DE859239C - Regulation for pumps, especially fuel injection pumps, with pump pistons driven in opposite directions - Google Patents

Description

Regulation for pumps, in particular fuel injection pumps, with counter-rotating driven pump piston The invention relates to a control for pumps, in particular fuel injection pumps, with two in a common pump cylinder pump pistons driven in opposite directions.

Fuel injection pumps with two in one ingenious pump cylinder pump pistons driven in opposite directions are known. The regulation of the injection quantity takes place in this case by changing the stroke of a pump piston, z. B. by means of a sliding camshaft. However, such a control is required for multi-cylinder pumps a relatively large overall length, since the individual pump cylinders are movable because of the Cams must have a certain minimum distance from each other. Can also be used for It is difficult to achieve precise control over small injection quantities. At the end of the pump pressure stroke the pistons have a distance from one another, which changes with the change in the piston stroke also changes.

There are also known fuel injection pumps in which two to each other pump cylinders that are parallel or at a V angle to one another share a common, optionally form a U-shaped pump chamber or connected to one another by Ouerkanal are, and in which the pump pistons are driven with a phase difference. The flow rate control takes place here z. B. in that the fuel supply channels be ground at adjustable times, which z. B. by sliding Inclined cam is to be achieved. Such pumps, apart from those mentioned above, have Disadvantages, the further disadvantage that the fuel column as a result of the large pump space alternately compressed becomes and expands again and through it fine control of the injection quantity is made impossible. Also is with pumps of the known type, the regulation as a result of the necessary requirement there, the included Keeping the volume of liquid sufficiently constant is practically limited.

In contrast, the invention aims at a fuel quantity control, which has the advantage of simple and very precise control with a large control range, an expedient control of the injection time and a short overall length and, for opposed piston pumps, a low overall height of the pump. It consists in particular on the one hand in such adjustability of the drive members driving the pump pistons in opposite directions that the drive phases (rotational position) of one piston relative to that of the other piston, e.g. B. by mutual! Twisting of them can be controlled camshafts are shifted and thereby the volume of fluid pumped is controlled, and on the other hand, that these by such control of the pistons at the end of: close to overall öffnetem outlet or are virtually close to one another and that of the: effective pressure stroke Both pistons delivered amount of liquid is completely or almost completely displaced into the outlet.

This enables precise and simple fine control to be achieved. At the same time, the lowest overall height is made possible with pistons rotating in opposite directions, whereby the least number of cylinders is required for a given number of pistons is.

One of the two pistons is expediently driven invariably, by regulating by relative rotation of the drive for the other piston he follows; however, both pistons or the ones driving them can optionally also be used Control shafts are subject to an adjustable adjustment, with z. B. a common middle drive can be provided for both shafts. The adjustment can be both arbitrarily, and possibly at the same time automatically, z. B. depending from the speed of the driving machine.

Furthermore, such a controllable control of the pump pistons is preferably z. B. by appropriate training of the control cam, provided that upon completion of the inlet, the pump piston has a variable size pump space and a correspondingly include variable large amount of liquid between them, and that this at least until the opening of the outlet pump chamber obtained until the end of the effective pressure stroke is reduced to zero or almost zero. To you as much as possible To allow a wide control range, the two will overlap with regard to their stroke Pump piston, e.g. B. by appropriate training of the control cam, in particular controlled so that the one pump piston the one, z. B. lower dead center relative long, the other, z. B. top dead center, on the other hand, only briefly passes through during the other pump piston passes through the dead centers in reverse, with the phase shift both pistons to each other in particular takes place in such a way that the pistons at greatest Injection quantity during its pressure stroke, with the lowest injection quantity, however, during their suction stroke have their greatest distance from each other, the opposite Each case approaches the limit value zero. This allows both pistons in terms of to shift their drive phases against each other by a relatively large amount, without the movement of one piston despite the mutual overlap of theirs Stroke is disturbed by the other piston. The mutual displacement of the drive or piston stroke phases take place here. expedient in such a way that at full load the two Pump pistons perform their return stroke almost together and in close succession, when executing the forward stroke, on the other hand, in particular when the Suction opening and opening of the pressure opening are at their greatest distance from each other, while when idling, conversely, the two pump pistons have the greatest phase difference in the return stroke have, on the other hand, in the forward stroke, especially at the end of the suction opening and when the pressure opening is opened, its corresponding to the idle quantity to be conveyed have the smallest distance from each other.

Overall, application of the invention is therefore particularly simple and expediently implemented a method for controllable operation of the pump in such a way that that after the liquid has been displaced into the outlet, first of all the suction opening opening pistons, e.g. B. with the formation of a partial vacuum, the other pump piston on its return stroke relatively leads by an amount corresponding to the regulation, is then overtaken by this at the end of the return stroke, so that the at Opening of the suction opening, all or part of the liquid that has flown in again the suction channel is pushed back, that also in the following, the actual Control effecting the forward stroke first of all the second-mentioned piston the first-mentioned Piston rushes ahead relatively, whereby the liquid is sucked in from the suction channel, until the suction opening at the distance between the two pistons corresponding to the regulation is locked from each other by the first-mentioned calving, and that after opening of the outlet through the second-mentioned piston is the one enclosed between the two pistons Amount of liquid through the first-mentioned one, which is relatively lagging according to the regulation Piston is displaced into the outlet.

After the liquid has been displaced into the pressure channel, on End of the effective pressure stroke, the liquid is sucked back out of the pressure channel to prevent, the pressure opening is blocked before or in the further _A moment when the pistons begin a relative movement that diverges. this can either be done in that the two pump pistons initially work together override the pressure opening, before their relative movement against each other begin, or that what in general with regard to the regulation by phase shift of the drive, it will be necessary to be independent of the drive of the pump piston Shutting off the pressure channel is provided, for example by arranging a Check valve as close as possible to the outlet or pressure port controlled by the piston.

The regulation also allows the times to be postponed for the effective funding period, i.e. in particular the times for the start of injection and the injection end on fuel injection engines. Particularly simple and functional The regulation is designed here when the is located after the suction opening Piston invariable (or generally invariable) and that after the pressure opening to located piston is controllably driven. The phase shift of the second adjustable pump piston has an effect here, with essentially unchangeable End of injection, by moving the start of injection forward at full load and moving it back of the start of injection at lower load or at idle.

Is an automatic regulation, e.g. B. depending on the speed, provided, this can be carried out in a particularly expedient manner by a hydraulic Medium, e.g. B: by the fuel delivered by the pump. For example can use a Vemtell piston to rotate one control shaft with it a coarse thread and so displaceable with a drive member for the control shaft be connected that, the drive from the drive member to the control shaft via the Adjusting piston takes place. For arbitrarily influencing the adjustment mechanism the adjusting piston or the same loading spring can, for example, from the outside be adjusted, z. B. by means of a linkage, which is axially to the adjusting piston arranged control shaft penetrated lengthways.

The drawing shows an embodiment of the invention, namely Fig. I shows a longitudinal section through a fuel injection pump, Fig. 2 shows a cross section along line AA of Fig. I, Fig. 3 shows a .Cross section along line BB of Fig. I, Fig. 4 the middle part of Fig. 2 in a somewhat expanded representation and on a larger scale, Fig. 5 and 6 the piston stroke curves (depending on the angle of rotation of the main drive shaft), namely Fig. 5 for full load and Fig. 6 for idling, Fig. 7 and 8 corresponding curves for a somewhat different control method.

In the upper and lower part of the pump housing i are the two Drive shafts or camshafts 2 and 3 are supported. The camshaft 2 is here as Main drive shaft in any known manner (usually unchangeable) from the prime mover, e.g. B. a Fahrzeugdieselmasch.ine, which from the pump is supplied with fuel, driven. The pump is in the exemplary embodiment designed as a 6-cylinder in-line pump, but the invention is also applicable to other types of pumps and applicable to any number of cylinders. Dlie camshaft 2 is used to control the lower piston 4, the camshaft 3 for control the upper piston 5. The two close in pairs between their two end faces pump pistons driven in opposite directions and moving in the same pump cylinder one pump chamber each, which in the bottom dead center of the piston (or the lower Piston) with the inlet or suction port 7 and the piston (or piston) at top dead center. of the upper piston) is brought into communication with the outlet or pressure opening 8.

The upper camshaft 3 is driven in the following way: The main drive shaft 2 is designed at its front end as a pinion g, which about the gears io, i i, 12 and 13, all of the same diameter as the pinion g own, the adjusting piston 14 drives. This stands with the Gear 13, through the longitudinal keys 15 and with the upper camshaft 3 by means of a (to avoid excessive friction, it is advisable to use the steepest possible thread) 16 in drive connection. (Instead of this, of course, the high helix thread, for example, could also be used be arranged on the gear 13 and the longitudinal keys 15 on the camshaft 3.) In contrast to the illustrated embodiment, in which the shafts 2 and 3 in the same Rotate the direction of rotation, the arrangement, for. B. by using an even number of translation gears, between the two shafts, of course, also hit in this way be that the direction of rotation of both shafts is opposite to each other.

The piston 14 is also supported against a control spring 17 or possibly also several, for example with the arrangement of an additional idling spring inside the illustrated spring i7, the same in turn against a z. B. multi-part linkage i8 supports (or supports). Since the piston 14 and the spring 17 take part in the drive movement of the camshaft 3, a pressure ball i9 is interposed in the linkage. The linkage 18 and thus the spring 17 with the Adjusting piston 14 can be adjusted to the right or left while maintaining the equilibrium between the spring and the pressure medium loading the piston 14. As a result, the camshaft 3 is rotated relative to the piston 14 and thus relative to the main camshaft 2 by means of the coarse thread 16. For example, the coarse thread 16 such Steiung on, the t to the full stroke of the variable displacement, the piston, a relative rotation of the camshaft 3 by 3o corresponds to 14 to 6o °.

The end positions of the piston i.i can optionally go through exchangeable or adjustable stops can be determined. For example can between the piston 14 and the camshaft 3 at i4 ″ an exchangeable number of washers are placed in between, while for the adjustable stroke limitation in the in the other direction the stop 14 'can be replaced by an adjusting screw. The adjustable stops can of course also be located on the piston 14.

As shown in Figure 3 in particular, the gears io, ii and 12 are as Gear pumps formed by the gears io and i i on the one hand and i i and 12 on the other hand each act as a gear pump. The liquid flows are in Fig. I and 3 indicated schematically by dash-dotted lines. Both pumps suck fuel from inside the pump housing. The gear pump io, ii serves here as a feeder pump for the injection pump by adding the fuel via line 2i into the inlet or suction chamber common to all pump cylinders 22 promotes. The pump 11, 1a serves as a regulating pump to act on the Regulating or adjusting piston 14 by conveying the fuel into a line 23, from where this on the one hand via the line 24 to the control room 25 and on the other hand via a line 24 'to the suction side of the pumps or into the interior of the pump housing can flow back. Since the line 26 to the fuel increases with the speed Offers resistance, which may still be provided by a special (possibly adjustable) Throttle device can be supported, will be in the control room 25 with The liquid oil increases with the speed; set the initial pressure. Therefore, if the speed increases, so the piston 1.4 will adjust against the spring 17 to the right, whereby the camshaft 3 is rotated in such a way in the manner described in more detail below is that the pump is set to a reduced fuel injection amount. Conversely, the piston 14 adjusts itself when the speed is falling, and therefore when it is falling Fluid pressure in control chamber 25 to the left, which means that the pump has a larger injection quantity supplies.

As particularly Fig. .I (schematic) shows, is immediately behind the pressure opening 8 controlled by the piston in space 27 'is a spring-loaded check valve 26 arranged, which is in the pressure stroke of the piston, d. H. «. When this is open Outlet 8 the fuel trapped between them by moving towards each other of the Iiolbenstirnflächen convey in the pressure line, opens, at one of the pistons on the other hand, the suction effect exerted on the pressure line closes. The pressure line 27 each leads to the associated injection nozzle of the internal combustion engine.

About a special precision work in the manufacture of the pump cylinders and an expensive grinding in of the pump plungers to the exact size to achieve this to avoid more precise injection quantities, as well as to compensate for other irregularities, are de pump cylinders intentionally z. E. about io per cent overdimensioned. The adjustment precise injection quantities are achieved by means of a throttle pin 28 (or the like), which is adjustable from the outside and the length of an annular gap 29 in a leakage burnt line 2g ', 2g ", which the. Space 27' behind the check valve 26 with the interior of the pump housing connects, regulates through adjustable throttling. The greater the set length of the throttle gap, the more fuel there is through line 27 to the nozzle promoted. By adjusting the throttle pin 28 you have it in your hand, Even without precise measurement of the pump cylinders and pistons, the injection quantity is very high to be adjusted precisely.

Instead of a cylindrical throttle pin, a conical one can also be used Throttle pin may be provided, the bores 2g 'and 2g "for inflow and outflow of the leak fuel to or from the throttle ti * ft not offset in the axial direction need to be.

Furthermore, a throttle slide, a throttle needle with the Effect of a throttle valve, replaceable throttle bores or the like. Used "earth.

If the pump is made of gray cast iron, light metal casting or a similar material, it is also advisable to make the pump chamber with suction and pressure openings and the controlling edges of the pistons made of a more wear-resistant material, e.g. B. steel to produce. For this reason, two steel bodies 30 and 3 i are cast in the middle part of the pump housing, of which the former the pressure openings 8 of the individual pump cylinders with the associated check valves, the latter the suction openings 7 with the common suction chamber 22, as well as the individual throttle devices for the leak fuel. The individual pump cylinders can be arranged at a particularly small distance from one another, so that the overall length is very short.

each of the two pump pistons 4 and 5 are directed towards each other In the usual way, inevitably driven by the two camshafts 2 and 3. The return stroke takes place non-positively by means of the springs 32 and 33, which are for each Pistons in bores 34 and 35 parallel to it, in pairs on both sides of the piston in planes perpendicular to the row of pump cylinders. By means of cross members 36 and 37, they are supported against the associated piston away. As a result of this arrangement of the springs, they do not require any additional height, but are housed in places that otherwise remain essentially unused would. Furthermore, this arrangement has the advantage that the cam run-up occurring tilting moments on the piston, which also acts as a plunger, with a large Lever arm are absorbed by the springs. These can also be proportionate weakly “counted” because they, apart from the task of sucking in the fuel, only have to overcome small inertia forces. That to the left open Pump housing is covered by a cover 38, which is also the cover for the gear pumps io, ii and 1i, 12 form and the control space 25 and the running surface for the z. B. composed of two parts, welded together or the like Way produced control piston 14 contains. Further housing covers 39, 40 and 41, possibly also a housing division in the plane of the main drive .-, shaft od. Like., are used to facilitate assembly of the pump.

The control and regulation of a pair of pistons 4, 5 rotating in opposite directions is shown in FIGS. The crank angles are each plotted on the abscissa from the top dead center of the lower piston, ie from the end of the injection period. The ordinates show the position of the pistons as a function of the crank angles, namely curve 4 'represents the piston stroke curve for the lower piston or for its controlling piston face, curve 5' or 5 "represents the piston stroke curve for the upper piston or piston. its controlling piston face, namely curve 5 'at maximum injection quantity, e.g. at full load (section 5), curve 5 "at idling (section 6). Dimensions 7 and outlet 8 are on both sides of the diagrams indicated on the ordinate. The total stroke of the two pistons, which are essentially close to one another at the two dead points, is denoted by i, that part of the stroke in which the inlet is open is denoted by e and that part of the stroke in which the outlet is open is denoted by a .

According to the shape of the control cam, pistons 4th and 5th now controlled in such a way that the piston 4 is relatively long in the lower, the suction opening to located dead center remains to be located the upper, -after the pressure opening Dead center, on the other hand, is controlled in a short time (see curve 4 '). A reverse control is, however, provided for the piston 5 (s1. curve 5 'or 5 "). This is how it is possible to move both curves by a relatively large amount in the direction of the crank angle to adjust, d. H. a relatively large relative rotation of both camshafts to each other and thus to enable a precise and sufficiently sensitive regulation.

As Fig. 5 shows, perform at full load (start enrichment or the like) both pump pistons, calculated from top dead center, initially almost one in common Downward movement, 'in that both pump pistons follow one another closely or relatively closely. However, while the lower piston initially remains for a while after the suction opening has been exposed remains at bottom dead center, the upper piston begins slowly sucking in of fuel immediately or immediately its upward stroke, until both pistons at the point P corresponds to a certain amount of the full load of the fuel sucked in here Have a distance x 'from each other. At this moment the lower piston closes the suction opening 7 (corresponding to a stroke e). The upper pump piston moves now essentially evenly or slightly offset up to the piston top dead center, the check valve 26 initially also after overriding the lower edge rz of the outlet through the upper piston keeps the outlet closed because the lower After the inlet is closed, the piston initially remains in its position and thus sucking back acts on the enclosed fuel. Only when the lower piston is also his Continued upward gear and reached point Q 'at which both pump pistons again have the distance x, the check valve 26 opens, so that with further -Upward movement of the lower piston to remove the trapped fuel from the pump chamber is displaced into the pressure line. The upward movement takes place here to achieve an injection process that begins as abruptly as possible with a relatively steep Curve slope. The use of stepped curves also achieves that Inlet and outlet remain closed as long as possible.

In the case of the smallest amount of fuel, i.e. in the borderline case in the stop position, is, as Fig. 6 shows, the control curve 5 "of the upper piston opposite the curve at full load (5 ') to the right by a crank angle a (e.g. from a maximum of 8o to go °) offset. The one sucked in at point P when the suction opening was closed The amount of fuel corresponds to the small distance x "between the two pistons also very small, namely in the limiting case = zero. The latter is practically already then the case if at the moment of completion of the suction opening only a fuel film is between the two pistons, so x "= - o, o5 to o, i (5 min is. (The same applies to the end of the pressure stroke.) That after completion between the suction opening as a result of the divergence of the two pistons The two pistons cannot move this time either due to the non-return valve 26 affect the pressure line 27 and is at point Q "just before top dead center of the piston (in the borderline case in this dead center itself) eliminated again when both Pistons again have the distance x 'from one another.

As can be seen, the fuel injection begins with the largest injection quantity by the angle β (from, for example, 30 to 45 °) earlier than with the lowest injection quantity. This angle is essentially determined by the steepness of the curve 4 'between the points Q' and Q ". However, an additional control, e.g. in the drive of the main control shaft 2 (for example by rotating the same relative to the crankshaft of the engine) can also be used. , be provided.

At part load, the curve for the piston 5 takes an intermediate position between the curves 5 'and 5 ", whereby at the same time (regardless of possibly provided additional regulations of the time) the injection time by a partial amount of the angle ß relocated.

As can also be seen from Fig. 6, with partial load and Idle through the downward movement of the lower piston so that after opening a vacuum the The suction opening at point R of the pump chamber between the pistons is filled with fuel which, however, is wholly or partially (the latter, by z. B. the upper piston has a slightly smaller stroke than the lower piston) back into the suction chamber: the pump is displaced, so that until it is closed again the suction opening through the lower piston at point P in any case only for the The amount of fuel required when idling remains in the pump room. A sucking back of fuel qus of the pressure line into the pump room at the beginning of the downward stroke, as long as the upper piston has not yet overridden the opening 8, is also through again the check valve26 avoided.

With a control according to Fig. 7 and 8, the only 'the last half show the piston bubble curve, the upward curve parts of the curves run z # and 5 '(bz «-. 5") parallel to one another and essentially straight. One such The course of the curve has the advantage that, for all loads or injection quantities, none Vacuum can arise between the two pistons during the upward stroke of the same. The injection begins at that point D 'or O "at which the curve 5' or 5 "begins to bend in the horizontal course. Compared to the first embodiment According to Fig. 5 and 6, this has the disadvantage that the start of injection does not occur as suddenly as it happened there. Furthermore, the shifting of the injection point corresponds to the respective phase shift of both curves (i.e. a so that one has with regard to the The choice of the phase shift angle is limited by the injection delay, unless an additional regulation of the latter is provided. The check valve: l 26 only prevents fuel from being sucked back from the in this case Pressure line when the lower piston descends. The piston stroke curves in the downward gear the piston can be arbitrary, e.g. B. mirror image of the upward gear.

To create a vacuum or suck back fuel when the piston goes down To avoid coming out of the pressure line, could possibly be between the two camshafts : 2 and 3 a torsion spring assembly be interposed, which causes When the piston moves downwards, the upper piston and the lower piston are under tension from the torsion spring follows closely, while the upward gear is released when the suspension is released adjustable distance between the pistons takes place. In this case, e.g. B. also from special adjustable stops at il "should be avoided.

Claims (4)

I? ATENT CLAIMS: i. Regulation for pumps, in particular for fuel injection pumps of internal combustion engines, with two in opposite directions in a common pump cylinder driven pump piston, characterized on the one hand by such adjustability the drive elements driving the pump pistons in opposite directions, that the drive phases (Rotational position) of one piston (5) relative to that of the other piston (6), z. B ,. by mutual rotation of the camshafts (2, 3) that control them can be and thereby the amount of liquid is controlled, and on the other hand by .ein such a control of the piston that this at the end of the effective pressure stroke when the outlet (8) is open, lie close or almost close together (6, Fig. 4) and the total or almost all of the amount of liquid conveyed by the two pistons is displaced into the outlet (g). 2. Regulation according to claim i, characterized by such a controllable control of the pump piston, for. B: by appropriate design of the control cams that when the inlet is closed (P, Fig. 5, 6) the pump pistons enclose a variable, coarse pump space and a correspondingly variable amount of liquid between them and that this pump space is maintained at least until the outlet is opened until the end of the effective pressure stroke (x ', x ") is reduced to zero or almost zero. 3. Regulation according to claim i and 2, characterized in that the one pump piston (z. B. 4) the one, z. B. bottom dead center relatively long, the other, z. B .. on the other hand only briefly passes through top dead center, while the other pump piston (e.g. 5) passes through dead center in the opposite way, the phase shift of the two pistons to each other in particular in such a way that the pistons move with the greatest injection quantity (x ', Fig. 5) during their pressure stroke (in the drawing: upstroke), with the lowest injection quantity (x ", Fig. 6), on the other hand, during their suction stroke (downstroke) have their greatest distance from each other, which in the opposite case approaches the equivalent of zero. 4. Regulation according to claim i to 3, characterized in that the pistons are controlled in such a way. That, for. B. by appropriate design of the control cam, the relocation of the start of injection (z. B: ß, Fig. 6) and the phase shift (a, Fig. 6) are unequal, preferably the former smaller than the latter. '' 5. Regulation according to claim i to 4, characterized in that the two pump pistons (4, 5), at z. B. evenly executed suction stroke (Abivärtshub), perform the pressure stroke (upward stroke) unevenly, in particular in such a way that the piston (5) located after the outlet (8), preferably with initially taking place, slow suction of fuel, immediately his approaches top dead center, while the lower piston initially remains in its position or essentially remains in its position after the suction opening (7) is closed and only executes its upward stroke shortly before the end of the pressure stroke: quickly executes and thus effects the injection. 6. Regulation according to claim i to 5, characterized in that the phase shift at the same time causes an equal shift of the injection time (Fig. 7 and 8) by z. B. the two pump pistons perform their pressure stroke (upstroke) evenly, in particular in such a way that under all loads from the closure of the suction opening to the opening of the pressure opening, both pump pistons have an invariable distance from one another '(x,', Fig. 7 or x, ", Fig. 8). 7. Regulation according to claims i to 6, characterized by a controllable control of the pump pistons such that, in the suction stroke of the pump, initially more fuel than required is sucked in and then in the pressure stroke until the suction opening is closed (P, Fig . 5 and 6) to the required amount of fuel (eg., x ", x") decreased. is, in particular such that after displacement of the fluid in the outlet (8) first of the suction opening issuing piston ben (4), e.g. with the formation of a: vacuum or partial vacuum., on its suction stroke (in the drawing: downward stroke) leads the other piston (5) by a certain (controllable) amount (a), then overtakes it at the end of the suction stroke will so that which flowed in when the suction opening was opened, e.g. B .. the largest possible amount of liquid is pushed back fully or partially back into the suction channel (7), that also in the subsequent pressure stroke (in the drawing: upward stroke) first the second-mentioned piston (5) the first-mentioned piston (4) while sucking liquid from the suction channel (7) runs ahead until the suction opening at the distance determined by the regulation (z. B. x ', x ") between the two pistons is blocked by the first-mentioned piston, and that after opening the Auslasis-es (8) by the second-mentioned piston (5) the amount of liquid (x, x ") trapped between the two pistons is displaced into the outlet (8) by the trailing first-mentioned piston (4). B. Regulation according to claim i to 7, characterized in that, after the liquid has been displaced into the pressure channel, the pressure opening (8) is shut off before or as soon as the pistons (4, 5) begin a divergent relative movement. 9. Regulator according to claim 8, characterized in that a check valve (26) is arranged in the pressure channel (27) expediently in the immediate vicinity of the outlet opening (8) controlled by the piston, so that when the two pump pistons diverge in the beginning of the suction stroke, back suction the liquid from the pressure channel (27) is prevented. ok Regulation according to claims i to g, characterized in that the end of the delivery of the liquid into the pressure channel (end of injection) is kept unchangeable or essentially invariable and the start of delivery into the pressure channel due to the variable phase shift of the two pump pistons (4, 5) to one another (8), ie the start of injection (e.g. Q ', Q ") is controlled, e.g. by driving the piston (4) controlling the suction opening essentially invariably and the piston (5) controlling the pressure opening in a controllable manner, in particular such that the phase shift (a) required for the transition from idle (Fig. 6) to full load (Fig. 5) essentially brings about the necessary advance of the injection time (ß), possibly in addition to that caused by the phase shift (a) Shifting the injection time (β), further measures can be provided for this, e.g. a device for rotating the pump drive shaft. Ii g according to claims i to io, characterized in that the counter-rotating pump pistons (4, 5) are each driven by a special control shaft (2, 3), e.g. B. in such a way that the pump pistons are driven directly by the associated control shafts at their opposite ends of the pump chamber and opposite one another, with z. B. one of the two control shafts (3) is driven only indirectly via the other control shaft (2), with the interposition of an adjusting device (14 to 17), to change the relative rotational position of the two control shafts to each other. 12. Control device, preferably for fuel injection pumps with two pump pistons working in opposite directions on the same pump chamber, in particular according to claims i to ii, characterized in that the drive of the two pump pistons relative to one another, in particular the rotational position of one control shaft (3) relative to the other control shaft (2), automatically depending on a certain company size, e.g. B. the speed of the drive is regulated. 13. Control device according to claim i to 12, characterized in that apart from or instead of the automatic change of the phase shift an arbitrary change of the same is provided. 14. Control device according to claim i to 13, characterized in that the control takes place hydraulically, preferably by the fuel conveyed by the pump. 15. Control device according to claim i to 14, characterized in that the relative rotation of the control shaft (3) is effected by means of a coarse thread (16) through the control piston (14), the control piston (14) rotating together with the control shaft (3) and can be connected displaceably (1,5) to a drive member (13) in such a way that the drive from the drive member (13) to the control shaft (3) takes place via the control piston (14). 16. Control device according to claim i to 15, characterized in that the end positions for the relative rotation of the control shafts to one another are adjustable from the outside, for. B. by adjustable or replaceable stops (adjusting screws, washers or the like.) For the control piston causing the rotation 17. Control device according to claim i to 16. characterized in that for arbitrary influencing of the adjusting mechanism (i4 to 17) of the control piston (14) hzw. the spring loading him (17), for. B. by means of the axially to the control piston (14) arranged control shaft (3) penetrating z. B. multi-part linkage (18), can be adjusted from the outside (2o), with a pressure ball (i9), z. B. in the interior of a control shaft penetrating hole for the multi-part linkage (i8) can be provided. Cited publications: German Patent Nos. I73 373, 5d-6 343, 5 17 868; U.S. Patent No. 886,047; Swiss patent specification No. 203 517.