US2778351A - Injection unit for combustion engines - Google Patents

Description

Jan. 22, 1957 INJECTION Filed Sept. 18 1951 H. K. LINKS UNIT FOR COMBUSTION ENGINES 4 Sheets-Sheet 1 K B D INVEIVVT E HEM/1? ;-cJ+

Jan. 22, 1957 H. K. LINKS INJECTION UNIT FOR COMBUSTION ENGINES 4 Sheets-Sheet 2 Jan. 22, 1957 H. K. LINKS 2,778,351

INJECTION UNIT FOR coxvnsusnow ENGINES Filed Sept. 18, 1951 4 Sheets-Sheet s INVENT E HEM R h K [1m #5 m Jan. 22, 1957 H. K. LINKS 2,778,351

INJECTION UNIT FOR COMBUSTION ENGINES Filed Sept. 18; 1951 4 Sheets-Sheet 4 H iNR)cEf,,K mks 3?;MMdMvM United States Patent INEECTION UNIT FOR COMBUSTION ENGINES Heinrich K. Links, Stuttgart, Germany, assignor to Daimler-Benz Aktiengeselischaft, Stuttgart-Unterturkheim, Germany Application September 18, 1951, Serial No. 247,152

Claims priority, application Germany September 21, 1950 Claims. (til. 123-139) This invention relates to an injection unit for combustion engines, particularly with an injection pump, in which a pump piston which moves to and fro in a pump cylinder and simultaneously performs a rotary motion relatively to the pump cylinder, supplies successively several engine cylinders with fuel. Such engines have the advantage of a particularly simple and, with respect to space and weight, favorable construction. By reason of the fact that in the place of several individual pumps only one pump is required, parts can be dispensed with, and thereby the costs of manufacturing can be materially reduced.

An object of the present invention is a further improvement of such injection pumps, particularly a simple and suitable regulation of the moments of injection as well as of the quantity of injection. In accordance therewith it is another object of the present invention to provide an injection pump arrangement in which the instances or moments of injection or the quantity of injection can be regulated by a relative initial or subsequent adjustment of the pump piston which is provided with control grooves or the like, in the direction of rotation. The beginning of the injection is thereby controlled, for example, by opening the injection pipe, the end of injection by opening an oveflow pipe at a moment, which can be adjusted by turning or twisting of the pump piston. According to a further characteristic of the present invention the pump piston is set into rotation by a pair of gear wheels with helical gears, whereby one of the two gear wheels is axially shiftable in such a manner that through the shifting of the gear wheel, the pump piston is initially or subsequently adjusted relatively to its driving shaft.

A further object of the present invention is to provide a suitable and simple drive of the fuel injection pump, particularly with fuel injection systems in which the compression stroke of the piston of the injection pump is effected by a pneumatic pressure, which is produced by the engine and controlled in timed relation with the injection, for example against the effect of a backstroke spring. in accordance with this it is a further object of the invention to provide for several engine cylinders only one pump piston. Particularly simple operating conditions result from a further characteristic of the present invention, when the pressure, which drives the pump piston, is taken from one or several cylinders of the engine and when the strokes which the piston executes in a number corresponding to the number of cylinders supplied by it, are effected by a successive connection of the pump space which serves for the drive of the pump piston, with the engine cylinders.

If the pump piston executes, in addition to a to and fro or reciprocating motion, a simultaneous rotary motion, whereby it is connected with the driving shaft in a shiftable manner and the parts of the driving shaft and of the control member for the simultaneous feed or deduction of ice the compressed air, which effects the compression stroke of the pump piston.

' Further characteristics and details of the present invention are to be taken from the following description of two examples of construction.

In this connection:

Fig. 1 shows a longitudinal cross-sectional view through the injection pump,

Fig. 2 shows a cross section through the injection pump, i. e. in the left part along the line A-B and in the right part along the line CD of Figure 1,

Fig. 2a shows an axial cross-sectional view perpendicular to Figure 2 through the upper end of the pump piston and Fig. 3 shows diagrammatically on a greatly enlarged scale the control of the injection pipes and of the backfiow pipes through the pump piston, unwinding the piston circumference, and laying it out fiat in the plane of the drawmg.

Fig. 4 shows a vertical cross-sectional view through v the pump and the combustion engine, which is shown in 2, which can be coupled in the usualmanner with the combustion engine, is supported in the pump casing. In four stroke injection combustion engines, the shaft 2 is driven with one half the number of revolutions of the crankshaft. The camshift is provided with four cams 3 all lying in the same plane, which move the plunger 5, which is secured against turning in the casing 1, upwardly and downwardly by. means of the roll 4. The plunger 5 is pressed downwardly by the pump spring 6. The latter is thereby supported with its upper end against a box, which is rigidly inserted into the casing, and with its lower end against a hat-shaped part 7, which extends around the lower collar 8 of the pump piston 8, so that the lower collar 8' is pressed against a ball 9 by the spring 6 and is thereby pressed from above against the plunger 5 which in turn, by means of the roll 4, is pressed against the cams 3. The'piston 8 is appropriately guided in a pump cylinder 10, which is rigidly inserted into the upper part of the pump casing 1. On the outer cylindrical surface of the pump cylinder 10 a helical gear wheel 11 is supported, the extendedhub 12 of which is coupled in its direction of rotation with the pump piston 8 by a catch 13 whichcan also be shifted in a longitudinal direction relative to the pump piston.

Thedrive of the gear wheel ll'is effected as follows:

On the camshaft 2 a spiral gear 14 is rigidly arranged,

which is in mesh with a spiral gear 15 on a shaft 16, which is parallel to the piston 8 and supported in casing 1. On its upper end the shaft 16 carries a helical gear wheel 17, which in turn is in constant mesh or engagement with the gear wheel 11, which is also provided with a helical gear. The transmission is thereby chosen in such a manner that with one rotation of the camshaft 2 the gear wheel also carries out one rotation. The piston Sexcutes consequently with one rotation of the gear wheel 11 four'full axialupward and downward motions. The support of the piston against the plunger 5 by means of the ball 9 permits the piston to turn itself alsov during the ,compres'sion'stroke of the pump without friction.

The fuel is sucked or drawn in through a central suction'pipe 18 and a suction valve 19 into the pump space 20 during downward movement of piston 8. During the upward movement of the piston 8, the fuel is forced under pressure into pipes 21, as long as no other possibility of escape exists for the fuel. Four of the pipes 21 extend radially from the sliding surface of the piston 8 in the cylinder 10 and lead to the pressure valves 22 which are arranged in a circle around the suction valve 19, and

through these valves 22 to the injection pipes 23, through Which the fuel is conveyed to theinjection nozzles of the engine. j

Furthermore provision is made in the pump cylinder 10 for fouroverflow openings 24, which are arranged in a circle and which lead to an annular overflow pipe 25, which is connected in any suitable manner with the interior of the pump casing. The control of the pressure pipe is efiected by a helical or spiral control groove 26, which opens directly into the pump space 20, the control of the overflow openings 24 through a second axially arranged control groove 27 in the pump piston, which is also in communication with the pump space through a central bore 28 (see particularly Fig. 2a).

For regulating the pump, there is provided a regulating 1 mechansm 29, which is laterally flanged to the pump casing 1 and which consists for the main part of a diaphragm 31, which is loaded by the spring 30, and which is coupled with the gear wheel 11 through a toggle lever 33. The space 34 of the diaphragm 31, which contains the spring 36), is exposed through a pipe 35 in a manner, which is known in itself, to the underpressure or vacuum which exists in the suction pipe of the engine. Through a lever 36 the lever 33 can be adjusted in any way independently or against the effect of the diaphragm 31.

The exemplified control of the pressure and overflow pipes is schematically illustrated in detail in Figure 3, whereby the piston circumference with the openings in the pump cylinder and the control grooves or the control edges of the pump piston is laid out fiat in the plane of the drawing. With it injection nozzles, the pressure openings 21, which are controlled by the piston, or the overflow openings 24, which are controlled thereby, have a distance of a=360/n, that is, 90 in the case of the illustrated construction of a four-cylinder engine. The stroke of the pump piston is marked with .h. Furthermore, it is assumed that through axial adjustment of the gear wheel 11 the pump piston can normally carry out an angle of adjustment in the direction of rotation around its axis relatively to its drive. The top edge of the piston is marked in the lowermost position of the piston with 37, in the uppermost position of the piston with 37". Every point on the piston carries out a harmonic motion relative to the stationary openings 21 and 24 in the course of the drive. Such a motion is, for example, indicated for the center of the control groove 27, that is, bythe curve x the motion of this point is indicated for the noload position of the pump, and by the curve x+ the motion of the same point for full load position, whereby the direction of this motion is indicated by arrows.

In the upper part of Figure 3 four stop positions of the control groove 26 are shown, which controls the pressure Opening 21. The four positions of the control groove 26 are shown as 26' forthe position thereof in the lower piston dead center during idling speed, with 26" as the position in-the upper piston dead center during idling speed, with 26+ as the position in the lower dead center during full load, and with 26++ as the position in upper dead center during full load. Analogous corresponding positions of the control groove 27 for the overflow openings are marked as 27', 27", 27+ and 27++ (lower part of Figure 3). Furthermore two intermediate positions of the control groove 27" or 27+++ are indicated in Figure 3.

Furthermore, the control groove 26 is constructed and dimensioned in such a manner that it places-that pressure opening 21, in Figure 3, the center pressure opening 21, which takes its turn at that time in the control sequence, into communication with the pump space 20 during the entire pressure stroke across the entire regu- 21, whereby the beginning of injection coincides for the main part with the beginning of the piston pressure stroke.

, The end of injection is reached, as soon as the control grove 27 begins to expose one of the overflow openings 24.

It the pump is adjusted to idling speed (curve x of the center of 27), then the control groove 27 begins after a relatively small stroke 71 in the circumferential direction of the piston, i. e., in the position 27", to expose the center overflow opening 24. The liquid, which is displaced by the pump piston can now instead of through the pressure opening 21, flow oif or escape through the overflow opening 24, whereby the injection of fuel into the engine is interrupted. Accordingly a relatively small quantity of fuel, which corresponds to the pump stroke at in the axial direction thereof and which is necessary for the idle speed, is conveyed or transmitted on to the injection nozzle. 7

At full load position corresponding to the curve .x+ the control groove 27 begins to expose the overflow opening 24 only after an essentially, larger stroke, i. e.,

shortly before the piston reaches its upper dead center and after it has carried out a stroke 72 in the circumferential directionflor a stroke a: in the axial direction, so that the injection period is only finished at that moment. Consequently a relatively large quantity of fuel, which corresponds to the stroke as, is conveyed to the injection nozzle.

This procedure repeats itself with every to and fro motion of the piston, until with a complete rotation of the piston all injection pipes are supplied with fuel one after another over the control groove 26.

For stopping the pump or for adjustment to an overload quantity, for example at starting, the piston can occasionally also be adjusted beyond the normal range of regulation in the one or the other circumferential direction. For this purpose may serve the lever 36, which can, for example, be adjusted from the drivers seat.

The control can, of course, in each case also be effected in kinematic inversion. For example instead of the piston, the pump cylinder 10 also'can be set into motion to offset the desired control However, with rotary motion of the. piston a relatively simple manner of control results. Furthermore instead of utilizing one single control groove 27 several of them, in the example of construction for example two or four, can also be utilized, in which case provision must only be made for two or only one overflow opening 24. Furthermore, the control grooves can be arranged in the cylinder and the control bores in the piston, or both the cylinder and the piston can be provided with control grooves or appropriately acting control edges.

Instead for four injection places a pump, which is developed in accordance with the invention, can alsobe utilized for more or less than four injection places. Furthermore, the present invention may also be applied to injection pumps with two or several pump elements, in that, for example, four cylinders each of an eight cylinder engine are controlled by groups by one pump element each. 7

The construction with a pneumatic drive of the pump is shown in Figures 4 through 7. The injection nozzles 1031: through 103d are inserted into the schematically indicated engine casing 101 provided with the cylinders 102a through 102d. At a suitable place of the engine easing, suitably at or on the cylinder head, an injection pump 104, which is common .to-all engine cylinders, is arranged. For the drive of the pump piston serves a shaft 105, which is, for example, driven by the distributor shaft or an otherwise arranged shaft of the engine.

The shaft 105 is shaped in a cup-like or cylindrical manner at its upper end, and serves as a cylinder for the pressure space 107, which is closed at the top by the pressure piston 108. The pressure piston 108 is connected in a suitable manner, for example, by means of a box 109, which can be inserted in a bayonnet-like manner into the pressure piston 108, with the pump piston 110 of the injection pump for axial movement therewith. Furthermore the cylinder part 106 of the pump shaft 105 is coupled in its direction of rotation by jaws 111 with a part 112, which is inserted in a rotative manner in the pump casing 104. The part 112 is in its turn coupled by a cross piece (a socalled lug) 113 with the pump piston 110 in such a manner, that the pump piston 110 together with the pressure piston 108 can carry out an axial to and fro motion relatively to the driving shaft 105, however, is taken along by the shaft in the direction of rotation. The pressure piston 108 is loaded by a spring 114, which seeks to press it downward together with the pump piston 110.

The casing 115 for the connection of the suction pipe 116 and the suction valve 116' is connected to the upper end of the casing 104. The pump piston is provided at its upper end, which is turned toward the pump space 117, provided with a control groove 118 at the outer circumference thereof. In the range of this control groove 118, i. e. below the upper edge of the pump piston 110 in the lower dead center of the latter, the four injection pipes 1190, 11%, 11% and 119d branch off radially from the pump cylinder, which lead to the nozzles 103a to 103d. A central bore 120 in the pump piston 110 leads to a control or cross bore 121, which is controlled by the control groove 122 of a control sleeve 123. The latter is provided with a gear-tooth system 124, which is shiftable in the axial direction by a gear wheel 125, which is adjustable from the outside in the direction of the arrow for example by hand or automatically.

Furthermore, the shaft 105 has a central bore 126, which is adjacent to the pressure space 107 and which is in communication with the outside of the shaft 105 through a contrcl or transverse bore 127. At the same level as the transverse bore 127, the four pipes 129a through 1290. or connected with the bearing part 128 of the shaft 105, i. e. in a radial manner corresponding to the pipes 119a through 119d. Between the pipes 129a through 129d provision is made for appropriate bores in the control part 128, which connect pipes 129a through 129d with the inside of part 128 for connection with bore 127.

The manner of operation of the pump is the following: The pump driving shaft 105 is driven in timed relation with the cycle of the engine, i. e. in two stroke engines with the same number of revolutions as the crankshaft, in four stroke engines with half the number of revolutions. As the pump piston 120 is fixedly coupled with the driving shaft 105 in the direction of rotation, the pump piston 110 rotates also with a corresponding number of revolutions.

Corresponding to the rotating driving shaft 105 the engine cylinders 102a, 102b, 1020 and 102d are successively connected with the pressure space 107 of the pump, i. e. in such a manner that in each case that engine cylinder is brought into connection with the pump space 107, which is just undergoing the compress-ion stroke. The pressure pistcn 108 and therewith the pump piston 110 are pressed thereby in an upward direction through the compression air, which enters the pressure space 107, whereby the fuel, which was sucked in before through the valve 116' is displaced into that injection pipe 119a through 119d, which is in connection with the pump space 117 through the control groove in conformity with the rotary position of the pump piston 110. If, for example, the pipe 12% connects the engine cylinder 102b with the pressure space 107, then simultaneously also the pipe 11%, which leads to the same engine cylinder, i. e., to the injection nozzle 10311, is in connection with the pump space 117 of the injection pump.

The pump piston executes thereby a constant compres-: sion stroke, which is determined by stops at the pump piston. The end of injection is reached, as soon as in the upward stroke of the pump piston 110 the transverse bore 121 comes into communication with the control groove 122 in the control sleeve 123, so that the fuel, which is further displaced by the pump piston, can flow off to the outside over the control bore 122. The moment for the end of injection or for the beginning of backflow can be governed by adjustment of the gear wheel 125,

With the further turning of the driving shaft or of the pump piston 110, the pipes, for example 12% and 11%, are shut off from pressure space 107 or from the pump space 117 of the injection pump and shortly thereafter the pressure space 107 is brought into communication with the relief bores 130 by means of the control bore 127, so that under the effect of the spring 114 the pressure piston 108 with the pump piston can move downwardly again and can thereby suck in fuel through the valve 116 and the valve 116' into the pump space 117.

The invention is not restricted to the illustrated examples of construction, but can be varied at discretion within the scope of the individual ideas of the invention. 1

What I claim is:

1. Injection pump comprising a pump cylinder,-a plurality of injection nozzles, aplurality of injection pipes connected to said pump cylinder in spaced relationship along the circumference thereof and leading to said irrjection nozzles, a pump piston movable in said pump cylinder, groove-like control means operated by said pump piston for opening and closing said injection pipes during rotary and axial movement of said pump piston thereby supplying fuel to said injection pipes, a suction line connected to said pump cylinder in a part thereof untraversed by said piston, means separate from said piston for controlling said suction line, a drive shaft coaxial with said pump piston, and means including a cylinder member for coupling said pump piston for simultaneous rotation and relative axial displacement with said. drive shaft, a piston member, said cylinder member and said piston member being axially movable with respect to each other by the force exerted on said piston member by a pressure medium, and means for connecting one of said members with said drive shaft and the other member to said pump piston.

2. Injection unit for combustion engines comprising several engine cylinders, an injection pump, a cylinder in said pump, a pump piston in said cylinder, injection pipes with connection openings, each pipe leading from said pump cylinder to the engine cylinders, the connection openings of said pipes being spaced along said pump cylinder in the circumferential direction thereof, means for driving said pump piston in the direction of rotation, control groove means in said pump piston forming control edges for alternately connecting and disconnecting said connection openings with the pump space formed between said pump cylinder and said pump piston upon turning of said pump piston, the means for driving said pump piston including cylinder means and piston means, one of said last-mentioned means being connected with said pump piston for common rotation therewith and the other of said last-mentioned means being connected with said pump piston for common reciprocating movement therewith, pipes connecting said cylinder means with the engine cylinders, and control means in said driving means for establishing and interrupting a connection from the engine cylinders with said cylinder means in timed relation sagzn'srarrrv with the engine. cycle to. thereby effect a to and fro motion of said pump piston.

3. Injection unit for a combustion engine comprising several engine cylinders, a pump cylinder, a pump piston, in said pump cylinder, means for conveying fuel from said pump cylinder to the engine cylinders, means for rotatingly driving said pump piston, means for axially moving .said. pump piston to and iro in said pump cylinder including a driving member movable with respect to said pump piston, a cylinder space for said pump piston, and control means for connecting said cylinder space with a predetermined one of said engine cylinders to move said pump piston to and fro in said cylinder space.

4. Injection unit for a combustion engine comprising several engine cylinders, only one common injection pump for allot said engine cylinders with only one pump piston, means for conveyirm fuel from said injection pump to saidcylinders, means for derivinga pneumatic pressure medium from the engine, and means for reciprocating said pump piston by said pneumatic pressure medium to inject fuel into said cylinders in timed relation.

'5. Injection. unit according to claim 4, wherein a portion of the compressed contents of said engine cylinders during the compression stroke is used as said pneumatic pressure medium.

6. Injection unit for a combustion engine comprisin several engine cylinders, a common injection pump for all of said engine cylinders, with a pump piston, means for conveying fuel from said injection pump to said cylinders, means for deriving a pneumatic pressure medium from the engine, and means for reciprocating said pump piston by said pneumatic pressure medium, a portion. of the compressed air contents of a. corresponding one of said, engine cylinders during a compression stroke being used as said pneumatic pressure medium, and said lastmentioned means comprising a cylinder, a piston connected with. said pump piston, pipes. connected between the engine cylinders and said last-mentioned cylinder, and means for alternately opening and closing said last-mentioned pipes.

7. Injection unit for a combustion engine comprising several engine cylinders, a common injection pump for all of said engine cylinders with a pump piston, means for conveying fuel from said injection pump to said cylinders, means for deriving a pneumatic pressure medium from the engine, means for reciprocating said pump pistonby said pneumatic pressure medium, means for driving said pump piston in a rotary direction, means for, alternately controlling the fuel supply of said engine cylinders by said rotating pump piston and means in said; driving means for controlling said pneumatic pressure. medium in timed relation with the engine cycle for producing a reciprocating movement of said pump piston.

8. Injection pump according to claim 2 further comprising at least one longitudinal bore in said pump piston terminating. in an opening in the outside thereof, a sleeve surrounding said pump piston, an opening in said sleeve for connection with the opening of said longitudinal bore with a predetermined position of said piston to thereby terminate the compression stroke of said piston, means for axially displacing said sleeve for regulating the instant of the end of the compression stroke, and a return line interconnecting the opening in said sleeve with the fuel supply.

9. Injection pump for multi-cylinder combustion engines comprising an injection pump, first means for delivering fuel to the various cylinders of the engine in timed relation, a pump piston in said injection pump, second means for drivingly connecting said pump piston to produce a reciprocating movement thereof, and third means for rotatingly driving said pump piston to control delivery of the fuel tothe various cylinders by said firstmentioned means, said second means including means for deriving a pressure medium from the engine cylinders in timed relation with the rotating movement of said pump piston to produce said reciprocating movement.

10. Injection pump for multi-cylinder combustion engines comprising an injection pump, means for delivering fuel to the various cylinders of the engine in timed relation, a pump piston in said injection pump, means for drivingly connecting said pump piston to produce a re ciprocating movement thereof, and means for rotatingly driving said pump piston to control the timed delivery of fuel to said various cylinders by said first-named means, said last-named means including adjusting means for selectively advancing or retarding said pump piston in the rotating. direction thereof with respect to the reciprocating movement thereof, and said second-mentioned means including means for deriving a pressure medium from the engine. cylinders to produce said reciprocating movement.

References. Cited in the file of this patent UNITED STATES PATENTS 1,951,340 Bohuslav Mar. 20, 1934 2,106,789 Boyd Feb. 1, 1938 2,455,571 Edwards Dec. 7, 1948 2,465,784 Berlyn et al Mar. 29, 1949 2,518,473 Hogeman et al Aug. 15, 1950 2,544,561 Meyer Mar. 6, 1951 2,602,702 Kovach July 8, 1952 FOREIGN PATENTS 326,095 Great Britain Mar. 6, 1930 373,443 Great Britain May 26, 1932

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