WO2014001020A1

WO2014001020A1 - Piston pump for conveying material to be conveyed in the manner of thick material

Info

Publication number: WO2014001020A1
Application number: PCT/EP2013/061273
Authority: WO
Inventors: Karl Westermann; Martin Mayer; Ralf WEIMER
Original assignee: Putzmeister Engineering Gmbh
Priority date: 2012-06-29
Filing date: 2013-05-31
Publication date: 2014-01-03
Also published as: DE102012211280A1

Abstract

The invention relates to a piston pump for conveying material to be conveyed in the manner of thick material, in particular unset concrete. The piston pump has at least one conveying cylinder (10) and an axially movable conveying piston (21) which is arranged centrally in the conveying cylinder (10) with radial play with the formation of an annular gap (38). The conveying piston (21) comprises a central piston frame (36), guide means (40) which point radially in the direction of the cylinder inner surface (54) and bridge the annular gap (38), and a piston sleeve (46) which is fixed on the end side on the piston frame (36) by means of a clamping element (44), bears against the cylinder inner surface (54) and points with the end surface thereof in the conveying direction. In order to reduce the friction of the conveying piston (21) in the conveying cylinder (10) and, as a result, to achieve a reduction in wear and an increase in the degree of efficiency, it is proposed according to the invention that the piston sleeve (46) has a neck part (52) with a smaller external diameter in comparison with the cylinder inner surface (54) and a lip-like stripping part (56) which protrudes on the end side beyond the neck part (52), bears against the cylinder inner surface (54) with bridging of the annular gap (38) and points with the end surface thereof in the conveying direction.

Description

The invention relates to a piston pump for conveying thick material, in particular fresh concrete, with at least one delivery cylinder, with a centrally movable in the delivery cylinder with radial clearance to form an annular gap, axially movable delivery piston, wherein the delivery piston a has a central piston frame, radially in the direction of Zylin- inside surface pointing, the annular gap bridging guide means and a frontally fixed by means of a clamping element on the piston frame, one against the cylinder inner surface fitting and pointing with its end face in the conveying direction piston sleeve. Piston pumps of this type are used, for example, for conveying industrial thick materials or fresh concrete. As a rule, thick matter pumps have two delivery cylinders whose front-side openings open into a material feed container and are alternately connectable to a delivery line during a delivery stroke, for example via a diverter valve and are open during a filling stroke while the material is being drawn to the material supply container. The pistons of the delivery cylinders are driven by hydraulic drive cylinders in push-pull. For this purpose, the delivery pistons are connected via a common piston rod with the piston of the drive cylinder. The delivery pistons are directly in contact with the conveyed material. Accordingly, the piston seals and the inner surfaces of the delivery cylinders are subjected to high stress and are subject to wear. The usually consisting of a metal body piston scaffold serves as a link between the piston drive and the conveyed for receiving and passing the forces generated during pumping. The guide means ensure a directionally accurate running of the delivery piston in the delivery cylinder and prevent in conjunction with the piston sleeve tilting of the delivery piston especially when pushing out the conveyed. The task of the piston sleeve is divided into two parts in the known piston pumps: First, it serves both during the filling stroke and during the delivery stroke for sealing the necessary for the movement of the piston in the cylinder annular gap. On the other hand, the piston sleeve seals the clamping element, also referred to as the piston flange, toward the piston frame and thus prevents the ingress of conveyed material into the piston. In order to offer the greatest possible resistance to the penetrating conveyed material, both sealing functions are usually realized by a sealing gap which is as long as possible and strongly compressed. For this purpose, the sealing collar at both sealing points is designed so that it rests flat over a longer distance on the cylinder wall or on the piston flange and in the uninstalled state has a significant excess. The latter leads in the mounted state to the compression necessary for achieving the sealing function.

During the delivery stroke, a delivery pressure builds up in the delivery cylinder, which acts as an axially acting surface load on the piston cuff. To counteract this load, the piston sleeve is supported in the axial direction on the piston frame. When Füllhub, in which conveyed material is sucked from a material feed container in the delivery cylinder, however, creates a negative pressure in the delivery cylinder. In this case, the surface load on the piston sleeve changes its sign; the negative pressure tries to lift the piston seal from the piston frame. The purpose of the clamping element here is to support the piston sleeve in such a way that lifting is prevented. In addition, the piston seal must be made sufficiently solid and pressed against the delivery cylinder, so that deformation around the clamping element is excluded around.

The way in which the sealing task of the piston sleeve is solved so far, brings some decisive disadvantages, especially the great friction between the piston sleeve and the cylinder inner surface by their large compression with the clamping element. This friction leads to a high wear of the piston seal at this point. Accordingly, modern piston boots with inserted reinforcement reach only a few satisfactory service life. On the other hand, since this friction has to be overcome by the piston drive, there is also a considerable power loss that can not be available for conveying the thick material. Consequently, the energy efficiency of a piston pump leaves something to be desired when using a present-day piston seal.

Proceeding from this, the present invention seeks to improve the piston pump of the type specified in that the friction losses are reduced to the delivery piston while maintaining good sealing properties.

To solve this problem, the feature combination specified in claim 1 is proposed. Advantageous embodiments and modifications of the invention will become apparent from the dependent claims.

The solution according to the invention is based primarily on the idea that the long sealing gap, together with the necessary compression in the area of the piston sleeve, is replaced by a piston collar which has a neck portion with a smaller outside diameter than the cylinder inner surface and a lip-like protrusion over the neck portion against the cylinder inner surface Having under bridging the annular gap fitting and pointing with its end face in the conveying direction stripping. For sealing a sealing gap with a lip, a significantly lower compression is required. By changing the sealing mechanism accordingly reduce the friction and energy losses and thus the wear of the piston skirt. A preferred embodiment of the invention provides that the stripping section has at least two annularly spaced sealing lips arranged at an axial distance from one another and resting against the cylinder inner surface. Because the Guide task with such a piston sleeve can not be taken over in the previous extent, it makes sense that the guide means, for example, by extension, multi-part design or other adjustments are designed so that the management task of the piston sleeve friction reducing completely or partially omitted.

In order not to have to solve the problem of Fördermannschettenverformung during Füllhub not by pressing the piston seal, it is proposed according to a preferred embodiment of the invention that the piston piston cuff on its neck near the cylinder inner surface form-fitting with the piston frame, the adjacent guide means or a correspondingly designed other Part of the piston is connected. This ensures that the lifting surface load due to the negative pressure in the delivery cylinder at the most critical point near the cylinder wall can be recorded and forwarded to the supporting elements of the delivery piston. The latter can be achieved, for example, in that the piston cuff has on its neck part a radially outwardly open circumferential annular groove, into which engages a piston ring on the arranged, radially inwardly facing circumferential annular rib. Alternatively, or in conjunction with this, this can also be achieved by the fact that the piston frame has a radially inwardly open circumferential annular groove into which engages a circumferential annular rib pointing radially outward on the piston sleeve in the region of its neck. A further stabilization of the piston sleeve on the piston frame can be achieved in that the piston frame has a frontally open ring receiving, in which the piston sleeve engages with a part of her neck area.

According to a further advantageous embodiment of the invention, the clamping element is provided with an annular flange which rests against the end face of the piston sleeve, leaving the Abstreifpartie and thereby presses the piston sleeve against the piston frame. In order to reduce the piston mass, the piston frame can one of the clamping element Have bridged central cavity, wherein the clamping element can be fixed by means of a cavity centrally penetrating the clamping screw on the piston frame. A further preferred embodiment of the invention provides that the guide means are inserted into at least one radially outwardly open circumferential groove of the piston stand. A particularly good sealing function is achieved when the guide means and / or the piston sleeve made of an elastomeric material.

According to a further preferred embodiment of the invention, the piston frame is at least partially made of an elastomeric material, wherein the guide means form an integrally connected to the piston frame guide portion.

Advantageously, the delivery piston is connected on its side facing away from the conveyed material in the region of its piston frame with a drive mechanism. The drive mechanism is advantageously designed as a hydraulic drive cylinder, the drive piston is connected via a piston rod to the delivery piston.

In the following the invention will be explained in more detail with reference to the embodiments schematically illustrated in the drawing. 1 shows a diagram of a two-cylinder piston pump for the delivery of thick materials;

Fig. 2a shows an enlarged section of the delivery cylinder after

Fig. 1 with a first embodiment of the delivery piston in a sectional view;

FIG. 2b shows an enlarged detail from FIG. 2a; FIG. Fig. 3 to 5 representations corresponding to Fig. 2a for three further embodiments of the delivery piston. The piston pump shown in Fig. 1 is intended for the promotion of thick material-like conveyed 1 1, in particular of fresh concrete. It consists essentially of two delivery cylinders 10, 10 'whose front-side openings 12, 12' open into a material feed container 14 and alternately during the delivery stroke D (pressure stroke) via a diverter valve 16 with a delivery line 18 connectable and during the Füllhubs S ( Suction stroke) under suction of the material to the material feed container 14 are open. The delivery cylinders 10, 10 'are driven by hydraulic drive cylinders 20, 20' in push-pull. For this purpose, the delivery pistons 21, 21 'are connected to the drive pistons 24, 24' via a common piston rod 22, 22 '. In the area between the delivery cylinders 10, 10 'and the drive cylinders 20, 20' there is a water tank 26 through which the piston rods 22, 22 'pass. The delivery cylinders 10, 10 'are open to the water box 26 out. Accordingly, the delivery piston 21, 21 'is acted upon on its rear side with the liquid from the water tank 26. Thus, both the mud passing through the delivery pistons 21, 21 'to the rear are washed away and a cooling effect is generated.

The drive cylinders 20, 20 'are acted on the bottom side via pressure lines 28, 28' at the terminals A and B by means of a hydraulic pump, not shown, alternately with pressurized oil. At their rod-side end, the drive cylinders 20, 20 'are hydraulically coupled together by a connecting line 30. To trigger the Umsteuervorgangs measuring probes 32, 32 ', 34, 34' in the wall of the respective drive cylinder 20, 20 'are arranged in the vicinity of the bottom and rod ends of the drive cylinder. The measuring probes respond to the drive pistons 24, 24 'passing in the course of the conveying and filling strokes and emit a digitally evaluable end position signal in the area of the switching points. In principle, instead of the above-described oil-hydraulic drive, it is also possible to use a mechanical or electro-mechanical drive mechanism for the delivery pistons.

A special feature of the invention is the special construction of the delivery piston 21, 21 ', whereby a reduction of the friction effect and thus the wear effect and a reduction of the driving forces in the region of the delivery cylinder 10, 10' to be achieved. For linguistic simplification is spoken in the following as well as in the claims each in the singular of a delivery piston 21 and a delivery cylinder 10, although in the case of a two- or multi-cylinder piston pump each two or more copies occur. The delivery pistons 21 shown in FIGS. 2 to 5 coincide with a central piston frame 36, which acts as a link between the piston drive on the side of the piston rod 22 and the high-pressure material under the delivery pressure on the side of the conveyed material 1 1 for transferring the fluid produced during pumping Forces are acting. Between the piston frame 36 and the delivery cylinder 10 is an annular gap 38 which is bridged in the embodiments shown in FIGS. 2 to 4 by guide means 40 which are inserted in the form of rings in radially outwardly open circumferential grooves 41 of the piston stand 36. The guide means 40 expediently consist of an elastomeric plastic, for example of polyurethane or polyethylene or derivatives thereof.

Furthermore, a piston collar 46 which is fixed on the front side in the conveying direction by means of a clamping element 44 on the piston frame 36 is provided. The piston sleeve 46, in conjunction with the guide means 40, prevents tilting of the delivery piston 21, in particular during the delivery stroke. Another function of the piston sleeve 46 is in the sealing of the necessary for the movement of the delivery piston 21 In addition, the piston sleeve 46 seals the clamping element 44 from the piston frame 36 out and thus prevents the penetration of conveyed material 1 1 in the delivery piston 21st The two points at which the conveyed material 1 1 tries to penetrate are indicated in FIGS. 2 to 5 in the form of a plurality of arrows 48. The piston sleeve is expediently made of a rubber-elastic material, for example made of NBR (natural butadiene rubber). In the embodiments shown in FIGS. 2 to 4, the piston frame 36 consists predominantly of a metal, for example aluminum or an aluminum alloy. In order to reduce the moving mass, the piston frame 36 contains a central cavity 42, which is covered by the clamping element 44 designed as an annular flange and is sealed against ingress of liquid by means of a piston collar 46. For this purpose, the clamping element 44 is clamped by means of a clamping screw 50 while interposing a part of the piston sleeve 46 on the piston frame 36. A peculiarity of the embodiment shown in Fig. 5 is that the piston frame 36 in its entirety consists of an elastomeric plastic and that the guide means 40 'are an integral part of the piston frame.

Another peculiarity of the invention is that the piston sleeve 46 in all four embodiments, a neck portion 52 with respect to the cylinder inner surface 54 smaller outer diameter and a front over the neck portion 52 projecting, against the cylinder inner surface 54 while bridging the annular gap 38 and abutting with its end face in Has conveying direction facing lip-like Abstreifpartie 56. In the exemplary embodiments shown, the radial sealing takes place via two rib-like sealing lips 58, which abut annularly on the cylinder inner surface 54. To seal the annular gap 38 with the sealing lips 58, a significantly lower compression is required than in the previously known two-dimensional contact. conditions of the piston sleeve. This leads to the fact that the friction and energy losses and thus also the wear of the piston sleeve 46 decrease with the same sealing effect. Similarly, the axial sealing gap between the clamping element 44 and the piston sleeve 46 can be sealed by means of annular sealing lips 59 with reduced contact pressure (see Fig. 2b).

During the delivery stroke D, a high discharge pressure builds up in the delivery cylinder 10 on the side of the conveyed product 11, which has an effect on the piston collar 46 as an axially acting surface load. To counteract this load, the piston sleeve 46 is supported in the axial direction on the piston frame 36. When Füllhub S, in which conveyed material 1 1 is sucked from the material feed container 14 in the delivery cylinder 10, however, creates a negative pressure on the side of the conveyed 1 1. The negative pressure attempts to lift the piston collar 46 from the piston frame 36. In order to largely prevent this, it is proposed according to the exemplary embodiments shown in FIGS. 3 to 5 that the piston sleeve 46 is connected in a form-locking manner to the piston frame 36 close to the cylinder inner surface 54. Thereby, the lifting surface load from the negative pressure in the delivery cylinder 10 is received at the critical point near the cylinder wall and forwarded to the supporting elements of the piston frame 36. In terms of design, this is achieved, above all, by the fact that the piston sleeve 46 has a circumferential groove 60 which opens radially outwards at its neck 52 and into which a circumferential annular rib 62 arranged radially inwardly on the piston frame 36 engages. In addition, the piston stand 36 has a radially inwardly open encircling second annular groove 64 into which engages a circumferential second annular rib 66 which points radially outward on the piston cuff 46 in the region of its neck area. To further stabilize the piston cuff 46, the piston frame 36 has an open end ring receiver 68 into which the annular collar 46 engages with a part of its neck portion 52. The ring receiver 68 is radially open edge to the cylinder inner surface 54, so that the piston sleeve 46 with its neck portion 52 through the Edge opening 70 has radially outward and directly to the cylinder inner surface 54 faces.

In the embodiments of the delivery piston according to the invention, it is basically possible to make the guide means 40, 40 ', for example, by extension, multi-part design (FIG. 4) or other adaptations (FIG. 5) such that the guiding task of the piston sleeve 46 is for the purpose of reducing friction completely or partially omitted. The measures according to the invention lead to a reduction in wear on the delivery piston 21 and to an increase in the service life. In addition, you get a significant energy savings and an increase in efficiency during operation of the piston pump. In summary, the following should be noted: The invention relates to a piston pump for conveying thick material conveyed, in particular fresh concrete. The piston pump has at least one delivery cylinder 10 and one in the delivery cylinder 10 with radial clearance to form an annular gap 38 centrally arranged, axially movable delivery piston 21. The delivery piston 21 comprises a central piston frame 36, radially in the direction of the cylinder inner surface 54 facing, the annular gap 38 bridging guide means 40 and a frontally fixed by means of a clamping element 44 on the piston frame 36, a te against the cylinder inner surface 54 and pointing with its end face in the conveying direction pointing piston sleeve te 46. In order to reduce the friction of the delivery piston 21 in the delivery cylinder 10 and thereby achieve a reduction in wear and efficiency increase, it is proposed according to the invention that the piston sleeve 46 a neck portion 52 with respect to the cylinder inner surface 54 of smaller outer diameter and a front over the neck portion 52 on - Having, against the cylinder inner surface 54 with bridging the annular gap 38 fitting and pointing with its end face in the conveying direction lip-like stripping section 56. LIST OF REFERENCE NUMBERS

10, 10 'delivery cylinder

1 1 conveyed goods

12, 12 'frontal openings

14 material supply containers

16 pipe switch

18 support line

20, 20 'hydraulic drive cylinder

21, 21 'delivery piston

22, 22 'common piston rod

24, 24 'drive piston

26 water tank

28, 28 'pressure pipes

30 connecting line

32, 32 'probes

34, 34 'probes

36 piston frame

38 annular gap

40, 40 'guiding means

42 cavity

44 clamping element

46 Piston sleeve

48 arrows

50 clamping screw

52 neck part

54 cylinder inner surface

56 Astreifpartie

58 sealing lips (radial)

59 sealing lips (axial)

60 ring groove

62 ring rib 64 ring groove

66 ring rib

68 ring holder

70 edge opening

A, B connections

D delivery stroke (pressure stroke)

S filling stroke (suction stroke)

Claims

claims

1 . Piston pump for conveying thick-like conveyed material, in particular of fresh concrete, with at least one delivery cylinder (10), with a in the delivery cylinder (10) with radial clearance to form a

Annular gaps (38) arranged centrally, axially movable delivery piston (21), wherein the delivery piston (21) a central piston frame (36), radially in the direction of the cylinder inner surface (54) pointing, the annular gap (38) bridging guide means (40) and a front side means Having a clamping element (44) on the piston frame (36), one against the cylinder inner surface (54) and facing with its end face in the conveying direction pointing piston sleeve (46), characterized in that the piston sleeve (46) has a neck portion (52) Having opposite the cylinder inner surface (54) of smaller outer diameter and a front side over the neck portion (52) lip-like protruding, against the cylinder inner surface (54) while bridging the annular gap (38) fitting and facing with its end face in the conveying direction stripping (56). 2. Piston pump according to claim 1, characterized in that the Abstreifpartie (56) at least two axially spaced from each other, against the cylinder inner surface (54) adjacent annular sealing lips (58). 3. Piston pump according to claim 1 or 2, characterized in that the piston sleeve (46) at its neck portion (52) near the cylinder inner surface (54) is positively connected directly or indirectly with the piston frame (36) or the guide means (44). 4. Piston pump according to one of claims 1 to 3, characterized in that the piston sleeve (46) at its neck portion (52) has a radially outwardly open circumferential annular groove (60) into which a on the piston frame (36) arranged, radially inwardly facing circumferential annular rib (62) engages.

Piston pump according to one of claims 1 to 4, characterized in that the piston frame (36) has a radially inwardly open circumferential annular groove (64) into which a on the piston sleeve (46) in the region of its neck portion (52) pointing radially outward encircling annular rib (66) engages.

Piston pump according to one of claims 1 to 5, characterized in that the piston frame (36) has a frontally open annular receptacle (68) into which the piston sleeve (46) engages with a part of its neck part (52).

Piston pump according to claim 6, characterized in that the ring receptacle (68) is open-edge radially towards the cylinder inner surface (54) and that the piston sleeve (46) with its neck portion (52) through the edge opening (70) of the ring receptacle (68) in the direction Cylinder inner surface (54) passes through.

Piston pump according to one of claims 1 to 7, characterized in that the clamping element (44) is provided with an annular flange which rests against the end face of the piston sleeve (46) leaving the Abstreifpartie (56) and thereby the piston sleeve (46) against the Press the piston frame (36).

Piston pump according to one of claims 1 to 8, characterized in that the guide means (40) in at least one radially outwardly open circumferential groove of the piston stand (36) are inserted.

10. Piston pump according to one of claims 1 to 9, characterized in that the guide means (40) and / or the piston sleeve (46) consist of an elastomeric material. 1 1. Piston pump according to one of claims 1 to 10, characterized in that the piston frame (36) at least partially consists of an elastomeric material, and that the guide means (40 ') form an integrally connected to the piston frame (36) guide portion.

12. Piston pump according to one of claims 1 to 1 1, characterized in that the delivery piston (21) on its the conveyed (1 1) facing away from back in the region of its piston frame (36) is connected to a drive mechanism.

13. Piston pump according to claim 12, characterized in that the drive mechanism comprises a hydraulic drive cylinder (20) which comprises a via a piston rod (22) connected to the delivery piston (21) drive piston (24).

14. Piston pump according to claim 1 to 13, characterized in that the piston frame (36) comprises one of the clamping element (44) bridged central cavity (42). 15. Piston pump according to claim 1 to 14, characterized in that the clamping element (44) by means of a cavity (42) centrally penetrating clamping screw (50) on the piston frame (36) is fixed.