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Piston pump for thick materials

Piston pump for thick materials description/claims

The present invention regards a pump for thick materials with features according to the non characterizing part of patent claim 1. In a broader sense it also regards the controls of such thick materials pumps.

Thick materials piston pumps have been used for a long time in particular at construction sites to feed concrete. Usually they are provided as hydraulically operated piston pumps, mostly with two cylinders, feeding concrete through hoses or pipes. Subsequently, in a simplified manner, concrete feeding is being referred to. The invention is not limited to an application with concrete feeding pumps but can be used for all similar thick materials pumps.

Such pumps have to fill a single feed line with two alternatively filled cylinders and associated pistons. The respectively filled cylinder is being connected with the feed line via a moveable pipe switch. Subsequently the piston pushes out the concrete (pump stroke), while the parallel piston is being retracted, in order to fill the cylinder with concrete again (suction stroke). At the end of each stroke the moving direction of the cylinder pistons is reversed and the pipe switch is shifted, so that pump strokes and suction strokes alternate continuously. The two pump pistons are preferably driven hydraulically coupled amongst each other, so that they basically work in a counteracting manner.

Common pipe switches (DE 29 33 128 C2) are arranged, so that they can be switched back and forth between two end positions, wherein they alternatively establish the connection between the cylinder openings and the feed line on the one hand, and the pre filling container on the other hand. From this results a discontinuous feeding.

U.S. Pat. No. 3,663,129 describe a concrete pump with continuous feeding, wherein the shift valve or its pipe switch consists of a so called sleeve slide. Its waist opening is continuously but pivotally connected with the mouth of the feed pipe as a downstream outlet. Its kidney shaped inseam opening (inlet, upstream) is long enough to cover the openings of both pump cylinders simultaneously. During the operation the pipe switch performs a continuously oscillating pivoting motion, whose axis is coaxial with the mouth of the feed pipe. The pivoting angle of the pipe switch is approximately 50° towards both sides from the middle.

The pistons of the pump cylinders are controlled depending on the momentary position of the pipe switch, so that in the moment when both cylinder openings are covered by the sleeve opening, one cylinder is at the end, and the other cylinder is at the beginning of a pump stroke. Thereby the feeding action continuously shifts from one cylinder to the other. In the state of the art control system for the suction stroke and for the pump stroke of each cylinder the same time span is used. Therefore there is no simultaneous feeding of both cylinders.

Due to the one sided bearing of the state of the art pipe switch on the side of the feed pipe and due to the enveloping support and sealing surfaces only surrounding the sleeve opening, the substantial tilting moments of the state of the art design can not be completely received. It can not be excluded, that due to gap formation substantial leaking losses occur in the seal area between the sleeve opening of the pipe switch and the feeding cylinders, which in turn denies the realization of a really continuous feed action.

The British Patent 1,063,020, as a gender defining state of the art describes a multi cylinder thick materials and concrete pump, whose shift valve in one embodiment comprises two rotating slides, (also formed as sleeve valves), each controlled by a lifting cylinder of their own. Their outlet ports are connected with a common Y-tube, which in turn is connected to the feed line downstream. Each rotating slide can either work together with a single, or with two pump cylinders. Though synchronous control of the rotating slides is mentioned, however with this state of the art pump and control system continuous feeding of the feeding cylinder into the common feed line is neither intended nor possible.

DE 30 06 542 C2 describes a guillotine flat valve for two cylinder thick materials pumps. It comprises a guillotine flap solidly connected with a control rod, which can be alternately moved back and forth between two end positions in a guide housing or -frame. This state of the art 2/2 way guillotine valve can also be installed between the flanges of a Y-tube and an intake or exhaust tube. In concrete pumps it is preferably installed between the bottom of a prefilling container and the exhaust pipes of a two-cylinder piston pump and/or the feed line and the exhaust pipes.

Furthermore it is also state of the art, to provide thick materials pumps of the kind that is being discussed here, with an insertion station, through which a cleaning body for removing unused thick materials, which have remained in the feed line, can be inserted. This insertion station comprises e.g. a chamber slide, moveable by a motor or hydraulically, with at least two chambers of equal cross section. In the resting position of the insertion station the one chamber forms a section of the feed line, while the other chamber is freely accessible. Into the latter the said cleaning body can be manually inserted from the outside. For a cleaning procedure, with the thick materials pump shut down, the insertion station is shifted into a working position, wherein the chamber containing the cleaning body replaces the other chamber within the feed line. Then the cleaning body can be pressed through the feed line with compressed air, whereby it pushes the thick material ahead of itself. These state of the art insertion stations, however have to be provided in addition to the shift valve discussed above.

The objective of the invention is to provide an improved thick materials pump and a process for controlling a thick materials pump with continuous feeding.

This objective is accomplished according to the invention with the features of patent claim one, with respect to the control process with the features of the independent claim 19.

The features of the dependent claims associated with the independent claims provide advantageous improvements of the invention.

While with the pumps according to the above explained U.S. and GB patents the control slides are mostly located at the thick materials container in an exposed manner, through providing the shift valve with two translatorically movable, in particular linear guided control slides, an embodiment, less exposed to the thick material especially to the concrete, can be created for the preferred application. On the one hand this is valid for abrasive uses, but also for loading through dynamic pressure in the feed line or in the feeding cylinders. In the area of the control slides the thick material is, different from the known sleeve slides, not redirected under pressure, but substantially run through the tubing sections in a straight manner. Only in the collector tube (also Y-tube) the concrete flows from the feeding cylinders are merged. This substantially contributes to the pressure relief of the slides themselves and does not only reduce the loads on the bearings, but also reduces the frictional forces when switching the control slides. Consequently this engineering solution noticeably reduces mechanical wear of the moveable and non moveable parts of the shift valve.

It should be noted that, though a two cylinder thick materials pump is discussed here in an a preferred embodiment, the design according to the invention can also be transposed to pumps with three or more cylinders, wherein a control slide would have to be associated with each feeding cylinder.

It is not absolutely necessary to guide the control slides in an exactly linear manner, but according to the invention a slight arc can be provided, whereby the major part of the motion remains translatoric.

Though it is conceivable to support the parallel control slides directly at the surfaces facing each other, preferably however the guidance structure for each control slide will have a dedicated slide rail allowing larger offsets of the control slides during their operational cycles.

For providing the shift valve (guidance structure and control slide) with sliding guides with friction and abrasion resistant materials and possibly with wear parts known means can be applied, so this does not need to be discussed in detail. The same applies for the seals between the control slides and the openings of the feeding cylinders and the collector tube.

According to the invention it is advantageous, when the control slides can occupy three different positions, a transfer position, a blocking position and an inlet position. To these three positions corresponds a design or a subdivision of the control slides into three different sections, this means a transfer section, a blocking section and an inlet section. The names of the sections or positions are self explanatory and will be discussed in connection with the description of the attached figures.

It is advantageously possible to provide/prefabricate the above mentioned sections as single modules and assemble them in the required order. Overall a control box or a control cage with the necessary valve travel or functions is created. This design can favor the simple replacement of single, prematurely worn or damaged sections, in particular when connections are provided amongst them, that can be disassembled.

It is understood that the two control slides are advantageously provided identical amongst each other; variations can result from space constraints, when attaching the respective drive systems.

A substantial advantage of the solution according to the invention is the simply applicable option to use at least one, possibly both control slides of the shift valve also as insertion station(s) for the cleaning bodies. The short tubing sections of the control slides and the feed line have to be cleaned during operation shut down of the pump, this means residual thick material or concrete leftovers have to be removed.

For this purpose the invention provides access to the control slides. This can be provided e.g. through flaps, which are normally closed, but provide access to the control slides after opening.

• Provisional Patent
• Utility Patent

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