EP0046902A2

EP0046902A2 - Concrete pumping device

Info

Publication number: EP0046902A2
Application number: EP81106280A
Authority: EP
Inventors: Alfredo Brandi
Original assignee: Libra SA
Current assignee: Libra SA
Priority date: 1980-09-03
Filing date: 1981-08-12
Publication date: 1982-03-10
Also published as: EP0046902A3; IT8024428A0; IT1132633B

Abstract

Pumping device for pasty materials, particularly concrete, of the type comprising two cylinders which, by way of an S-shaped valve, are connected alternatively to a delivery pipe and to a hopper placed above said valve.

In said device, the housing or tank (7) of the valve is formed by two flat parallel headwalls (8), one of which holds a first support (13) for the control shaft of the S-shaped valve (5), telescopic cylinder ends (11) connecting said valve with the pumping cylinders (1), and ribs ending into four ears (12) which make it possible to rotate the tank about vertical axes, while the other wall holds a second valve support (18) and a flange (20) of connection to the delivery pipe (4); by two partially inclined sidewalls (9) which are radiused to the bottom; and by a bottom cover formed by a cylindrical wall, the axis of which coincides with the valve rotation axis.

Moreover, in the device described, the axis of the pumping cylinders is positioned higher than the valve rotation axis and the delivery pipe.

Description

The present invention relates to an improved device for the pumping of pasty material, particularly concrete.
Devices for pumping pasty materials, especially concrete pumps, are already known and widely used in technique; in such devices, the material to he pumped is sucked through pumping cylinders from a charging hopper and sent under pressure, through said cylinders and through a deviating valve, into the delivery pipe.
The technicians dealing with the construction of such devices are particularly concerned with the production and working of the deviating valve, this being the most delicate and important element of said devices and the technical characteristics of this element having so far provided no satisfactory results from the structural point of view, as well as from the point of view of the working, reliability, maintenance and life of said element.
A type of deviating valve, most widely used at present, is the S-shaped valve which rotates about the axis of the delivery pipe, supported by two end supports, one on the side of the pumping cylinders and the other on the side of said delivery pipe, and controlled by a hydraulic jack system in order to alternatively connect either one of a pair of pumping cylinders with the delivery pipe.
The present invention aims at improving the deviating valves of this type with particularly brilliant results, in that it supplies a concrete pumping device which guarantees an improvement of the suction conditions and of the volumetric efficiency, a reduced requirement for preventive maintenance, a higher working reliability and a very fast adjustment of the ,-ear parts, with obvious advantages from the point of view of the use.
It should be remembered that the devices in question have to satisfy, at the same time, a great number of requirements which can be summed up as follows:

a) There should be the least possible height between the lower limit of the pump and the upper limit of the charging hopper, in order to allow favourable solutions of assembly and obtain, at the same time, maximum hopper volumes, particularly in the case of apparatuses mounted on lorries.
b) The geometric shape of the device should be such as to allow the pumping cylinders to take up a position of assembly being as close as possible to the horizontal position, in order to ensure favourable conditions for the suction of the material and to simultaneously obtain a minimum distance of the charging hoppers from the ground.
c) The parts subject to wear should be of simple shape and easy- ly replaceable.
d) The moulding and the change of shape of the vein of the material being worked should be minimum; the wear and the power required for operation should be the least possible.
e) The self-cleaning action must be efficient; the requirements of cleaning and maintenance should be the least possible.
f) It should be possible to use the valve - which is relatively costly - in connection with various types of hopper.
g) Simple systems of wear compensation should be available.
h) The axis of the pumping cylinders should be above that of the valve and, in particular, above that of the delivery pipe, in order to make the cleaning easy and safe.

All these requirements are only partly satisfied by the solutions known so far. A whole series of S-shaped deviating valves comprises, between the valve and the bottom of the hopper, devices for scraping the material of the most varied shapes; the bottom parts are mostly flat, whereby the material pieces of larger dimensions wedge in between the valve and the bottom, producing high stresses and preventing at times the rotary movement, or even causing breakages.
Other solutions provide for the combination of a certain number of scraping devices with stirring devices, mostly arranged near the top of the valve and in the form of blades: the result of such arrangements is however scarce, due to the limited angular displacement of the deviating valve.
Still further solutions provide for a direct contact between the valve and the bottom of the hopper, causing the profiles of the opposed surfaces to mate.
Such solutions have the advantage of reducing to a minimum the quantity of material which cannot be sucked, but on the other hand they have the drawback of presenting wide sliding surfaces, which produce severe wears and a high waste of power.
Moreover, their configuration is such that the wear element on the valve front is subjected to wear both on the flat portion and on the circular portion, which are at right angles to each other, giving rise to wear problems which are difficult to solve since these points are further away from the centre of rotation of the valve and, as such, they have a top relative speed.
In other arrangements, the compensation for front wear of the S-shaped valve is obtained automatically by an axial displacement, operated by hydraulic means, in the directioh of the sliding surfaces. This solution implies however considerable costs and a further complexity of the device.
Many pumping devices of known technique provide for welded structures; this however increases the areas in which concrete settles, whereby the need for cleaning accordingly rises.
In other solutions, the operation of the deviating valve takes place sidewards in respect of the delivery pipe; in this way, the hydraulic device for rotating the valve is within easy reach, but there is less accessibility to the hopper on the part of the truck mixers or other charging means; it is moreover necessary to provide for an expensive system of protection from possible mechanical collisions and from accidental concrete pourings.
Furthermore, a characteristic common to all known solutions is to arrange the axis of the pumping cylinders beneath the delivery pipe, thereby forming a trap which makes the cleaning difficult creating problems of material stagnation.
The above drawbacks, typical of the solutions known so far, are all eliminated dth the device according to the present invention.
In such device, the housing (or tank) of the deviating valve is formed by two flat, parallel headwalls, holding the supports, and by two inclined sidewalls radiused with the bottom. This latter is formed by a cylindrical surface, the axis of which coincides with the rotation axis of the valve. The top part of said walls ends with a lip or flange, being preferably bent on the walls parallel to the rotation axis, and flat on the remaining walls. This shape mates well with that of the hopper, if this is provided with a mixer. It is instead preferable for the walls of the valve housing to have a completely flat lip in case of using a hopper of frustoconical shape, which generally requires no mixer. In both alternatives, the valve and its housing can be associated to different types of concrete feeding hoppers. The cylindrical bottom of the valve housing is constructed like an articulated reversible cover, the sealing of which is guaranteed by an elastic gasket. Owing to its particular shape, the cover has high rigidity. Its articulation point may be on any side, but it will preferably be a hinge on the most accessible side; the hinges and the closing hook are adjustable, so as to make up in the long run for the permanent deformations of the gasket. It is moreover possible to operate the bottom cover with a hydraulically controlled kinematic motion.
The wall of the tank, on the side of the pumping cylinders, is provided with four ribbed ears.The tank can be rotated around these ears (according to vertical axes), thereby facilitating the access to the various members of the pump for making inspections. The tilting of the tank and overlying hopper may be operated manually or by hydraulic means.
The "S" valve is constructed in one piece, as a bent pipe of circular section and varying thickness; it bears on two end supports in correspondence of the tank headwalls. The axial stresses being imparted on the valve, due to the pumping action, are born by a pair of bearings housed into the external support. To the same is anchored a flange of connection to the delivery pipe; the connection with the delivery pipe is carried out through a lever joint, this pipe being also bent and forming an angle of 180⁰ in the case of apparatuses mounted on lorries, or a right angle in the case of apparatuses mounted on a dolly or on a fixed base.
The section line of the material vein is formed by two opposed planes: one belonging to the ring keyed onto the valve mouth, the other to an eye-shaped wear plate forming part of the tank.
The wear produced during movement of the valve - due to the material (granules of different shape and nature) interposing between the two sliding surfaces, which has a high abrasive power - is never uniform, since the various points of the ring which move in respect of the plate do not cover the same spaces.
In order to keep the phenomenon of abrasion within acceptable levels, the wear ring is designed to have a particular shape, that is, a rake of ≥ 30" with scraping function, as well as possessing special wear-resisting requirements. The eye-shaped plate is placed in contact with the flat wall, on the side of the pumping cylinders, its fixing screws are embedded and far from the wear area, and it is made in such a way as to allow both planes to be used as counter- faces to the ring.
Since the efficiency of the pump depends on the wear clearance between the two division planes of the material vein (reasons for fluid escapes), such clearance will have to be taken up when it becomes so wide that it can no longer be tolerated. This operation can be carried out in two different ways, that is, either by causing the ring to slide on the valve towards the plate, by means of two setscrews housed in said plate, or by causing the plate to advance towards the ring by means of the adjusting screws provided for the purpose. The easiest way will be chosen according to the case.
A space is provided between the lower edge of the "S" valve and the bottom cover, in accordance with the invention, said space being dimensioned according to the largest granulometry of the material to be pumped, and housing a rib fixedly connected to the valve itself and acting as support for blades scraping the bottom. In fact, the material interposing in this space cannot stagnate, due to the self-cleaning action operated by the blades. Such blades are made so as to have a rake of ≥ 30° and they are fixed to the rib of the valve in such a way as to allow taking up the wear clearance. Since in this function the counterface is constituted by the bottom cover, this latter is provided to be lined with a wear plate fixed with screws. In this way the cover will no longer undergo wear. The valve is operated by two opposed hydraulic cylinders which are coupled on one side with a crank and on the other side with ears obtained directly on the tank.
Further characteristics and details of the invention will result from the detailed description given hereinafter of a preferred embodiment of the improved pumping device, with reference to the accompanying drawings in which:

Fig. 1 is a vertical section view of the pumping device according to the invention, in a version apt to be mounted on lorries, showing the end of the pumping cylinders, the tank conveying the material, the S-shaped valve with the relative supports and wear parts, the delivery pipe and the charging hopper;
Fig. 2 is a view of the same device, taken from the side of the delivery pipe and showing the tank with the hingeing and fixing ears, the bottom cover with the closing hand lever and the adjusting tie rod, the external support with pipe connection flange and the hopper (section lining);
Fig. 3 is a plan view of the device showing the flange edge of the hopper, the external support of the valve with flange of connection to the delivery pipe, the delivery pipe bent at 180⁰ for pumps mounted on lorries and (in section lining) the end of the base frame;
Fig. 4 is a vertical section view of the device with the eye--shaped plate and the wear ring, the valve control handle and the operating cylinders;
Fig. 5 shows a detail of the wear ring with the clearance adjusting screws and the eye-shaped plate;
Fig. 6 shows further details of the eye-shaped wear plate with the fixing screws and the clearance adjusting screw;
Fig. 7 is a section view, on an enlarged scale, showing a detail of the tank bottom with the scraping blades, the inserted wear plate and the bottom cover; and
Fig. 8 is a longitudinal view showing the pumping device of the preceding figures, mounted on a lorry.

With reference to figures 1 to 4, the device consists of two pumping cylinders 1 with push-pull operating pistons 2. Thus, for instance, while one of the two pistons sucks the material from the hopper 3, the other piston pumps the material into the delivery pipe 4 through the valve 5, which is in the appropriate position.
The suction mouth 6 of the cylinders communicates with an open area inside the tank 7, such as not to limit the flow of the material being sucked. When the material flows through, no resistance should be opposed, as this would have a negative effect on the volumetric efficiency of the pump. The position of the suction mouth, which is just below the bottom of the hopper, favours the suction process, increasing the filling level of the cylinders.
The tank 7, into which flows the material from the hopper 3 and which houses the valve 5, is formed by two flat, parallel headwalls 8 and by two partially inclined sidewalls 9, which form a rest surface for the cylindrical bottom cover 10.
Into the wall 8, on the side of the cylinders, are obtained the cylinder ends 11 in the form of telescopes connected, through joints, with the cylinder liners. The device comprises moreover appropriately ribbed ears 12, around which the whole assembly can be rotated, thereby creating a passageway for operations of maintenance.
Into the wall 8, on the side of the cylinders, is also obtained the valve support 13, through which is operated the "S" valve. On the inside of the wall and parallel thereto bears the eye-shaped wear plate 14, which is fixed by screws and nuts 15-16 and positioned with adjusting screws 17. Said wear plate will preferably have, in correspondence of its fixing holes, recesses on both its surfaces, so that it can be mounted first with one surface and then, after wear of this latter, with the other surface, after rotation by 180°.
The recesses for the fixing screws are far from the areas subjected to wear, so as not to create any areas of absorption of abrasive bodies.
On the flat wall 8, opposite to that described, is mounted the external valve support 18 on the side of the delivery pipe. Said support houses the ball (or roller) bearings 19, apt to bear the axial stresses deriving from the pumping pressure and the radial stresses deriving from the "S" shape of the valve. On this same support is anchored the flange 20 of connection to the delivery pipe 4; all this is connected to the tank 7 by means of screws 21-22. The support 18 also houses two wear bushings 23-24 and two sealing rings 25 which slide on said bushings, thereby preventing the outlet of fluid from the tank and from the delivery pipe. The purpose of said bushings is to fully preserve the valve from normal wear which may occur in the long run between the reciprocating parts, considering that the valve 5 - in the context of the apparatus - is a relatively costly element.
With reference to figure 1, the deviating valve 5 is formed by a circular tube with an evenly decreasing diameter - from the side of the cylinders towards the side of the delivery pipe - and with a suitable "S" shape so that, by alternatively oscillating about the axis Y, it connects the delivery pipe 4 with the pumping cylinders 1 through the telescopic ends 11.
It should be noted that the axis of the mouth of the valve 5, which extends towards the telescopic ends 11 of the cylinders, is positioned higher than the axis of the mouth which extends towards the delivery pipe 4. Thus arranged, the "S" valve finds itself in optimal conditions for the cleaning operations, since the risks of material stagnation - present in the known solutions - are thereby eliminated. On the side of the delivery pipe, the actual valve body acts as rotation pin, while on the side of the cylinders the rotation pin 26 is inserted in the valve body and fixedly connected thereto by known methods. On said pin 26 is rigidly keyed a crank 27, onto which hinge the ends of the actuating cylinders 28.
Generally, the support 13 will house a sealing element and a bearing for rotation, as in the case of the support 18. A wear ring 29 is keyed on the valve mouth, on the side of the cylinders, the surface of said ring sliding onto the face of the eye-shaped plate 14; such ring protects the valve body and will preferably be made of a particularly abrasion-proof material, it being possible to improve this characteristic by an appropriate previous heat-treatment. As shown in figure 5, the outer shape of said ring will have a rake of ≥ 30°, so as to obtain an improved scraping action in respect of the plate and consequently a self-cleaning effect.
The wear clearance can be compensated in two ways, as can be argued from figures 5 and 6: that is, either by moving the ring 29 towards the plate 14 - by acting on the screws 30 contained in the two ears 31 obtained on the valve body - or by moving the plate 14 towards the ring 29 - by acting on the adjusting screws 17 and on the corresponding fixing screws 15-16.
For each case one can choose the most appropriate way to carry out said operation. The replacement of the wear parts - in the event that groovings should appear on the opposed faces, such as to disturb the pumping efficiency - is operated by drawing out from the top, first the plate 14 and subsequently the ring 29.
Figure 7 shows a vertical section of the tank and of the valve, close to the external support 18, in which can be noted the structural detail of the valve and of the bottom cover. According to the drawing, the valve has a stout and strongly projecting rib 32, acting as support for the scraping blades 33 which are apt to slide onto the bottom cover 10; the geometrical shape is designed with a rake of ≥ 30°, to obtain an improved scraping and self-cleaning action. The bottom cover joins with the tank in correspondence of the flat edge, which is provided to house a seal 36; the anchorage can be obtained through the pins 37 and by a rotation on all the sides. It is anyhow advisable to perform the rotation about an axis parallel to the "Y" axis of the pump, providing also to obtain an adjustable closing through the threaded eye hinges 48 and a locking hook 38, so as to guarantee not only a proper pressure on the seal, but also the recovery of permanent deformations of said seal. An example of adjustable locking hook 38 is shown in figure 2. Different solutions can however be adopted, for instance by using a hydraulic cylinder, apt to keep the cover in a closing position, and others still.
Onto the bottom there is also a wear plate 35, which is anchored to the cover 10 by means of oval-headed socket screws and self-locking nuts 39-40. Also this plate, like the heretofore described wear parts, can be easily replaced without the basic structure suffering from any damages due to wear.
The slack between the blades 33 and the plate 35 can be taken up by moving the blades towards the plate, thanks to the slots provided in the anchorage rib 32 in correspondence of the securing through screws 34.
The operation of adjustment or of replacement of the above elements can easily be carried out with open cover. The wear elements 33 and 35 have high wear-resisting characteristics.
A rim 41 is obtained on the upper part of the tank 7, said rim having a rectilinear shape in correspondence of the walls 8 and a concave curved shape on the sides 9. Said concave shape is designed to coincide with the convex shape of the bottom of the hopper 3, shown in figure 1, into which rotates a shaft with blades, or screw, having the function of mixing the material and sending it towards the tank 7. A set of holes 42 is furthermore provided to obtain the connection between the tank and the hopper. The hopper 3, visible in figures 1 and 2, represents a solution which has been found to be the best, especially for pumps mounted on lorries.
Other solutions can be provided, in the case of pumps mounted on a stationary base or on a dolly.
A further detail concerning the tank 7 is the bracket 43 (figure 4) for anchoring the cylinder 28 which operates the valve; it is advisable for this bracket to be obtained in one piece (by casting) with the tank into which should preferably discharge the stresses due to the thrust of the cylinders. Also different solutions are however possible.
Figure 8 shows, in accordance with the invention, a side view of the pumping device, mounted on a chassis. The bulk determined by the differential gear 44 has been placed in evidence, said bulk being common to all the types and makes of current lorries, which are mostly preferred for the combination in question.
The "X" axis of the pumping cylinders is inclined, in respect of the horizontal line, by an angle of β ≤ 8°; the "Y" axis is the rotation centre of the valve and of the delivery pipe, and is positioned beneath the "X" axis; the "Z" axis, tangent to the wheel of the lorry 46 and passing through the lowest point of the pump, determines with the ground level a profile angle of α ≥ 12°; the dimension "A" results ≤ 1350, and the dimension "B" results ≤ 2500. Such characteristics can be found only partially in the already known solutions, since generally a limited height of the hopper edge from the ground (A) is achieved to the detriment of the inclination of the pumping cylinders, which is far greater than that proposed herein, or else, a limited inclination of the cylinders matches with an exceeding height of the hopper. The proposed solution attains an optimization of the parameters connected with the mounting of the pump on a chassis, just on account of the particular geometrical configuration, such as described so far. In general, for pumps coupled with a dolly or with a stationary base, the "X" axis of the cylinders will be parallel to the "Y" axis and always above this latter. Also the delivery pipe 4, which in the embodiment of figures 3 and 8 is bent by 180° and has a uniformly decreasing diameter, will be preferably straight so as to be connected to a stationary network. Figure 8 also illustrates the articulation point ₄₅ between the structure of the pump 7 and the base frame.

Claims

1) Pumping device for pasty materials, particularly concrete, of the type comprising two cylinders which, by way of an S-shaped valve, are connected alternatively to a delivery pipe and to a hopper placed above said valve, characterized in that the housing or tank(7) of the valve is formed by two flat parallel headwalls (8), one of which holds a first support (13) for the control shaft of the S-shaped valve (5), telescopic cylinder ends (11) connecting said valve with the pumping cylinders (1), and ribs ending into four ears (12) which make it possible to rotate the tank about vertical axes, while the other wall holds a second valve support (18) and a flange (20) of connection to the delivery pipe (4); by two partially inclined sidewalls (9) which are radiused to the bottom; and by a bottom cover formed by a cylindrical wall, the axis of which coincides with the valve rotation axis; and in that the axis of the pumping cylinders is positioned higher than the valve rotation axis and the delivery pipe.

2) Pumping device as in claim 1, wherein charging hoppers of different shapes and capacities can be applied on the upper rim (41) of the tank.

3) Pumping device as in claim 2, wherein the tank is connected to the pumping cylinders by means of telescopic cylinder ends (11) obtained in one piece with the tank and bent in the direction of the axis of said cylinders, and to the valve by means of an eye-shaped wear plate (14).

4) Pumping device as in claims 1 to 3, wherein a first support (13) for the valve, and an upper rim (41) having two flat sides and two bent sides for receiving a hopper, are obtained in the tank of the device itself.

5) Pumping device as in claims 1 to 4, wherein a wear ring (29), having a rake of ≥ 30⁰ so as to obtain an improved scraping effect, and wear bushings (23) and (24) onto which slide sealing rings (25), are inserted frontally on the valve (5).

6) Pumping device as in claims 1 and 5, wherein the wear clearance between the eye-shaped plate (14) and the ring (29) can be taken up by acting either internally on the valve adjusting screws (30), or externally on the tank screws (16) and (17).

7) Pumping device as in claim 6, wherein the wear plate (14) can be used on both its faces, by simply turning it over in respect of the tank.

8) Pumping device as in claims 1 to 7, wherein the bottom cover is hinged to the tank and is tightly closed by means of a reversible hook. with the interposition of sealing gaskets.

9) Pumping device as in claims 1 to 8, wherein the valve (5) is obtained by casting with a rib (32) apt to support blades scraping the bottom cover (10) in order to prevent material stagnation within the space lying between the valve and the bottom.

10) Pumping device as in claims 1 to 8, wherein a wear plate (35) is fixed, by means of socket screws, inside the bottom cover (10), with said wear plate engaging said scraping blades (33) fixed to the valve (5).

11) Pumping device as in claims 1 to 10, wherein the wear clearance between said scraping blades (33) and said wear plates (35) is taken up by acting on screws (34) securing the scraping blades (33), which screws can be shifted along the rib (32) due to the presence of slots.

12) Pumping device as in claims 1 to 11, wherein the closing of the cover (10) can be adjusted to guarantee the fluid seal even after deformation of the interposed gasket (36).

13) Device as in claims 1 to 12, wherein the telescopic cylinder ends (11) connecting the pumping cylinders are positioned in the top part of the valve tank.

14) Pumping device as in claims 1 to 13, wherein the axis of the pumping cylinders (1) has an inclination of ≤ 8°.