Pumps – Motor driven – Fluid motor
Reexamination Certificate
2002-10-01
2004-09-21
Yu, Justine R. (Department: 3746)
Pumps
Motor driven
Fluid motor
C417S900000, C417S516000
Reexamination Certificate
active
06793467
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thick matter pump comprising at least two pump units alternating in the pump and suction mode, a delivery line, a suction line, and a switching valve for switching between the pump units, one pump unit being connected in the pump mode by the switching valve to the delivery line, and one pump unit being connected in the suction mode to the suction line.
Thick matter pumps are used in very many cases for conveying concrete, but materials of a similar type can also be conveyed by such pump units. Known are, in particular, pump arrangements in which the pump units are formed by cylinder/piston pumps which are alternately connected via a pipe slide to a delivery line or to a suction line. There are arrangements in which the pipe slide is arranged within a supply container and in the suction mode the cylinder/piston pump directly sucks the thick matter from the supply container. The supply container is upwardly open in most cases, so that thick matter can be refilled.
In other pump constructions, a suction line terminates at the lower end of a supply container, the thick matter being discharged through the suction line. A conveying unit, e.g. a screw, can also be arranged thereby in the supply container for ensuring a better filling degree. The other end of the suction line section leading away from the supply container is followed by a pipe slide housing, which ensures a suitable switching between the pump units and a connection of the pump unit either to the delivery line or to the suction line.
With all of these different pump constructions, attempts are made to produce a pump flow which is as continuous as possible, despite the switching operation of the pipe slide.
In a generic construction which is disclosed in DE 197 35 091 A1, a well-known activation method for the pump units is resorted to and used with a pipe slide device arranged outside of the supply container. In this known method the cylinder/piston pump operates faster in the suction mode than in the pump mode, whereby the suction operation of the one pump unit is already completed while the pump operation of the other pump unit still continues. Subsequently, the thick matter fillings which are in contact with the first pump unit are separated from the supply container by means of slide elements, which are also known. The thick matter is subsequently precompressed by means of the delivery piston of the first pump unit until a desired pressure is built up. Meanwhile the second pump unit is still in the pump mode. It is only after the application of the preloading pressure that the pipe slide switches over. The one end of the pipe slide is in permanent contact with the suction line section leading away from the supply container, whereas the delivery line is in permanent communication with the cavity of the pipe slide housing. The preloaded thick matter comes now in contact with the pressurized thick matter in the pipe slide housing. This operation does not lead to any vibrations in the delivery column because the preload is preferably at the pressure level in the delivery line and the thick matter column does therefore not slump in the delivery line. As soon as the second pump unit has completed its pumping operation, the first pump unit takes over the pumping operation. Subsequently, the second pump unit is connected to the supply container by means of the pipe slide and by opening the slide. The cycle starts again with exchanged pump units.
Constructions in which the pipe slide is in permanent communication with the delivery line and the suction line section leads to the pipe slide housing can also be operated with such a method on condition that corresponding slides are used. See, for instance, the construction in DE 196 41 771 A1.
Said constructions, however, have the drawback that part of the delivery volume of the pump units is wasted because of this preloading operation. That is why the pump units must have a larger size than would be necessary.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to provide a thick matter pump of the above-mentioned type which allows an improved design of the pump units.
To this end a pressure boosting device which is independently operative of the pump units is provided according to the invention in the area of the suction line for actively effecting a thick matter precompression.
This means that, either independently of the pump unit or in support thereof, there is provided a separate device which from the direction of the suction line effects a pressing of the thick matter for providing a precompression. When a cylinder/piston pump is used, the necessary path for a precompression is reduced thereby, or a path is no longer needed at all when the pressure boosting device entirely takes over the precompressing operation. Thus, the pump units need no longer convey the very volume required for precompression. This reduces the size of the pump units. Moreover, this yields a further positive effect. Thanks to the active pressing of the thick matter by the pressure boosting device, the pump unit and suction line, respectively, are filled in an improved way. So far the cross-sections of the openings of cylinder/piston pumps have required a specific size, for instance for concrete, so that a high filling of the cylinder could be achieved by the action of negative pressure. The size of this opening can now be reduced due to the continuous supply of the thick matter by the pressure boosting device. This, however, has also the effect that the pump units can be arranged closer to each other and the switching times can thereby be reduced considerably, e.g. by using a pipe slide. The elements which follow the openings, for instance pipe slides, etc., can also be reduced in size, which is of great advantage in particular with respect to the forces acting within the system due to the thick matter pressure. Thick matter which is difficult to suck can also be pumped with the help of a pressure boosting device without any problems. Moreover, the pump unit can be operated in the suction mode at a faster pace because the losses in the sucking action can be compensated by the pressure boosting device. A separate pressure boosting device is excellently suited for a later modification of existing thick matter pumps. When existing pump units are kept and when the separately acting pressure boosting device is now used in addition in accordance with the invention, the pumping efficiency can be improved by up to 20% due to the better filling of the pump unit in the suction mode.
In an advantageous embodiment, the suction line comprises an elastically deformable section and the pressure boosting device comprises squeezing elements by which the elastically deformable section of the suction line can be compressed for increasing the pressure. Advantageously, such a deformable section can be connected to a supply container. Suitable squeezing elements will then ensure a closing of the elastically deformable section with subsequent pressure build-up. Due to the relatively low compressibility of the thick matter, air inclusions must mainly be overcome. The deformable section is therefore deformed to such a degree that the desired pressure build-up is achieved in the suction line. This could also be carried out with the help of a plurality of squeezing elements. Moreover, a squeezing element may be designed with respect to its shape such that said function takes place in one operation.
Moreover, it is also possible that rotatably supported squeezing elements first compress the deformable section and thus close the suction line and are then moved towards the pump unit. This process reminds of the delivery of media by means of a hose pump. That is why according to one variant it is additionally of advantage when the elastically deformable section of the suction line is a hose piece. Hose pieces that withstand correspondingly high pressures are very well known in the prior art.
Hose pumps are already used in part for conveying co
Hudelmaier Jorg
Lin Han L
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