EP1788249A2

EP1788249A2 - Positive-displacement pump

Info

Publication number: EP1788249A2
Application number: EP06124108A
Authority: EP
Inventors: Roberto Manzini
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-11-16
Filing date: 2006-11-15
Publication date: 2007-05-23
Also published as: ITBO20050697A1; EP1788249A3

Abstract

A positive-displacement pump (1) consists of a containment body (2) having a first and a second pipe (3a, 3b) for the passage of a liquid to be pumped. The pipes (3a, 3b) are both in fluid communication with a cavity (7) made in the containment body (2). The cavity (7) houses a rotor (11) moved by movement means (12). The pump (1) also has a movement part (15) attached to the containment body (2) for moving the body (2) relative to the rotor (11).

Description

The present invention relates to a positive-displacement pump.
In detail, the present invention relates to a positive-displacement pump used for transporting food liquids such as wine.
As is known, the positive-displacement pumps used in oenology have a rotor housed in a containment chamber in which the pipe for infeed and outfeed of the liquid to be pumped converges.
The rotor has a plurality of elastically deformable vanes, normally made of rubber and is keyed on the shaft of a respective motor. The rotor is also positioned eccentrically in the containment chamber with the respective vanes resting on the inner surface of the chamber and sliding on it during rotor rotation.
In this way, suction and subsequent compression of the liquid is achieved by elastic deformation of the rotor vanes.
In fact the rotor, mounted eccentrically relative to the longitudinal extension of the chamber, is moved towards a portion of the inner surface of the containment chamber in which the vanes are more deformed. In this way, during rotor rotation the vanes are continuously deformed to suck then compress the liquid towards the outfeed pipe.
However, the positive-displacement pumps briefly described above have significant disadvantages.
A first disadvantage is the fact that the direction of transfer is closely linked to the direction of rotation of the rotor, therefore, to invert the flow the direction of rotation of the rotor must be inverted, resulting in rapid deterioration of the deformable vanes.
Moreover, during periods when it is not used, the rotor is stationary for lengthy periods (think of the typically seasonal use of this type of pump), therefore the vanes tend to take on a deformed configuration with a certain bending which, if inverted to change the direction of transfer, is more likely to result in breakages.
Another disadvantage of the known pumps is rotor wear. The rotor has two sealing rings attached to the ends of the rotor and coaxial with the longitudinal extension of the rotor. Said sealing rings are abutted to lateral walls of the containment chamber. During rotor rotation the sealing rings slide on said walls, causing the sealing rings to overheat and consequently wearing the rotor, which must be substituted. It should be noticed that such sealing rings, normally made of rubber, are not rendered wet by the passage of the liquid, since, as described above, they are directly abutted to the walls.
In this context, the main technical purpose of the present invention is to propose a positive-displacement pump which is free of the above-mentioned disadvantages.
In particular, the aim of the present invention is to provide a versatile positive-displacement pump able to vary the flow rate and invert the direction of movement of the liquid pumped without inverting the direction of rotation of the rotor.
Another aim of the present invention is to propose a positive-displacement pump which is strong and has no moving parts which are easily damaged.
The stated technical purpose and the afore-said aims are substantially achieved by a positive-displacement pump which has the technical characteristics described in one or more of the claims herein.
Further characteristics and advantages of the present invention are more apparent from the description which follows, of a preferred, nonlimiting embodiment of a positive-displacement pump, with reference to the accompanying drawings in which:

Figure 1 is a front elevation view of the positive-displacement pump in accordance with the present invention;
Figure 2 is a side elevation view of the positive-displacement pump from Figure 1;
Figure 3 is a top plan view of the positive-displacement pump from Figure 1;
Figure 4 is a perspective view of the positive-displacement pump in accordance with the present invention, in a respective operating condition;
Figure 5 is a perspective view of the positive-displacement pump in a respective non-operating condition;
Figures 6a, 6b and 6c are front elevation views of the pump from Figure 1 in different operating conditions;
Figures 7 and 7a are perspective views respectively of a pump movement part;
Figure 8 is a front elevation view of a rotor belonging to the positive-displacement pump, in a non-operating condition;
Figure 9 is a schematic view of the movement path of the axis of the pump chamber relative to the rotor.

With reference to the accompanying drawings, the numeral 1 denotes as a whole a positive-displacement pump in accordance with the present invention.
The pump 1 has a containment body 2 in which a first and a second pipe 3a, 3b for the passage of a liquid to be pumped are made. Each pipe 3a, 3b has a substantially tubular shape and extends along the same longitudinal axis A. The pipes 3a and 3b also have respectively a coupling end 4 facing outwards and made ready to receive a manifold for coupling a delivery and/or intake pipe, and an inner end 5 in fluid communication with a cavity 7 made in the containment body 2.
As is better illustrated in the perspective view in Figure 5, the cavity 7 has a substantially tubular shape and extends along a respective longitudinal axis X better illustrated in Figure 3.
The cavity 7 has a respective circular end 7a, coaxial with the axis X, which can be attached to a lid 8. In particular, the lid 8 consists of a rod 9 pivoting at the body 2 at a respective end. As shown in Figures 4 and 5, the rod can move towards and away from the circular end 7a of the cavity 7. Moreover, the lid 8 has a circular element 10, preferably made of a transparent material, attached to the rod 9. In this way, when the rod 9 is moved towards the circular end 7a, the element 10 is abutted to a circular seal positioned circumferentially along said end. Advantageously, the cavity 7 is closed by the lid but remains visible from the outside through the circular element 10.
The cavity 7 houses a rotor 11 operatively connected, as is described in more detail below, to respective movement means 12 designed to drive the rotation of the rotor 11 about a respective axis of rotation B parallel with the longitudinal axis X.
In detail, the rotor 11, better illustrated in Figure 8, has a main cylindrical body 13 extending along the axis of rotation X and at least one vane 14 projecting from the outer surface of the body 13.
Advantageously, the main body 13 has at least one hollow end 13a extending about the axis of rotation X and externally delimited by a raised seal 31 which divides the region 13a from the wet zone 30 coinciding with the minimum radius circular area 33 swept by the recesses present between the vanes 14. In accordance with the invention, the outer projection 31 is roughly star-shaped with radial expansions 32 coinciding with the points of radial extension of the vanes, and projecting radially by a measurement at least equal to the minimum radius 33 of the wet zone 30.
Advantageously, the liquid in the region 30 contributes to wetting the parts of the projection 31 projecting beyond the minimum radius of the region 30, so that the projection 31 is never "dry", thus reducing wear on the head of the rotor and extending the operating life.
The rotor 11 preferably has a plurality of vanes 14 positioned along the cylindrical extension of the main body 13 and equidistant from one another. Even more preferably, the rotor 11 is made of a deformable plastic material, such as rubber. In this way, when the rotor 11 is in the cavity 7, the vanes are deformed and angled according to the direction of rotation of the rotor 11 itself.
As is better illustrated in Figures 1 and 6b, the vanes 14 are abutted to the inner surface of the cavity 7 and bent back on themselves. In this way, each vane 14 forms a concave surface 14a for containing the liquid to be pumped and a convex surface 14b opposite the concave surface 14a.
As already indicated, the pump 1 also has movement means 12 for the rotor 11. The movement means 12 preferably consist of an electric motor 12a, with a shaft 12b on which the rotor 11 is keyed.
The pump 1 also has a movement part 15 attached to the containment body 2 for moving the body 2 relative to the rotor 11.
In other words, the movement part 15 can switch between a first "home" operating condition illustrated in Figures 6b and 9, in which the axis of rotation B of the rotor 11 is roughly coaxial with the longitudinal axis X of the cavity 7, and at least a second operating condition illustrated in Figures 6a, 6c and 9, in which the longitudinal axis X is eccentric (vertically) relative to the axis of rotation B of the rotor 11. In this situation, it should be noticed that in the first operating condition the rotor 11 in conjunction with the inner surface of the cavity 7 forms a symmetrical liquid passage cross-section S (absence of flow rate), whilst in the second operating conditions, the rotor in conjunction with the inner surface forms an asymmetrical liquid passage cross-section Sv with the generation of a flow rate, to the right or to the left, depending on the movement of the axis X.
In greater detail, as illustrated in Figure 9, the movement part 15 is attached to the body 2 to move the axis X into the respective operating conditions, causing it to follow a circular path in which the axis performs a limited horizontal movement (to limit rotor displacement) and a significant vertical movement (to vary the flow rate).
In this path, the home position P1 has performed a limited movement relative to the axis B (Figure 3) shifted by a limited value "d" from the fixed axis X in such a way that it is substantially coaxial, whilst in the second operating condition P2/P2' the movement part 15 moves a first curved portion 16a of the inner surface of the cavity 7 towards the rotor 11, and moves a second curved portion 16b opposite and adjacent to the first 16a away from the rotor 11 to create different volumes in which the fluid passage cross-section Sv is formed by the space between the rotor 11 and the first curved portion 16a and between the rotor 11 and the second curved portion 16b.
Advantageously, it should be noticed that at the first curved portion 16a, the vanes 14 are more deformed and bent back over themselves (Figures 6a, 6b); whilst due to the elastic properties of the vanes 14, they are partly extended at the second curved portion 16b.
The pump 1 is preferably supported by a fixed supporting frame 17 attached to the containment body 2. The frame 17 is designed to support the body 2, the movement means 1 and the part 15, and preferably has wheels to facilitate transportation of the entire pump 1.
In detail, the movement part 15 consists of an anchoring portion 18, better illustrated in Figure 7, irremovably engaging with the fixed frame 17. Moreover, the movement part 15 has an actuator 19, attached to the anchoring portion 18 and to the body 2 to move the body into the above-mentioned operating conditions.
The actuator 19, better illustrated in Figure 7, consists of a lever 20 which substantially has the shape of a rod and has one end 20a projecting from the pump 1 and an opposite end 20b pivoting at the anchoring portion 18 to rotate about an axis parallel with the axis of rotation B of the rotor 11. The actuator 19 also has at least one connecting plate 21 with a first end 21a attached to the lever 20 and a second end 21b opposite the first end 21a. The actuator 19 preferably has two plates 21, each supporting a cylinder 22 at the second end 21b. In detail, each cylinder 22 extends about a respective longitudinal axis parallel with the axis of rotation of the lever 20 and has a first end 22a attached to the second end 21b of the respective plate 21 by a flat connecting support 23 and a second end 22b opposite the first end 22a.
In greater detail, it should be noticed that the flat support 23 pivots at the second end 21b of the plate 21 to rotate the cylinder 22 about the respective longitudinal axis after rotation of the lever 20.
Each cylinder 22 also has a pin 24 projecting from the second end 22b. The projecting pin 24 extends along a respective longitudinal axis parallel with the axis of rotation of the cylinder 22 and eccentric to the cylinder. Moreover, the pin 24 is attached to the containment body 2 to move the body 2 after rotation of the cylinder 22.
In other words, starting from the "home" condition illustrated in Figure 6b in which the rod 20 is vertical and the rotor 11 is roughly coaxial with the longitudinal axis of the cavity 7, the body 2 is moved to bring the cavity 7 off centre relative to the rotor 11 (path of axis B in Figure 9). In other words, manually moving the lever 20 to the left, as in the example illustrated in Figure 6a, the cylinders 22 are rotated, moving the respective pins 24 downwards. Consequently, the body 2 attached to the pins 24 is lowered relative to the frame 17 and the rotor 11 following a circular trajectory generated by the cam 24.
Thanks to the mechanism used, with reference to the diagram in Figure 9, the body 2 performs a significant vertical movement, thus obtaining the desired flow rate variation, and a limited horizontal movement, minimising the rotor phase displacement, all without having to mount the body 32 on a system of vertical guides which would have considerably complicated mechanical production of the mechanism.
In this situation, the first curved portion 16a is positioned above the rotor 11 and the liquid, due to clockwise rotation of the rotor 11, is conveyed from the second pipe 3b to the first pipe 3a. The vanes 14 more compressed in the first curved portion 16a, extend at the second pipe 3b to suck the liquid which is contained at the concave surface 14a. In this way, the liquid is conveyed by the vanes 14 along the second curved portion 16b towards the first pipe 3a where the vanes again encounter the first curved portion 16a and are bent back over themselves more. Advantageously, when the vanes 14 are bent the liquid contained in the concave surface 14a is compressed towards the first pipe 3a.
Alternatively, moving the lever 20 to the right as illustrated in Figure 6c, the body 2 is moved upwards, forming the above-mentioned first curved portion 16a below the rotor.
In this situation, without changing the direction of rotation of the rotor 11, the liquid is now moved in the opposite direction to the previous one, from the first pipe 3a to the second pipe 3b.
The liquid is sucked at the first pipe 3a, conveyed along the second curved sector 16b which in this case is above the rotor 11, then compressed towards the second pipe 3b.
Advantageously, in the intermediate positions, without changing anything but the position of the cavity 7, there is a continuous variation in the flow rate, from a maximum in one direction of transfer to a maximum in the opposite direction.
The invention overcomes the problems encountered in the prior art and achieves the preset aims.
Firstly, it should be noticed that the pump 1 is very versatile and able to convey the liquid in different directions and with variable flow rates without changing the direction of rotation of the rotor 11.
By manually acting on the movement part 15 it is possible to move the body 2 relative to the rotor 11 so as to invert the position for suction and subsequent compression of the liquid.
Another advantage is the absence of rotor 11 zones subject to wear. It should be noticed that the rotor 11 is rendered completely wet by the liquid present in the cavity 7 thanks to the presence of the hollow end 13a forming an auxiliary containment chamber for the liquid pumped. Advantageously, the rotor 11 is not damaged due to dry moving portions.

Claims

A positive-displacement pump comprising:
- a containment body (2) with a first and a second pipe (3a, 3b) for the passage of a liquid to be pumped, the pipes (3a, 3b) both being in fluid communication with a cavity (7) made in the containment body (2);

- a rotor (11) with deformable vanes (14), housed in the cavity (7);

- movement means (12) for the rotor (11) designed to drive the rotation of the rotor about an axis of rotation (B);
the pump being characterised in that it also comprises a movement part (15) attached to the containment body (2) for moving the cavity (7) relative to the rotor (11).
The pump according to the foregoing claim, characterised in that the movement part (15) can switch between a first operating condition in which the rotor (11) in conjunction with an inner surface of the cavity (7) forms a symmetrical cross-section (S) for passage of the liquid, and at least a second condition in which the rotor (11) in conjunction with said inner surface forms an asymmetrical cross-section (Sv) for passage of the liquid.
The pump according to the foregoing claim, characterised in that the cavity (7) has a substantially tubular shape, the axis of rotation (B) of the rotor (11) in the movement part (15) first operating condition being parallel and roughly coaxial with the longitudinal axis (X) of extension of the cavity (7) and in the movement part (15) second operating condition being eccentric to said axis (X).
The pump according to any of the foregoing claims, characterised in that the rotor (11) comprises a cylindrical main body (13) extending along the axis of rotation (B) and at least one vane (14) projecting from the cylindrical body (13).
The pump according to the foregoing claim, characterised in that the rotor (11) comprises a plurality of vanes (14) positioned along the cylindrical extension of the main body (13) and equidistant from one another.
The pump according to the foregoing claim, characterised in that the vanes (14) are abutted to the inner surface of the cavity (7); each vane (14) having a concave surface (14a) to contain the liquid and a convex surface (14b) opposite the concave surface.
The pump according to the foregoing claim, characterised in that in the movement part (15) second operating condition the inner surface of the cavity (7) has a first curved portion (16a), and a second curved portion (16b) adjacent to the first portion (16a), the axis of rotation (B) of the rotor (11) being moved towards the first curved portion (16a).
The pump according to the foregoing claim, characterised in that the vanes (14) are more deformed at the first curved portion (16a).
The pump according to claim 7 and/or 8, characterised in that it comprises a channel for passage of the liquid at the second curved portion (16b).
The pump according to any of the foregoing claims, characterised in that it also comprises a fixed frame (17) supporting the containment body (2): the movement part (15) comprising an anchoring portion (18) irremovably engaging with the fixed frame (17); and an actuator (19), attached to the anchoring portion (18) and to the body (2) for moving the body.
The pump according to the foregoing claim, characterised in that the actuator (19) comprises: a lever (20) having one end (20b) pivoting at the anchoring portion (18) to rotate about an axis parallel with the axis of rotation (B) of the rotor (11); at least one connecting plate (21) having a first end (21a) attached to the lever (20) and a second end (21b) opposite the first end (21a); and at least one cylinder (22) which can rotate about a respective axis and which has a first end (22a) attached to the second end (21b) of the connecting plate (21) and a second end (22b) opposite the first end (22a) with a projecting pin (24) attached to the containment body (2).
The pump according to the foregoing claim, characterised in that the projecting pin (24) extends along a longitudinal axis parallel with the axis of rotation (B) of the cylinder (22) and eccentric to it; the pin (24) being attached to the containment body (2) so as to move the body (2) after rotation of the cylinder (22).
The pump according to one or more of the foregoing claims, characterised in that the rotor (11) has a hollow end (13a) extending about the axis of rotation (B) and externally delimited by a raised seal (31) dividing the region (13a) from a wet zone (30) coinciding with the minimum radius circular area (33) swept by the recesses present between the vanes (14), wherein the outer projection (31) is star-shaped with radial expansions (32) projecting radially by a measurement at least equal to the minimum radius of the wet zone (30).
A rotor (11) for pumps comprising a main body (11) from which there project radially a number of vanes (14) and which has a hollow end (13a) extending about the axis of rotation (X) and externally delimited by a raised seal (31) dividing the region (13a) from a wet zone (30) coinciding with the minimum radius circular area swept by the recesses present between the vanes (14), the rotor being characterised in that the outer projection (31) is star-shaped with radial expansions (32) projecting radially by a measurement at least equal to the minimum radius (33) of the wet zone (30).
The rotor according to claim 14, wherein the vanes are deformable vanes.