US3650259A - Fuel injection pumps for combustion engines - Google Patents

Abstract

A fuel injection pump of known type, wherein the metering means consist of a nonrotating metering ring which is slidably mounted on the rotary distributor in leaktight manner and has a discharge orifice which is capable of communicating in a variable manner with radial discharge passages formed in the rotary distributor and extending from the axial duct of the said distributor in order that the fuel should be discharged in a variable manner both in time duration and in flow rate according to the axial position taken up by the said metering ring on the said distributor and according to the relative angular position of the said passages, the said ring being on the one hand thrust back elastically by oppositely acting springs towards a position corresponding to zero discharge and on the other hand thrust back axially in the discharge position by all-speed regulating means comprising a bell-crank lever actuated hydraulically by a pushrod plunger in dependence on the supply pressure which exists periodically between two successive injections within the axial duct of the distributor, the movement of the said lever under the action of the said plunger being limited by an adjustable stop and controlled in dependence on a manually adjustable elastic push-rod, the said metering ring being also controlled in the discharge position by means which are responsive to the speed of rotation of the engine and to the controlling action of the accelerator.

Description

United States Patent [45] Mar. 21, 1972 Garnier [54] FUEL INJECTION PUMPS FOR COMBUSTION ENGINES [72] Inventor: Georges Garnier, Blois, France [73] Assignee: Rom-Diesel, Clichy (Hauts-de-Seine),

France [22] Filed: July 6, 1970 [21] Appl. No.: 52,182

[30] Foreign Application Priority Data July 10, 1969 France ..6923487 [52] U.S. CI. ..123/140, 123/139, 123/139 AP, 123/139 AQ, 123/140 FG, 417/296, 417/462 [51] int. Cl ..F02d 31/00 [58] Field of Search ..123/139, 139 AM, 139 AN, 139 AP, 123/139 A0, 140, 140 F0; 417/462, 279, 284, 296

[56] References Cited UNITED STATES PATENTS 2,790,432 4/1957 Shallenberg et a1. ..123/139 3,311,100 3/1967 Maddalozzo ..123/140 3,460,479 8/1969 Kemp ..123/140 X Primary Examiner-Laurence M. Coodridge Attomey-Clelle W. Upchurch [57] ABSTRACT A fuel injection pump of known type, wherein the metering means consist of a nonrotating metering ring which is slidably mounted on the rotary distributor in leaktight manner and has a discharge orifice which is capable of communicating in a variable manner with radial discharge passages formed in the rotary distributor and extending from the axial duct of the said 1 distributor in order that the fuel should be discharged in a hydraulically by a push-rod plunger in dependence on the supply pressure which exists periodically between two successive injections within the axial duct of the distributor, the movement of the said lever under the action of the said plunger being limited by an adjustable stop and controlled in dependence on a manually adjustable elastic push-rod, the

said metering ring being also controlled in the discharge position by means which are responsive to the speed of rotation of the engine and to the controlling action of the accelerator,

PATENTEU MAR 21 I97? SI'IEET 1 OF 6 PATENTEDMARZ] m2 SHEET 2 OF 6 PATENTEBMARZI m2 3,650,259

SHEETS 0F 6 FIG. I2

50 57b 48 51a 76b 52 53 FUEL INJECTION PUMPS FOR COMBUSTION ENGINES This invention relates to fuel injection pumps of the type comprising a rotary distributor and a supply pump which are mounted within a casing and both driven by the combustion engine in which the injectors are to be supplied from said injection pump, said rotary distributor being pierced by an axial duct which communicates respectively with a high-pressure radial distributor passage which opens successively into the outgoing lines to the injectors,'with radial admission passages adapted to communicate periodically with stationary supply ducts which are continuously connected to the discharge end of the supply pump, with radial bores containing plungers operated by the cams of a nonrotating external cam ring, and with means for metering the fuel flow to the injectors by discharging a fraction of the fuel which is delivered by the plungers.

In accordance with the present invention, the fuel injection pump is more especially characterized in that the metering means consist of a nonrotating metering ring which is slidably mounted on the rotary distributor in leak-tight manner and has a discharge orifice which is capable of communicating in a variable manner with radial discharge passages formed in the rotary distributor and extending from the axial duct of said distributor in order that the fuel under high pressure should be discharged in a variable manner both in time-duration and in flow rate according to the axial position taken up by said meterin g ring on said distributor and according to the relative angular position of said passages, said ring being on the one hand thrust back elastically by oppositely acting springs towards a position corresponding to zero discharge and on the other hand thrust back axially in the discharge position by all-speed regulating means comprising a bellcrank lever actuated hydraulically by a push-rod plunger in dependence on the supply pressure which exists periodically between two successive injections within the axial duct of the distributor, the movement of said lever under the action of said plunger being limited by an adjustable stop and controlled in dependence on a manually adjustable elastic push-rod, said metering ring being also controlled in the discharge position by means which are responsive to the speed of rotation of the engine and to the controlling action of the accelerator.

It is apparent that the suppression or momentary reduction of the discharge by means (either automatic or controlled) for carrying out a displacement of the metering element will result in a variation in the rate of flow to the injectors and especially an excess quantity which will facilitate starting.

Further properties of the invention will be brought out by the following description which relates to an injection pump for a four-cylinder engine, said pump being provided with the improvements in accordance with the invention and being illustrated diagrammatically in the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of the pump assembly with mechanical regulator and automatic feed;

FIG. 2 is a transverse sectional view in the plane of the admission openings along line "-11 of FIG. 1 and showing the means for supplying the pump;

FIG. 3 is a transverse sectional view taken along line IIIIII of FIG. I in the plane of the high-pressure pumping elements;

FIGS. 4, 5, 6, 7, 8 and 9 are diagrams relating to the mode of operation of the pump;

FIG. 10 is a view in elevation which is partially broken away and shows a safety device provided in the event of seizure of the metering ring;

FIG. 11 is a view taken at right angles to FIG. 10 as considered in the direction of the arrow XI;

FIG. 12 is a view in sectional elevation and partially broken away showing a pump with hydraulic governor and fitted with means for producing the displacement of the metering ring as a function of the speed;

FIG. 13 is a diagrammatic front view of a flow-correcting system for producing action on the metering ring;

FIG. 14 is a view taken at right angles to FIG. 13;

FIG. 15 is an axial sectional view of a metering ring arranged to divide each injection into two stages;

FIG. 16 is a diagram of the two injection stages which are obtained as a result of the arrangement of FIG. '15.

In the form of construction which is illustrated in FIGS. 1 to l 1, the injection pump comprises a supply pump I of the vane type which is incorporated in one end of the injection pump and draws up previously filtered fuel from a storage tank (not shown) for subsequent delivery at a so-called supply pressure (or transfer pressure") which is variable with the engine speed by means of a pressure governor which discharges the excess fuel at the pump inlet 2. The fuel which passes out of the pump 1 and is at the supply pressure arrives at a distributor 3 via a duct 4 which is formed in a stationary body or shell 5 and via three openings 6 which are supplied from said duct 4 through a semicircular channel 7 formed in said stationary shell 5. The fuel then penetrates into the axial duct 8 of the distributor 3 via supply passages 9 which are formed in said distributor.

The fuel thus flows on the one hand so as to separate the pumping elements 10 in the centrifugal direction and on the other hand as a bypass or diversion through a valve 11 beneath a push-rod plunger 12 which controls automatically the displacement of the metering ring 13. Finally, if the need should arise, the fuel can supply an automatic advance device 15, the mode of action of which will be described hereinafter.

The valve 11 is made up of a ball and a spring which is calibrated so as to open only in respect of a predetermined value of the supply pressure and therefore in respect of a given speed comprised between the starting speed and the slowrunning speed in order to actuate the ring 13 by means of a bellcrank lever 16 only at the moment which is chosen and depending on the application which is contemplate; the ring 13 will be put to discharge only at this moment (elimination of overpressure).

The supply pressure therefore produces action on the bellcrank lever 16 by means of the plunger 12, thereby producing a translational movement of the metering ring 13 which has the effect of displacing the end of injection. This operation will be described below in greater detail.

The pumping means which are constituted by the two plungers 10 carried by the distributor 3 and consequently driven in rotation by this latter are outwardly displaced (suction stage) under the action of the supply pressure to a maximum extent as previously determined by a stop 18 which limits the displacement of shoes 17 which are actuated by the plungers 10 (it should be noted that the total mass flow is equal to the maximum operating flow on full load as increased by the excess flow at the time of start-up).

Rollers 21 provide a contact between the pumping elements and an internal cam ring 20 during the movement of rotation of the distributor unit 3. As a result of the upward motion of said rollers on suitable ramps or flanks formed by the earns, the plungers 10 are caused to move in the centripetal direction (delivery stage) while compressing the fuel which is trapped between the plungers and which flows through the duct 8 of the rotary distributor 3, then arrives via a radial distribution passage 8a in ducts 22 which are connected to the injectors, thus producing the injection.

A ball-valve 23 which is incorporated in the circulation system and calibrated at a value comprised between the supply pressure and the injection pressure serves to isolate the two supply and high-pressure systems (discharge side) in spite of possible angular interferences of the different ducts. During the period of admission, said ball-valve is closed and there is no readmission in countercurrent flow through the discharge end.

The cam ring 20 which may be connected if necessary to a known automatic advance system 15 which imparts a slight movement of rotation to said ring permits angular displacement of the cam flanks, thereby producing the delivery stroke of the plungers as a function of the engine speed (advanced injection as a function of the speed).

If provision is made for an incorporated regulating system which is adapted to impart an axial translational movement to the metering ring 13, said movement will result in a variation in flow rate.

The pump of FIGS. 1 to 11 comprises a centrifugal governor, the flyweights 24 of which produce by means of a lever 26 which is pivotally mounted on a fulcrum bearing 27 and under the action of centrifugal force an action which is opposed to the action of a controlling spring 25. The other extremity of the spring 25 is attached to an inner lever 28 which provides a connection with the accelerator (not shown in the drawings) by means of an outer lever 29 which is rigidly fixed to said lever 28.

At a constant speed, the energy of the flyweights is maintained in equilibrium by the tension of the regulating spring 25. If the speed of the engine falls off as a result of an increase in the load torque, the energy of the flyweights decreases and the governor reduces the tension of the spring 25 which releases the metering ring 13. Said ring is then subjected to the action of its restoring springs 36 and thus endowed with a movement of translation in the direction corresponding to a reduction in discharge (therefore in an increase in the injected flow) until a further equilibrium is established. If the speed increases, the reverse process takes place. The regulating spring 25 is actuated by the driver. A load applied to the spring 25, that is to say a speed, corresponds to each position given to the lever 28.

A manually adjustable spring-loaded correcting device 30 which is accessible from the exterior and calibrated so as to produce action only within a predetermined range of speeds prevents the movement of the plunger 12 which would otherwise tend to undergo a displacement as a function of the engine speed; the action of the device 30 thus results in a correction of the law of delivery which is appropriate for this type of pump in accordance with requirements. In fact, as said correcting device 30 comes into contact with the bellcrank lever 16, the load applied by the spring opposes the thrust developed by the supply pressure which produces action through the intermediary of the plunger 12.

An increase in supply pressure corresponds to an increase in speed, thereby compressing the correcting spring of the device 30 as well as the restoring springs 36 (the stiffness of which is judiciously chosen); the bellcrank lever 16 then displaces the metering ring 13 in the direction corresponding to a reduction in the full load fuel delivery. Conversely, a reduction in supply pressure corresponds to a reduction in speed and results in expansion of the correcting spring, thereby releasing the bellcrank lever 16 which in turn releases the ring 13. Said ring then moves under the action of the expansion of the springs 36 (only one of which is shown in FIG. 1) in the direction corresponding to an increase in the full load delivery.

An adjustable oblique screw 31 which is accessible from the exterior and applied against the lever 16 limits the displacement of said lever and thus necessarily limits the movement of translation of the metering ring 13 under the action of said lever (maximum-delivery setting).

The restoring springs 36 ensure that the metering ring 13 is continuously in contact either with the stop carried by the lever 16 in all positions of maximum fuel delivery or with the sleeve 24a of the flyweight governor 24 in all positions of low fuel delivery. Said ring 13 is coupled in rotation (for automatic advance) with the cam ring 21 by means of a guide 37 which also ensures guiding of said ring in translational motion. A ball-valve 38-can be mounted in the duct 8 of the distributor 3 in order to isolate and maintain the high-pressure system under pressure after the injection and at the moment of discharge or pressure relief as will be explained hereinafter.

The engine can be stopped by operation of a lever (not shown in'the drawings) which controls a push-bar 39. Said push-bar is intended to thrust the metering ring 13 at any moment into the position of full and immediate discharge and therefore into its position of zero fuel delivery to the injectors.

The diagrammatic FIGS. 4, 5, 6, 7, 8 and 9 are simplified presentations of the essential element of the invention, namely the metering system.

FIG. 4 shows the stage of supply (suction) of the plumbing means. The distributor 3 rotates within the stationary shell 5; the pumping elements or plungers 10 are not in contact with the flanks of the cams of the ring 20; the orifice 13a of the metering ring 13 is in partially overlapping relation with one of the corresponding radial ducts 40 which are formed in the distributor 3 and is isolated from the circulating system (duct 8) by the valve 23, said valve being calibrated at an opening pressure which is higher than the supply pressure and lower than the injection pressure. The fuel which is at the supply pressure I therefore fills the entire shaded zone; the passage 22 which extends to the injector is closed.

The diagrammatic FIG. 5 represents the stage of deliveryinjection after a movement of rotation of the distributor. The plungers 10 move towards the centerline as the rollers 21 and shoes 17 pass on the flanks of the cams of the ring 20 and compress the fuel, the pressure of which causes the valve 23 to open. The fuel at the injection pressure fills the entire shaded zone and is conveyed to the corresponding injector via a passage 22. The supply passage 9 and discharge passage 40 are closed. This is the injection stage.

The diagrammatic FIG. 6 shows the distributor 3 after continued rotation of this latter; the distributor communicates through one of its radial passages 40 with the passage 13a of the metering ring 13. This is the discharge stage. This stage begins as soon as one of the passages 40 is located opposite to the discharge passage or orifice 13a.

The plungers 10 continue to move towards each other under the action of the cam flanks of the ring 20 which produce action on the rollers but the flow to the injector is cut off since one of the passages 40 of the distributor communicates with the discharge passage 13a of the metering ring 13, thereby ensuring a discharge which results in an abrupt pressure drop.

The fuel fills the shaded zone and changes over from the injection pressure to the residual pressure. The supply is still cut off and the passageway to the injector is also closed.

The cycle then begins again in the case of the other cylinders until a complete revolution of the distributor pump which, as will be recalled, is designed in this case for a fourcylinder engine.

FIGS. 7, 8 and 9 show the principle of adjustment of the metering ring 13.

The passage or orifice 13a of the ring 13 is circular and of large diameter. The useful portion of said orifice is delimited by one-quarter of a circle (or a portion of a skew ellipse as ob tained by oblique drilling of the metering ring orifice, the curvilinear edge of which permits the selected variation of travel). In fact, as can be seen from- FIG. 7, the end of the discharge passage 40 of the rotary distributor 3 does not open into the discharge passage 13a of the ring. The entire quantity of fuel which is admitted between the plungers 10 passes to the injector. This setting corresponds to the overpressure" stage (starting of the engine).

FIG. 8 shows the metering ring 13 which has carried out a movement of translation a which causes the curvilinear edge of the opening of its passage 13a to intercept the opening of the corresponding distributor passage 40 so as to determine an angular discharge stage represented by the dimension 0:. Over the whole extent of the dimension (1, the fuel is partly discharged and a smaller quantity of fuel will therefore be supplied to the injector. Adjustment of this dimension determines the normal running setting.

FIG. 9 shows the metering ring 13 which has continued its movement of translation over a distance al, the dimension 111 being greater than the dimension a of the previous figure. If the point A which corresponds to the commencement of highpressure delivery of the passage 40 of the distributor 3 corresponds to the beginning of the injection, the entire quantity of fuel admitted between the plungers 10 is delivered to the discharge passage 13a; since the injector is not supplied, this is the stop stage or end of regulation.

The useful curvilinear portion (having the shape either of a circle or of a skew ellipse) of the outlet of the passage 13a of the metering ring 13 can be replaced by an inclined helical or rectilinear groove or by any other means for producing a variation in the angular discharge stage (dimension or) starting from a movement of translation of the ring 13.

The variation ofa which arises from the variation ofa results in a variation in the fuel delivery.

At the beginning of the discharge stage (end of injection) the high-pressure lines" which extend to the injectors are isolated from the discharge by means of the valve 38 which, as shown in FIG. 1, is a ball-valve. However, this is only a nonlimitative example since this valve may be replaced by a socalled volumetric re-suction valve of a well-known conventional type which can be fitted in its place within the duct 8 between the plane of the supply passages 9 and the plane of the high-pressure distribution passages 22. A volumetric resuction valve of this type will permit metering of the desired quantity of fuel and serve to balance the residual pressure between two injections in each high-pressure line.

By reason of the fact that the supply of fuel to the rotary distributor 3 is carried out via passages 9 which are specifically reserved for this purpose and that the high-pressure distribution in the passage 22 is ensured by means of the delivery passage 8a which is separate from said passages 9, the pump therefore comprises elementary equal-flow systems for the three stages, namely supply, injection and discharge.

The essential functional property of the pump is to ensure a constant commencement of injection and a variable end ofinjection as a function of the load torque of the engine or in other words of the quantity of fuel to be injected.

A driving shaft 32 rigidly fixed to a driving hub 33 which is connected to the engine to be supplied drives the distributor 3. Said shaft 33 rotates within a bearing 34 of the pump body which is suitably designed to permit mounting of the pump on the engine.

A seal 35 which is fitted in the bearing 34 serves to isolate the engine from the injection pump while lubrication of the different components is ensured by the fuel itself by means of a suitable leak of the distributor element.

In addition to the device for providing regulation by means of the ring 13, the improved pump in accordance with the invention can also be endowed with further properties.

It thus follows from the foregoing that, in order to overcome the disadvantages arising from accidental seizure of the ring 13 on the rotary distributor 3, the pump can comprise safety means adapted to cause the injection pressure to fall to zero instantaneously, thereby resulting in stoppage of the engine which is supplied by the pump.

A preferred embodiment of the safety means aforesaid is illustrated in FIGS. and 11. In this form of construction, said means consist of an auxiliary chamber 43 having the shape of a radial lug which is fixed on the ring 13 and adapted to cooperate with stationary stops 41 and 42 in the form of studs. Said auxiliary chamber 43 communicates with that portion of the axial duct 8 which is located downstream of the valve 23 via an annular channel 44 formed in the distributor 3 and via a duct 46 which provides a communication between the duct 8 and the channel 44. During normal operation, the auxiliary chamber 43 constitutes a dead volume which does not play any part in the operation.

In the event of seizure of the distributor 3, the ring 13 (which is nonrotating under normal operating conditions) is driven in rotation by said distributor but in that case the auxiliary chamber 43 cooperates with either of the two studs 41 and 42 (depending on the direction of rotation of the pump), the extremities of said studs being located on the path of said chamber so that this latter is broken under the effect of the impact when it strikes one of said studs 41, 42, with the result that the delivery duct 8 is put into communication with the interior of the pump casing. In other words, total discharge takes place, the injection pressure falls to zero and the engine stops.

In FIGS. 1 to 11, the adjustment (in the axial direction) of the ring 13 as a function of the speed of rotation of the engine is carried out mechanically by the centrifugal governor 24.

The above-mentioned mechanical adjustment can be replaced by a system of hydraulic regulation carried out by the push-rod plunger 12 in conjunction with the arrangement which is shown in FIG. 12.

In this arrangement, the bellcrank lever 16a (which is actuated by the push-rod plunger 12 in order to carry out the axial translation motion of the ring 13) comprises an additional arm 16!; controlled by a regulating spring 48 which is mounted in series with a slow-running spring 50. Both springs work in opposition with respect to the push-rod plunger 12. The spring 48 is interposed between two supporting cups 51a-51b which are slidably mounted on a guide rod 49, said rod being screwed in the casing at 49a. Said arm 16b is applied against the cup 51a and the return travel of the arm is limited by a nut 52 and a locknut 53 which are screwed on the threaded extremity of the rod 49. The nut 52 is intended to regulate the overpressure delivery by ensuring that provision is made between the elements 51a and 16b for a clearance which corresponds to the necessary travel of the metering ring 13 in order to eliminate the excess quantity in the flow which is necessary for starting.

An outer lever 55 which is connected to the accelerator is rigidly coupled (for rotation) with an inner lever 54 and this latter is applied against a supporting cup 47 which serves as a bearing surface for one end of the slow-running spring 50, the other end of which is applied against the supporting cup 5 lb.

During normal operation, the accelerator therefore controls the load on the regulating spring 48.

At constant speed, the metering ring 3 is in an equilibrium position which is determined by the thrust of the plunger 12 (proportional to the speed of rotation of the pump) and the compression of the spring 48.

If the speed decreases, the thrust of the plunger 12 decreases in favor of the regulating spring 48 which displaces the ring 13 by means of the lever 16:: and in the direction of a reduction of discharge (that is to say in the direction of in creased delivery to the injectors) until the appearance of a new equilibrium, this being achieved without any change in the position of the accelerator.

The reverse process takes place in the case of an increase in speed.

It has been seen earlier that the automatic advance system 15 produces action on the angular position of the cam ring 20 which carries the guides 37 provided for the sliding motion of the metering ring 13 which is thus made angularly dependent on the position of the ring 20. This can be turned to useful account for the purpose of producing a correction of the flow rate at the time of angular motion of the metering ring (under the action of the advance system 15). To this end and as shown in FIGS. 13 and 14, the ring 13 is provided in the zone of action of the feeler 16x carried by the lever 16 (or 16a) with a cam profile 13:: which produces a slight translational movement of the ring 13 relative to said feeler 16x (considered as a fixed bearing point). Said translational movement results in a slight variation in discharge and therefore in delivery of the injected fuel under the action of the automatic advance system.

In some cases, the injection into each cylinder of an engine can advantageously be preceded by a preinjection" or pilot injection".

A pre-injection of this type can readily be carried out by means of the metering ring 13 which is accordingly provided as shown in FIG. 15 and independently of the discharge passage 13a with a discharge slot 13b, said slot being intended to cooperate with a discharge groove 60 which is formed in the rotary distributor 3 and adapted to communicate with each discharge passage 40 of said distributor. As a result of cooperation of the slot 13b with each groove 60, there takes place at a given moment a slight discharge which divides the injection stage into two or in other words converts an injection into a pre-injection which is separated from the injection proper or main injection by a short auxiliary discharge, the value of the pre-injection being determined by the positions and dimensions of the slot 13b and of the groove 60.

The action of the elements 13b and 60 becomes clear from 'the diagram of FIG. 16 in which the tip of one of the cams of the cam ring 20 is shown diagrammatically, the travel C of one of the plungers 10 being plotted as ordinates while the angular values of rotation of the distributor 3 are plotted as abscissae (O), the direction of rotation being designated as R.

A study of the diagram of HG. 16 as well as the diagram of FIG. 15 thus shows that the complete injection stage corn: prises pre-injection ll, initial discharge D1, main injection or second injection l2 and final discharge or second discharge D2.

The improved injection pump which has been described in the foregoing makes it possible to obtain:

constant initial injection,

overpressure at the time of starting,

automatic adjustment of delivery to the injectors,

safety stopping of the engine in the event of seizure of the metering ring on the distributor,

hydraulic regulation of the delivery,

correction of delivery as a function of the automatic advance,

pre-injection or pilot injection followed by the main injection.

What I claim is:

1. In a fuel injection pump of the type comprising a rotary distributor and a supply pump which are mounted within a casing and both driven by the combustion engine in which the injectors are to be supplied from the said injection pump, the said rotary distributor being pierced by an axial duct which communicates respectively with a high-pressure radial distributor passage which opens successively into the outgoing lines to the injectors, with radial admission passages adapted to communicate periodically with stationary supply ducts which are continuously connected to the discharge and of the supply pump, with radial bores containing plungers operated by the cams of a nonrotating external cam ring, and with means for metering the fuel flow to the injectors by discharging a fraction of the fuel which is delivered by the plungers, the fact that the metering means consist of a nonrotating metering ring which is slidably mounted on the rotary distributor in leak-tight manner and has a discharge orifice which is capable of communicating in a variable manner with radial discharge passages formed in the rotary distributor and extending from the axial duct of the said distributor in order that the fuel should be discharged in a variable manner both in time-duration and in flow rate according to the axial position taken up by the said metering ring on the said distributor and according to the relative angular position of the said passages,

the said ring being on the one hand thrust back elastically by oppositely acting springs towards a position corresponding to zero discharge and on the other hand thrust back axially in the discharge position by all-speed regulating means comprising a bellcrank lever actuated hydraulically by a push-rod plunger in dependence on the supply pressure which exists periodically between two successive injections within the axial duct of the distributor, the movement of the said lever under the action of the said plunger being limited by an adjustable stop and controlled in dependence on a manually adjustable elastic push-rod, the said metering ring being also controlled in the discharge position by means which are responsive to the speed of rotation of the engine and to the controlling action of the accelerator.

2. An injection pump in accordance with claim 1, wherein the means which are responsive to the speed consist of a centrifugal governor whose action on the metering ring is opposed elastically by means of the accelerator.

3. An injection pump in accordance with claim 1, wherein the means which are responsive to the speed are constituted by the bellcrank lever which is subjected to the action of the push-rod plunger and provided with a third arm which is controlled from the accelerator by means of a slow-running spring mounted in series with an adjustable regulating spring.

4. An injection pump in accordance with claim 1, wherein, in order to prevent any damage resulting from seizure of the metering ring on the rotary distributor, the said ring is provided with an auxiliary chamber which communicates continuously with the axial duct of the distributor and is designed in the form of a radial lug which projects from the periphery of the metering ring and is capable in the event of rotation of the ring of coming into contact with at least one stationary stop stud which breaks the said lug away from the ring in order to cause full discharge which results in stopping of the engine.

5. An injection pump in accordance with claim '1 further comprising a system for correction of discharge (therefore of flow rate) controlled by an automatic advance system for producing an angular displacement of the cam ring with which the metering ring is rigidly coupled for rotation and the said correction system consists of a cam-profile groove provided on the metering ring and intended to cooperate with that portion of the bellcrank lever which produces action on the said metering ring.

6. An injection pump in accordance with claim 1, wherein, in order to obtain a pre-injection which precedes the injection proper or main injection, the metering ring is provided with a discharge slot on which grooves formed in the surface of the said distributor can be superposed in a transient manner during the rotation of the distributor, the said grooves being each intended to communicate respectively with the outlet of one of the discharge passages of the distributor.

Claims (6)

1. In a fuel injection pump of the type comprising a rotary distributor and a supply pump which are mounted within a casing and both driven by the combustion engine in which the injectors are to be supplied from the said injection pump, the said rotary distributor being pierced by an axial duct which communicates respectively with a high-pressure radial distributor passage which opens successively into the outgoing lines to the injectors, with radial admission passages adapted to communicate periodically with stationary supply ducts which are continuously connected to the discharge and of the supply pump, with radial bores containing plungers operated by the cams of a nonrotating external cam ring, and with means for metering the fuel flow to the injectors by discharging a fraction of the fuel which is delivered by the plungers, the fact that the metering means consist of a nonrotating metering ring which is slidably mounted on the rotary distributor in leak-tight manner and has a discharge orifice which is capable of communicating in a variable manner with radial discharge passages formed in the rotary distributor and extending from the axial duct of the said distributor in order that the fuel should be discharged in a variable manner both in time-duration and in flow rate according to the axial position taken up by the said metering ring on the said distributor and according to the relative angular position of the said passages, the said ring being on the one hand thrust back elastically by oppositely acting springs towards a position corresponding to zero discharge and on the other hand thrust back axially in the discharge position by all-speed regulating means comprising a bellcrank lever actuated hydraulically by a push-rod plunger in dependence on the supply pressure which exists periodically between two successive injections within the axial duct of the distributor, the movement of the said lever under the action of the said plunger being limited by an adjustable stop and controlled in dependence on a manually adjustable elastic push-rod, the said metering ring being also controlled in the discharge position by means which are responsive to the speed of rotation of the engine and to the controlling action of the accelerator.

2. An injection pump in accordance with claim 1, wherein the means which are responsive to the speed consist of a centrifugal governor whose action on the metering ring is opposed elastically by means of the accelerator.

3. An injection pump in accordance with claim 1, wherein the means which are responsive to the speed are constituted by the bellcrank lever which is subjected to the action of the push-rod plunger and provided with a third arm which is controlled from the accelerator by means of a slow-running spring mounted in series with an adjustable regulating spring.

4. An injection pump in accordance with claim 1, wherein, in order to prevent any damage resulting from seizure of the metering ring on the rotary distributor, the said ring is provided with an auxiliary chamber which commuNicates continuously with the axial duct of the distributor and is designed in the form of a radial lug which projects from the periphery of the metering ring and is capable in the event of rotation of the ring of coming into contact with at least one stationary stop stud which breaks the said lug away from the ring in order to cause full discharge which results in stopping of the engine.

5. An injection pump in accordance with claim 1 further comprising a system for correction of discharge (therefore of flow rate) controlled by an automatic advance system for producing an angular displacement of the cam ring with which the metering ring is rigidly coupled for rotation and the said correction system consists of a cam-profile groove provided on the metering ring and intended to cooperate with that portion of the bellcrank lever which produces action on the said metering ring.

6. An injection pump in accordance with claim 1, wherein, in order to obtain a pre-injection which precedes the injection proper or main injection, the metering ring is provided with a discharge slot on which grooves formed in the surface of the said distributor can be superposed in a transient manner during the rotation of the distributor, the said grooves being each intended to communicate respectively with the outlet of one of the discharge passages of the distributor.

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