DE3448016A1 - Duplex-plunger pump - Google Patents

Abstract

Hydrostatically driven duplex-plunger pump (10) for delivering liquids laden with abrasive particles, flowable sludges, emulsions or the like. Each plunger (14) is coupled with a double-acting hydraulic piston-cylinder unit (16a; 16b), which can be actuated by hydraulic fluid in a controlled manner in such a way that its pistons always travel in opposite directions. The actuation of the hydraulic piston-cylinder units (16a; 16b) is achieved in this context by control valves (82; 98), which can be actuated by a control unit (72), as a function of the position of the plungers (14). The position of the plungers is determined by electrical sensors (68) which produce electrical signals and feed them to the control unit. <IMAGE>

Description

■ I- ■; ■■. ^; "...

Klaus Obermann, Brothers-Grimm-Str. 2d, 6107 Reinheim-Ueberau

Duplex plunger pump

The invention relates to a hydrostatically driven one Duplex plunger pump for pumping with abrasive Particle-laden liquids, flowable slurries or emulsions, each of which has a plunger cylinder the piston rod of a double-acting hydraulic piston-cylinder unit is coupled, the application of which is controlled with hydraulic medium by means of hydraulic control elements that their pistons are each in opposite directions Perform lifting movements.

Hydrostatically driven duplex piston pumps of this type are known as flushing pumps for deep drilling rigs or press water pumps (DE-AS 1 019 5 & 3) t whereby the pumps conveying the actual flushing medium are designed as double-acting piston pumps, which are used for conveying liquids and loaded with abrasive particles Sludges are less suitable than those provided in the context of the present invention

piston - known per se - plunger or immersion ^ umpen, at which no piston seals subject to wear are provided. Only the plunger heads Seals that seal on the exit side of the plunger cylinder are exposed to the attack of the pumped Medium and thus exposed to wear and tear and must therefore be arranged and / or exchangeable as easily as possible be designed in a special way protected against wear.

The invention is based on the object of developing the known hydrostatically driven duplex pumps so that that they also promote the promotion at high delivery rates

- Ό-

of highly abrasive media, with high reliability on the one hand, and a simple and quick assembly of wear parts on the other will.

Based on a pump of the type mentioned, this object is achieved according to the invention in that the maximum working stroke of the hydraulic piston-cylinder units compared to the working stroke of the plunger each coupled feed pump is dimensioned larger by such an amount that the plunger at full Extending the maximum working stroke of the piston-cylinder units completely from the assigned plunger cylinder be pulled out that the return stroke of the hydraulic piston-cylinder units during normal pump operation however, by appropriate control of the hydraulic control elements on a corresponding to the working stroke of the plunger piston Degree is limited and that the hydraulic Control organs are selectively controllable in such a way that the hydraulic piston-cylinder units have the maximum Execute working stroke. This makes it possible - especially with larger pump units - relatively large and thus heavy plunger pistons through the piston-cylinder units built into the pump itself from the plunger cylinder pulled out if this is necessary - for example to replace worn seals. Any leaks between the plunger and the plunger cylinder can therefore be avoided in the shortest possible time Dismantling of the entire pump set can be remedied.

The hydraulic control elements are preferably controlled as a function of the stroke position of the plunger pistons electrical signals developed in a control unit

actuated control valves, wherein the control unit with at least the stroke end positions of the plunger scanning electrical sensors is connected and has a comparator unit in which the Time synchronization of the stroke end positions of both plungers compared and if one of them remains behind Plunger developed a control signal for the associated hydraulic piston-cylinder unit in this way that the supply of hydraulic medium to the piston-cylinder unit assigned to the leading plunger is reduced or completely blocked until the trailing plunger reaches its end of stroke position has reached.

In addition, it can be expedient to provide electrical sensors which scan the central stroke position of the plunger pistons and are connected to the control unit and which enable additional synchronization of the plunger pistons during their working strokes. In addition, the signals generated in these electrical sensors can be used to control the synchronization of another similar duplex pump, which is ^{interconnected with a phase shift of its strokes by 90 mi * cL eI} "pump according to the invention for the purpose of increasing the delivery capacity.

The piston-cylinder units assigned to the plunger pistons can in principle each be separated from one under Pressurized hydraulic medium delivering pressure medium source can be acted upon in a controlled manner. XJm the control effort for separate control organs for both piston-cylinder units To reduce, however, it has proven to be useful to assign the plunger Hydraulic coupling of piston-cylinder units by connecting them in series.

Either the rodless working spaces of the cylinders of the piston-cylinder units can be a line can be connected directly, while the spaces of the piston-cylinder units penetrated by the piston rods each to a hydraulic medium supplying depending on the position of the control elements or outgoing line are connected. Alternatively, the piston rods can also pass through them Working spaces of the cylinders of the piston-cylinder units be directly connected by a line, while the piston-rodless working spaces of the piston-cylinder units each to a depending on the position of the S expensive organs hydraulic medium supplying or discharging Line are connected. In the first-mentioned case, that supplied at a certain pressure applies Hydraulic medium on the piston ring surface of the hydraulic piston-cylinder units designed as differential cylinders. Compared to the application of the full piston area provided in the second alternative thus a lower hydrostatic drive force for generated by the plunger, but a faster piston stroke occurs because the piston rods penetrated Working spaces of the piston-cylinder units have a displacement volume that is smaller by the volume of the piston rod and are therefore filled faster. Of the two aforementioned alternatives of hydraulic coupling of the piston-cylinder units, the first alternative is therefore expediently used when high flow rates at lower pressures are aimed for, while conversely in the second case higher pressures with lower flow rates can be achieved. Hydraulic circuits are even conceivable in which the piston-cylinder units initially in the first alternative, i.e. with a high delivery rate and low delivery pressure and - after the

Back pressure through. Switchover after the second Alternatively, they can be operated with a lower delivery rate and higher delivery pressure.

On which the working spaces of both piston-cylinder units directly connecting line or at least one of the work rooms connected by this line is appropriate a compensating line is connected, which is controlled by the control unit via a ¥ ege valve with the the line supplying the hydraulic medium or the line leading away the hydraulic medium can be connected to or against Flow is closable. Hydraulic medium supplied or discharged via the compensation line can therefore possible leakage losses of hydraulic medium are compensated, which leads to an unsynchronized drive of both plunger pistons lead.

The structural design of the pump according to the invention can be made so that the plunger pumps and the respectively assigned piston-cylinder units are in alignment with one another at a distance from one another corresponding to the maximum possible working stroke of the piston-cylinder units supported and the plunger by the piston rods bridging this distance with the piston of each associated hydraulic piston-cylinder unit connected are, in which case the electrical sensors are formed by proximity switches arranged directly next to the piston rods, which are controlled by one on the trigger provided for the respective piston rod. The pumps constructed in this way, however, have one relatively large axial extension, especially since the construction for the complete pulling out of the plunger from the Plunger cylinder required additional stroke of the piston-cylinder units must be taken into account.

A reduction in the axial length of such pumps results when the axial distance between the plunger pumps and the associated hydraulic piston-cylinder unit by using the they coupling component as a functional part of both the Plunger pump as well as the associated piston-cylinder unit is decreased.

For example, it is possible to use the cylinder of the hydraulic piston-cylinder units at the same time as Plunger piston of the respectively assigned plunger pump to train.

The electrical sensors for controlling the stroke and synchronizing the two drives are then next to the stroke of the cylinder of the piston-cylinder units arranged proximity switches, which by one of the Outside of the respective cylinder protruding trigger can be switched.

On the other hand, it is also possible to design the piston rods of the hydraulic piston-cylinder units at the same time form the plunger of the respectively assigned plunger pump.

The arrangement of the electrical sensors for the control

then
The pump is made possible by the fact that the piston rods of the hydraulic piston-cylinder units are drilled hollow over their entire length and only closed at the end lying in the plunger cylinder, while the hollow bore at the opposite end is through the piston of the piston-cylinder units is passed through and in the working chamber facing away from the plunger cylinder

-7- 3U8Q16

Piston-cylinder-unit opens openly that the plunger-cylinder-remote working space of the respective hydraulic piston-cylinder-unit is penetrated by a tube made of non-magnetic material, which is held in the end wall closing this working space at the end remote from the piston and which enters the hollow bore, in which the dead center of the Hydraulic piston-cylinder units and optionally a central stroke position corresponding distances magnetically triggerable switches are arranged as electrical sensors, and that a magnet is provided in the hollow bore _f which triggers the electrical switch in the respectively assigned stroke position and so the control unit feedable and developed into their processable signal.

The magnetically triggered switches are expediently reed contacts arranged in the non-magnetic tube, which by means of a cast resin that is cast into the pipe after its assembly and then cured can be fixed.

To reduce the wear and tear of the plunger sealing in the exit area from the plunger cylinder It is advisable to seal this seal on the rear side facing away from the plunger working space by means of a bottom Pressurized barrier fluid, e.g. press water, must be applied.

A configuration in which the pressure is particularly effective with regard to reducing wear is then particularly effective the barrier fluid by means of a pressure control device is controlled in proportion to the pressure currently prevailing in the medium to be conveyed.

The invention is in the following description several Embodiments explained in more detail in connection with the drawing, namely shows:

Fig. 1 is a partially sectioned plan view of a first embodiment of a Duplex plunger pump according to the invention, in which also schematically shows a circuit diagram of the hydraulic drive of the piston-cylinder units is shown; ·.

2 shows a longitudinal center section through a single unit a second embodiment of the plunger pump according to the invention; and

3 shows a longitudinal center section through a single unit of a third embodiment of a plunger pump according to the invention.

In Figure 1, a duplex plunger or plunger pump according to the invention, designated in its entirety by 10, is shown, which is composed of two similar individual pump units 10a and 10b arranged parallel next to one another, which in turn each consist of the actual feed pump 12a or 12b and one each on the plunger piston l4 of these feed pumps coupled double-acting hydraulic piston-cylinder unit l6a and l6b are assembled. The hydraulic piston-cylinder units 16a, 16b can be acted upon with hydraulic medium in a controlled manner via a hydraulic circuit from a pump 18 in such a way that their pistons 20 and thus the coupled plungers Ik each execute reciprocating movements, ie when the feed pumps 12a, b are driven mechanical rotary drives such as crank drives would be referred to as a stroke movement of the plunger with a phase shift of 180.

The structure of the components of the individual pump units 10a, 10b is largely conventional, so that it is sufficient the design of the feed pumps 12a, b of the piston-cylinder units 16a, b and their coupling below only briefly to explain schematically.

The feed pumps 12a, b consist of a plunger cylinder 22, one end of which is the Plunger l4 through seals 24 against the outlet of the medium to be conveyed sealed and longitudinally displaceable is passed through. In the opposite front end is the suction line for the product to be conveyed Medium connected via a check valve 26, which prevents the plunger from flowing back during the suction stroke 14 from the plunger cylinder 12 in its interior 28 sucked conveying medium in the suction line when subsequent delivery or working stroke prevented. Much more the medium to be conveyed is via an in the immediate vicinity of the seals 24 the ¥ andung of the plunger cylinder 22 penetrating outlet opening 30 into a downstream Pressure line 32 displaced, with a second, the outlet opening 30 downstream check valve 34 ensures that the conveyed medium in the following The suction stroke is not sucked back into the interior space 28. The check valve 34 can - as well like the check valve 26 - be designed as a ball check valve.

One end is at the free end of the plunger 14, i.e. the end protruding from the plunger cylinder 22 a piston rod 38, which is attached to its other, sealed by an end cover 40 of the cylinder 42 the associated piston-cylinder unit 16a, b guided

- 10 -

End carries the piston 20, which the interior of the
Cylinder 42 in two resizable work spaces
44, 46 subdivided. These working spaces 44, 46 are through openings 48 and 50 in the end cover 40 and
in an end cover 52 which closes the end of the cylinder 42 opposite the end cover 40, connected to lines 54, 56, via which hydraulic medium is alternately fed from the pump 18 into the working spaces 44, 46 and discharged again.

The plunger cylinders 22 of the feed pumps 12a, b and the cylinders 42 of the piston-cylinder units 16a, b are
arranged with aligned longitudinal center lines at a predetermined distance from each other in a support structure, which in the case shown, each of one, the plunger cylinder 22 and the cylinder 42 holding support plate 58 and 60 and holding these plates at the predetermined distance
welded longitudinal struts 62 is formed. The ends of the piston rods 38 and the plunger 14, which are connected to one another, oscillate in the intermediate space formed in the support structure, the connection being made in each case by a separable connecting clip 64 with a
radially circumferential flange 66 takes place, which serves as a trigger for electrical sensors held by the longitudinal struts 62 in the form of proximity switches 68 that work without contact. These proximity switches are held in such a position on the side members 62 that an electrical control signal is generated in them by the radial flange 66 of the respectively associated connection clamp 64 when the associated plunger l4 is in one or the other stroke or dead center position. The distance a between the two outermost proximity switches 68 of a single pump unit IQa, b

_ 11 _

is therefore the same, the working stroke a of the associated plunger 14. For certain, more detailed below explained purposes may be halfway between the Proximity switches 68, i.e. with a stroke length a / 2, one more each, only dash-dotted in the drawing indicated proximity switch 68 is provided be. The signals generated in the proximity switches 68 are via electrical lines 70 of a control unit 72 supplied, from which the application of the Piston-cylinder units l6a, l6b is controlled with hydraulic medium.

The length of the cylinders 42 of the piston-cylinder units 16a, 16b is dimensioned so that the maximum possible working stroke of their pistons 20 is longer than the working stroke by the distance b a is the plunger 14. The additionally possible stroke b is chosen so that the plunger when using the maximum possible working stroke a + b of the piston-cylinder units l6a, b completely from the associated plunger cylinder 22 is pulled out. This may be necessary, for example, if the the plunger 14 in the associated plunger cylinder 22 sealing seals 24 replaced due to wear Need to become. During normal operation, the proximity switch 68 on the other hand, only the normal stroke a is covered in the piston-cylinder units.

That for the loading of the hydraulic piston-cylinder units 16a, b required hydraulic medium is driven by the above-mentioned, by a motor 78 High pressure pump 18 supplied, which it sucks from a reservoir 80 and into one to an electromagnetically

- 12 -

Switchable directional control valve 82 feeds line 84 from which, on the other hand, a line 86 leads back to the reservoir 80. In the exemplary embodiment shown, the directional control valve 82 is on the other hand connected via lines 88 and 90 to the passage openings 48 leading to the working spaces 44 of the piston-cylinder units 16a, b. Depending on the switching position of the valve 82, the hydraulic medium conveyed by the pump 18 is thus conveyed into the working spaces 44 of the piston-cylinder unit l6a or the piston-cylinder unit l6b, the hydraulic medium on the other hand not coming from the pump 18 connected working space 44 flows back to the reservoir 80. In a third switching position, on the other hand, the valve 82 is switched to unpressurized circulation, ie the hydraulic medium conveyed by the pump 18 then flows directly back into the storage container. The working chambers 46 of the piston-cylinder units opposite the working chambers 44 are directly connected by the line 56, so that when the working chamber 44 of the one piston-cylinder unit is acted on, the hydraulic medium is inevitably displaced by its piston 20 from the opposite working chamber 46 flows over into the working chamber 46 of the other piston-cylinder unit, the piston 20 of which moves, the hydraulic medium being displaced from the working chamber 44 of this piston-cylinder unit and being conveyed back to the storage container 80. The hydraulic piston-cylinder units 16a, 16b are thus coupled via the line 56 in the sense of a series connection in such a way that their pistons and thus piston rods each execute strokes in opposite directions. It is clear that the switching of the directional control valve 82 and thus the control of the stroke movement of the piston-cylinder units from the control unit J2 via a

" ¹ / ~ '" 3448018

Signal line 92 occurs when the proximity switch em 68 signals that the pistons 20 of the piston-cylinder units 16a and 16b have each reached the opposite dead center.

Since hydraulic circuits - different from form-fitting mechanical drives - are not completely inevitable due to possible minor leakage losses it cannot be ruled out that the piston 20 of a piston-cylinder unit may occur during a working or return stroke compared to the piston 20 of the respective other piston-cylinder unit something remains behind and thus the proximity switch 68 assigned to its end of travel still has no signal to the Control unit 72 delivers when the other's stroke ends Proximity switch 68 assigned to the piston has already reached the end of the stroke has signaled. Because of the lack of the second signal, the control unit will also no changeover signal developed for the directional control valve 82, i.e. the drive of the plunger pump 10 would come to a standstill. To avoid this, a compensating line is attached to line 56 94 connected, through which as long as hydraulic medium in the working chamber 46 of the trailing Piston-cylinder unit is replenished until the piston 20 of this unit has also reached its end position. Since both proximity switches 68 then deliver a signal to the control unit 72, the switching of the directional control valve 82 triggered and the piston-cylinder unit acted upon with hydraulic medium in the opposite stroke direction. The described electro-hydraulic circuit thus inevitably also causes something like a synchronization of the two piston-cylinder units.

• ZO-

The control of the replenishment of hydraulic medium via the line ^ h is carried out by two hydraulic switching valves 96 and 98 », of which the valve 96 is designed as a weighing valve, which is controlled by the pressure in the lines 88 and 90 itself in such a way that it is the straight line Line 88 or 90, which is under higher pressure, connects to the second switching valve 98, which can be actuated electromagnetically from the control unit 72 via a signal line 97. Such an actuation signal is developed by the control unit when only one of the proximity switches 68 signals that the piston of its piston-cylinder unit has reached the dead center position. The switching valve 98 is then switched by this signal from the previously closed to an open position, in which pressurized hydraulic medium supplied via the switching valve 96 is replenished until the piston of the second piston-cylinder unit is also excited by the one assigned to it Proximity switch 68 reports to control unit 72. It should also be pointed out that in the hydraulic control system described, only the switching elements essential for the control function have been described, while the pressure relief valves, filters, etc. that are customary in hydraulic circuits for safeguarding are not shown and described in the drawing for the sake of clarity. .

FIG. 2 shows a longitudinal section through one of the individual pump units 10a or 10b according to FIG. 1 functionally corresponding single pump unit 110, That is, by interconnection with a similar pump unit 110 in the manner described above

forms a duplex plunger pump according to the invention. To avoid repetition, the following are provided only those made in relation to the configuration according to the exemplary embodiment shown in FIG Modifications described, while it is sufficient for the rest to refer to the preceding description, especially since functionally identical parts of the pump unit 110 with the same reference numerals as the corresponding parts of FIG Pump unit 10a, however, are denoted by a preceding "1".

The fundamental difference between the pump unit 110 and the pump unit 10a is that the piston-cylinder unit 116 is arranged in the reverse position, i.e. with the piston rod I38 pointing away from the feed pump 112, so that its cylinder 142 slidably engaging the plunger cylinder 122 simultaneously engages the plunger the delivery pump 112 forms. So that the cylinder 142 can fulfill its function as a plunger piston, must he - depending on the admission of his work rooms 144 or 146 - be displaceable on the piston 120 and within the interior 128 of the plunger cylinder 122. Accordingly, the piston must be turned from the end of the piston rod I38 be set at a predetermined distance from the plunger cylinder 122, for which a (not shown) support structure in accordance with the support structure 58, 60, 62 described in connection with FIG. 1 can be.

The working spaces 144 and 146 are acted upon via the hollow-drilled piston rod I38, in which Hollow bore in addition a tube 147 of smaller diameter is introduced, which at its ends in the Hollow bore is inserted sealed and the Hohlbohr ting

SÄ-

divided into a central passage channel leading to the working space 146 and an outer passage passage for hydraulic medium, which is annular in cross section and leading to the working space ikk.

As a trigger 166 for the proximity switch 168 in In this case, a radial flange on the cylinder cover 14O closing the cylinder 142 on the piston rod side to serve·

Due to the partially nested arrangement the piston-cylinder unit 116 in the feed pump 112 is a substantial reduction in the overall length of the individual pump unit 110 and thus a duplex pump constructed from two of these pump units 110 is achieved.

The following applies to the further modified exemplary embodiment of a single pump unit 210 shown schematically in FIG analogously to what was stated above for the single pump unit 110, but in this case the piston rod 238 of the piston-cylinder unit 216 at the same time forms the plunger oscillating in the plunger cylinder 222. In this case, too, the dual function the length of the piston rod 238 saved. A detailed description of the components is not necessary again, because in this case, too, components that are functionally the same with the same reference numerals as in Embodiment according to Figure 1 are designated, wherein in this case, however, a "2" is also prefixed.

- 17 -

The arrangement of the proximity switches 68 resp. l68 The electrical sensors formed in the previous exemplary embodiments are used in this Fall within the pump unit 210, for which the Piston rod 238 is provided with a hollow bore 239 over essentially its entire length, which only is closed at the end lying in the plunger cylinder 222, while it is still closed at its opposite end. through the piston 220 of the piston-cylinder unit 216 is passed through. In this hollow bore, a pipe 241 enters, which penetrates the working space 246, and in a hole in this working space 246 on the end face closing end wall 252 is attached. In this The tubes can be operated magnetically at suitable intervals Proximity switch 268 arranged in the form of reed contacts and fixed by a subsequently hardened cast resin filling 243, which is also the inside of the pipe 241 running (not shown) from sections of the signal lines 270 to the control unit (also not shown).

The reed contacts 268 are triggered in the corresponding stroke positions by a ring magnet 260 arranged in the vicinity of the mouth of the hollow bore 238 in the piston 220, which thus takes on the function of the radial flanges 66 or I66 of the exemplary embodiments described above.

Should be noted, further, that even with the embodiments according to Figures 2 and 3 the piston-cylinder units Ho and 216 a maximum possible stroke have the complete withdrawal of the plunger,

¹⁸ - cop /

i.e., cylinder 142 and piston rod 238, respectively the plunger cylinder 122 or 222 for the purpose of easy and enables quick replacement of seals 124 and 224, respectively. The electro-hydraulic control of the Piston-cylinder units 116 and 216 are their piston stroke during normal operation of the duplex plunger pumps limited to a working stroke corresponding to the working stroke of the plunger in the plunger cylinder.

Mention should also be made of a possibility of reducing the wear of the plunger pistons 14, 142, 238 in the plunger cylinder 22, 122, 222 sealing gaskets 24, 124, 224 to decrease. This possibility is the pressure difference between those directed towards the interior of the plunger cylinder Side of the seal and its opposite side to reduce, so that the prerequisite with abrasive Particle-laden medium to be pumped tends to a lesser extent between the seal and the plunger to enter. This can be done, for example, by applying a pressurized seal to the back of the seal Sealing liquid happen, it may be useful, the pressure prevailing in the sealing liquid as a function of the pressure to be demanded at the moment Liquid prevailing in the interior of the plunger cylinder Control pressure.

It can be seen that within the scope of the inventive concept Modifications and developments of the exemplary embodiments described above can be implemented. So can the Control of the hydraulic loading of the working spaces of the piston-cylinder units also via separate ones Switching valve - possibly even from your part separately driven separate pumps out - in

-19 -

- as-

Parallel connection. By taking appropriate measures is then only to ensure that a synchronization of the opposing piston strokes of the piston-cylinder units he follows. By comparing the generated in the electrical sensors as a function of the stroke position electrical signals in the control unit and corresponding changes in the application of the unsynchronously running This is piston-cylinder units with hydraulic medium possible. Also the summary of two of the described Duplex plunger pumps to a pump unit with doubled output is possible, with the electrical sensors of the corresponding phase-shifted Drive of the two pumps is synchronized.

- 20 "

- L6e rsei'te -

Claims (1)

Claims 1. Hydrostatic, driven duplex plunger pump for pumping liquids loaded with abrasive particles, flowable slurries or emulsions. in which each pinnaker piston is coupled with a double-acting hydraulic piston-cylinder unit whose application of hydraulic medium is controlled by means of hydraulic control elements in such a way that their pistons each execute reciprocating stroke movements, characterized in that the hydraulic control elements are characterized by depending on the stroke position of the plunger piston (l4) in a control unit (72) developed electrical signals are actuated control valves (82; 98) that the control unit (72) is connected to at least the stroke end positions of the plunger (14) scanning electrical sensors (68), and that the control unit ( 72) has a comparator unit in which / the time synchronization of the stroke end positions of both plunger pistons (lk) is compared and, if a plunger piston (l4) remains behind, a control signal for the associated hydraulic piston-cylinder unit (l6a; lob) is developed in such a way that the Supply of hydraulic medium to the the piston-cylinder unit (l6a {l6b) assigned to the leading plunger piston (l4) is reduced or blocked until the trailing plunger piston (l4) has reached its stroke end position. -21 - . Pump according to Claim ^, characterized in that electrical sensors (68) connected to the control unit (72) are provided which scan the central stroke position of the plunger pistons (14). . Pump according to one of Claims 1 to 2, characterized marked, wet the piston cylinder units (l6a} l6b) assigned to the plunger (l4) hydraulically coupled by series connection are. 4. Pump according to claim 3, characterized in that the rodless working spaces (46) of the cylinder (42) the piston-cylinder units (l6aj 16b) through a line are directly connected, while the work spaces (44) penetrated by the piston rods (38) of the piston-cylinder units each at an in Depending on the position of the control elements (82) line supplying or removing hydraulic medium (88; 90) are connected. 5. Pump according to claim 3 »characterized in that the working spaces (44) of the cylinders (42) of the piston-cylinder units penetrated by the piston rods (38) (16aj 16b) are directly connected by a line, while the rodless work3-spaces (46) the piston-cylinder units in each case one depending on the position of the control elements (82) supplying or discharging hydraulic medium Line are connected. 22 " 5. Pump up. Claim. K or 5, characterized in that on the line (56) directly connecting the working spaces (46) of both piston-cylinder senses (16a), 16b), or at least one of the working spaces (46) connected by this line, a compensating line (94 ) is connected, which via a directional valve (98) controlled by the control unit (72) can be connected to the line (88} 90) supplying the hydraulic medium or the line (90; 88) removing the hydraulic medium, or can be closed to prevent the flow from flowing through it. 7. Pump according to one of claims 1 to 6, characterized in that the feed pumps (l2a; 12b) and the respectively associated Ko Ib en-ZyI Indian - »- units (l6a; l6b) are aligned with one another in one of the maximum possible Working stroke (a + b) of the Eo Ib en-cylinder units (l6aj l6b) corresponding distance from each other and the plunger (l4) supported by the piston rods (38) with the piston (20) of the respectively assigned hydraulic Piston-cylinder unit (l6a | I6b) are connected, and H _fl fl the electrical sensors are formed by proximity switches (68) arranged directly next to the piston rods (38), which are triggered by a trigger (radial flange) provided on the respective piston rod (38) 66) can be switched. -23 - G. Pump according to one of claims 1 to 6 »characterized characterized in that the axial distance between the feed pumps (ll2j 212) and the respectively associated hydraulic piston-cylinder unit (116; 2l6) by using the coupling device Component as a functional part of both the feed pump (112} 212) and the associated piston-cylinder unit (116j 216) is decreased. . Pump according to claim 8 »characterized in that the cylinder (l42) of the hydraulic piston-cylinder units (ll6) at the same time as the plunger each associated feed pump (ll2) is formed. . Pump according to claim 9, characterized in that the electrical sensors (168) next to the stroke of the cylinders (l42) of the piston-cylinder units (Ho) arranged proximity switches (I68), which by one of the outside of the respective Cylinder (l42) protruding trigger (radial flange I66) can be switched. . Pump according to claims, characterized in that the piston rods (238) of the hydraulic piston-cylinder unit en (216) at the same time the plunger of the respectively assigned feed pump (212) form. - 24- 12. Pump according to claim 11, characterized in that the piston rods (238) of the hydraulic piston-cylinder units (216) substantially above their Hollow drilled over the entire length and only closed at the end lying in the plunger cylinder (222) are, while the hollow bore (239) at the opposite end through the piston (220) of the piston-cylinder unit (216) is passed and in plunger cylinder facing away from the working space (246) Piston-cylinder unit (216) opens open that the Working space (246) facing away from the plunger cylinder Respective hydraulic piston-cylinder unit (216) from an end wall which closes this working space (246) at the end remote from the piston (252) held, in the hollow bore (239) entering tube (24l) made of non-magnetic material is penetrated, in which in the dead centers of the hydraulic piston-cylinder unit (216) as well if necessary corresponding to a mid-stroke position, Magnetically triggered switches (268) are arranged as electrical sensors, and that in the hollow bore a magnet (266) is provided, which the electrical switch (268) in the triggers the respectively assigned stroke position and thus an electrical signal that can be fed to the control unit developed. 13. Pump according to claim 12, characterized in that the magnetically triggerable switches (268) are reed contacts arranged in the non-magnetic tube. - 25- COPY 14 · Pump according to claim. 12. or iy _t, characterized in that the magnetically releasable switches (268) are fixed in the non-magnetic tube by a cured casting resin (243). 13. Pump according to one of claims 1 to 14 > characterized in that the plunger (l4} 142} 238) in the exit area from the plunger cylinder sealing gasket (24) 124} 224) on the dem Plunger working space (28} 128} 228) facing away from the rear is acted upon by a pressurized barrier fluid. 16. Pump according to claim 15, characterized by a Pressure control device for the barrier fluid, which increases the pressure of the barrier fluid in proportional Controls depending on the pressure currently prevailing in the medium to be conveyed.