US3114321A - Self-regulating reciprocating pumps, in particular for the injection of fuel into internal combustion engines - Google Patents

Description

Dec. 17, 1963 p, azss ,114,321

SELF-REGULATING RECIPROCATING PUMPS, IN PARTICULAR FOR THE INJECTION 0F FUEL INTO INTERNAL COMBUSTION ENGINES Original Filed July 25, 1960 NVENTOR 'Pii fr: E ITEM/F BA-ssIkr-E 5 Y 6 Mam ATTORNEYS United States Patent Ofifiee Patented Dec. 17, lfifi? 3,114,321 SELF-REGULATING RECIPRGCATENG PUMPd, IN PARTICULAR FQR THE INJECTION F FUEL INTO INTERNAL COMBUSTION ENGHJES Pierre Etienne Bessiere, Neuilly-sur-Seine, France, as-

signor to Societe Anonyrne pour lExploitation des Procedes Chimiques et Physiques, Zug, Switzerland, 21 I Swiss company Continuation of application Ser. No. 44,919, July 25, 1960. This application June 29, 1962, Ser. No. 206,398 Claims priority, application France May 9, 1958 2 Claims. (Cl. 103-41) The present invention relates to self-regulating reciprocating pumps and it is more especially, but not exclusively, concerned with pumps for the injection of fuel into internal combustion engines.

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

The pump according to the present invention includes a main piston having a reciprocating movement in a main cylinder communicating with a discharge conduit, the opening and closing of this discharge conduit being cont-rolled by a shuttle piston acting as a slide valve, said shuttle piston being driven in one direction by a liquid under pressure delivered into a variable volume chamber formed between the shuttle iston and a cylindrical housing in which it is slidable, this liquid under pressure being periodically ted to said chamber, through a circuit having no communication with the liquid circuit of the main pump, by an auxiliary reciprocating pump driven in synchronism with the main pump, this shuttle piston being urged in the other direction by resilient means against the action of a braking system constituted by a throttled passage formed in a portion of an outflow conduit through which flows a liquid delivered by the shuttle piston during the stroke thereof where it is returned by said resilient means.

According to my invention, the throttled passage of said outflow conduit is regulated through means responsive to variations of the speed at which the pump is driven.

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

F168. 1 and 2 are diagrammatic sectional views of two different embodiments, respectively, of an injection pump made according to the present invention.

Each of the pumps of FIGS. 1 and 2 includes a main cylinder 1 in which rec-iprocates a main piston 2 driven through any suitable means, such for instance as a cam 22. This piston controls the opening 3 of a fuel inlet conduit 4, this conduit being fed with fuel from a pump (not shown) which supplies said fuel under a low pressure. The delivery end of cylinder 1 communicates with a delivery conduit 5 leading to the injector or injectors of the engine fed by the pump, a check valve 6 being advantageously provided in said delivery conduit 5.

Cylinder l is provided with discharge conduit elements 7a and 7b, discharge conduit element 7a leading from cylinder to a cylindrical casing 11 and conduit element 7b from said cylindrical casing 11 to the outside. This discharge conduit is controlled by a shuttle piston 3 slidable in casing 11 and provided with a groove 25 through which the points where conduit elements 7a and 7b open into casing 111 may be placed in communication. Shuttle piston S is hydraulically driven in the upward direction (to place conduit elements 7a and 7b in communication with each other near the end of the upward stroke of shuttle piston 8) during the delivery stroke of the main piston (which is an upward stroke), said shuttle piston 8 being moved in the downward direction (return stroke), during the suction stroke of piston 2, by

, resilient return means.

These return means are preferably constituted by a spring l0 (although it is possible to make use for instance of compressed air means).

The upward strokes of shuttle piston 8 are produced hydraulically by a liquid fed from an auxiliary pump working in synchronism with the pump l-2 into a variable volume chamber 23 formed at the bottom of casing 11 under shuttle piston 8.

The auxiliary pump is obtained by providing the main piston 2 with an extension 2a of larger diameter which is slidable with a fiuidtight fit in a cylinder la in line with the main cylinder 1, the annular space 17 thus formed between piston 3 and cylinder in being connected through a conduit 3'18 with the variable volume chamber 23. Conduit 3.8 is provided with a check valve 24 which prevents liquid from flowing back from chamber 23 toward space 37. A feed conduit 19, opening into annular space 17, serves to feed liquid under pressure, for instance fuel, from the above mentioned primary pump (not shown). A discharge conduit 20, starting from cylindrical housing 11, is located in such a manner as to be closed by shuttle piston 8 during every upward stroke of shuttle 8, the opening of said discharge 2% producing the end of said stroke.

Annular space 17 may be used to house a spring 21 which keeps the whole of pistons 2 and 2a applied against the driving cam 22.

Liquid can escape from variable volume chamber 23 through an outflow conduit 12 provided with a thr-ottled passage 13. Out-flow conduit 12 might open to the outside. In the embodiment shown by the drawing, it leads to annular space 17.

The pump above described works in the following manner.

On the drawings, combined piston 2-2.5: is shown in its lower dead center position and shuttle piston 3--Sa in its lowest position (determined by abutment 4%) where it closes discharge conduit element 7b.

During the delivery stroke of main piston 22a (upward stroke), this main piston first closes port 3 and the opening of feed conduit 19. Piston 2 then delivers, through delivery conduit 5, the fuel contained in cylinder 1. Shnultaneously, pontion 2a (auxiliary pump) delivers liquid irom annular space 117 into charnlber 23, thus driving; shuttle piston 8 in the upward direction until discharge conduit 20 is opened, which then stops said shuttle piston. At mhis time, the opening or" discharge conduit element 7 b has been cleared by the top portion of shuttle piston 8, thus stopping injection.

During the suction stroke of main piston 22a (downward stroke), shuttle 8 is pushed back in the downward direction by spring 1d. The downward movement of the shuttle piston is braked due to the fact that it must cause the fuel present in chamber 2-3 to flow through throttled passage 13. When piston 2-2a reaches its lower dead center position, cylinder 1 is filled with fuel through conduit 4 and annular space '17 is filled with liquid flowing through conduit 19.

When the internal combustion engine fed with fuel from the injection pump above described runs at a speed lower than a given value, shuttle piston 8 is given sufficient time to reach its lowest position (on abutment 46)) before main piston 22a starts back upon its next delivery stroke, and consequently before said shuttle piston is compelle-d to move back in the upward direction by the fluid under pressure tfed firom. chamber 17 into chamber 23-. The stroke of shuttle piston 8-8a then has a constant 3 amplitude and the amount of fuel injected on every cycle is constant and maximum.

When the engine speed exceeds the above mentioned limit value, shuttle piston 3 moves back in the downward direction through only a portion of its maximum downward stroke, this portion decreasing as the speed increases. It follows that discharge conduit element 7b is opened at an earlier relative time during the delivery stroke of piston 2 and the amount of fuel injected during every cycle decreases as the speed increases.

If the speed of the engine still increases, there comes a time when shuttle piston 8 is no longer capable of closing discharge conduit element 7a and any injection ceases. This is a top speed that cannot be exceeded by the engine.

The dimension of throttled passage 13 may be made adjustable by means of a movable member.

According to the present invention, said member is operated automatically as a function of the speed of the engine fed with fuel b the pump. In the embodiment of FIG. 1, this member, Which is a throttling slide valve designated by reference numeral 27, is actuated by a governor 23 of the centrifugal type.

In the construction of FIG. 2, the throttling slide valve 27 movable toward the left against a return force produced by a spring 29 is provided with a groove 39 determining, in cooperation with conduit 12, a passage the cross section of which is the smaller as slide valve 27 is moved to a greater distance toward the left.

In the embodiment of FIG. 2, the force that displaces slide valve 27 toward the left is supplied by a hydraulic governor.

I may provide different laws of variation of the cross section of throttled passage 13 as a function of the speed but, as a rule, this cross section is reduced when the speed increases.

in the device shown by FIG. 2, the above mentioned variable force is supplied by the pressure of a liquid, such as oil, delivered by a constantly running auxiliary pump the delivery rate of which, measured in volume, is proportional to the speed at which it is driven. This auxiliary pump is for instmce a gear-pump 31 driven by the engine which also drives the main pump piston 2. The liquid under pressure supplied by pump 31 acts on the right hand end face of slide valve 27. The delivery conduit 32-33 of gear-pump 31 is throttled (in its portion 33 which opens to the outside and constitutes a discharge conduit) by a slide valve 124a such that the cross section of the throttled passage is automatically varied in accordance with the variations of a factor upon which depends the amount of fuel delivered by the pump, this factor being possibly the speed of the engine on which the pump is mounted, that is to say the speed at which auxiliary pump 31 is driven.

Thus, according to FIG. 2, a slide valve 124- inserted across the portions 33 of delivery conduit 3233 of auxiliary pump 31 is caused to move under the effect of the pressure existing in said delivery conduit. For this purpose, the portion 32 of said delivery conduit is connected through a conduit 13% with the right hand end of the cylinder in which slide valve 124 is movable. "I he throttled pass-age in conduit portion 33 is controlled by a groove 12452 of said valve 124. Slide valve 124 is urged by a return spning 125 against an abutment 127.

In a possible construction, which is not that shown by FIG. 2, groove 124a is arranged in such manner that slide valve 124, as soon as it begins to move against the action of spring 125 reduces the cross section of the last mentioned throttled passage and this the more so as the delivery pressure of auxiliary pump 17 rises. In this case, there is some risk of over regulation since an increase of the pressure in conduit 32 causes a reduction of the cross section of the throttled passage through groove 124a which in turn causes a further increase of the pressure in conduit 32 and so on. It may then happen that the correction of the delivery rate of the pump is effected quicker than the change in the speed of the engine and that consequently slide valves '124and 27 are given a periodical movement. In order to avoid this phenomenon, means may be provided to brake the displacement of slide valve 124 and of slide valve 12, preferably by providing a throttled section in conduit 136' and/or a throttled section in conduit 21, these throttled sections being either identical or different. The slide valves may also be provided with damping means constituted for instance b dash-pots. All these means are intended to damp the transmission of sudden pressure variations to the respective slide valves.

Anyway, in this construction (not shown) according to which an increase of the speed produces a reduction of the cross section of the throttled passage provided in the discharge conduit of auxiliary pump 31, I obtain, in response to a rise of the speed, an increase of the fineness of regulation, the term fineness designating the reciprocal of the ratio of the momentaneous speed which constitutes the adjustment factor (given in number of revolutions per unit of time) to the variation undergone by said speed (this variation being also given in number of revolutions) to achieve the desired regulation effect.

In some cases, it is of interest to obtain a fineness which, for all values of the speed or at least for a large range of different speeds, remains at least approximately constant. The embodiment of FIG. 2 permits of obtaining this result.

A governor as shown by FIG. 2 is characterized in that when the speed increases, the throttled passage in the discharge conduit controlled by slide valve 124 does not decrease but on the contrary increases, thus moderating the action of the hydraulic governor.

According to this embodiment, groove 124a is disposed in such manner that the throttled passage it controls has a minimum cross section when the slide valve is in position of rest, that is to say when spring applies slide valve 124 against fixed abutment 127, whereas the cross section of said throttled passage (corresponding to the portion of groove 124a located in conduit 33) increases more and more as the pressure in delivery conduit 32 moves slide valve 124 to a greater distance from abutment 127. An abutment 143 limits the displacement of slide valve 124 toward the left so as to prevent the cross section of the above mentioned throttled passage from decreasing after groove 124a has reached the position corresponding to the maximum cross section of the throttled passage.

The present application is a continuation of my copending application Ser. No. 44,919, filed on July 25, 1960, which was itself a continuation-in-part application of my prior application Ser. No. 811,176, filed on May 5, 1959.

What I claim is:

1. A self-regulating liquid pump which comprises, in combination, a main cylinder, a main piston fitting slidably in said cylinder, means reciprocating said piston in said cylinder, a delivery conduit in communication with one end of said cylyinder, means forming a housing having at least one internal cylindrical portion, a first discharge conduit elernent leading from said cylinder to a point of said cylindrical portion of said housing, a second discharge conduit elyement leading from another point of said cylindrical portion of said housing to the outside, a reciprocating shuttle piston having a cylindrical portion thereof fitting slidably in said cylindrical portion of said housing so as to form therein a slide valve controlling the communication between said two discharge conduit elements through the inside of said housing, said shuttle piston defining, together with said housing a variable volume chamber so that variation of the volume of said chamber corresponds to a movement of said shuttle piston in said housing, an auxiliary reciprocating pump operatively connected with said main piston so as to work in synchronism therewith, conduit means connecting the delivery of said auxiliary pump with said variable volume chamber so as to move said shuttle piston in said housing in one direction in response to every delivery stroke of said auxiliary pump, the above mentioned points of said housing being so located as to be placed in communication with each other through said housing by said shuttle piston moving in said direction, on every reciprocation thereof, valve means in said last mentioned conduit means for preventing the fiow of liquid therethrough from said variable volume chamber toward said auxiliary pump delivery, resilient means urging said shuttle piston in the opposed direction, an outflow conduit connected to said variable volume chamber, a throttle valve in said outflow conduit to brake the displacements of said shuttle piston in said second mentioned direction, an auxiliary pump driven at a speed proportional to the mean speed of said main piston, said last mentioned auxiliary pump being of the type which has a volumetric fiow rate proportional to the speed at which it is driven, said second mentioned auxiliary pump having a delivery circuit, throttling means in said delivery circuit to produce a liquid pressure in a portion of said delivery circuit extending between said last mentioned auxiliary pump and said throttling means, said throttling means including a slide valve slidable transversely to said delivery circuit, conduit means transmitting to one end of said slide valve the liquid pressure in said lelivery circuit portion, resilient means opposing the thrust of said liquid pressure on said slide valve, and said throttle valve having means operatively connected therewith and responsive to variations of the liquid pressure acting on said slide valve for controlling said throttle valve in response to variations of said liquid pressure, said last means being connected with said portion of said delivery circuit.

2. A pump according to claim 1 in which said slide valve is arranged so that the throttling of said auxiliary pump delivery circuit by said throttling means is reduced when said liquid pressure in said delivery circuit is increased.

No reference cited.

Claims (1)

1. A SELF-REGULATING LIQUID PUMP WHICH COMPRISES, IN COMBINATION, A MAIN CYLINDER, A MAIN PISTON FITTING SLIDABLY IN SAID CYLINDER, MEANS RECIPROCATING SAID PISTON IN SAID CYLINDER, A DELIVERY CONDUIT IN COMMUNICATION WITH ONE END OF SAID CYLINDER, MEANS FORMING A HOUSING HAVING AT LEAST ONE INTERNAL CYLINDRICAL PORTION, A FIRST DISCHARGE CONDUIT ELEMENT LEADING FROM SAID CYLINDER TO A POINT OF SAID CYLINDRICAL PORTION OF SAID HOUSING, A SECOND DISCHARGE CONDUIT ELEMENT LEADING FROM ANOTHER POINT OF SAID CYLINDRICAL PORTION OF SAID HOUSING TO THE OUTSIDE, A RECIPROCATING SHUTTLE PISTON HAVING A CYLINDRICAL PORTION THEREOF FITTING SLIDABLY IN SAID CYLINDRICAL PORTION OF SAID HOUSING SO AS TO FORM THEREIN A SLIDE VALVE CONTROLLING THE COMMUNICATION BETWEEN SAID TWO DISCHARGE CONDUIT ELEMENTS THROUGH THE INSIDE OF SAID HOUSING, SAID SHUTTLE PISTON DEFINING, TOGETHER WITH SAID HOUSING A VARIABLE VOLUME CHAMBER SO THAT VARIATION OF THE VOLUME OF SAID CHAMBER CORRESPONDS TO A MOVEMENT OF SAID SHUTTLE PISTON IN SAID HOUSING, AN AUXILIARY RECIPROCATING PUMP OPERATIVELY CONNECTED WITH SAID MAIN PISTON SO AS TO WORK IN SYNCHRONISM THEREWITH, CONDUIT MEANS CONNECTING THE DELIVERY OF SAID AUXILIARY PUMP WITH SAID VARIABLE VOLUME CHAMBER SO AS TO MOVE SAID SHUTTLE PISTON IN SAID HOUSING IN ONE DIRECTION IN RESPONSE TO EVERY DELIVERY STROKE OF SAID AUXILIARY PUMP, THE ABOVE MENTIONED POINTS OF SAID HOUSING BEING SO LOCATED AS TO BE PLACED IN COMMUNICATION WITH EACH OTHER THROUGH SAID HOUSING BY SAID SHUTTLE PISTON MOVING IN SAID DIRECTION, ON EVERY RECIPROCATION THEREOF, VALVE MEANS IN SAID LAST MENTIONED CONDUIT MEANS FOR PREVENTING THE FLOW OF LIQUID THERETHROUGH FROM SAID VARIABLE VOLUME CHAMBER TOWARD SAID AUXILIARY PUMP DELIVERY, RESILIENT MEANS URGING SAID SHUTTLE PISTON IN THE OPPOSED DIRECTION, AN OUTFLOW CONDUIT CONNECTED TO SAID

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