US3016838A - Reciprocating action pumps, in particular fuel injection pumps - Google Patents

Description

Jan. 16, 1962 P. E. BESSIERE 3,016,838

RECIPROCATING ACTION PUMPS, IN PARTICULAR FUEL INJECTION PUMPS Filed Feb. 12, 1959 2 Sheets-Sheet 1 I 9;; (I 1 24 I? 32' 2a 16 2 25 1 Q 2 6%,; 21 6:3) 25 j a: 34 4 INVENTOR $2317: Ezieua Ens 3a B Jan. 16, 1962 E. BESSIERE 3,016,838

P. RECIPROCATING ACTION PUMPS, IN PARTICULAR FUEL INJECTION PUMPS Filed Feb. 12, 1959 2 Sheets-Sheet 2 United States Patent 3,616,838 RECEPRUQATING ACTHQN PUMPS, EN PARTECU- LAR FUEL INHECTIQN PUMPS Pierre Etienne Bessiere, 55 Blvd. Commandant Charcot, Neuiliy sunSeine, France Filed 12, 195?, Ser. No. 72,%3 6 Claims. (Ci. Hid-3E) The present invention relates to reciprocating action pumps, that is to say pumps in which the active member (piston, diaphragm or the like) has a reciprocating move ment in a cylinder which is divided by said member into two chambers. The invention is more especially concerned with fuel injection pumps for internal combustion engines.

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

For this purpose, the active member of the pump, which is subjected, alternately, to the action of means such as hydraulic means for imparting thereto its delivery stroke as far as an end position which is generally fixed, and to the action of means for imparting thereto its return stroke as far as a variable end position which, at least for speeds of the pump above a given value, becomes the closer to said fixed end position as the speed of the pump is higher, is characterized by the fact that the active member, during its return stroke, is acted upon in one direction by resilient means and in the opposed direction by a continuous flow of fluid producing a pressure variable with the speed of the pump in one of the two chambers, said chamber being provided with a throttled discharge conduit so that the above mentioned variable end position is that for which the action of the fluid pressure admitted in said last mentioned chamber and the action of the resilient means balance each other.

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:

FIGS. 1 and 2 are diagrammatic sectional views of two different embodiments of the invention, respectively.

In the following description, it will be supposed that the invention is applied to the case of a fuel feed pump for a diesel engine and serves to send fuel to one or several injectors belonging to said engine.

The pump includes an active member, for instance a piston 1, hereinafter called shuttle, which has a reciprocating movement in a cylinder 2 which is divided by said piston into two chambers 2 and 2 Chamber 2 which will be hereinafter called delivery chamber is connected with the injector or injectors of the diesel engine by delivery conduit 3 advantageously provided with a check valve 4. Piston 1 is subjected alternately to the action of means for imparting thereto its delivery stroke as far as a generally fixed end position and to the action of means for imparting thereto its return stroke as far as a variable end position which, at least for speeds of the pump above a given value, becomes closer and closer to the fixed end position as the speed of the pump increases.

According to the invention, said piston 1 is subjected, during its return stroke, to the action in one direction of resilient means and in the opposed direction of a continuous flow of fluid producing a pressure variable with the speed of the pump in one of the chambers 2,, and 2 said chamber being provided with a thro-ttled discharge conduit so that the variable end position is that where the action of the fluid pressure admitted in said chamber and the action of the resilient means balance each other.

The means for actuating this piston 1 in the delivery stroke direction may be mechanical means consisting for instance of a push-piece driven by a rotating cam 5 driven at a speed proportional to that of the engine to be fed with fuel. But it seems more advantageous to make use of hydraulic or pneumatic means and in particular of a piston 6 applied against said cam 5 by a spring 7 and capable of delivering a fluid under pressure into chamber 2 which communicates for this purpose through a conduit 8 with the cylinder 9 in which piston 6 rwiprocates. The delivery stroke of shuttle piston 1 is limited by a discharge conduit 35 which is placed in communication with said chamber 2;, when it is cleared by the edge of shuttle 1.

The variable pressure which is to be produced in one of the chambers 2,, and 2,, may be obtained by varying, as a function of the speed of the pump, the delivery rate of the means which supply the continuous flow of fluid and/or the cross section of the throttled passage of the discharge conduit starting from said chamber. The means for feeding the fluid under pressure are constituted, in the example shown, by a volumetric pump such as a gear pump 10.

When the fluid delivered by pump 10 is fed to chamber 2 (opposed to delivery chamber 2 the pressure of this fluid must increase when the speed of the pump increases by increasing the delivery rate of pump 19 and/or by reducing the cross section of the throttled passage of the discharge conduit starting from said chamber 2 In this case, said fluid may be constituted by the fuel itself, by another liquid or even by a gas.

When the fluid delivered by pump 1% is fed to delivery chamber 2 the pressure of the fluid rnust decrease when the speed of the pump increases, by reduction of the delivery rate of the pump and/or by increase of the cross section of the throttled passage of the discharge conduit leading out from said chamber 2 In this case, the fluid is necessarily constituted by the fuel itself.

The resilient means acting upon shuttle piston 1 are constituted by a spring 11 housed in the chamber opposed to that into which the fluid under pressure is fed.

The first of the two above mentioned cases is illustrated by FIG. 1, according to which the delivery conduit 12 of pump 10 communicates with chamber 2 through conduit 8, spring 11 being housed in chamber 2 and the fluid in cylinder 9 being the same as that fed by pump 10. Pump 10 is driven at a speed proportional to that of the engine to be supplied with fuel.

Cylinder 9 may be fed with liquid either from pump 10 or, according to a modification shown in dotted lines, through a feed conduit 13 located at a level such that it is closed by piston 6 as long as said piston is not in the vicinity of its lower dead center position. In this modification, a check valve 14 is provided in conduit 8 upstream of the point where conduit 12 opens thereinto.

The throttled discharge conduit in communication with chamber 2,, is shown at 15 and it extends across a chamber 16 in which is movably mounted a slide valve 17 provided with a groove 18, the walls of this groove, which advantageously have a convex profile, limiting, together with the ends of conduit 15, the above mentioned throttled passage 19.

In order to reduce the cross section of this throttled passage 19, slide valve 17 is subjected to the opposed ac tions of a pressure which increases with the speed of the engine and of a spring 20 preferably adjustable by means of a screw 21. This pressure may be supplied by a second volumetric pump 22, for instance a gear pump, driven at a speed proportional to that of the engine. The deliv ery conduit 23 of this pump 22 is connected to chamber 16 and it is also provided with a calibrated discharge orifice 24, preferably adjustable by means of a screw 25, either manually or automatically as a function of the speed.

In order to feed fuel into chamber 2 this chamber is connected through a conduit 26 with a low pressure feed pump (not shown), or primary pump. Finally, in order to separate chamber 2,, from auxiliary pump 10 and throttled passage 19 when shuttle piston 1 is moving on its delivery stroke, conduits 12 and are provided Wtih respective slide valves 27 and 23, each of said slide valves being subjected to the opposed actions of a return spring and of a cyclically produced fluid pressure. Preferably, this last mentioned pressure is supplied by a piston 29 driven in synchronism with piston 6 and consisting for instance for a portion of larger diameter thereof. In this case, the delivery chamber 30 of piston 29, which is fed with fresh fluid through a conduit 31 and which is connected to slide valves 27 and 28 through conduit 32 may serve to house spring 7. Furthermore, instead of providing the usual check valve in conduit 26, I may make use of a third slide valve 33 arranged and operated in the same manner as slide valves 27 and 28, a discharge conduit 34 limiting the upward movement of slide valve 33 and at the same time of the two other slide valves.

If the fuel is used as active fluid in cylinder 9, in chamber 2,, in delivery chamber 30 and in chamber 16, conduits 13 and 31 may be connected to the primary pump and discharge conduits 15, 34, 35, discharge orifice 24 and the intakes of pumps 10 and 22 are connected to the usual fuel tank.

Of course, since the delivery conduit 12 of pump 10 is closed by slide valve 27 during a portion of the cycle, this delivery conduit must be provided, upstream of said slide valve, with a safety valve (not shown) to permit the outflow of liquid from pump 10 during this period.

Such a pump works as follows.

When piston 629 moves upwardly from the position shown on the drawings, the liquid delivered by piston 29 closes slide valves 27, 28 and 33 and slide valve 33 opens discharge conduit 34, thus acting as a safety valve. Piston 6 drives out liquid from cylinder 9 through condut 8 into chamber 2,, thus pushing back shuttle piston 1 against the action of spring 11. Shuttle 1 in turn drives out fuel from chamber 2 into conduit 3 so as to produce fuel injection into the engine, and this until by-pass conduit is cleared by shuttle piston 1 which then stops. Piston 6 keeps for a short time driving out liquid through conduit 35, then it stops, after which it starts back in the downward direction.

The three slide valves 27, 28 and 33 then open. Pump 10 then delivers liquid to conduit 8.

When conduit 13 and check valve 14 do not exist, the liquid delivered by pump 10 first flows into cylinder 9 thus pushing back piston 6 down to its lower dead center position. During this time, shuttle piston 1 is pushed upwardly by spring 11, due to the fact that the outlet throttled passage 19 causes the pressure to drop in chamber 2,,. At the same time chamber 2 is fed with fuel through conduit 26.

Finally, when cylinder 9 is filled with fuel, pump 10 delivers fuel only into chamber 2,, a portion of this fuel flowing out past throttled passage 19.

If the speed of the engine is constant, the cross section of throttled passage 19 does not vary. The pressure existing in chamber 2,, immediately before the next upward movement of piston 6 is therefore constant and shuttle piston 1 comes into a position where the acion of the pressure in chamber 2,, is balanced by the action of spring 11 on shuttle 1. The volume of fuel which will be injected on the next stroke of the pump is proportional to the distance H indicated on FIG. 1 and this volume is therefore directly measured by said spring. This volume will remain constant if the working speed of the engine remains constant.

An increase of the speed of the engine causes both an increase of the delivery rate of pump 10 and a reduction of the cross section of throttled passage 19. The pressure in chamber 2,, therefore varies quicker than the speed of the engine, especially if the groove 18 of slide valve 19 has a convex profile, as above mentioned.

The flow rate of the pump per stroke thereof, which is proportional to H, therefore decreases as the speed increases and this in such manner that a regulating effect is obtained.

If the speed of the engine further increases, a time comes when the upper edge of shuttle piston 1 is constantly below the upper edge of discharge conduit 35 so that no injection takes place. This speed is a limit speed.

The delivery rate of the pump may be adjusted by displacing screws 21 and/ or 25. The law of variation of the delivery flow rate may be adjusted by modifying the profile of groove 18.

Of course, in order to obtain an operation of the pump as above described, it is necessary to have the delivery rate of pump 10, the volumes swept by piston 6 and shuttle piston 1 and the characteristics of spring 11 chosen in a suitable manner. In particular the delivery rate of pump 10 must be chosen sufiiciently high with respect to the volume swept by shuttle piston 1. Furthermore, the variation of the pressure in chamber 2,, must correspond to the characteristics of spring 11.

In the modification which includes a feed conduit 13 and a check valve 14, the whole of the delivery of auxiliary pump it is sent to chamber 2 Shuttle piston 1 therefore moves up more slowly under the action of spring 11 and reaches its final position directly without oscillation. In this position of shuttle 1, the pressure in chamber 2,, increases when the speed increases proportionally to a power of this speed higher than 1. An increase of the speed of the engine therefore produces a very great reduction of distance H and a very good regulation is obtained.

In another modification, I might dispense with pump 22 and have slide valve 17 controlled by pump 16 by connecting conduit 23 with the delivery conduit 12 of said pump 10, as described in my French patent of July 8, 1957 for Improvements Brought to Hydraulic Speeds Regulator, in Particular for Fuel Injection Pumps.

When the fluid delivered by pump 10 is fed to delivery chamber 2 said pump may be driven as well at a constant speed as at a speed proportional to that of the engine. FIG. 2 shows such a construction. The delivery conduit 12 of pump 19 (which further plays the same part as the feed conduit 26 of the construction of FIG. 1) opens into chamber 2 Furthermore, discharge conduit 15 starts from said chamber 2 Finally, slide valve 17 is arranged in such manner as to increase the cross section of throttled passage 19 sufficiently quickly, when the speed of the engine increases, to cause the counter pressure due to this throttled passage to decrease when the speed increases.

Of course, the check valve 4 controlling the flow of fuel to delivery conduit 3 must open at a pressure higher than the maximum delivery pressure of pump 19, which is limited for instance by a discharge valve 36.

In the construction of FIG. 2, slide valves 27 and 28 form a single piece and are subjected to the action of the same return spring. Furthermore, means have been provided for adjusting the action of spring 11, these means consisting in a screw 37.

The pump of FIG. 2 works as follows.

When piston 6-29 moves up from the position shown on the drawings, the liquid delivered by piston 29 moves slide valve 27-28 so as to close conduits 12 and 15 and to open discharge conduit 34-. Then piston 6 closes conduit 13 (a check valve such as shown at 14 on FIG. 1 is not necessary in this case). It will be noted that when piston 6 is in its lower dead center piston, its upper face is at a distance a below conduit 13 so that said conduit 13 can be closed only after slide valve 27-23 has been closed. Piston 6 drives the liquid present in cylinder 9 through conduit 8 into chamber 2,, so as to push shuttle piston 1 toward the right, with the help of spring 11. Shuttle piston 1 in turn drives the liquid present in chamber 2 into delivery conduit 3 and this until discharge conduit 35 is cleared by shuttle piston 1 which then stops. Piston 6 still moves some distance driving out liquid through conduit 35, then it stops and starts back on its next downward stroke.

Slide valve 27-48 then opens. Pump feeds fuel into chamber 2 and shuttle piston 1 is moved back toward the left by the pressure of this fuel, compressing spring 11. At the same time, fuel flows out past throttled passage 19, check valve 4 remaining closed.

Shuttle piston ii is stopped when the thrust exerted by spring it added to the pressure of the primary pump which has served to feed fuel to cylinder 9 is balanced by the pressure in chamber 2 Then the above mentioned cycle is repeated.

If the speed of the engine increases, the cross section of throttled passage 19 also increases which reduces the pressure in chamber 2,,. The leftward movement of shuttle piston 1 is therefore shortened and the amount of fuel injected on every cycle is reduced. If the speed increases to a given value, orifice 19 is wide open and shuttle piston 1 no longer moves toward the left so that there is no injection of fuel. This is the limit speed of the engine.

As in the construction of FIG. 1, adjustment may be obtained by displacing screws 21 and 25. To every position of these screws, there corresponds a given limit speed of the engine so that the regulation is of the all speeds type. The pump delivery characteristic can be modified by modifying the shape of groove 18.

In a general manner, while I have, in the above de scription, 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 vdthout departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. A reciprocating action pump which comprises, in combination, a cylinder, a member reciprocable in said cylinder parallel to the axis thereof, said member dividing the inside of said cylinder into two chambers of variable volumes, one of said chambers being a liquid delivery chamber, a delivery conduit leading out from said delivery chamber, driving means operatively connected with said member for imperatively transmitting thereto liquid delivery displacements in the direction which reduces the volume of said delivery chamber as far as a fixed upper limit, liquid feed means opening into one of said chambers for supplying it with a continuous flow of liquid, a discharge conduit leading out from said last mentioned chamber, said discharge conduit being distinct from said delivery conduit, throttling means in said conduit, valve means in said liquid feed means and said discharge conduit for controlling the communication of said liquid feed means and said discharge conduit with said last mentioned chamber, said valve means being operatively connected with said driving means to open this communication only during the displacements in the opposed direction of said member in said cylinder, regulating means operatively connected with said liquid feed means and with said throttling means for varying the pressure in said last mentioned chamber during said last mentioned displacements when the number of reciprocations of said member per unit of time varies, and resilient means interposed between said member and said cylinder for acting on said member in the direction opposed to that of the thrust exerted by said continuous flow of liquid on said member.

2. A reciprocating action pump according to claim 1 in which said means for imperatively transmitting to said member liquid delivery displacements in the direction which reduces the volume of said delivery chamber are hydraulic means.

3. A reciprocating action pump which comprises, in combination, a cylinder, a piston fitting slidably in said cylinder so as to be reciprocable therein, said piston dividing the inside of said cylinder into two chambers of variable volumes one of said chambers being a liquid delivery chamber, a delivery conduit leading out from said delivery chamber, hydraulic driving means operatively connected with said piston for imperatively transmitting thereto liquid delivery displacements in the direction which reduces the volume of said delivery chamber, by-pass means for cutting off the action of said hydraulic means so as to limit the position reached by said piston at the end of its delivery displacements, a continuous flow auxiliary pump driven at a speed proportional to the number of reciprocations of said piston per unit of time, a feed conduit extending from the delivery of said auxiliary pump to the other of said chambers, a discharge conduit leading out from said chamber, valve means in said feed conduit and in said discharge conduit to control the flow of liquid through said two last mentioned conduits, said valve means being operatively connected with said driving means to open said two last mentioned conduits only during the displacements in the opposed direction of said piston in said cylinder, resilient means interposed between said piston and said cylinder for urging said piston in the last mentioned direction, and means in said discharge conduit for throttling it more and more as said number of reciprocations increases.

4. A pump according to claim 3 in which said last mentioned means include a slide valve mounted across said discharge conduit for variably throttling it, spring means operatively connected with said slide valve for urging it in the direction that reduces the throttling action thereof, and an auxiliary liquid pump driven at a speed increasing when said number of reciprocations increases having its delivery connected with said slide valve for exerting thereon a liquid pressure in the direction that increases said throttling action.

5. A reciprocating action pump which comprises, in combination, a cylinder, a piston fitting slidably in said cylinder so as to be reciprocable therein, said piston dividing the inside of said cylinder into two chambers of variable volumes one of said chambers being a liquid delivery chamber, a delivery conduit leading out from said delivery chamber, hydraulic driving means operatively connected with said piston for transmitting thereto liquid delivery displacements in the direction which reduces the volume of said delivery chamber, by-pass means for cutting off the action of said hydraulic means so as to limit the position reached by said piston at the end of its delivery displacements, a continuous flow auxiliary pump driven to deliver a stream of liquid, a feed conduit extending from the delivery of said auxiliary pump to said delivery chamber, a discharge conduit leading out from said delivery chamber, said discharge conduit having a throttled passage therein, valve means in said feed conduit and in said discharge conduit for controlling the flow of liquid through said two last mentioned conduits, said valve means being operatively connected with said driving means to open said two last mentioned conduits only during the displacements in the opposed direction of said piston in said cylinder, resilient means interposed between said piston and said cylinder for urging said piston in the first mentioned direction, and means in said discharge conduit for increasing the cross section of said throttled passage more and more as said number of reciprocations increases.

6. A pump according to claim 5 in Which said last mentioned means include a slide valve mounted across said discharge conduit so as to form said throttled passage in said conduit, spring means operatively connected with said slide valve for urging it in the direction that reduces the cross section of said throttled passage, and an auxiliary liquid pump driven at a speed increasing when said number of reciprocations increases having its delivery connected With said slide valve for exerting thereon a liquid pressure in the direction that increases the cross section of said throttled passage.

References Cited in the file of this patent FOREIGN PATENTS 127,951 Great Britain June 5, 1919

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