The present invention relates to pumps, particularly but not exclusively to heavy duty fluid pumps for large scale applications.

BACKGROUND

Reciprocating pumps are used in a variety of applications and for a wide range of purposes. One such application is the conveyance of fluids in large-scale plants for earth drilling or mining. Some examples of such pumps and their application are described in earlier patent publications US 8,920,146 B2, US 2015/0260178 A1 , WO 2020/193151 A1 and US 9,695,808 B2. The type of pumps therein described are commonly used, for example, to pump mining slurry or drilling mud, i.e., fluid mixtures with demanding properties, for example, having a considerable amount of solid particles suspended therein.

Such pumps for the applications mentioned above or other, similar fields of use, often have demanding operating conditions, which may include requirements for high output pressures or flow rates and the need to handle challenging media, for example, abrasive liquids and/or liquids containing solid particles. Many such pumps are used in mobile or remote installations, for example, on drilling rigs, and have high demands for operational reliability and low maintenance requirements. There is furthermore a desire for compactness and low weight in most applications.

There is a continuous need for improved pump technology, for example in the mining industry and for other heavy duty applications.

SUMMARY

The objective of the present invention is to provide fluid pumps with improvements in one or more of the abovementioned aspects, or at least to provide useful alternatives to known technology.

In an embodiment, there is provided a pump comprising a plurality of pump cylinders, each pump cylinder of the plurality of pump cylinders comprising a piston arranged therein, each piston dividing an interior volume of the pump cylinder into a first working chamber and a second working chamber; an intake line; and a discharge line, wherein each first working chamber is operatively connected to the intake line and to the discharge line of a fluid to be pumped, and each second working chamber is fluidly connected to a first working chamber of another pump cylinder of the plurality of pump cylinders.

The detailed description below outlines further examples and embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other characteristics will become clear from the following description of illustrative, non-restrictive examples, with reference to the attached drawings, in which:

Fig. 1 shows an example of a slurry pump according to the prior art.

Fig. 2 shows a schematic view of the operational principle of a piston diaphragm pump according to the prior art.

Fig. 3 is a schematic view of the operational principle of a single acting triplex piston diaphragm pump according to the prior art.

Fig. 4 is a schematic view of the operational principle of a double acting triplex pump according to the prior art.

Fig. 5 is a schematic view of the operational principle of a three-cylinder double acting diaphragm pump according to an example.

Fig. 6 is a schematic view of the operational principle of a three-cylinder double acting diaphragm pump according to an example.

Fig. 7 is an illustration of a pump arrangement. Fig. 8 is an illustration of volume displacement rates of two interconnected working chambers in a pump according to an example.

Fig. 9 illustrates a four-cylinder double acting diaphragm pump according to an example.

Fig. 10 illustrates a three-cylinder double acting pump according to an example.

DETAILED DESCRIPTION

Fig. 1 shows an example of a slurry pump 100 (see, for example, the abovementioned US 9,695,808 B2). The pump 100 comprises a drive part 101 , in this case a crank drive mechanism. The drive part 101 also includes a motor, such as an electric motor, to drive the crank drive mechanism. The pump 100 also comprises a pump part 102 having a plurality of pump cylinder units, in this example, three pump cylinders driving six diaphragm pump chambers. The pump cylinder units have pump pistons (not visible in Fig. 1) driven by the crank drive mechanism, for example, in the manner described below.

Pumps such as the slurry pump 100 shown in Fig. 1 are typically used to transport slurries or other fluids containing solids. They may have power ratings of several hundred kilowatts or more, and each diaphragm housing and corresponding diaphragm may have a diameter of one meter or more.

Fig. 2 illustrates the principal design and operation of a piston diaphragm pump, in this case a single-acting pump. Fig. 2 illustrates one pump cylinder unit 10. The pump cylinder unit 10 has a pump piston 1 (or an equivalent drive element, such as a plunger), which is driven by a drive unit (not shown) via a piston rod 31 in an oscillating motion. The piston 1 thereby moves back and forth within a pump cylinder 2 (as indicated by the double arrow). The drive unit may, for example, be a crank system. By this movement, the piston 1 displaces a volume of fluid in an intermediate fluid chamber 3, usually a hydraulic oil. The intermediate fluid chamber 3 is delimited by the piston 1 , a pump chamber housing 15 (which may or may not include or be integral with the pump cylinder 2), and a flexible, fluid-impermeable separation diaphragm (also denoted membrane) 4. Via the flexible separation diaphragm 4, the fluid chamber 3 is fluidly separated from, but operatively connected to, a pump chamber 5, which contains a medium to be pumped. The medium may, for example, be a mud or a slurry. The movement of the piston 1 causes displacement of fluid in (or into and out of) the intermediate fluid chamber 3, which again causes a back- and-forth displacement of the separation diaphragm 4 (indicated by the double arrow), and thereby an increase or reduction in the volume of the pump chamber 5. The separation diaphragm 4 moves between its outer positions a and b. The end stroke position ‘a’ illustrates the end of a suction stroke / start of a discharge stroke, while the end stroke position ‘b’ (dashed) illustrates the end of a discharge stroke / start of a suction stroke.

The pump chamber 5 has an inlet 25 and is fluidly connected to a fluid source 16 via an intake line 9 having an intake line valve 8. The fluid source 16 may, for example, be a pit or a pipe system supplying fluid to be transported by the pump 100, such as a slurry. The pump chamber 5 further has an outlet 26 which is fluidly connected to a fluid receiver 14 (for example a fluid reservoir or piping system for conveying the pumped fluid for further transport), via a discharge line 11 , having a discharge line valve 12. The pressure in the fluid receiver 14 is during ordinary operation higher than at the fluid source 16.

The valves 8,12 are typically passive one-way valves but may, however, optionally be of a different type, e.g., actively controlled valves. By the oscillating movement of the piston 1 and the resulting volume change of the pump chamber 5, the fluid to be pumped is sucked via the intake line valve 8, into the pump chamber 5 and then compressed. When the pressure in the pump chamber 5 and the discharge line 11 upstream the discharge line valve 12 exceeds that of the fluid receiver 14, the discharge line valve 12 opens (or is opened) and the pumped fluid is conveyed from the pump chamber 5 to the fluid receiver 14.

Fig. 3 illustrates the operational principle of a single acting triplex piston diaphragm pump according to the prior art. The triplex piston diaphragm pump comprises three pump cylinder units 10a-c, each of which designed and operating as described in relation to pump cylinder unit 10 described above. The three pistons 1 a-c are driven by piston rods 31 a-c, for example via a crank drive mechanism. The crank drive mechanism will typically be arranged so that there is an operational phase shift of 120 degrees between the three pump cylinder units 10a-c. In Fig. 3, the arrows illustrate the instant mechanical and fluid motions in the system at an exemplary point in time; the figure illustrates the pump cylinder unit 10a carrying out a discharge stroke, pump cylinder unit 10b carrying out a suction stroke and the pump cylinder unit 10c carrying out a discharge stroke.

Fig. 4 illustrates the operational principle of a double acting triplex pump according to the prior art. In this arrangement, each pump cylinder 2a-c comprises a double acting piston 1a-c, where each side of the piston 1a-c is operatively connected to a pump chamber housing 15a-f. This arrangement of the pump part 102 is that used in the pump 100 illustrated in Fig. 1. The arrows in Fig. 4 indicate an example of motions and fluid flows at one point in time during operation of the pump. Unlike in the single acting pump, the piston rod side of the piston(s) 1a-c are utilized for pumping fluid in a double acting pump. Although a higher pumped volume flow is possible with such a double-acting arrangement, the constructive complexity of the pump is a drawback. The arrangement shown requires 6 diaphragms with associated housings, and 12 valves. This adds complexity at the pump part 102, for example, reducing accessibility for maintenance and increasing manufacturing costs.

Fig. 5 is a schematic view of the operational principle of a three-cylinder double acting diaphragm pump according to an embodiment. Items of similar function as described above are given the same reference numeral.

In the embodiment of Fig. 5, the pump has three pump chamber housings 15a-c, each of which having a diaphragm 4a-c arranged therein. The pump chamber housings 15a-c may be separate housing structures, or they may be integrally formed as a common pump chamber housing structure defining several interior volumes therein. The diaphragms 4a-c separate an interior volume of each pump chamber housing 15a-c into a pump chamber 5a-c and an intermediate fluid chamber 3a-c, and each pump chambers 5a-c is operatively connected to intake line 9 and the discharge line 11 via respective valves so as to receive and discharge the fluid to be pumped (for example, a slurry or mud). The intake and discharge lines 9,11 may, for example, be pipes forming part of the pump 100 and having interfaces (such as connectors) to an external piping system. Three pump cylinders 2a-c are arranged with double acting pistons 1a-c defining two working chambers 7a-f in the respective pump cylinder 2a-c. The pistons 1 a-c are operatively connected to a crank mechanism 30 (see Fig. 7) which is configured to drive the pistons 1a-c in the pump cylinders 2a-c by means of a piston rod 31 a-c. The piston rods 31a-c extend out of the pump cylinder 2a-c so that each piston 1 a-c define one piston side working chamber 7a,c,e and one rod side working chamber 7b,d,f.

Each of the intermediate fluid chambers 3a-c is fluidly connected to two separate working chambers 7a-f in different pump cylinders 2a-c. The fluid connections are two-way connections, for example, via pipes or channels, such that the working fluid can flow freely between the intermediate chambers 3a-c and working chambers 7a-f according to the motion of the pistons 1a-c and the pressure levels in the system. In the illustrated embodiment, the fluid connections are pipes 29a-f.

As the pistons 1 a-c are driven in a reciprocating manner, working fluid will be displaced into or out of the intermediate chambers 3a-c, and thereby effectuate a reciprocating motion of the diaphragms 4a-c, thereby driving alternating suction and discharge strokes in the pump chambers 5a-c. Pumped fluid will thereby be transported from the fluid source 16 to the fluid receiver 14.

As can be seen from Fig. 5, the second working chambers 7b,d,f are in this example fluidly connected to a respective first working chamber 7a,c,e of another pump cylinder 2a-c via one of the intermediate fluid chambers 3a-c. Alternatively, the second working chambers 7b,d,f may be directly connected to a respective first working chamber 7a,c,e, for example, via a dedicated pipe or fluid channel therefor (similarly as the arrangement of pump cylinders 2a-c shown in Fig. 10).

Fig. 6 illustrates another an embodiment of the present invention wherein each pump chamber housing 15a-c is integral with a respective pump cylinder 2a-c. In this configuration, the working chambers 7a,c,e and the intermediate fluid chambers 3a-c are formed as a common chamber. The rod side chambers 7b,d,f are connected to a respective piston side chamber 7a,c,e and/or intermediate fluid chamber 3a-c via fluid lines or pipes 29a-c, which may, for example, be hydraulic pipes or channels, such as machined channels in the housing structure. The functionality and operation is otherwise the same as described in relation to Fig. 5.

Advantageously, each intermediate fluid chamber 3a-c is connected to one piston side working chamber 7a,c,e and one rod side working chamber 7b,d,f of a different pump cylinder 2a-c. For example, as shown in Fig. 5, intermediate fluid chamber 3b may be connected to piston side working chamber 7c in pump cylinder 2b and rod side working chamber 7b in pump cylinder 2a. This may provide advantages in relation to the volume flows, in that the phase shift between the working chambers is more beneficial. In a three-cylinder embodiment, and with the crank mechanism 30 arranged to drive the pistons 1 a-c with a 120° phase shift (as is the common arrangement in a three-cylinder pump), the piston side chamber and the rod side chamber will operate with a phase shift of approximately 60° between them to supply the same intermediate fluid chamber 3a-c. (See also Fig. 8.)

Fig. 7 is an illustration of a pump 100 having a drive part 101 and a pump part 102. (See also, generally, Fig. 1 .) The pump part 102 comprises a plurality of pump cylinders and related components, along with interfaces to the intake line 9 and discharge line 11 , as described above and below. The drive part 101 may comprise a crank mechanism 30 with a crankshaft 32 interconnected with a connecting rod 33 to drive each piston 1 via a piston rod 31 . A crosshead mechanism 34 may be provided so as to allow the piston rod 31 to move fully linearly in a reciprocating manner. The crankshaft 32 may be driven by an appropriate motor, such as an electric motor arranged in or as part of the drive part 101 . The crank mechanism 30 is arranged to drive all the pistons 1 ,1a-d of the pump 100. The crankshaft 32 is for this purpose designed with an appropriate phase shift between each connecting rod interface. A pump with three pump cylinders 2a-c (a triplex pump) may have a phase shift of 120 degrees between each piston 1a-c. A pump with four pump cylinders 2a-d may have a phase shift of 90 degrees between each piston 1a-d.

The pump 100 further comprises a pump part 102 comprising the plurality of pump cylinders 2a-d and associated components. The pump part 102 may comprise an arrangement such as that described in the embodiments herein, for example, such as the embodiments illustrated in Figs. 5, 6, 9 and 10. Fig. 8 is an illustration of volume displacement rates of two interconnected working chambers in a pump according to an embodiment of the present invention. In Fig. 8, the vertical (y) axis illustrates the rate of displacement, for example, in liters (dm ³ ) per second, while the horizontal (x) axis illustrates the revolution of the crank mechanism 30.

Fig. 8 illustrates the displacement rates over two crank revolutions of the pump 100, and for two interconnected working chambers in a triplex (three-cylinder) pump such as the one illustrated in Fig. 5. Graph Q1 illustrates the volume displacement rate in a piston side working chamber, for example, chamber 7c in Fig. 5. Graph Q2 illustrates the volume displacement rate in a rod side working chamber, for example, chamber 7b in Fig. 5. Graph Q3 illustrates the combined volume displacement rates, i.e., the sum of graphs Q1 and Q2. Referring still to Fig. 5 and chambers 7b and 7c as an example, graph Q3 would thereby represent the volumetric flow rate of working fluid being provided to intermediate chamber 3b. As can be seen, the total flow rate (Q3) in this arrangement is higher than that obtained from a single working chamber (e.g. chamber 7c, graph Q1). Graph Q1 alone would be representative for the volumetric displacement in a single acting triplex pump such as the prior art pump of Fig. 3.

Fig. 9 illustrates a four-cylinder double acting diaphragm pump according to an embodiment. Save for the number of cylinders and associated components, the arrangement is similar to that illustrated in Fig. 6, with the same reference numerals used for corresponding components.

Fig. 10 illustrates a three-cylinder double acting pump according to another embodiment. In this embodiment, the pump does not employ a diaphragm as in the embodiments above but operates directly on the fluid to be pumped. The working chambers 7a,c,e are for this purpose directly connected to the intake line 9 and discharge line 11 so as to receive fluid to be pumped in the first working chambers 7a,c,e. Each of the rod side working chambers 7b,d,f is fluidly connected to a respective working chamber 7a,c,e of another one of the pump cylinders 2a-c via fluid lines or pipes 29a-c. For this three-cylinder (triplex) embodiment, the volumetric delivery flow rate profile of the pump is substantially equivalent to that described in relation to Fig. 8 above, i.e., an enhanced total flow rate compared to a single-acting pump with the same piston/cylinder dimensions.

In any of the embodiments described herein, the fluid lines or pipes 29a-f are two- way, open fluid connections, i.e., free of valves or other dedicated flow restrictions.

In any of the embodiments described herein, the pump cylinders 2a-d and pump cylinder chambers 7a-g may be ring-coupled so that each pump cylinder 2a-d is sequentially interconnected with each other and the last pump cylinder 2c, 2d is connected to the first pump cylinder 2a.

The pump 100 may for example have exactly three pump cylinders 2a-c, as illustrated in Figs. 5 ,6 and 10, and wherein:

- a second chamber 7b of the first pump cylinder 2a is connected to a first chamber 7c of the second pump cylinder 2b,

- a second chamber 7d of the second pump cylinder 2b is connected to a first chamber 7e of the third pump cylinder 2c, and

- a second chamber 7f of the third pump cylinder 2c is connected to a first chamber 7a of the first pump cylinder 2a.

Alternatively, the pump 100 may, for example, have exactly four pump cylinders 2a- d, as illustrated in Fig. 9, and wherein:

- a second chamber 7b of the first pump cylinder 2a is connected to a first chamber 7c of the second pump cylinder 2b,

- a second chamber 7d of the second pump cylinder 2b is connected to a first chamber 7e of the third pump cylinder 2c,

- a second chamber 7f of the third pump cylinder 2c is connected to a first chamber 7g of the fourth pump cylinder 2d, and

- a second chamber 7h of the fourth pump cylinder 2d is connected to a first chamber 7a of the first pump cylinder 2a.

Each of working chambers 7a,c,e or 7a,c,e,g may be piston side chambers, and each of working chambers 7b,d,f or 7b,d,f,h may be rod side chambers. The embodiments described herein may be particularly suitable for large-scale pump system, for example, pump system for transporting muds or slurries. In any of the embodiments described herein, the pistons 1a-d may have a diameter larger than 300 mm, for example, larger than 400 mm, for example, larger than 500 mm, for example, larger than 600 mm. In any of embodiments described herein, each diaphragm 4a-d may have a diameter larger than 500 mm, for example, larger than 600 mm, for example, larger than 750 mm, for example, larger than 1000 mm, and/or an area larger than 0.2 m ² , for example, larger than 0.5 m ² . In any of the embodiments described herein, the pump may have a design output of more than 250 kW, for example, more than 500 kW, for example, more than 1000 kW pumping power. In any of the embodiments described herein, the pump may be a pump for pumping slurry or drilling mud. In any of the embodiments described herein, the maximum design outlet pressure of the pump may, for example, be more than 30 bar (3000 kPa), for example, more than 75 bar (7500 kPa), for example, more than 100 bar (10,000 kPa).

The skilled reader will understand that the specific design of a pump may be adapted to a given use case, for example in relation to the number of cylinders, the sizing of components, etc. According to examples and embodiments described herein, high pumped flow rates can be obtained while keeping the pump compact and with a low number of moving parts. Examples and embodiments can provide lower construction complexity, for example, with a reduced number of valves and, in a diaphragm pump, the number of diaphragms/membranes and associated housings and piping can be kept low. This may reduce manufacturing and maintenance costs, and improve operational reliability. In some examples, when compared to a single-acting pump, a higher pump flow rate can be obtained using smaller pistons 1 a-d, thereby reducing pump size and manufacturing costs.

The invention is not limited by the embodiments described above; reference should be had to the appended claims.

The following numbered clauses outline further inventive examples and embodiments according to the present disclosure:

1 . A pump (100) comprising: a plurality of pump cylinders (2a-d), each pump cylinder of the plurality of pump cylinders comprising a piston (1 a-d) arranged therein, each piston (1a-d) dividing an interior volume of the pump cylinder (2a-d) into a first working chamber (7a,c,e,g) and a second working chamber (7b,d,f,h); an intake line (9); and a discharge line (11), wherein, each first working chamber (7a,c,e,g) is operatively connected to the intake line (9) and to the discharge line (11 ) of a fluid to be pumped, and each second working chamber (7b,d,f,h) is fluidly connected to a first working chamber (7a,c,e,g) of another pump cylinder of the plurality of pump cylinders (2a-d). The pump (100) as recited in any preceding clause, wherein each second working chamber (7b,d,f,h) is fluidly connected to exactly one first working chamber (7a,c,e,g) of another pump cylinder of the plurality of pump cylinders (2a-d). The pump (100) as recited in any preceding clause, wherein the fluid connection of each second working chamber (7b,d,f,h) to a first working chamber (7a,c,e,g) of another pump chamber of the plurality of pump cylinders (2a-d) is a direct connection. The pump (100) as recited in any preceding clause, wherein the plurality of pump cylinders (2a-d) consists of three pump cylinders or of four pump cylinders or of more than four pump cylinders. The pump (100) as recited in any preceding clause, wherein the operative connection of each first working chamber (7a,c,e,g) to the intake line (9) and to the discharge line (11) is a direct connection, respectively. The pump (100) as recited in any preceding clause, the pump (100) comprising a plurality of diaphragms (4a-d), and wherein each of the first working chambers (7a,c,e,g) is operatively connected to the fluid intake and discharge lines (9,11 ) via a respective diaphragm (4a-d). The pump (100) as recited in any preceding clause, wherein the diaphragms (4a-d) are arranged in a pump chamber housing (15a-d), each diaphragm (4a-d) dividing a respective interior volume (3a-d,5a-d) of the pump chamber housing (15a-d) into a pump chamber (5a-d) and an intermediate fluid chamber (3a-d), and wherein each of the first working chambers (7a,c,e,g) is fluidly connected to an intermediate fluid chamber (3a-d), the intake line (9) and the discharge line (11 ) are fluidly connected to the pump chambers (5a-d).

8. The pump (100) as recited in any preceding clause, wherein each intermediate fluid chamber (3a-d) is fluidly connected to the first working chamber (7a,c,e,g) and to the second working chambers (7b,d,f,h) of two different pump cylinders (2a-d) of the plurality of pump cylinders.

9. A pump comprising: at least one pump chamber housing (15a-d); a plurality of pump cylinders (2a-d), each pump cylinder of the plurality of pump cylinders comprising a piston (1a-d) having a piston rod (31a-d) attached thereto, the piston rod (31 a-d) being configured to extend out of the pump cylinder (2a-d), the piston (1 a-d) dividing the pump cylinder into a first working chamber (7a,c,e,g) on a side of the piston (1 a-d) where the piston rod (31 a-d) is not arranged, and a second working chamber (7b,d,f,h) on a side of the piston (1 a-d) wherein the piston rod (31 a-d) is arranged; a plurality of diaphragms (4a-d) arranged in the pump chamber housing(s) (15a-d), one respective diaphragm (4a-d) of the plurality of the diaphragms (4a-d) being arranged to divide the first working chamber (7a,c,e,g) from a pump chamber (5a-d); an intake line (9); and a discharge line (11), wherein, each pump chamber (5a-d) is operatively connected to the intake line (9) and to the discharge line (11 ) of a fluid to be pumped, and each second working chamber (7b,d,f,h) is fluidly connected to exactly one first working chamber (7a,c,e,g) of another pump cylinder of the plurality of pump cylinders (2a-d).

10. A pump comprising: at least one pump chamber housing (15a-d); a plurality of diaphragms (4a-d), one respective diaphragm (4a-d) of the plurality of the diaphragms (4a-d) being arranged in a respective interior volume (3a-d,5a-d) of the at least one pump chamber housing (15a-d), each diaphragm (5a-d) being configured to divide an intermediate fluid chamber (3a-d) from a pump chamber (5a-d) in the at least one pump chamber housing (15a-d); a plurality of pump cylinders (2a-d), each pump cylinder of the plurality of pump cylinders comprising a piston (1a-d) having a piston rod (31a-d) attached thereto, the piston rod (31 a-d) being configured to extend out of the pump cylinder (2a-d), the piston (1 a-d) dividing the pump cylinder into a first working chamber (7a,c,e,g) on a side of the piston (8a-d) where the piston rod (31 a-d) is not arranged, and a second working chamber (7b,d,f,h) on a side of the piston (1 a-d) wherein the piston rod (31 a-d) is arranged; an intake line (9); and a discharge line (11); wherein, each pump chamber (5a-d) is operatively connected to the intake line (9) and to the discharge line (11 ) of a fluid to be pumped, and each intermediate fluid chamber (3a-d) is fluidly connected to the first working chamber (7a,c,e,g) and to the second working chambers (7b,d,f,h) of two different pump cylinders (2a-d) of the plurality of pump cylinders.

11 . The pump (100) as recited in any preceding clause, further comprising: a plurality of crank mechanisms (30), wherein, each respective one of the plurality of crank mechanisms (30) is configured to drive one respective piston (1a-d).

12. The pump (100) as recited in any preceding clause, wherein, each respective one of the plurality of crank mechanisms (30) is configured to drive the one respective piston (1a-d) with a phase shift with respect to another or each other piston (1 a-d).

13. The pump (100) as recited in any preceding clause, wherein the plurality of crank mechanisms (30) is interconnected by a common crankshaft (32).

14. The pump (100) as recited in any preceding clause, wherein the phase shift between each piston (1a-d) is 360° divided by a number of the plurality of pump cylinders (2a-d).

15. The pump (100) as recited in any preceding clause, wherein each pump chamber (5a-d) is operatively connected to the intake line (9) and to the discharge line (11) via valves (8,12).

16. The pump (100) as recited in any preceding clause, further comprising: a plurality of piston rods (31 a-d), wherein, each piston (1 a-d) has one piston rod of the plurality of piston rods (31a-d) attached thereto so that the one respective piston rod extends out of the respective one of the plurality of pump cylinders (2a-d).

17. The pump (100) as recited in any preceding clause, wherein each second working chamber (7b,d,f,h) is provided as a piston rod side chamber.

18. The pump (100) as recited in any preceding clause, wherein each pump cylinder (2a-d) is formed integrally with a pump chamber housing (15a-d).

19. The pump (100) as recited in any preceding clause, wherein the pump comprises exactly three pump cylinders (2a-d) or exactly four pump cylinders (2a-d).

20. The pump (100) as recited in any preceding clause, wherein the number of diaphragms (4a-d) equals the number of pump cylinders (2a-d).

21 . The pump (100) as recited in any preceding clause, wherein each intermediate fluid chamber (3a-d) is connected to one piston side working chamber (7a,c,e,g) and one rod side working chamber (7b,d,f,h) of the pistons (1 a-d).

22. The pump (100) as recited in any preceding clause, wherein each intermediate fluid chamber (3a-d) is fluidly connected to two different pump cylinders (2a-d).

23. The pump (100) as recited in any preceding clause, wherein the second working chambers (7b,d,f,h) are fluidly connected to a respective first working chamber (7a,c,e,g) of another one of the pump cylinders (2a-d) via one of the intermediate fluid chambers (3a-d).

24. The pump (100) as recited in any preceding clause, wherein each second working chamber (7b,d,f,h) is fluidly connected to exactly one first working chamber (7a,c,e,g) of another pump cylinder of the plurality of pump cylinders (2a-d). 25. The pump (100) as recited in any preceding clause, wherein the pump has exactly three pump cylinders (2a-d) and: a second chamber (7b) of the first pump cylinder (2a) is connected to a first chamber (7c) of the second pump cylinder (2b), a second chamber (7d) of the second pump cylinder (2b) is connected to a first chamber (7e) of the third pump cylinder (2c), and a second chamber (7f) of the third pump cylinder (2c) is connected to a first chamber (7a) of the first pump cylinder (2a).

26. The pump (100) as recited in any preceding clause, wherein the pump has exactly four pump cylinders (2a-d) and: a second chamber (7b) of the first pump cylinder (2a) is connected to a first chamber (7c) of the second pump cylinder (2b), a second chamber (7d) of the second pump cylinder (2b) is connected to a first chamber (7e) of the third pump cylinder (2c), a second chamber (7f) of the third pump cylinder (2c) is connected to a first chamber (7g) of the fourth pump cylinder (2d), and a second chamber (7h) of the fourth pump cylinder (2d) is connected to a first chamber (7a) of the first pump cylinder (2a).

27. The pump (100) as recited in any preceding clause, wherein each of the first working chambers (7a,c,e,g) is a piston side chamber, and each of the second working chambers (7b,d,f,h) is a rod side chamber.

LIST OF REFERENCE NUMERALS

10, 10a-c Pump

101 Drive part

102 Pump part

1 , 1 a-d Pump piston

2, 2a-d Pump cylinder

3, 3a-d Intermediate fluid chamber

4, 4a-d Flexible separation diaphragm / Membrane

5, 5a-d Pump chamber 7 Working chamber

7a, c, e, g First working chamber

7b, d, f, h Second working chamber

8 Intake line valve

9 Intake line / Fluid supply line

10, 10a-c Pump cylinder unit

11 Discharge line

12 Discharge line valve

14 Fluid receiver

15, 15a-f Pump chamber housing

16 Fluid source

25 Inlet

26 Outlet

29 Pipe / Fluid line

30 Crank mechanism

31 , 31a-d Piston rod

32 Crankshaft

33 Connecting rod

34 Crosshead mechanism a End of suction stroke / Start of discharge stroke b End of discharge stroke / Start of suction stroke