WO2015071503A1

WO2015071503A1 - Hydraulic axial piston pump having a floating rotatory drum

Info

Publication number: WO2015071503A1
Application number: PCT/ES2013/000251
Authority: WO
Inventors: Antonio PARÉS CRIVILLÉ
Original assignee: Eco-Sistems Watermakers, S.L.
Priority date: 2013-11-13
Filing date: 2013-11-13
Publication date: 2015-05-21
Also published as: EP3070329B1; DK3070329T3; ES2739073T3; EP3070329A1; US20160273525A1; EP3070329A4

Abstract

The invention relates to a pump comprising: a housing (1); a drum (2) having cylinders in which pistons (3) are mounted, which pistons are supported by supporting shoes (32) on a fixed inclined plate (4); and first and second fluid-distributing plates (5a, 5b) having openings (51, 52) for alternately establishing the connection between first mouths (23) of the cylinders (22) and a first inlet (11) and first outlet (12) of primary liquid, and between second mouths (24) and a second inlet (13) and outlet (14) of secondary liquid. The pump also comprises first and second strips (6a, 6b) disposed between the drum (2) and the distributing plates (5a, 5b), said strips being movable in a longitudinal direction and permitting the drum to tilt to a certain extent, forming a sealed closure between the ends of the drum (2) and the distributing plates (5a, 5b).

Description

DESCRIPTION

HYDRAULIC PUMP OF AXIAL PISTONS WITH FLOATING ROTATING DRUM.

Object of the invention.

The present invention relates to an axial piston hydraulic pump with floating rotating drum; Applicable mainly in seawater desalination plants using reverse osmosis.

State of the art

Various documents are known regarding axial piston pumps intended for use in equipment, for example seawater desalination, which require the provision of a primary high-pressure liquid for operation, which is driven by the axial piston pump, and that return a secondary liquid at a pressure slightly lower than the supply; incorporating the aforementioned axial piston pumps means for harnessing the energy of the secondary liquid rejected or returned by the equipment in question.

In the specific case of seawater desalination equipment by reverse osmosis, the primary liquid is constituted by seawater that is supplied at high pressure to the osmosis membranes; while the secondary liquid is constituted by the rejection water with a high salt content supplied by the osmosis membrane at a pressure lower than that of the primary liquid.

Some of the axial piston pumps of this type are described for example in the documents: US 7799221 B1 (MACHARG JOHN P); WO 2010025729 A1 (DANFOSS AS ET AL.) Or in PCT / ES application 2012/000279 (BOLSAPLAST SL) of the same inventor of the present invention. The axial piston pumps with energy use described in said documents generally comprise a housing in which a rotating drum is provided provided with a drive shaft for actuation by an external motor, and a plurality of cylinders arranged circularly around to the geometric axis of said drum and communicated at its ends by first mouths of entry and exit of primary liquid and second mouths of entry and exit of secondary liquid; said first and second mouths being defined at a first end and a second end of the rotating drum.

In the drum cylinders, pistons are extended axially that extend into rods that protrude through a second end of the drum and that end in support skates on a fixed inclined plate, so that when rotating the drum said pistons alternately describe a forward and reverse movement inside the cylinders.

These pumps comprise a first plate and a second fluid distributor plate, facing opposite ends of the drum, provided with conveniently distributed holes for alternately establishing, during the rotation of the drum, the connection of the first mouths of the cylinders with the first inlet and first outlet of primary liquid from the housing; and the connection of the second mouths of the cylinders with the second inlet and the second outlet of secondary liquid; said connections being established synchronously with the direction of movement of the pistons inside the cylinders.

A general problem with this type of pump is determined by the need to establish a tight seal between the opposite ends of the rotating drum and the corresponding fluid distribution plates that remain static.

Obviously between the opposite ends of the rotating drum and the fluid distribution plates there must be a proper tolerance to allow rotation of the drum, however the existence of these tolerances results in the existence of leaks between the drum and the distribution plates because said drum tends to swing laterally and misalign with respect to the axial direction due to the axial displacement and opposite directions of the pistons inside the cylinders.

This tilting or lateral pitching of the drum causes the opposite ends thereof, at diametrically opposite points, to exert excessive pressure against the respective fluid distribution plates and at the diametrically opposite points thereof they distance themselves from said distribution plates providing leakage areas of liquid.

This problem, generalized in the aforementioned background, prevents this type of axial pumps with energy recovery from working correctly for a long time since excessive wear due to irregular friction of the drum against the fluid distribution plates occurs.

In this type of axial piston pumps with energy recovery, the primary liquid accesses through the first inlet to the anterior zone of the cylinders to be propelled to the first outlet during the advance of the pistons; while the secondary liquid enters through the second inlet to the rear area of the cylinders and collaborates in the forward movement of the pistons before being expelled through the second outlet during the retraction of said pistons.

This determines that the pressures of the primary liquid and the secondary liquid also act on the drum causing an imbalance of the drum in the axial direction.

The technical problem that arises is the development of an axial piston hydraulic pump, with energy recovery, of the type mentioned above, but that effectively solves the problems of the aforementioned background. Description of the invention

The axial piston hydraulic pump with floating rotating drum, object of this invention, being of the type mentioned above, has constructional features oriented to guarantee a tight seal between the opposite ends of the rotating drum and the fluid distribution plates by interposing between a first end of the drum and the first distributor plate and between a second end of the drum and the second distributor plate of a first and a second plate that rotate together with the drum and allow a floating assembly or with a certain slack of the rotating drum both in the longitudinal direction as in the axial direction maintaining said seal tightness.

Another object of the invention is to achieve the cancellation of the horizontal components of the forces produced by the pressures of the primary and secondary liquids on the drum, regardless of the value of said pressures.

Another object of the invention is to achieve the axial direction of the plates responsible for establishing the tight seal between the ends of the drum and the distribution plates with the collaboration of the primary and secondary liquid pressures themselves.

The first and second plates that rotate together with the drum, and are responsible for establishing a tight seal against the fluid distribution plates have holes facing the first and second mouths of the drum, and suitable coupling means to allow a displacement of the first and the second plate in axial direction with respect to the drum and the frontal action of said plates against the respective distributor plates, said plates establishing a tight seal between the ends of the drum and the respective distribution plates. The holes of the plates are peripherally extended in sleeves suitable to be housed in the first and second mouths of the drum with the interposition of sealing elements; allowing a certain tilting or misalignment of the drum, and to receive, as a result of the pressure of the primary and secondary liquids, a thrust that axially displaces said plates against the distributor plates.

These coupling between the drum and the plates ensures that the plates remain parallel and establish a tight seal against the distributor plates even if the rotating drum tilts or does not remain perfectly aligned.

Said sleeves are also suitable for receiving, by the effect of the pressure of the primary and secondary liquids, axial thrusts that move the first and the second plate frontally against the respective distributor plates, said plates establishing a tight seal between the opposite ends of the drum and the respective distribution plates.

Another relevant feature of the invention is that the surfaces of the drum intended to contact the primary and secondary liquids have a suitable arrangement and dimensions so that the result of the forces generated by the pressure of the primary and secondary liquids on the drum have a null component in axial direction. In this way the drum is kept balanced.

According to the invention, it comprises between the first end of the drum and the first plate, and between a second end of the drum and the second plate, springs oriented in the axial direction and suitable to guarantee a certain pressure of said plates against the respective distribution plates.

These springs are effective especially during the initial start-up phase of the pump in which the first liquid and the second liquid are without pressure. These springs also contribute initially to the centering of the drum with respect to the first and the second plate.

As mentioned earlier, this pump also has characteristics aimed at achieving a balanced tabor in the axial direction preventing the forces produced by the pressures of primary liquid and secondary liquid on the drum tend to move it in one direction or another in the axial direction .

For this, and according to the invention, the first inlet and outlet mouths of the primary liquid are axially aligned with the drum cylinders and have diameters coinciding with those of said cylinders to prevent the pressure of the primary liquid from producing on the drum a thrust force in axial direction.

On the other hand, the second inlet and outlet mouths of secondary liquid are connected to the drum cylinders by means of suitable geometry and dimensions conduits so that the result of the set of forces generated by the pressure of the secondary liquid on the drum has a component zero in axial direction.

Description of the figures.

To complement the description that is being made and in order to facilitate the understanding of the characteristics of the invention, a set of drawings is attached to the present specification in which, for illustrative and non-limiting purposes, the following has been represented:

- Figure 1 shows a schematic elevational view of an embodiment of the axial piston hydraulic pump with floating rotating drum, according to the invention, sectioned by a vertical plane. - Figure 2 shows an exploded view of the different internal elements of the pump.

Preferred embodiment of the invention.

As can be seen in the attached figures, the pump comprises a housing (1) with a first inlet (11) and a first outlet (12) of primary liquid, and with a second inlet (13) and a second outlet (14) of secondary liquid

Inside the housing (1), the rotating drum (2) is operable by a motor element (not shown) through the drive shaft (21).

The drum (2) has a plurality of cylinders (22) arranged circularly around its geometric axis.

The cylinders (22) are communicated with the first mouth (23) of inlet and outlet of primary liquid and with a second mouth (24) of inlet and outlet of secondary liquid.

In the cylinders (22) there are mounted pistons (3) extended by one of its ends in some rods (31) that pass through holes made in the rear surface of the cylinders (22) and protrude from the drum (2 ) and finish on respective skates (32) acting on a fixed inclined plate (4).

The pump comprises a first and a second liquid distribution plate (5a, 5b) facing the respective ends of the drum (2) and provided with holes for the alternative connection of the first mouth (23) of the cylinders with the first inlet (11) and the first outlet (12) of primary liquid, and the alternative connection of the second mouth (24) of the cylinders (22) with the second inlet (13) and the second outlet (14) of secondary liquid during the drum rotation (2). The confrontation of the first mouth (23) and the second mouth (24) with the inputs and outputs of primary and secondary liquid is synchronized with the reciprocating axial movement of the pistons (3), when moving on the inclined plate ( 4).

The entry of primary liquid at low pressure, of the order of 2 bar, to any one of the cylinders (22) is carried out during the backward movement of the corresponding piston (3); while the secondary liquid will enter the same cylinder during the advance of said piston (3), contributing the pressure of said secondary liquid, together with the action of the inclined plate (4) to move the piston (3) towards the area above and to push the primary liquid towards the first outlet (12) of primary liquid.

In order to establish an effective closure between the opposite ends of the drum and the respective distributor plates (5a, 5b), a first and a second closing plate (6a, 6b) which rotate together with the drum (2) are mounted between said elements. .

For the passage of the primary and secondary liquids, said plates (6a, 6b) are provided with holes extended by their periphery in sleeves (61 and 62) respectively coupled in the first mouths (23) and the second mouths (23) of the drum with the interposition of sealing elements (7) represented by O-rings, These couplings allow a certain tilting or pitching of the drum (2) while the plates (6a, 6b) are kept parallel to the first and second distributor plate (5a, 5b), exerting a closure against them due to the push of the primary and secondary liquids against the ends of said sleeves (61 and 62) of the plates (6a and 6b).

Between the opposite ends of the drum (2) and the closing plates (6a, 6b) there are arranged springs (8) that press said plates (6a, 6b) against respective distribution plates (5a, 5b) contributing to obtaining a tight seal.

The first mouths (23) because the first inlet and outlet mouths of the primary liquid are axially aligned with the cylinders (22) of the drum and have diameters coinciding with those of said cylinders (22), preventing the pressure of the primary liquid transmit a thrust force in the axial direction to the drum (2).

The second mouths (24) for entering and exiting the secondary liquid are connected to the corresponding cylinders (22) by means of respective ducts (25) with the second mouths (24) presenting a section equal to that corresponding end surface of the cylinder (22) which it is exposed to the pressure of the secondary liquid, so that the set of forces generated by the pressure of the secondary liquid on the drum has a zero component in axial direction, as well as those generated by the pressure of the primary liquid, whereby it is possible to keep the drum (2) balanced during the operation of the pump.

Once the nature of the invention has been sufficiently described, as well as a preferred embodiment, it is stated for the appropriate purposes that the materials, shape, size and arrangement of the described elements may be modified, provided that this does not imply an alteration. of the essential features of the invention that are claimed below.

Claims

1.- A hydraulic piston axial pump with floating rotating drum; comprising:

- a housing (1) provided with: a first inlet (11) for the admission of a primary liquid; a first outlet (12) for the delivery of said primary liquid at high pressure; a second inlet (13) for the admission of a secondary liquid at a pressure lower than the delivery pressure of the primary liquid and a second outlet (14) for the delivery of said secondary liquid;

- a drum (2) provided with a drive shaft (21) and a plurality of cylinders (22) arranged circularly around the geometric axis of said drum (2) and communicated at its ends with first inlet mouths (23) and exit of the primary liquid and with second mouths (24) of inlet and outlet of secondary liquid, said first and second mouths (23, 24) being defined at a first end and a second end of the drum (2);

- pistons (3) mounted on the respective cylinders (22) and which extend into rods (31) that protrude through one end of the drum (2) and end in skates (32) supporting a tilted plate (4) ) permanent;

- a first plate (5a) and a second plate (5b) distributing fluid, facing opposite ends of the drum (2) and provided with holes (51, 52) conveniently distributed to establish alternately, during the rotation of the drum ( 2), the connection of the first mouths (23) of the cylinders (22) with the first inlet (1 1) and the first outlet (12) of primary liquid of the housing (1) and the connection of the second mouths ( 24) of the cylinders (22) with the second inlet (13) and the second outlet (14) of secondary liquid, said connections being established synchronously with the direction of movement of the pistons (3) through the interior of the cylinders ( 22); characterized because: between a first end of the rotating drum (2) and the first distributor plate (5a), and between a second end of the drum (2) and the second distributor plate (5b), they are mounted with a certain clearance in axial direction, a first and second plates (6a, 6b) that rotate together with the drum (2); said first and second plates (6a, 6b) having holes facing the first and second mouths (23, 24) of the drum and suitable coupling means to allow a displacement of the first and second plate (6a, 6b) in axial direction with respect to the drum (2) and the frontal actuation of said plates (6a. 6b) against the respective distributor plates (5a, 5b), said plates (6a. 6b) establishing a tight seal between the ends of the drum (2 ) and the respective distribution plates (5a, 5b).

2. - A pump according to claim 1, characterized in that the surfaces of the drum (2) intended to contact the primary and secondary liquids have a suitable arrangement and dimensions so that the result of the forces generated by the pressure of the liquids Primary and secondary on the drum (2) have a zero component in axial direction.

3. - A pump according to claim 1, characterized in that the holes of the plates (6a, 6b) are peripherally extended in sleeves (61, 62) suitable to be accommodated in the first and second mouths (23, 24) of the drum ( 2) with the interposition of sealing elements (7) allowing a certain tilting or misalignment of the drum; and to receive, by action of the pressure of the primary and secondary liquids, a thrust that axially displaces said plates (6a, 6b) against the distributor plates (5a, 5b).

4. - A pump according to claim 1, characterized in that it comprises between a first end of the drum (2) and the first plate (6a), and between a second end of the drum (2) and the second plate (6b) springs (8) oriented in axial direction, suitable to guarantee a certain pressure of said plates (6a, 6b) against the respective distributor plates (5a, 5b).

5. - A pump according to claim 2, characterized in that the first mouths (23) of the drum (2) are axially aligned with the cylinders (22) of the drum and have diameters coinciding with those of said cylinders to prevent the Primary liquid pressure produces a thrust force in the axial direction on the drum (2).

6. - A pump according to claim 1, characterized in that the second mouths (24) of the drum (2) are axially oriented and connected to the cylinders (22) by means of intermediate ducts (25) presenting the second mouths (24) a section equal to an end surface (26) of the corresponding cylinder (22) exposed to the pressure of the secondary liquid, so that the result of the set of forces generated by the pressure of the secondary liquid on the drum (2) has a null component in axial direction.