion of said piston which carries said I helical groove constituting said valve means in said conduit.

has cleared said discharge port, said shuttle member fitting movably in said casing so as to limit with the inner wall thereof a variable volume chamber, the movements of said shuttle member in said casing in the direction for which the volume of said chamber is increased being called outward strokes, resilient means interposed between said casing and said shuttle member for urging said member to move in said casing in the opposed direction, the movements of said shuttle member in said last mentioned direction being called return strokes, a passage in said casing extending from said cylinder working space to said casing variable volume chamber, valve means in said passage operative by liquid pressure variations in said cylinder working space for opening said passage during the delivery strokes of said piston and otherwise closing it, a conduit starting from said casing variable volume chamber for the outflow of liquid from said chamber during the return strokes of said shuttle member, said conduit including a throttled portion for braking said shuttle return strokes, and valve means in said conduit for closing said conduit during the delivery strokes of said pump piston and opening said conduit temporarily during at least portions of the time intervals between said delivery strokes, said throttled portion being arranged to produce a braking action such that, for speeds of operation of the pump above a predetermined value, the return strokes of said shuttle member are the shorter as the speed of operation of the pump is higher, said throttled portion being in the form of a slide valve comprising means forming a cylindrical slide valve housing inserted between two sections of said conduit, one of said conduit sections opening into said housing transversely thereto, near one end thereof, the other of said conduit sections opening into said housing near the other end thereof, a cylindrical slide valve body fitting slidably in said cylindrical housing, said body being provided with a circumferential groove adapted to cooperate with the opening of said first mentioned conduit section, said slide valve being provided with a longitudinal passage connecting said annular groove with the opening of said second mentioned conduit section, cooperating abutment means carried by said housing and said body for limiting the displacements of said body in said housing in one direction to the position for which said groove wholly clears the opening of said first mentioned conduit section into said housing, and governor means carried by said casing and operatively connected with said slide valve body, said governor means being responsive to variation of a given factor of operation of said engine for moving said body in said casing in the opposed direction from said position when said factor varies.

No references cited.

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