EP0024343A1 - Pump for the delivery of viscous substances, in particular for concrete - Google Patents

Abstract

In the case of a thick matter pump, in particular for conveying concrete through the housing (3) of a pipe switch (2), which has a swivel body (26) attached to a swivel shaft (44), which also has an outlet opening (25) made in a housing wall (4) alternately connecting two inlet openings (6, 7) arranged in another housing wall (4), the center points of the inlet (6, 7) and outlet openings (25) each being arranged at a radial distance from the shaft axis (35) is for reduction the mechanical loads on the housing openings (6, 7) having the housing wall (4) through the swivel body (26) without having to accept increased bending loads on the swivel shaft (44), the swivel shaft (44) is axially supported and the distances between the inlet openings (6,7) and the outlet opening (25) from the shaft axis (35) are chosen so differently that the distance (R1) of the inlet openings (6,7) is greater than the distance (R2) of the outlet opening (25) is. Complete freedom from moments is achieved if in the swivel body (26) the product of the exit surface or surfaces (32) and the distance of the common surface center of gravity from the shaft axis (35) is equal to the product of the entry surface (28) and the distance of their surface center of gravity from the shaft axis (35).

Description

The invention relates to a thick matter pump, in particular for conveying concrete through the housing of a pipe switch, which has a swivel body fastened to a swivel shaft, which alternately connects an outlet opening made in a housing wall with two inlet openings arranged in another housing wall, the center points of the inlet and outlet openings are each arranged at a radial distance from the shaft axis.

Thick matter pumps not only serve to convey concrete, but can also mix substances with a mud-like consistency, e.g. B. Promote sewage sludge. The invention is however in following described on the basis of the promotion of concrete, because this is for various reasons, e.g. B. is due to the deterioration of the liquid deterioration of the concrete and the wear effect of the sand contained in the concrete is a particularly difficult to pump medium. A thick matter pump generally has two alternately conveying cylinders, each of which is assigned an inlet opening in the housing of the pipe switch, through which the partial quantity expressed by the relevant piston from the cylinder reaches the swivel body. The outlet opening, on the other hand, is preferably assigned to only one delivery line into which the pumped concrete is directed. The pipe switch enables the respective suction feed cylinder to suck in the concrete from a prefilling container, which is usually attached above the housing, which is then conveyed in the following pump cycle.

The principle of such concrete pumps described above is not easy to master in practice, especially when high delivery resistances have to be expected. Because here occur considerable hydrostatic forces, for. B. in the order of 20,000 kp, which lead to the fact that deformations occur even with ample dimensioning of the elastic components loaded with this, which must provide the opposing forces. These deformations lead to the formation of gaps on the sealing bodies of the pipe switch sliding on one another. This creates leaks without the worsening influence of the unavoidable wear, which leads to the squeezing out of liquid components from the concrete and thus to malfunctions. In addition, parts of the sand penetrate into the resulting gap, which are clamped in after the relief occurs with each swiveling operation of the pipe switch. This leads to switching malfunctions and great wear.

From DE-OS 26 14 895 it is known to provide seals to eliminate such problems, for. B. in the swivel body axially displaceably arranged wear ring which is loaded with the pressure of the medium and is pressed. Here too leads however, the sand jams. This is because the annular gap between the end of the swivel body and the wear ring arranged on it changes its length with the load and the resulting expansion of the counter-holding device and becomes larger by several millimeters during the pressure stroke; during the switching process of the pipe switch, a relief occurs, which also relieves the elastically tensioned counter-holding device, so that the annular gap mentioned is in turn compressed again. It is therefore endeavored to keep the elastic deformations as small as possible by means of short tie rods or bending beams.

From DE-PS 12 85 319 it is also known to design the swivel body as a tube which is bent approximately S-shaped, the outlet opening of the swivel tube having the same free area as the outlet opening of the housing. At this point, the hydrostatic forces, which otherwise act in the shaft axis, are balanced. However, bending moments occur at the inlet openings, which are arranged at a distance from the axis of the pivot shaft, which are determined by the magnitude of the forces and their radial distance from the shaft axis. This leads to tilting of the prefilling container because the pivot shaft is mounted in its wall and thus to the gap formation mentioned at the inlet openings.

In another thick material pump known from DE-AS 21 04 191, an approximately S-shaped tube is also used as the swivel body, but the moments mentioned are taken up in the bearing of the shaft. Then there are very large shaft diameters, without that elastic deformations and thus gap formation could be avoided entirely. Given the high conveying resistances, such embodiments are therefore practically impossible to achieve.

From DE-PS 21 62 406 a thick matter pump is known, in which an approximately U-shaped tube is preferred as the swivel body can be seen, whose back is supported on a cross yoke in the region of the lower pivot. This support from the swivel tube slides in the fluid, which further increases friction and wear. In addition, the transverse yoke must be held with relatively long tie rods. The elastic deformations that occur due to the considerable elastic expansion of the tie rods and the deflection of the yoke in turn lead to considerable orders of magnitude of the gaps that form at the inlet openings.

Finally, a thick matter pump is known from US-PS 12 78 247, in which the pipe switch is provided with a swivel body adapted to the curvature of the housing base, which has a round inlet opening and two outlet openings, the boundary edges of which partially coincide. The distance of all three openings from the axis of the swivel shaft is the same. To seal the inlet openings, a spectacle plate is placed on the relevant inner wall of the housing. A considerable axial force then acts on this component. If you wanted to transfer this axial force to the housing with the help of the swivel shaft, there would be considerable forces perpendicular to the shaft, which would elastically bend the shaft, provided it is sufficiently strong, and thus lead to tilting of the housing and the swivel body in the housing. This also results in the jamming that occurs due to the gap formation when switching the swivel body, the considerable wear based thereon and the lack of operational safety attributable to this.

The invention seeks to remedy this. The invention, as characterized in the claims, solves the problem of designing such a thick matter pump in such a way that the mechanical loads on the housing wall having the inlet openings are greatly reduced by the swivel body without having to accept increased bending loads on the swivel shaft.

The advantages achieved by the invention are essentially to be seen in the fact that the choice of the distances in relation to a point lying on the shaft axis allows freedom from moments or approximately freedom from moments to be achieved. In this way, the remaining axial force can be removed with the shaft without bending, for example via a bearing that is subjected to pressure or tension. This camp can be arranged outside the masses to be conveyed. In addition, the sealing is simplified by relieving the pressure on the housing wall, which gives the possibility of arranging axially movable sealing rings at the openings of the swivel body.

Complete freedom of torque is achieved, in a further development of the invention, when the product of the exit surface or surfaces and the distance of the common center of gravity from the shaft axis is equal to the product of the entry surface and the distance of its center of gravity from the shaft axis in the swivel body.

In order to keep the swivel angle of the swivel body as small as possible, provision can further be made for the outline of the partially coinciding outlet openings to be kidney-shaped in the swivel body.

A thrust bearing arranged on the outlet side of the housing is expediently provided for axially supporting the pivot shaft. This thrust bearing is loaded with the pivot shaft in the opposite direction to the conveying direction.

The pivot shaft advantageously has an axial thrust bearing on the inlet side of the housing, which is designed as a clamping device for the housing.

With a shortened design of the swivel body, there are shortened components of the housing, which are so strong without much effort can lead to only minimal expansion of the housing in the axial direction. The axial expansion of the housing is considerably reduced by the axial force which is transmitted from the swivel shaft via the axial bearing to the housing in the opposite direction. If the swivel shaft is also provided with the clamping device described on the inlet side, the axial expansion of the housing can be almost completely suppressed due to the rigidity of the swivel shaft in relation to tensile loads.

Finally, it is expedient to surround the openings of the swivel body with wear rings which are mounted so as to be axially movable on the respective end face of the pressure body.

In the thick matter pump according to the invention, the swivel body is only axially guided by the swivel shaft and is also supported on the swivel shaft in the axial direction, as a result of which the swivel shaft is not subjected to any bending loads and the control housing is not subjected to twisting thrust loads. This is based on u. a. the advantage that sealing rings placed on the swivel body, which optimally fit under the concrete pressure against the boundary surfaces of the control housing running perpendicular to the swivel shaft, can adapt to the latter. As a result, uneven wear and tear as well as structural faults in the housing can be compensated for.

In addition, the design according to the invention ensures that the friction during the pivoting process and thus also the wear can be kept to a minimum because the axial force can be supported outside the concrete on a normal rotary slide bearing. Since the remaining axial expansions of the housing are very small, any tendency to jam is effectively counteracted by sand particles pressed into the gaps.

• Fig. 1 in abgebrochener Darstellung eine erfindungsgemäße Dickstoffpumpe in Seitenansicht und teilweise im Schnitt,
• Fig. 2 einen Schnitt längs der Linie II-II der Fig. 1,
• Fig. 3 einen Schnitt längs der Linie III-III der Fig. 1,
• Fig. 4 einen Schnitt längs der Linie IV-IV der Fig. 1 und
• Fig. 5 einen Schnitt längs der Linie V-V_'der Fig. 3.

In the following, the invention is explained in more detail with reference to drawings that show only one exemplary embodiment. It shows

• 1 is a broken view of a slurry pump according to the invention in side view and partially in section,
• 2 shows a section along the line II-II of FIG. 1,
• 3 shows a section along the line III-III of FIG. 1,
• Fig. 4 is a section along the line IV-IV of Fig. 1 and
• 5 shows a section along the line VV _' of FIG. 3rd

Under a pre-filled container 1 indicated by a dot-dash line, there is a pipe switch generally designated 2 according to FIG. 1. The pipe switch 2 has an axially short housing 3. This housing 3 is divided in the transverse direction by means of a rib which forms a transverse wall 4.
On the transverse wall 4, an eyeglass plate 5 is fastened, in which inlet openings 6 and 7 are formed for the concrete conveyed by two conveying cylinders 8 and 9 (FIG. 2). The ends of the two delivery cylinders 8 and 9 are held in sleeves 10 and 11, respectively, which have seals 12 on their end faces and are held in the rear housing wall 5 'except in the transverse wall 4. The housing, which is formed in one piece with the walls 4 and 5 ′ mentioned, is closed by a cover 14. Screws 15 are arranged on a bolt circle of the cover 14, which screws can be screwed into corresponding bores in the housing flange 16. On the inside of the cover there is a wear plate 17 with an outlet opening 25. A bushing 19 with seals 20 or 20 'serves for the liquid-tight connection of a delivery line 21 into which the pump presses the delivered concrete.

The two delivery cylinders 8 and 9 suck from the prefill container 1 Concrete alternately on the interior 24 of the housing 3. In the following cycle, the cylinders alternately press the sucked-in concrete through the inlet openings 6 and 7 in the spectacle plate 5. Before this cycle begins, the inlet openings 6 and 7 are connected to the outlet opening 25 of the housing 3 provided in the wear plate 17. For this purpose, a swivel body, generally designated 26 (FIGS. 1 and 2), is used, the design of which results in particular from FIGS. 3 and 4. According to FIG. 3, the swivel body 26 has an entry opening 28 which is surrounded by the axially movable ring 27 shown in FIG. 2 and which is surrounded by the edge designated 29 in FIG. 2. This edge gives the inlet opening 28 a circular clear cross section. The center of gravity is therefore in the middle of the circular area.

Furthermore, as shown in particular in FIG. 4, the swivel body has at its opposite end an exit surface surrounded by an axially movable ring 30. This area is delimited by the end edge 31 of the swivel body 26 and is designated 32. Its outline is kidney-shaped, as can be seen in particular from FIG. 4. Accordingly, the circular outlet openings partially collapse within the kidney-shaped boundary. The center of gravity lies in the middle of the kidney-shaped outlet opening 32. It has a radial distance R ₂ from the geometric axis designated 35 in FIG. 1, while the inlet opening 28 has a radial distance R ₁ from the geometric axis 35.

The swivel body 26 is formed in one piece with an arm 37 which interacts with a bearing cover 38. The bearing cover 38 can be connected to the arm 37 by means of two pairs of screws 39 and 40, so that a central section of a pivot shaft 44 can be clamped between the two parts described.

5, the swivel shaft 44 is provided with a polygonal section 45 in the region of the swivel body 26. This ends at a collar 46 with an enlarged diameter, so that the swivel body 26 can be axially fixed on the shaft. The collar 46 merges into a reduced-diameter cylindrical section 47, which is supported in a combined radial and axial bearing 48. On the opposite side, the polygonal section 45 merges into a reduced-diameter cylindrical section 49, which continues into a further reduced-diameter spindle section 50. A nut 52 with a lock nut 51 can be screwed onto the spindle section. Above the nuts, the pivot shaft is supported on a multi-part disk 53, which in turn is supported on the end face of a bearing bush 54. The bearing bush 54 is therefore an axial thrust bearing which is loaded against the direction of conveyance of the concrete by the swivel body 26.

Assuming that the hydrostatically loaded surface of the swivel body 26 at the inlet opening 28 according to FIG. 3 is F ₁ and the hydrostatically loaded surface of the kidney-shaped outlet surface 32 of the swivel body 26 according to FIG. 4 is F ₂ , the result is

In this function, the value z denotes a size which depends on the construction and indicates how many times the hydrostatically acted area of the swivel body at the inlet opening is smaller than the hydrostatically acted area of the kidney-shaped exit area.

Da nun

ist

Assuming further that each inlet opening is hydraulically loaded with K ₁ , but the outlet opening with K ₂₁ results as a condition for the torque compensation

Because now

is

However, this means that the forces V indicated in FIG. 1 on the two bearings of the pivot shaft do not occur. It is

It follows from this: If the radial distances R from the swivel shaft are chosen such that the distance R _{1 of} the inlet opening is z times greater than the distance R _{2 of} the center of gravity of the kidney-shaped outlet opening, then no vertical forces arise on the shaft and thus on its bearings, because the moments are zero. The shaft is therefore not subjected to bending. The housing is also not tilted. The pivot shaft 44 is actuated by means of a thrust piston gear 60 via a crank 61 which, as shown in FIG. 5, acts on the end 47 of the shaft provided with splines 62. While the cylinder-side end of the shaft 44 is only guided in the bearing 48 according to the exemplary embodiment according to FIG. 5, this swivel shaft end in the exemplary embodiment of FIG. 1 has a configuration which corresponds to the mounting which is realized on the housing side carrying the housing cover 14 . With the aid of a nut 63 and a nut 64, the pivot shaft 44 can accordingly be tensioned at both ends, so that deformations of the parts which absorb the axial bearing loads can be counteracted. The keyways 62 are therefore arranged behind the nuts 63 and 64, which enable the axial bracing and belong to the bearing generally designated 6.6.

According to the invention, the arrangement is selected such that the pivot shaft 44, on which the pivot body 26 is suspended, is axially supported on at least one bearing 54 or 66, which is arranged on the front or rear housing wall 17 or 4, 5 ' can be.

The inlet openings 6, 7, which are touched by the swivel body 26 or its sealing rings 27 and are arranged according to the exemplary embodiment in an eyeglass plate, are arranged such that the distance between their center or center of gravity from the axis of the swivel shaft is greater than the corresponding one Distance of the outlet opening is.

In contrast, the swivel body 26 is designed such that it covers one of the two inlet openings 6, 7 in the housing in the two end positions of the swivel shaft 44 and covers the outlet opening in the housing on the opposite side of the housing. The swivel body or the arm 70 connecting it to the swivel shaft in FIG. 5 or 37 in FIG. 3 are designed such that the assignment of the swivel body to the swivel shaft described at the outset results.

Claims (6)

1. thick matter pump, in particular for conveying concrete through the housing (3) of a pipe switch (2), which has a swivel body (26) attached to a swivel shaft (44), which has an outlet opening (25) provided in a housing wall (14) alternately connecting two inlet openings (6, 7) arranged in another housing wall (4), the center points of the inlet (6, 7) and outlet openings (25) each being arranged at a radial distance from the shaft axis (35), characterized in that that the pivot shaft (44) is axially supported and the distances between the inlet openings (6, 7) and the outlet opening (25) from the shaft axis (35) are selected so differently that the distance (R ₁ ) of the inlet openings (6, 7) is greater than the distance (R ₂ ) of the outlet opening (25). 2. thick matter pump according to claim 1, characterized in that in the swivel body (26) the product of the exit surface or surfaces (32) and the distance of the common center of gravity from the shaft axis (35) equal to the product of the entry surface (28) and the distance of its surface center of gravity from the shaft axis (35). 3. thick matter pump according to claims 1 or 2, characterized in that in the swivel body (26) the outline of the partially coincident outlet openings (32) is kidney-shaped. 4. slurry pump according to claims 1 to 3, characterized in that for axially supporting the pivot shaft (44) on the outlet side of the housing (3) arranged thrust bearing (51-54) is used, which with the pivot shaft (44) in the conveying direction is loaded in the opposite direction. 5. thick matter pump according to claim 4, characterized in that the pivot shaft (44) on the inlet side (4, 5) of the housing (3) has an axial pressure bearing (66) which as a clamping device (63, 64) for the housing (3rd ) is trained. 6. slurry pump according to claims 1 to 4, characterized in that the openings of the swivel body (26) are surrounded by wear rings (27, 30) which are axially movable in the respective end face of the swivel body (26).

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