US3417703A

US3417703A - Fuel injection pump

Info

Publication number: US3417703A
Application number: US588550A
Authority: US
Inventors: Eckert Konrad; Eheim Franz
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1965-10-15
Filing date: 1966-10-21
Publication date: 1968-12-24
Anticipated expiration: 1985-12-24
Also published as: GB1162694A; DE1258187B; FR1462334A; SE327223B; US3380052A; DE1541464B2; GB1171628A; FR1462344A; DE1541464A1

Description

Dec. 24, 1968 K. ECKERT ErAL 3,417,703

FUEL INJECTION PUMP Filed oct. 21, 196s s sheets-sheet 1 30a ,i i] i0 `c0 w g "7 i' g 25,4 120 fg 25v f5 fda 7a/Jbl' f J/ f a y J/ 9L /f /'a/ j a, y i 5 Ii/J//s/ I j il? 25a l l I l |i /a 7 l i 5 Ja n M11/M7099: /nru/ chaff Franz, Eik/P1 DCC. 24, 1968 K ECKERT EI'AL FUEL INJECTION `PUMP Filed Oct. 21. 1966 5 Sheets-Sheet 2 l i Q5 Dec. 24, 1968 Filed Oct. 2l, 1966 K. EcKERT ETAL 3,417,703

FUEL INJECTION PUMP 5 Sheets-Sheet 5 Dec. 24, 1968 K. Ecm-:R1- E'r AL 3,417,703

FUEL INJECTION PUMP Filed Oct. 21. 1966 5 Sheets-Sheet 4 Dec. 24, 1968 K, ECKERT ETAL 3,417,703

FUEL INJECTION PUMP Filed Oct. 21, 1966 5 Sheets-Sheet 5 United States Patent O 1s Claims. icl. 10s-41) ABSTRACT F THE DISCLOSURE A fuel injection pump for internal combustion engines wherein the amounts of fuel admitted to the cylinders of the engine can be varied infinitely by means of a shuttle piston movable from a starting position to an open position in which latter position fuel pumped by the pump is discharged through an overflow channel so that injection of fuel to the cylinders of the engine is terminated and in which a return movement of the shuttle piston to the starting position under the force of a return spring is regulated by adjustable throttling means controlling outflow of fuel from the chamber in which the shuttle piston reciprocates. The pump includes further rst adjusting means for regulating the distance between the starting and open position of the shuttle piston, second adjusting means for regulating the braking action of the throttling means, and common actuating means for the two adjusting means.

The present invention relates to injection pumps, and more particularly to improvements in fuel injection pumps of the type disclosed in Patent No. 3,122,100 granted to Bessiere on Feb. 25, 1964.

The patent to Bessiere discloses a self-regulating fuel injection pump wherein the outilow of fuel from a working cylinder is controlled by a regulating valve, also called shuttle piston, which is provided with an inclined face and is rotatable in its chamber to thereby establish or terminate a connection between two sections of an overflow channel. The operation of the pump is regulated automatically in each speed and load range of the engine whose cylinders receive fuel from the working cylinder. However, it is often desirable that the operator of the vehicle which is driven by an engine receiving fuel from an injection pump should be in a position to arbitrarily select the amounts of fuel which are injected into the cylinders of the engine, especially to arbitrarily select such amounts when the engine is not idling or when the engine is not driven at a maximum speed. The operation is smoother if the driver of the vehicle is in a position to determine the amounts of fuel in each but the two extreme conditions of operation.

Accordingly, it is an important object of the present invention to provide a novel and improved injection pump for liquid fuel and to construct and assemble the pump in such a way that its operation will be fully automatic when the engine receiving fuel therefrom is idling Or operates at a maximum permissible speed but that the operator will be in a position to determine the amounts of injected fuel in the entire intermediate range of operation.

3,417,703 Patented Dec. 24, 1968 ICC Another object of the invention is to provide a fuel injection pump of the just outlined character wherein all such adjustments which are necessary in actual operation can be carried out by means of a single actuating member.

A further object of the invention is to provide a fuel injection pump wherein the amounts of fuel admitted to the cylinders of an internal combustion engine can be varied infinitely so that such amounts can be Selected with utmost accuracy by full consideration of momentary operating conditions.

An additional object of the invention is to provide a novel system of adjustable throttling elements which can be utilized in our fuel injection pump.

Briefly stated, one feature of our present invention resides in the provision of a fuel injection pump for internal combustion engines, particularly for internal combustion engines of automotive vehicles. The pump comprises a main cylinder or working cylinder, a main piston or working piston reciprocably received in the main cylinder to respectively draw and expel fuel therefrom, drive means for reciprocating the main piston at a speed which is a function of engine speed, fuel line means arranged to receive fuel from the main cylinder for injection into the cylinder or cylinders of the engine, overflow channel means connected with the main cylinder and including a regulating chamber, an adjustable regulating Valve or shuttle piston reciprocable in the regulating chamber and movable from at least one starting position to at least one open position in which latter position the overflow channel means is effective to evacuate fuel from the main cylinder instead of the fuel line means so that the injection of fuel into the cylinder or cylinders of the engine is terminated on movement of the regulating valve to open position, biasing means for urging the regulating valve to starting position, auxiliary pump means operating in synchronism with the main piston to deliver fuel to the regulating chamber for moving the regulating valve from starting position while the main piston performs a working stroke, a discharge line connected with the regulating chamber to evacuate fuel during movement of the regulating piston under the action of biasing means back toward starting position while the main piston performs a return stroke, adjustable throttling means for braking the flow of fuel through the discharge line during return movement of the regulating piston toward starting position, first adjusting means for regulating the distance between the starting and open positions of the regulating valve, second adjusting means for regulating the braking action of the throttling means, and common actuating means for the two adjusting means.

The operative connection Abetween the two adjusting means preferably comprises an adjustable coupling which is arranged to maintain `the second adjusting means in at least one rst position corresponding to minimal braking action of the throttling means when the first adjusting means is set for operation of the engine at full load or higherepartial-load, and to maintain the second adjusting means in second positions corresponding to increasing braking action of the throttling means as a function of changes in load when the first adjusting means is set for operation of the engine at lower-partialload and during idling. In the first position of the second adjusting means, the braking action of the throttling means is too low or too ineffective to prevent return movement of the regulating valve to starting position while the engine operates at less than a preselected maximum speed (i.e., while the main piston reciprocates at less than a predetermined maximum speed) so that the first actuating means can select the amounts of fuel which are supplied to the fuel line means in the entire full-load and higherpartialload range of engine operation while the engine speed remains fbelow the predetermined maximum speed.

The fuel injection pump preferably comprises secondary throttling means adjustable independently of the rst mentioned throttling means to determine the rate of fuel ow in the discharge line in the first position of the second adjusting means by bringing about a braking action which exceeds the braking action of the iirst mentioned throttling means when the engine operates at full load or at higher-partial-load.

The novel features "which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved fuel injection pump itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. l is a diagrammatic sectional View of a fuel injection pump which embodies one form of our invention;

FIG. 2 is a similar diagrammatic sectional view of a second fuel injection pump;

FIG. 3 is a fragmentary front elevational view of a coupling in the second pump as lviewed in the direction of arrow Ill in FIG. 2;

FIG. 4 is a diagrammatic sectional view of a third fuel injection pump;

FIG. 5 is a fragmentary diagrammatic sectional view of a fourth pump which constitutes a modification of the pump shown in FIG. 4;

FIG. 6 is a similar fragmentary sectional view of a fifth pump which also constitutes a slight modification of the pump shown in FIG. 4;

FIG. 7 is a fragmentary diagrammatic sectional view of a sixth fuel injection pump which is similar to the pumps of FIGS. 4 to 6;

FIG. 8 is an enlarged fragmentary horizontal section as viewed in the direction of arrows from the line VIII- VIII of FIG, 4;

FIG. 9 is a fragmentary diagrammatic sectional View of aseventh fuel injection pump which constitutes a modification of the pumps shown in FIGS. 4 to 7;

FIG. 10 is a fragmentary section through the body of a fuel injection pump and illustrates a lid serving to normally seal the opening which affords access to the throttles; and

FIG. l1 is a similar fragmentary section through the pump fbody and illustrates a device which can be used to preset two needle-like throttles.

Referring rst to FIG. l, there is shown a fuel injection pump which comprises a pump body or housing 1 including a working cylinder or main cylinder 2 and an auxiliary cylinder 3. The two cylinders are coaxial and respectively receive a main piston or working piston 4 and an auxiliary piston 5. The pistons 4, 5 together form a multi-stage piston which is rotated and reciprocated by a drive D of the internal combustion engine E whose cylinders receive fuel from the working cylinder 2 via fuel lines 12 only one of which is actually shown in FIG. l. The piston 5 and its cylinder 2i together constitute an auxiliary pump whose purpose is to shift a reciprocable regulating valve or shuttle ,piston 13 in a regulating chamber 15. The diameter of the auxiliary piston S extends the diameter of the working piston 4, and these pistons are rotated and reciprocated at a speed which is a function of the rotational speed of the engine E. The drive D which transmits motion from the engine E to the piston 5 may be constructed in a manner as disclosed, for example, in U.S. Patent No. 3,058,455 to Hfer et al., granted Oct. 16, 1962, which is assigned to the same assignee. A drive including a cam fixed to the piston 5 and rotated by the engine, stationary roller followers which engage the face of the cam, and a spring lwhich biases the cam against the followers is preferred at this time. Reciprocatory movements of the pistons 4, 5 are used to respectively suck and expel fuel from the cylinders 2, 3, and rotary movements of the piston 4 are utilized to distribute measured amounts of fuel to successive fuel lines 12. Each such fuel line receives a measured amount of fuel once during each revolution of the piston 4.

The pump body 1 defines a suction space 6 which is connected with a fuel pump P by a pipe 1a. A supply bore 7 can connect the suction space 6 with a circumferential groove 8 of the working piston 4, and the latter comprises an axially extending bore 9 which connects the groove 8 with the interior of the working cylinder 2. The position of the supply bore 7 is selected in such a way that its discharge end is sealed by the piston 4 when the latter performs a working (upward) stroke; however, when the piston 4 moves downwardly (suction stroke), the space 6 can communicate with the groove 8 through one of several axially parallel peripheral grooves 10 of the working piston so that the latter can suck fuel into the interior of the working cylinder 2. The working piston 4 is provided with an axially parallel peripheral distributor groove 11 which connects the interior of the working cylinder 2 with one of the fuel lines 12 during each working stroke of the piston 4. Each fuel line 12 contains a one-way valve 12a which prevents return flow of fuel. The injection nozzles (not shown) at the ends of the fuel lines 12 admit fuel into the respective cylinders of the engine E. The intake ends of all fuel lines 12 are located in a common plane which is normal to the axis of the working piston 4, and such intake ends are equidistant from each other. As stated before, one fuel line 12 will communicate with the distributor groove 11 during each working stroke of the piston 4 and the number of such working strokes per revolution of the piston 4 corresponds to the number of cylinders in the engine E, i.e., to the number of fuel lines 12.

The aforementioned regulating chamber 15 forms part of an overflow channel which further comprises a bore 14 connecting the chamber 15 with the interior of the cylinder 2 and a bore 16 connecting the chamber 15 with the suction space 6. The valve 13 comprises two cylindrical sections or plungers 13a, 13b which are slidably but sealingly fitted into the chamber 15 and define between themselves an annular groove or recess 17 adapted to establish a connection between the bores 14 and 16. The annular end face 17a of the plunger 13b will permit partial or full communication between the chamber 15 and bore 16, depending on the axial position of the valve 13 which is permanently biased by a helical return spring 19 tending to maintain the plunger 13a in abutment with an axially reciprocable adjusting pin 20. This pin will determine the starting or initial position of the valve 13 and forms part of a rst adjusting unit which further comprises a helical expansion spring 27, a roller follower 20a at the outer end of the pin 20, and a reciprocable cam 26 which is guided in stationary ways 26A for movement in directions at right angles to the axis of the pin 20. When the plunger 13a abuts against the inner end of the adjusting pin 20, the plunger 13b seals the annular groove 17 from the bore 16 so that the latter is sealed from the bore 14 and from the interior of the working cylinder 2. In order to permit escape of fuel from the cylinder 2 into the suction space 6, the valve 13 must be shifted in a direction to the right until the autres 5 end face 17a of the plunger 13b permits at least some communication between the annular groove 17 and bore 16.

The function f the auxiliary pump including the piston and cylinder 3 is to shift the valve 13 axially against the opposition of the return spring 19 so that the plunger 13b will be in a position to permit ow of fuel from the annular groove 17 into the bore 16. This automatically interrupts the admission of fuel to that fuel line 12 which is in registry with the distributor groove 11 because the resistance offered by one-way valves 12a and the injection nozzles (not shown) to the fiow of fuel through such fuel lines exceeds the resistance offered 'by the

overfiow channel

14, 15, 16 to the tiow of fuel from the interior of the working cylinder 2 back into the suction space 6. In other words, whenever the valve 13 establishes a path for flow of fuel via overflow channel 14-16, the delivery of fuel to the respective fuel line 12 is terminated in a fully automatic way.

The auxiliary cylinder 3 receives fuel from the suction space 6 through a supply bore 21a and through one of several axially parallel grooves 5a machined into the periphery of the piston 5. One of the grooves 5a will communicate with the supply bore 21a when the piston 5 completes a suction (downward) stroke but each of these grooves is invariably sealed from the bore 21a when the piston 5 performs an upward stroke whereby the fuel filling the interior of the auxiliary cylinder 3 escapes through a feed line 21 which discharges into the left-hand end of the regulating chamber 15, i.e., at one axial end of the plunger 13a. The feed line 21 contains a one-Way valve 22 which prevents return flow of fuel from the chamber 15 into the interior of the auxiliary cylinder 3. The intake end of the feed line 21 receives fuel through one of the grooves 5a when the piston 5 performs an upward stroke. Fuel entering the left-hand end of the regulating chamber 15 via feed line 21 will displace the valve 13 against the opposition of the spring 19 whereby the length of strokes necessary to be performed by valve 13 in order to establish a connection between the bores 14, 16 of the overflow channel 14-16 depends on the axial position of the adjusting pin and also on the fact whether or not the spring 19 had enough time to expel fuel from the chamber 15 and to return the valve 13 into actual abutment with the pin 20 before the auxiliary piston 5 starts to perform the next working stroke.

In normal operation of the engine, the return spring 19 will move the plunger 13a back into abutment with the adjusting pin 20 before the auxiliary piston 5 begins to perform the next working stroke. During such return movement of the valve 13 in a direction to the left, as viewed in FIG. 1, the plunger 13a expels a certain amount of fuel through a discharge line 23 which connects the left-hand end of the regulating chamber 15 with the interior of the auxiliary cylinder 3. The discharge line 23 is provided with a throttling orifice or passage 24l whose cross-sectional area may be varied by an adjustable needle-like throttle 25. The purpose of the throttle 25 is to brake the return flow of fuel via discharge line 23 in such a way that, starting from a predetermined speed of the engine E, the spring 19 will be unable to return.

the plunger 13a all the way into abutment with the adjusting pin 20 before the piston 5 starts the next working stroke. Thus, the valve 13 will have to cover a shorter than normal distance in order to permit flow of fuel from the `bore 14 into the bore 16 so that the amount of fuel admitted to the fuel lines 12 is reduced accordingly, namely, as a function of the position of the valve 13 when the auxiliary piston 5 begins to perform an upward stroke. The exact engine speed at which the valve 13 cannot return into actual abutment with the adjusting pin 20 can be selected by a cam 28 which controls the axial position of the throttle 25. The regulating action of the valve 13 upon the amounts of fuel admitted to the fuel lines 12 is called a liquid abutment or liquid stop and is fully disclosed in the aforementioned patent No. 3,122,100 to Bessiere.

As long as the speed of the engine E remains below the aforementioned predetermined speed, the amounts of fuel admitted to the fuel lines 12 will depend on the distance which the valve 13 must cover from abutment with the adjusting pin 20 to a position in which the end face 17a of the plunger 13b allows fuel to tiow from the bore 14 into the bore 16. The greater such distance, the greater is the amount of fuel which is admitted into a fuel line 12. The just mentioned distance will depend on the axial position of the adjusting pin 20, i.e., on the position of the aforementioned cam 26 which is shiftable by an actuating member here shown as a lever 30 rockable about a pivot pin 30a between a plurality of positions two of which are indicated by phantom lines. If the cam 26 is moved upwardly, the spring 27 can Shift the pin 20 in a direction to the left so that the stroke of the valve 13 increases and each of the fuel lines 12 receives more fuel. When the engine operates at maximum load, the pin 20 will be shifted to its leftmost position which means that the actuating lever 30 will be rocked in a counterclockwise direction.

The aforementioned throttle 25 is biased by a helical expansion spring 29 which tends to maintain a roller follower 25a of the throttle in contact with the face of the cam 28. The

cams

26 and 28 are coupled to each other by an adjustable coupling device which resembles a turnbuckle and includes a pair of spindles 26h, 2817 respectively connected with the

cams

26, 28 and having left-hand and right-hand threads, and a spindle nut 32 which meshes with `both spindles so that its rotation in opposite directions will respectively move the

cams

26, 28 nearer to or away from each other. The

parts

25a, 28, 29 constitute a second adjusting unit which controls the throttle 25 and whose operation is synchronized with that of the adjusting

unit

20, 20a, 26, 27. The cam 28 is guided in the ways 26A.

The faces of the

cams

26, 28 are configurated in such a way that the cam 28 allows the throttle 25 to assume its outer end position (minimal throttling action) when the cam 26 maintains the adjusting pin 20 in an axial position corresponding to the operation of engine E under maximum load or higher-partial-load. Thus, and assuming that the actuating lever 30 is pivoted to its upper end position, the effective cross-sectional area of the throttling orifice 24 in the discharge line 23 will assume a maximum value and the adjusting pin 20 will be held in the left-hand end position to insure that the working piston 4 will inject into each fuel line 12 a maximum amount of fuel before the interior of the cylinder 2 begins to communicate with the suction space 6 via overflow channel 14-16'.

The liquid stop becomes effective regardless of the momentary load and insures that the amount of fuel admitted into the cylinders of the engine E is reduced automatically when the rotational speed of the engine exceeds a given value. This will be readily understood because, even when the throttle 25 is held in the fully withdrawn (outermost) position of FIG. l, it offers a certain resistance to return flow of fuel into the interior of the auxiliary cylinder 3 so that the spring 19 has no time to return the plunger 13a. into abutment with the adjusting pin 20 (in the leftmost position of this pin) when the intervals between successive upward strokes of the auxiliary piston 5 are too short. The actual amounts of fuel which are admitted into the fuel lines 12 can be regulated at the operators discretion until the rotational speed of the engine E reaches such given value, i.e., before the liquid stop becomes effective.

When the actuating lever 30 is moved to a position corresponding to idling or lower-partial-load upon the engine E, namely, when the adjusting pin 20 is moved to a predetermined extent from its left-hand end position, the follower 25a begins to track a lobe 28a of the cam 28 and the braking action of the throttle 25 is intensified. This reduces the cross-sectional area of the orifice 24. The rotational speed of the engine will decrease proportionally with rightward movement of the adjusting pin 20. In response to a certain rightward axial displacement of the pin 20, the speed of the engine E is reduced to idling speed, i.e., the amounts of fuel injected by the piston 4 into successive fuel lines 12 are reduced to a minimum.

In the fuel injection pump of FIG. l, the throttle 25 can limit the maximum rotational speed at full load and at higher-partial-load. In addition, the throttle 25 will determine various idling speeds and speeds at lowerpartial-load. However, it is normally preferred to provide a secondary throttle 31a which controls the effective area of a second throttling orice or passage 31 in the discharge line 23. The throttle 31a is adjustable, but not automatically, and its purpose is to take over some of the functions of the throttle `25. Thus, the throttle 31a will insure that the speed of the engine E at maximum load or higher-partial-load will not exceed a predetermined value, and the throttle 24 will be effective only when its follower 25a engages the lobe 28a of the cam 28, namely, when the tip of the throttle 25 begins to reduce the effective cross-sectional area of the orifice 24. In other words, the throttle 25 will control the operation of the engine E at lower-partial-load or during idling. When the secondary throttle 31a is provided, its setting is such that the cross-sectional area of the orifice 31 does not exceed the cross-sectional area of the orifice 24 when the throttle 25 is moved to its lefthand end position. This contributes to greater versatility of the fuel injection pump because the operator can arbitrarily select the maximum rotational speed of the engine at full load or at higher-partial-load, i.e., the maximum rotational speed can be selected in accordance with the requirements of the engine.

FIG. 2 illustrates a modified fuel injection pump. Such parts of this modified pump which are analogous to those already described in connection with FIG. l are denoted by similar reference numerals each followed by a prime.

An important difference `between the fuel injection pumps of FIGS. l and 2 is that the latter pump comprises a regulating valve or shuttle piston 13' which is rotatable and reciprocable in its chamber 15 and that the adjusting unit including the pin and cam 26 of FIG. l is replaced by an adjusting unit which changes the angular position of the valve 13'. The annular groove 17' can establish a connection between the bores 14', 16 of the overfiow channel in response to changes in axial and/or angular position of the valve 13. Futhermore, the fuel injection pump of FIG. 2 is provided with a different throttle which replaces the throttle 25 of FIG. l and controls the effective cross-sectional area of an orifice or passage 24'. Instead of being effective solely due to its axial displacement as the throttle 25, the throttle 25' of FIG. 2 is also turnable in the pump body 1' and such turning is utilized to change the effective cross-sectional area of the orifice 24' by means of an inclined edge face 39 of the throttle 25.

The plunger 13b of the valve 13 has an inclined end face 33 which replaces the end face 17a shown in FIG. l and controls the flow of fuel from the annular groove 17' into the bore 16'. As clearly shown in FIG. 2, the axial distance which must becovered by the valve 13 from its left-hand end (starting) position to the position in which the groove 171 can communicate with the bore 16 will be varied in response to changes in angular position of the valve 13. The starting position of the valve 13 is determined by a collar 34 which then abuts against an internal stop surface of the pump body 1. The adjusting unit which can change the angular position of the valve 13' comprises a shaft 36 which is coaxial with the plungers 13a', 13b' and is rotatable in the pump body 1. This shaft 36 is coupled with a flange 38 of the valve 13 by an axially parallel pin 37 which permits the valve to move axially toward and away from the shaft 36 in response to or against the bias of the return spring 19. The spring 19 is received in a recess provided in the left-hand end face of the shaft 36. It will be seen that the motion transmitting connection between the shaft 36 and valve 13 does not interfere with operation of the return spring 19' which tends to maintain the collar 34 in abutment with the stop surface 35.

The pump body 1 has a bore 1b which receives the throttle 25 and a portion of this bore 1b forms part of the discharge line 23 which connects the interior of the auxiliary cylinder 3 with the left-hand end of the regulating chamber 15. The secondary throttle 31a is adjustably mounted on the throttle 25' and controls the flow of fuel toward the orifice 24. The orifice 31 whose cross-sectional area is regulated by the throttle 31a is provided in the throttle 25.

The coupling vdevice which connects the throttle 25 with the shaft 36 comprises two

intermeshing gear segments

41, 42 best shown in FIG. 3. The function of the

gear segments

41, 42 is to change the angular position of the throttle 25' as a function of angular displacement of the shaft 36 and regulating valve 13. The actuating lever 30 is connected with the gear segment 41 or directly with the shaft 36, and the angular position of the throttle 25 with reference to the shaft 36 can be changed by means of a plate 45 which is releasably fixed to the shaft 36 by a nut 46 and has an arcuate slot 44 receiving the stem of the lock screw 43 which meshes with the gear segment 41. The latter is rotatable on the shaft 36 and is held against rotation with reference to this shaft when the lock screw 43 is drawn tight to prevent rotation of the shaft 36 with reference to the gear segment 41 or vice versa. By loosening the screw 43, the operator can change the angular position of the throttle 25 While the angular position of the shaft 36 remains unchanged,

or vice versa.

The angular position of the regulating valve 13 with reference to the throttle 25 and the inclination of the end face 33 on the plunger 13b are selected in such a way that the angular positions of the valve 13 requiring long travel of the end face 33 into a position to establish a connection between the bores 14 and 16 (when the engine operates at full load or higher-partial-load) correspond to such positions of the throttle 25' in which the effective crosssectional area of the orifice 24 is at a maximum value. In such positions of the throttle 25 only the secondary throttle 31a is effective to interfere with return flow of fuel through the discharge line 23' and to thus determine the maximum rotational speed of the engine at full load or higher-partial-load. When the angular position of the regulating valve 13 is such that a short axial movement of the valve sufiicies to establish a connection between the bores 14 and 16 (i.e., when the engine is idling or operates under lower-partial-load), the edge face 39 of the throttle 25' reduces the effective cross-sectional area Of the orifice 24 so that fuel flowing back through the discharge line 23' meets a greater resistance. In such ranges of operation of the engine, the secondary throttle 31a' is ineffective because the cross-sectional area of the orifice 24' is then smaller than that of the orifice 31.

A torsion spring 47 is provided to eliminate backlash between the teeth of the

gear segments

41, 42. One end of this spring is anchored in the pump body 1 and its other end is fixed to the gear segment 42.

The pump body 1 is further provided with a bypass channel 48 which connects the suction space 6 with the regulating chamber 15' and one end of which is normally sealed by the plunger 13a. A portion of the throttle 25' regulates the flow of fuel between the two branches of the bypass channel 48. The effective cross-sectional area of the throttling orifice 49 in the channel 48 can be varied by an inclinded edge face 50 of the throttle 25' in such a way that the area of the orifice 49 increases when the area of the orifice 24' decreases and vice versa. The plunger 13a will permit flow of fuel from the chamber into the bypass channel 48 before the chamber 15 is permitted to communicate with a relief channel 51 discharging into the bore 16 of the overflow channel. The relief channel 51 limits the strokes of the valve 13 by permitting fuel delivered by the auxiliary pu-mp 3', 5 to escape into the bore 16. The function of the bypass channel 48 is to vary the proportional band of regulation of the fuel injection pump.

In the fuel injection pumps of FIGS. 1 and 2, regulation during idling and during lower-partial-load upon the engine is effected by Varying the effective cross-sectional area of the throttling orifice 24 or 24 and by simultaneously varying the distance between the starting position of the valve 13 or 13 and that position in which the plunger 13b or 13b connects the

bores

14, 16 or 14', 16 of the respective overflow channel. FIG. 4 illustrates `a third fuel injection pump which differs from the previously described pumps in that during starting, idling and operation at lower-partial-load, the regu-lation is effected by means of fuel flowing through a spill passage or spill conduit 52. This spill passage 52 connects the suction space 6 with the regulating chamber 15 at the free end of the plunger 13a", i.e., with that region of the chamber 15" from which the valve 13" expels fuel in response to expansion of the return spring 19 and which receives fuel from the

auxiliary pump

3, 5". At very low engine speeds (during starting), at least a portion of fuel delivered by the auxiliary piston 55 can escape through the spill passage 52 so that the strokes of valve 13" from its starting position are short and the working piston 4" delivers to fuel lines 12" maximum amounts of fuel. The spill passage 52 has a throttling orifice 53 whose cross-sectional area may be regulated by a needle-like throttle 55. This throttle 55 insures that, once the engine is started and its r.p.m. rises to a certain value, the fuel pressure suflices to open the overflow channel 14"-16".

The interior of the `auxiliary cylinder 3 is further connected with a discharge line 54 corresponding to the discharge line 23 of FIG. 1 and containing an orifice 24 adjustable by a needle-like throttle 25 which brakes the return movement of valve 13 to starting position. The throttle 25 insures that the liquid stop develops when the engine speed rises to a predetermined value. The

throttles

25, 55 are adjustable by hand and their position then remains unchanged.

Such parts of the pump shown in FIG. 4 which are clearly analogous to those described in connection with FIGS. l and 2 are denoted by similar reference numerals each of which is followed by two primes.

The flow of fuel through the`discharge line 54 and spill passage 52 is further controllable by a rotary overriding throttle 56 which is coupled with the regulating valve 13" substantially in the same way as described in connection with the valve 13 and throttle 25 of FIG. 2. The throttle 56 can seal the line 54 and passage 52 or it can reduce the flow of fuel more than the

throttles

55 and 25". An inclined end face 57 of the regulating valve 13" performs the same function as the end face 33 shown in FIG. 2, i.e., the distance which the plunger 13b" must cover by moving from its starting position in order to establish a connection between the bores 14" and 16 can be varied by changing the angular position of the valve 13 through the intermediary of actuating lever 30, shaft 36" and coupling pin 37". The starting position of the valve 13l is determined by the collar 34 and stop surface 35".

The coupling between the shaft 36 and overriding throttle 56 includes gear segments 41", 42". The actuating lever 3G is connected with the gear segment 41" and can be pivoted to an infinite number of positions each of which corresponds to a different setting of the valve 13" and throttle 56. The backlash eliminating spring `47 is not shown in FIG. 4 but the coupling 41, `42 of FIG. 4

l0 can be provided with such a spring or with an analogous device which eliminates play between the intermeshing teeth.

The overriding throttle 56 is formed `with

arcuate cutouts

56a, 56h which can be moved into partial or full registry with the spill passage 52 and discharge line 54. The configuration of the cutout 56b is shown in FIG. 8 and the cutout 56a is preferably of similar configuration.

The angular position of the throttle 56 with reference to the regulating valve 13 is selected in such a way that the spill passage 52 is sealed when the engine operates at full load or higher-partial-load. The discharge line 54 is then fully open, i.e., the overriding throttle 56 does not interfere with flow of fuel through the line 54 and such flow is then controlled solely by the throttle 25". This means that the selected cross-sectional area of the orifice 24" determines the maximum rotational speed of the engine. Such maximum rotational speed is selected in advance by setting of the throttle 25 but the operator is free to vary the amounts of fuel delivered to fuel lines 12 in the speed range below the preselected maximum speed by changing the angular position of the regulating valve 13". When the valve 13 is moved to an angular position which corresponds to idling of the engine, the overriding throttle 56 seals the discharge line S4 or throttles the flow of fuel through the line -54 more than the throttle 25". At the same time, the throttle S6 places its cutout 56a into full or substantially full registry with the spill passage 52 so that the flow of fuel through the passage 52 is controlled exclusively by the throttle 55.

Closing of the discharge line 54 and opening of the spill passage 52 will be effected gradually with a plurality of intermediate positions of the overriding throttle 56. For example, the throttle 56 will start to open the spill passage 52 lbefore it begins to close the discharge line 54. Also, the line 54 is sealed completely before the passage 52 is fully open.

Angular displacements of the actuating lever 30 from the position corresponding to full load to the position corresponding to idling of the engine will bring about the following results:

At the outset, i.e., when the engine operates at full load or at higher-than-average load (nearly full load), angular displacement of the lever 30 Iwill cause turning of the valve 13 in order to `reduce the amounts of fuel delivered to the fuel lines 12 in response to successive working strokes of the piston 4". The discharge line 54 remains fully open and the spill passage 52 is sealed, i.e., the cutout 56a is out of registry with the passage 52 and the flow of fuel through the line 54 is determined solely Iby the setting of the throttle 25".

When the lever 30 is moved to a position in which the amounts of fuel delivered to the fuel lines 12 correspond to between 75 and 80 percent of the amount at full load, the cutout 56a of the overriding throttle 56 begins to move into partial registry with the spill passage 52 while the cutout 5611 still remains in full registry with the discharge line Up to such position of the lever 30, the maximum rotational speed remains substantially constant and, as long as the actual rotational speed is below such maximum speed, the fuel injection pump operates in a range without automatic regulation. In other words, the amounts of fuel which will enter the cylinders of the engine can be selected by the operator, not by the automatic regulating system of the pump.

If the operator continues to turn the lever 30" in a direction away from the position corresponding to full load, namely, toward the position corresponding to idling of the engine, the throttle 56 begins to close the discharge line 54.b y :moving the cutout S6b out of full registry with the adjommg sections of the line 54. The throttling effect of the throttle 25 is then greater than that of the throttle 25". This starts the regulation at lower-than-average load -which is automatic and determines the rotational speed of the engine. If the lever 30 continues to reduce the amounts of fuel which enter the fuel lines 12", the cutout 56a reaches an angular position in which the throttle 56 cannot interfere with the ow of fuel through the leak passage 52 while the throttle 56 simultaneously reduces considerably the flow of fuel in the discharge line 54. The spill passage 52 is fully open when the valve 13" assumes an angular position in which the fuel lines 12" receive just as much as or a little more fuel than necessary for idling of the engine. In the idling position of the lever 30", the throttle 56 completely seals the discharge line 54 or leaves only a very narrow path for the flow of fuel through the cutout 56b which means that the fuel lines 12" will receive no fuel as soon as the rotational speed of the engine exceeds a predetermined idling speed. If the lever 30 moves beyond such idling position, a peripheral connecting groove 58 of the plunger 13b establishes a direct connection between the annular groove 17" and the bore 16 so that the interior of the working cylinder 2 is in continuous communication with the suction space 6" and the engine cylinders receive no fuel at all. This brings the engine and hence the pistons 4", 5" to a halt.

FIG. 7 shows a fourth fuel injection pump which is very similar to the pump of FIG. 4. Therefore, the reference numerals used in FIGS. 4 and 7 are the same. In addition to the structure of FIG. 4, the pump -body 1" of this fourth pump is provided with a bypass channel 59 corresponding to the channel 48 of FIG. 2. The flow of fuel in the channel 59 is controlled by a preset needle-like throttle 59a and also by an inclined edge face bounding one side of a cutout 56p` in the overriding throttle 56. The latter seals the channel 59 when the engine operates at full load or higher-partial-load. The channel 59 will convey fuel in that range of operations when the rotational speed of the engine is determined automatically, not at the will of the operator. The rate of fuel ow in the channel 59 will determine the proportional band of the regulation.

It will be noted that the throttles `25 and 55 in the pumps of FIGS. 4 and 7 are disposed between the regulating chamber and the

cutouts

56h, 56a of the overriding throttle 56. These throttles 55 are installed in parallel. The passage 52 and discharge line 54 communicate with a portion of the regulating chamber 15 which is located downstream of a one-way valve 60 provided in a feed line 21" corresponding to the feed line 21 of FIG. l.

FIG. 5 shows a portion of a fifth fuel injection pump wherein the throttles 25", S5 are installed in series. When the spill passage 52 is open, fuel fiowing therethrough must pass first through the orifice 24, thereupon through the orifice 53, and finally through the cutout 56a of the overriding throttle 56. Such arrangement renders it possible to provide the body 1 with an orifice 53 of relatively large cross-sectional area. When the throttle 56 assumes an angular position in which the

cutouts

56a, 56b respectively open the passage 52 and discharge line S4, a first portion of fuel displaced by the regulating valve 13 from the chamber 1S" fiows through the orifices 24, S3, cutout 56a and back to the suction space 6". A second portion of such fuel flows from the orifice 24 to cutout 56b and via discharge line 54 back into the auxiliary cylinder 3" which is not shown in FIG. 5.

The reference numerals employed in FIG. 5 are the same as those in FIGS. 4 and 7. The same holds true for the fuel injection pump of FIG. 6.

In the pump of FIG. 6, the throttles 2S", 55 are installed in the spill passage 52 and discharge line 54 downstream of the

cutouts

56a, 56b in the throttle 56. The passage 52 branches from the downstream portion of the discharge line 54 so that it bypasses the one-way valve 60 in the feed line 21". Consequently, the throttle 55 which controls the orifice 53 is effective only during forward movement of regulating valve 13" (against the opposition of return spring 19 which is not shown in FIG. 6) and only during idling and starting of the engine. When the valve 13" moves under the bias of the return spring 19",

12 fuel which fills the regulating chamber 15" below the valve 13 will escape only through the cutout S611, orifice 24 and through the discharge line 54 back into the interior of the auxiliary cylinder 3" (not shown).

In this embodiment of our fuel injection pump, the throttle 56 will not completely seal the discharge line 54 when the engine is idling. Automatic selection of the maximum speed with application of the liquid stop will be made by means of the throttle 2S". The throttle 55 retards the forward stroke of the valve 13 and thus increases the amounts of fuel which are supplied to the fuel lines 12".

In the embodiments which are illustrated in FIGS. 4 to 7, the flow of fuel through the discharge line 54 and spill passage 52 can be regulated by a single control element, namely, by the overriding throttle 56 having the

aforementioned cutouts

56a, 56b. In order to render the regulating system even more versatile, one can vary the relationship of positions in which the throttle 56 permits, throttles or prevents the flow of fuel through the passage 52 and line 54. Such a modified fuel injection pump is shown in FIG. 9 wherein the overriding throttle 56 comprises two inclined camming edges 56d, 56e which respectively bound portions of the

cutouts

56a, 56h. The edges 56d, 56e are located in mutually inclined planes making an acute angle with the axis of the throttle 56 and the latter is movable axially without interrupting the connection established by the

coupling

41, 42" (only the gear segment 42" is actually shown in FIG. 9). The means for adjusting the throttle 56 axially comprises a threaded adjusting member 63 which can transmit motion to a tiange 62 of the throttle 56 by means of a two-armed lever 61. A spring 62a operates between the fiange 62 and the pump body 1" to maintain the lever 61 in permanent abutment lwith the flange 62 and adjusting member 63. The motion transmitting connection between the gear segment 42 and throttle 56 comprises an axially parallel coupling pin 62]; which is slidable in the flange 62 and/or in a flange 42b of the shaft 42a" for the gear segment 42".

Many reference numerals employed in FIG. 9 are the same as those in FIGS. 4-8 because the structure for adjusting the axial position of the throttle 56 can be readily incorporated in the pumps of FIGS. 4 8.

As stated before, the

throttles

25, 55 of FIGS. 4 to 7 are adjusted when the respective fuel injection pump is idle and thereupon remain in such preselected positions. FIGS. l() and 1l illustrate the manner in which the throttles 25, 5S may be adjusted. The adjusting arrangement comprises a cover plate 64 which can be fitted into an opening 65 provided in a wall 70 bounding the suction space. The cover plate 64 is then sealingly affixed to the wall by screws 71.

Two lmotion transmitting bolts 66, 67 are rotatably mounted in the cover plate 64 and have slotted outer ends 666, 67b so that each thereof can be rotated by a screwdriver or another rudimentary tool. The inner end portions 66tz, 67a of the bolts 66, 67 constitute sockets which can receive non-circular heads of the throttles 25", 55. The sockets 66a, 67a are in engagement with the respective throttles when the cover plate 64 is affixed to the wall 70.

When the adjustment is completed, the cover plate 64 is removed and the opening 65 is sealed by a lid 68. This lid 68 remains attached to the wall 70 when the fuel injection pump is in actual use.

Of course, and in order to be able to utilize the cover plate 64, the designer of the fuel injection pump must install the throttles 25", 55 sufiiciently close to and in parallelism with each other, otherwise, the body of the pump will be provided with several openings so that the operator can gain access to all such throttles which are not adjustable by the

lever

30, 30 or 30".

The cover plate 64 can remain attached to the wall 70 when the pump is in actual use, at least during testing of the engine, so that the operator can make eventual adjustments if the engine fails to run properly. The lid 68 will be applied when the operator has found a satisfactory angular position for each of the throttles 25", 55.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is:

1. A fuel injection pump for internal combustion engines comprising a main cylinder; a main piston reciprocable in said main cylinder to respectively draw and expel fuel therefrom; drive means for reciprocating said piston at a speed which is a function of engine speed; fuel line means arranged to receive fuel from said cylinder for injection into the engine; overow channel means connected with said cylinder and including a regulating chamber; an adjustable regulating valve reciprocable in said chamber and movable from at least one starting position to at least one open position in which said channel means is effective to evacuate fuel from said cylinder instead of said fuel line so that the injection of fuel into the engine is terminated on movement of said valve to said open position; biasing means for urging said valve to said starting position; auxiliary pump means operating in synchronism with said main piston to deliver fuel to said chamber for moving said valve from said starting position; a discharge line connected with said chamber to evacuate fuel during movement of said valve to said starting position; adjustable throttling means in said discharge line for restricting the cross section thereof and for thus braking the ow of fuel through said discharge line; first adjusting means for regulating the distance between starting and open positions of said valve; second adjusting means for adjusting said throttling means to regulate the throttling action thereof; coupling means between said adjusting means and arranged to maintain said second adjusting means in at least one first position when said first adjusting means is set for maximum or near maximum of fuel delivery per stroke and to maintain said second adjusting means in second positions corresponding to increasing braking action of said throttling means when said first adjusting means is set for minimum or near minimum of fuel delivery per stroke; and common actuating means for said first and second adjusting means.

2. A fuel injection pump as defined in claim 1, further comprising secondary throttling means adjustable independently of said first mentioned throttling means to determine the rate of fuel fiow in said discharge line in said rst position of said second adjusting means by bringing about a braking action which exceeds the braking action of said first mentioned throttling means during maximum or near maximum fuel delivery per stroke.

3. A fuel injection pump as defined in claim 1, wherein each of said adjusting means comprises a cam and said first adjusting means further comprises an adjusting member shiftable by the respective cam and having a portion extending into said regulating chamber to deteimine the starting position of said regulating valve, said throttling means comprising a throttle reciprocable by the respective cam and having a portion extendable into said discharge line to obstruct the ow of fuel from said chamber.

4. A fuel injection pump as defined in claim 3, wherein said coupling means comprises a turnbuckle adjustably connecting said cams to each other and wherein said actuating means comprises an actuating member connected with one of said cams.

5. A fuel injection pump as defined in claim 1, further comprising spill conduit means connected with said regulating chamber to evacuate some of the fiuid from said chamber independently of the position of said regulating valve when said actuating means is set for minimum or near minimum delivery per stroke, said throttling means comprising means for stopping the flow of fuel through said conduit means when said actuating means is set for maximum or near maximum delivery of fuel per stroke.

6. A fuel injection pump as defined in claim 5, wherein said throttle means comprises a rotary overriding throttle a portion of which constitutes said means for stopping the flow of fuel through said conduit means.

7. A fuel injection pump as defined in claim 6, wherein said overriding throttle comprises a second portion rigid with said first mentioned portion and arranged to regulate the flow of fuel in said discharge line.

8. A fuel injection pump as defined in claim 7, further comprising third adjusting means for moving said overriding throttle axially, said portions of the overriding throttle having mutually inclined edges which change the rate of fuel ow in said discharge line and said conduit means in response to axia-l adjustment of the overriding throttle.

9. A fuel injection pump as defined in claim S, wherein said coupling means is arranged to effect sealing of said conduit means by said throttling means in the first position of said second adjusting means and to fully open said conduit means when said actuating means is set for idling of the engine.

10. A fuel injection pump as defined in claim 5, further comprising bypass vchannel means having an end connected with said regulating chamber, said end of said bypass channel means being sealed by said regulating valve in the starting position and during movement of said valve to a position at a predetermined distance from such starting position, said throttling means comprising a portion arranged to regulate the ow of fuel in said bypass channel means.

11. A fuel injection pump as defined in claim S, further comprising second throttling means for regulating the flow of fuel in said spill conduit means independently of said first mentioned throttling means.

12. A fuel injection pump as defined in claim 11, further comprising third throttling means for regulating the flow of fuel in said discharge line independently of said first mentioned throttling means.

13. A fuel injection pump as defined in claim 12, wherein said second and third throttling means are installed in series so that said third throttling means regulates the fiow of fuel in said discharge line and in said spill conduit means while said second throttle means regulates the flow of fuel only in said conduit means.

14. A fuel injection pump as defined in claim 1, further comprising a feed line for supplying fuel from said auxiliary pump means to said regulating chamber, oneway valve means provided in said feed line, and spill conduit means directly connected with said auxiliary pump means and adapted to receive fuel therefrom, said throttling means comprising means for stopping the fiow of fuel through said conduit means when said actuating means is set for maximum and near maximum fuel delivery per stroke.

15. A fuel injection pump as defined in claim 1, wherein said first adjusting means comprises means for 4changing the angular position of said regulating valve and wherein said valve is arranged to perform strokes of different length between said starting and open positions thereof in response to angular displacement by said first adjusting means.

16. A fuel injection pump as defined in claim 15, wherein said throttling means is rotatable by said second adjusting means and wherein said coupling means comprises intermeshing gear members.

17. A fuel injection pump as dened in claim 1, where- 15 in said auxiliary pump means comprises an auxiliary cylinder coaxial with said main cylinder and an auxiliary piston rigid 'with said main piston, said pistons being arranged to draw fuel from a common source and said overflow channel means being arranged to discharge into said common source.

18. A fuel injection pump -as dened in claim 17, wherein said drive means ycomprises means for rotating said pistons at the speed of the engine and said fue] line 4means comprises a plurality of fuel lines each arranged to normally receive fuel from said main cylinder during each revolution of said main piston.

References Cited UNITED STATES PATENTS 3,120,189 2/1964 Bessiere. 3,157,173 11/1964 Martyn et al. 3,267,865 8/ 1966 Deininger 103-41 3,320,893 5/1967 Koster etl` al. 103-41 LAURENCE M. GOODRIDGE, Primary Examiner.

U.S. Cl. XR.