EP0561262B1 - Pump for viscous materials having cylinders, in particular two cylinder concrete pump - Google Patents

Abstract

The invention relates to a pump for viscous materials having cylinders, especially to a two-cylinder concrete pump having a viscous-material flow control between a feed hopper, the two cylinders and a delivery line, a linkage circuit which controls the drives of the cylinders and the viscous-material flow control, a control valve and an equalising cylinder which during switch-over of the control valve precludes breaks in the flow of the viscous material. According to the invention it is provided that the linkage circuit causes the drive of the cylinder which is delivering at any given time to increase delivery by the measure of the amount of viscous material received by the equalising cylinder, and delays switch-over of the control valve in such a way that one of the valve plates, which are assigned to each cylinder at both ends of the inlet orifice of the control valve and whose size is matched to an area between the cylinder ports in such a way that in the switching centre position of the control valve the cylinder port is sealed by the valve plates and the inlet orifice in the control valve is sealed on the face between the cylinders, in order to carry out a part stroke of the cylinder piston, which part stroke compresses the viscous material drawn in, closes the port of the delivering cylinder. <IMAGE>

Description

The invention relates to a thick matter pump with delivery cylinders, in particular a two-cylinder concrete pump according to the preamble of claim 1.

The basic mode of operation of known thick matter pumps, particularly those used for concrete delivery, in two-cylinder piston pumps is that the two delivery pistons in the delivery cylinders are usually driven by hydraulic cylinders in such a way that during the one delivery the other sucks in. The piston play changes in the stroke end positions. The movement of the pistons is synchronized, i. that is, if the hydraulic cylinder driving the feed cylinder, e.g. B. is applied to the piston side with hydraulic oil, the piston rod-side displaced oil is passed via a bridge line to the piston rod side of the suction feed cylinder, so that this travels its suction stroke at the same speed as the advancing cylinder because of the identical area ratios of the two drive cylinders. As a result, both pistons reach their end positions simultaneously in the feed cylinders.

Since the delivery cylinders are each connected to the delivery line during the delivery stroke or to the filling funnel containing the thick matter during the suction stroke, a logic circuit is required which controls the concrete flow between the strokes after reaching the end of the stroke and the connection of the delivery cylinders with the delivery line or with the Inlet funnel reverses.

It is characteristic of these and other thick matter pumps that the delivery of the delivery cylinders comes to a standstill between the delivery strokes, namely for the duration of the switching of the control member. As a result, the thick matter feed is interrupted. In the known thick matter pump, the duration of the interruption in accordance with the degree of filling, which is dependent on the air content, the flow resistance of the concrete, the suction speed and the cylinder diameters, is further increased by the time that the feed cylinder requires at the beginning of the delivery stroke by to compact the thick matter.

In addition, there is another unpleasant phenomenon, namely the backflow of the thick material from the delivery line into the pump cylinder during the switchover phase of the concrete slide valve.

The interruptions in the flow of funding have an overall adverse effect. In fact, there is a pulsating delivery, which causes vibrations. These have a particularly disadvantageous effect if the thick matter pump is installed on a vehicle and the delivery line is attached to a bendable placing boom. Because this results in an oscillatory system that shows signs of resonance at the usual piston stroke frequencies.

This leads to the requirement to create a pump with which a continuous flow can be achieved.

According to a prior art (A), efforts have already been made to shorten or even eliminate the interruptions in the thick matter conveyance between the conveying strokes of the conveying cylinders.

In such a previously known proposal (US Pat. No. 3,663,129) a compensating cylinder is provided for this purpose, which presses thick matter into the delivery line during the switching over of a swivel tube designed as a uniform hollow body and during the subsequent delivery stroke one of the two delivery cylinders with thick matter from the delivery line is filled. This is done in that the mouth of the compensating cylinder with the hollow body serving to control the concrete flow is controlled in the same way as the openings of the delivery cylinders. The logic circuit works with limit switches which are actuated by the delivery cylinder pistons and initiate the suction or delivery stroke of the compensating cylinder.

Such a two-cylinder concrete pump does not achieve the goal of a more uniform concrete delivery through the delivery line. This is because the lack of compression of the concrete sucked in at such a pump at the beginning of each piston stroke leads to a standstill of the concrete flow.

According to another prior art (B), namely DE-OS 29 09 964, it is known to accomplish the concrete flow control with a pipe switch, which is realized with two S-shaped curved pipes. These tubes are pivoted in the hopper and curved in an S-shape. Each tube is in constant contact with its openings with a delivery line connection located on one side of the hopper, while the other opening serves as an inlet opening and is alternately aligned with the opening of the delivery cylinder assigned to it on the opposite side of the hopper or releases it, so that the delivery cylinder opening is opened in the hopper and the cylinder is able to suck in the thick matter.

The necessity to provide several swivel tubes for the control of the thick matter flow results from the fact that the interruptions in conveyance are not compensated by the conveying stroke of a compensating cylinder, but rather by the fact that the combination circuit controls the cylinders in such a way that during the period of the effective conveying stroke shortened by the degree of filling, one Delivery cylinder; the other feed cylinder sucks in the thick matter at a significantly higher speed over a full stroke, the swivel tube slide assigned to this cylinder closes the opening of this feed cylinder with its slide plate in a first switching step, this feed cylinder then also executes a partial stroke corresponding to the filling error volume at an increased speed while doing so sucked thick material compacted, and that the associated swivel tube slide in a second switching step in its end position, d. H. the feed cylinder with its precompressed thick matter content is in a pump-ready position.

In the aforementioned prior art, not only is the considerably higher speed for suction and compression stroke disadvantageous as a result of a longer total switching time because of multiple switching paths, but also because of the two necessary swivel tube slides, a considerably higher technical outlay is required.

Finally, from the prior art (C), the US-A-3 963 385, a thick matter pump with delivery cylinders, in particular a two-cylinder concrete pump with a thick matter flow control between a feed hopper, the delivery cylinders and a delivery line, as well as one of the drives of the delivery cylinders and the thick matter flow controlling logic circuit, known, in which the thick matter flow runs through a control slide, which is permanently connected with its outlet opening to the delivery line and is provided with at least one inlet opening, which is alternately in front of the openings of the feed cylinder, a compensating cylinder excluding thick material interruptions during switching of the control slide and the logic circuit is designed such that the compensating cylinder presses thick material into the delivery line during the switching of the control slide and during the subsequent delivery cycle one of the delivery cylinders with thick material is filled, and in which on each side of the inlet opening of the control slide associated slide plates are adjusted in size to an area between the feed cylinder openings such that in the switching center position of the control slide, the openings of the feed cylinders from the slide plates and the inlet openings in the control slide on the surface between the delivery cylinders are sealed.

This solution has the disadvantage that when the opening of the feed cylinder that has sucked in the thick matter is released, the thick matter flow in the feed line is interrupted because the feed piston must first compress the thick matter in the feed cylinder before the thick matter flow can start in the feed line.

The object of the invention is therefore to easily realize a thick matter pump with a continuous and pulsation-free flow.

In order to obtain funding without the disadvantages of the prior art, the invention is based on a new way of looking at the previously known two-cylinder high-density pumps, which is illustrated by the example of a known pump II Art is explained below, which has neither a pre-compression nor a compensating cylinder. With such a thick matter pump, the time for the effective delivery stroke (pump stroke) is determined by the actually required concrete delivery quantity and by the volumetric efficiency η.

Darin bedeuten:

t_Fo =

Zeit für den effektiven Pumphub in (sec.) bei 100 % Saugfüllung

V_o =

gesamtes Volumen des Förder(Pump)Zylinders in [dm³]

Q_o =

effektiv geforderte Betonfördermenge in (m³/h).

Bei Berücksichtigung eines volumetrischen Wirkungsgrades η lautet die Gleichung $$\text{t}{\text{}}_{{\text{F}}_{\text{1}}}\text{=}\frac{{\text{V}}_{\text{o}}\text{· η · 3,6}}{{\text{Q}}_{\text{o}}}$$

Übertragen auf den Stand der Technik (B) muß, wenn nach dessen Zielsetzung ein kontinuierlicher Förderfluß erfolgen soll, folgende Zeitäquivalenz gegeben sein: $$\text{t}{\text{}}_{{\text{F}}_{\text{1}}}\text{= t}{\text{}}_{{\text{S}}^{\text{+}}}\text{t}{\text{}}_{{\text{K}}^{\text{+}}}{\text{t}}_{\text{Sch}}$$

Darin bedeuten:

t_S =

Zeit für den Saughub

t_K =

Zeit für den Kompressions(Verdichtungs)hub

t_Sch =

gesamte Zeit für das Schalten der Betonschieber und diverser Hydraulikventile.

Diesen Zeiten zugeordnet sind:

V_o =

das vom Kolben des saugenden Förderzylinders abgefahrene Volumen (entspricht dem vollen Zylindervolumen)

V_K =

das vom komprimierenden Kolben abgefahrene Saugfüllungsfehlvolumen gemäß der Gleichung

$${\text{V}}_{\text{K}}{\text{= V}}_{\text{o}}\text{(1 - η )}$$

Aus den Kolbenlaufzeiten für den Saug- und Kompressionshub und den diesen zugeordneten Zylindervolumina ergeben sich Betonfördermengengrößen Q_S* und Q_K*. Da diese Größen frei wählbar sind, sei für die weitere Ableitung vorausgesetzt $${\text{Q}}_{\text{s}}^{\text{*}}{\text{= Q}}^{\text{*}}{}_{\text{K}}{\text{= Q}}^{\text{*}}$$

Eingesetzt in Gleichung [ 3 ] ergibt sich $$\frac{{\text{V}}_{\text{o}}\text{· η · 3,6}}{{\text{Q}}_{\text{o}}}\text{=}\frac{{\text{V}}_{\text{o}}\text{· 3,6}}{\text{Q*}}\text{+}\frac{{\text{V}}_{\text{o}}\text{· (1-η) · 3,6}}{\text{Q*}}{\text{+ t}}_{\text{Sch}}$$

Da die Laufgeschwindigkeit eines Kolbens in einem Zylinder proportional zur Fördermenge ist, ermittelt sich der Faktor f1, um welchen die Laufgeschwindigkeit der Kolben für Saugen und Komprimieren in einer Pumpe (I) gemäß dem Stand der Technik (B) größer sein muß, als die Laufgeschwindigkeit der Kolben für das Pumpen, als Quotient aus Q^* und Q_o nämlich $$\text{ƒ1 =}\frac{\text{Q*}}{{\text{Q}}_{\text{o}}}\text{=}\frac{\text{2 - η}}{\text{η-}\frac{{\text{t}}_{\text{Sch}}}{\text{t}{\text{}}_{{\text{F}}_{\text{o}}}}}$$

Bei einem praxisüblichen Beispiel ergibt sich unter der Voraussetzung:

Q_o =

120 (m3/h)

V_o =

83,5 (1)

η =

0,85

t_Sch =

0,9 (sec) (für zwei Betonschieber und Hydr. Ventile)

T_Fo =

$$\frac{{\text{V}}_{\text{o}}\text{·3,6}}{{\text{Q}}_{\text{o}}}\text{= 2.505}\left(\text{sec}\right)$$

für f1 ein Wert in Höhe von $$\mathit{\text{f}}\text{1 = 2,342.}$$

According to this, the basic equation applies to η = 100%, i.e. complete cylinder filling by suction, and the pump stroke for the pump stroke $$\text{t}{}_{{\text{F}}_{\text{O}}}\text{=}\frac{{\text{V}}_{\text{O}}}{{\text{Q}}_{\text{O}}}\text{· 3.6}$$

Where:

t _{F O} =

Time for the effective pump stroke in (sec.) With 100% suction filling

V _o =

total volume of the delivery (pump) cylinder in [dm ³ ]

Q _o =

effectively required concrete delivery rate in (m ³ / h).

When considering a volumetric efficiency η, the equation is $$\text{t}{}_{{\text{F}}_{\text{1}}}\text{=}\frac{{\text{V}}_{\text{O}}\text{· Η · 3.6}}{{\text{Q}}_{\text{O}}}$$

Transferred to the state of the art (B), the following time equivalence must be given if a continuous flow of funding is to take place according to its objective: $$\text{t}{}_{{\text{F}}_{\text{1}}}\text{= t}{}_{{\text{S}}^{\text{+}}}\text{t}{}_{{\text{K}}^{\text{+}}}{\text{t}}_{\text{Sch}}$$

Where:

t _S =

Time for the suction stroke

t _K =

Time for the compression (compression) stroke

t _Sch =

total time for switching the concrete slides and various hydraulic valves.

These times are assigned:

V _o =

the volume traversed by the piston of the suction feed cylinder (corresponds to the full cylinder volume)

V _K =

is the suction charge miss volume driven by the compressing piston according to the equation

$${\text{V}}_{\text{K}}{\text{= V}}_{\text{O}}\text{(1 - η)}$$

Concrete delivery quantities Q _S * and Q _K * result from the piston running times for the suction and compression stroke and the cylinder volumes assigned to them. Since these sizes can be freely selected, it is a prerequisite for further derivation $${\text{Q}}_{\text{s}}^{\text{*}}{\text{= Q}}^{\text{*}}{}_{\text{K}}{\text{= Q}}^{\text{*}}$$

Inserted in equation [3] we get $$\frac{{\text{V}}_{\text{O}}\text{· Η · 3.6}}{{\text{Q}}_{\text{O}}}\text{=}\frac{{\text{V}}_{\text{O}}\text{· 3.6}}{\text{Q *}}\text{+}\frac{{\text{V}}_{\text{O}}\text{· (1-η) · 3.6}}{\text{Q *}}{\text{+ t}}_{\text{Sch}}$$

Since the running speed of a piston in a cylinder is proportional to the delivery rate, the factor f 1 is determined by which the running speed of the pistons for suction and compression in a pump (I) according to the prior art (B) must be greater than that Running speed of the pistons for pumping, namely as a quotient of Q ^* and Q _o $$\text{ƒ1 =}\frac{\text{Q *}}{{\text{Q}}_{\text{O}}}\text{=}\frac{\text{2 - η}}{\text{η-}\frac{{\text{t}}_{\text{Sch}}}{\text{t}{}_{{\text{F}}_{\text{O}}}}}$$

In a practical example, the following results under the condition:

Q _o =

120 (m3 / h)

V _o =

83.5 (1)

η =

0.85

t _Sch =

0.9 (sec) (for two concrete slides and hydraulic valves)

T _{F O} =

$$\frac{{\text{V}}_{\text{O}}\text{· 3.6}}{{\text{Q}}_{\text{O}}}\text{= 2,505}\left(\text{sec}\right)$$

for f 1 a value of $$\mathit{\text{f}}\text{1 = 2,342.}$$

However, this factor f 1 determined in this way for a continuous pump (I) according to the prior art (B) is not yet a real comparative variable which proves the advantages of the invention.

Because a comparison is to be made of a generic pump (II) which is still largely customary in practice and in which no measures have been taken for continuous delivery. A pump, in which the piston speed is the same for suction and pumping, and the flow is interrupted while the concrete slide valve is switched.

If you want to achieve an average effective delivery rate Q _o , even if discontinuously, with such a pump (II), a delivery rate Q ** which is greater than Q _o must be provided during the effective delivery stroke.

wobei die Zeit t_Fo für einen vollen Förderhub aus den Zeitintervallen t_K (Zeit für die Verdichtung des gesaugten Betons, also Ausgleich des Saugfüllungs-fehlvolumens) und t_F1 (Zeit für den effektiven Pumphub gem. Gleichung [ 2 ]) besteht, also $$\text{t}{\text{}}_{{\text{F}}_{\text{o}}}{\text{= t}}_{\text{K}}\text{+ t}{\text{}}_{{\text{F}}_{\text{1}}}$$

Der Faktor f2, um den Q** bei vorgenannter Pumpe (II) größer sein muß als Q_o ist somit $${\text{ƒ}}_{\text{2}}\text{=}\frac{{\text{t}}_{\text{ges}}}{\text{t}{\text{}}_{{\text{F}}_{\text{1}}}}\text{=}\frac{\text{1 +}\frac{{\text{t}}_{\text{Sch}}}{\text{t}{\text{}}_{{\text{F}}_{\text{o}}}}}{\text{η}}$$

Da vorgenannte Pumpen (II) in der Regel nur einen Steuerschieber aufweisen, ist die Schaltzeit kürzer als bei einer Pumpe (I) mit mehreren Schiebern.The total time for a pump cycle t _tot results from the time intervals t _Fo (time for a full cylinder stroke) and t _Sch (time for the switching of the concrete slide valve and various hydraulic valves) $${\text{t}}_{\text{total}}\text{= t}{}_{{\text{F}}_{\text{O}}}{\text{+ t}}_{\text{Sch}}$$

where the time t _Fo for a full delivery stroke from the time intervals t _K (time for the compression of the sucked concrete, i.e. compensation of the defective suction filling volume) and t _F1 (time for the effective pumping stroke according to equation [2]) $$\text{t}{}_{{\text{F}}_{\text{O}}}{\text{= t}}_{\text{K}}\text{+ t}{}_{{\text{F}}_{\text{1}}}$$

The factor f 2 by which Q ** in the aforementioned pump (II) must be greater than Q _o is thus $${\text{ƒ}}_{\text{2nd}}\text{=}\frac{{\text{t}}_{\text{total}}}{\text{t}{}_{{\text{F}}_{\text{1}}}}\text{=}\frac{\text{1 +}\frac{{\text{t}}_{\text{Sch}}}{\text{t}{}_{{\text{F}}_{\text{O}}}}}{\text{η}}$$

Since the aforementioned pumps (II) generally have only one control spool, the switching time is shorter than in the case of a pump (I) with several spools.

Der Vergleich von f1 und f2 besagt, daß die max. Kolbenlaufgeschwindigkeit (Saugen/Komprimieren) bei einer kontinuierlich fördernden Pumpe (I) nach dem Stand der Technik (B) gegenüber einer gattungsgemäßen Pumpe (II) um den Faktor f3 nach der Gleichung $${\text{ƒ}}_{\text{3}}\text{=}\frac{{\text{ƒ}}_{\text{1}}}{{\text{ƒ}}_{\text{2}}}$$

relativ erhöht ist. In dem beschriebenen praktischen Beispiel also um den Faktor $${\text{ƒ}}_{\text{3}}\text{=}\frac{\text{2,342}}{\text{1,4113}}\text{= 1,659.}$$

In the aforementioned practical example, the switching time should be set at t _sch = 0.5 (sec), which results in a value of f for $$\mathit{\text{f2}}\text{= 1.4113.}$$

The comparison of f 1 and f 2 means that the max. Piston running speed (suction / compression) in a continuously pump (I) according to the prior art (B) compared to a generic pump (II) by a factor of f 3 according to the equation $${\text{ƒ}}_{\text{3rd}}\text{=}\frac{{\text{ƒ}}_{\text{1}}}{{\text{ƒ}}_{\text{2nd}}}$$

is relatively increased. So in the practical example described by the factor $${\text{ƒ}}_{\text{3rd}}\text{=}\frac{\text{2,342}}{\text{1.4113}}\text{= 1.659.}$$

From the above explanations it can be seen that the running speed of the pistons is substantially / significantly determined solely by the switching time tSch, given otherwise the same requirements with regard to the required delivery rate (Q _o ), delivery cylinder volume (V _o ) and volumetric efficiency (η).

High piston speeds lead to increased wear of the delivery pistons and, due to the higher flow resistance of the suction flow of the thick matter in the delivery cylinders, to an increased vacuum, which reduces the filling level of the delivery cylinders and thus further reduces the volumetric efficiency.

According to the invention, it follows that a conveying stroke of the compensating cylinder directly adjoins the conveying stroke of a conveying cylinder, and the conveying break that has occurred so far is thus avoided in this phase. Furthermore, according to the invention, the delivery stroke of the other delivery cylinder is connected directly to the delivery stroke of the compensating cylinder, so that overall delivery pauses can no longer occur. This also ensures the invention in that the switching of the control slide including the various hydraulic valves and the compression stroke take place during the delivery stroke of the compensating cylinder.

Accordingly, two separate time and volume equivalence considerations are to be carried out for the pump (III) according to the invention, with comparison to the state of the The following design data must be specified for the technology:

The volume (V _A ) of the compensating cylinder is determined by the first time and volume equivalence consideration, which relates to the pumping phase of the compensating cylinder.

bzw. ausgehend von der Forderung, daß die Betonfördermenge des Ausgleichszylinders gleich Q_o sein muß $${\text{t}}_{\text{A}}\text{=}\frac{{\text{V}}_{\text{A}}}{{\text{Q}}_{\text{o}}}\text{· 3,6}$$

Das Volumen V_A des Ausgleichszylinders errechnet sich somit zu $${\text{V}}_{\text{A}}\text{=}\frac{{\text{Q}}_{\text{o}}}{\text{3,6}}{\text{· (t}}_{\text{Sch}}{\text{+ t}}_{\text{K}}\text{)}$$

The duration of the pumping phase of the compensating cylinder (t _A ) is equal to the sum of the switching time (t _Sch ) and the compression time (t _K ) $${\text{t}}_{\text{A}}{\text{= t}}_{\text{Sch}}{\text{+ t}}_{\text{K}}$$

or based on the requirement that the concrete delivery volume of the compensating cylinder must be Q _o $${\text{t}}_{\text{A}}\text{=}\frac{{\text{V}}_{\text{A}}}{{\text{Q}}_{\text{O}}}\text{· 3.6}$$

The volume V _{A of} the compensating cylinder is thus calculated $${\text{V}}_{\text{A}}\text{=}\frac{{\text{Q}}_{\text{O}}}{\text{3.6}}{\text{· (T}}_{\text{Sch}}{\text{+ t}}_{\text{K}}\text{)}$$

The second consideration of time and volume equivalence is intended to determine the running time or running speed of the piston of the delivery cylinder during the pumping stroke.

wobei das dabei effektiv in die Förderleitung abgegebene Volumen verringert ist, nämlich durch die Entnahme des AAusgleichsvolumens V_A während dieser Phase, also $$\text{V}{\text{}}_{{\text{P}}_{\text{eff}}}{\text{= V}}_{\text{o}}{\text{· η - V}}_{\text{A}}$$

The volume (V _P ) driven by the piston of a delivery cylinder during the effective pumping stroke $${\text{V}}_{\text{P}}{\text{= V}}_{\text{O}}\text{· Η}$$

the volume effectively discharged into the delivery line being reduced, namely by removing the _A compensation volume V _A during this phase, ie $$\text{V}{}_{{\text{P}}_{\text{eff}}}{\text{= V}}_{\text{O}}{\text{· Η - V}}_{\text{A}}$$

As explained in the first part of the combination of features according to the invention, the compensation takes place Reduction of the effective delivery volume of the pumping delivery cylinder an acceleration of the effective running speed of the piston in this pumping delivery cylinder, which results in a pump delivery rate Q ***, which is increased and must be such that the delivery rate effectively delivered to the delivery line is equal to Q _o is.

und, verglichen mit Gleichung (2) $$\text{t}{\text{}}_{{\text{F}}_{\text{1}}}\text{=}\frac{{\text{V}}_{\text{o}}\text{· η · 3,6}}{{\text{Q}}_{\text{o}}}$$

ergibt sich, da Zeiten und Geschwindigkeiten und somit Zeiten und Fördermengen umgekehrt proportional sind, ein Faktor f4 zu $${\text{ƒ}}_{\text{4}}\text{=}\frac{\text{t}{\text{}}_{{\text{F}}_{\text{1}}}}{{\text{t}}_{\text{F}}^{\text{***}}}\text{=}\frac{\text{Q***}}{\text{Qo}}\text{=}\frac{\text{1}}{\text{1 -}\frac{{\text{V}}_{\text{A}}}{\text{Vo·η}}}$$

um den die Laufgeschwindigkeit des Kolbens des pumpenden Förderzylinders der Pumpe (III) bei Entnahme von Fördergut aus der Förderleitung durch den Ausgleichzylinder größer ist, als ohne diese Entnahme.This is expressed as follows in a functional equation for determining the time t _F ^*** resulting from the delivery quantity Q ^*** for the effective pump stroke: $${\text{t}}_{\text{F}}\text{*** =}\frac{{\text{V}}_{\text{O}}{\text{· Η - V}}_{\text{A}}}{{\text{Q}}_{\text{O}}}\text{· 3.6}$$

and, compared to equation (2) $$\text{t}{}_{{\text{F}}_{\text{1}}}\text{=}\frac{{\text{V}}_{\text{O}}\text{· Η · 3.6}}{{\text{Q}}_{\text{O}}}$$

since times and speeds and thus times and delivery rates are inversely proportional, a factor f 4 results $${\text{ƒ}}_{\text{4th}}\text{=}\frac{\text{t}{}_{{\text{F}}_{\text{1}}}}{{\text{t}}_{\text{F}}^{\text{***}}}\text{=}\frac{\text{Q ***}}{\text{Qo}}\text{=}\frac{\text{1}}{\text{1 -}\frac{{\text{V}}_{\text{A}}}{\text{Vo · η}}}$$

by which the running speed of the piston of the pumping delivery cylinder of the pump (III) is greater when removing material to be conveyed from the delivery line through the compensating cylinder than without this removal.

Here, too, the dependence of the piston speed, indirectly via V _A , on the switching time t _{Sch is shown} .

also $${\text{t}}_{\text{K}}\text{= 0,25 (sec)}$$

und darausfolgend V_A nach Gleichung (14) zu $${\text{V}}_{\text{A}}{\text{= 25 (dm}}^{\text{3}}\text{)}$$

woraus sich ein Wert für den Faktor f4 ergibt in Höhe von $$\mathit{\text{f}}\text{4 = 1,543.}$$

On the basis of the aforementioned practical example for pump (I) and pump (II) and takes a delivery quantity Q _K = 1.5 for the compression stroke of the pump (III). Q _o an, then t _{K is} calculated $${\text{t}}_{\text{K}}\text{=}\frac{{\text{V}}_{\text{O}}\left(\text{1-η}\right)}{{\text{Q}}_{\text{K}}}\text{· 3.6}$$

so $${\text{t}}_{\text{K}}\text{= 0.25 (sec)}$$

and consequently V _A according to equation (14) $${\text{V}}_{\text{A}}{\text{= 25 (dm}}^{\text{3rd}}\text{)}$$

which results in a value for the factor f 4 of $$\mathit{\text{f}}\text{4 = 1.543.}$$

und errechnet sich in dem beschriebenen praktischen Beispiel zu $${\text{ƒ}}_{\text{5}}\text{=}\frac{\text{1,543}}{\text{1,4113}}\text{= 1,0933.}$$

The relative increase factor f 5 compared to the pump (II) is thus $${\text{ƒ}}_{\text{5}}\text{=}\frac{{\text{ƒ}}_{\text{4th}}}{{\text{ƒ}}_{\text{2nd}}}$$

and is calculated in the practical example described $${\text{<figure-callout id="5" label="ƒ" filenames="imgf0006.png" state="{{state}}">ƒ</figure-callout>}}_{\text{5}}\text{=}\frac{\text{1,543}}{\text{1.4113}}\text{= 1.0933.}$$

The preceding derivations show that the invention has succeeded in using the measures according to the invention of claim 1 to achieve both the desired continuity of the conveyance and the piston speed according to factor f 5 = 1.0933 to be increased only insignificantly, in contrast to the state the technology (pump (I)), in which the piston speed is increased by a factor of f 3 = 1.659, and thus to avoid the disadvantages of this prior art.

Fig. 1

eine Verknüpfungsschaltung gemäß der Erfindung,

Fig. 2

eine Einzelheit der Verknüpfungsschaltung,

Fig. 3-4

weitere Einzelheiten der Verknüpfungsschaltung,

Fig. 5

eine weitere Verknüpfungsschaltung in der Fig. 1 entsprechender Darstellung und

Fig. 6

eine weitere Ausführungsform in den Fig. 1 und 4 entsprechender Darstellung.

The details, further features and other advantages of the invention result from the following description of an embodiment with reference to the figures in the drawing.

Fig. 1

a logic circuit according to the invention,

Fig. 2

a detail of the logic circuit,

Fig. 3-4

further details of the logic circuit,

Fig. 5

a further logic circuit in Fig. 1 corresponding representation and

Fig. 6

another embodiment in FIGS. 1 and 4 corresponding representation.

The representations of the figures are based on a two-cylinder concrete pump. The two feed cylinders are labeled L and R. The letter A, on the other hand, denotes a compensating cylinder which opens into the delivery line 105. The feed cylinder and the compensating cylinder are each driven by a hydraulic working cylinder, the letters each referring to the unit consisting of the feed cylinder and drive cylinder. The end positions of the pistons in the cylinders are conveyed to the logic circuit by pulses from sensors which are identified by the letters a-f. These sensors control valves that are identified with Arabic numbers. The control pulses of the sensors can be electrical, hydraulic, mechanical or pneumatic.

The concrete flow control provided in the invention is carried out with a swivel tube 100 which has a control plate 101 and 102 on opposite sides of its inlet opening and is therefore referred to as a control slide (104). A hydraulic drive is used to impart motion is generally designated B. This is also controlled via a directional valve, which is shown at 3. A hopper has on its side opposite the openings of the delivery cylinders L and R a pivot bearing 103 for the control slide 104 and the rotationally fixed connection of the pump-side end of a concrete delivery line 105.

During pumping, the combination circuit accelerates the drive piston of the conveying cylinder currently being conveyed, so that its conveying piston runs faster and thereby conveys more in this phase, which corresponds to the size of the amount of concrete removed from the filling funnel at the front of the equalizing cylinder. This is done by adding additional hydraulic medium (oil). If the area ratio of the compensating cylinder drive piston to the compensating cylinder feed piston is the same as that of the feed cylinders, the hydraulic drive medium which the rear of the compensating cylinder drive piston displaces through the outlet cylinder feed piston when the concrete is sucked in from the delivery line is sufficient.

The control slide 104 is switched between the piston clearances of the delivery cylinders R and L. In the embodiment according to FIG. 1, the switching takes place in two successive steps, the first of which holds the control slide in a central position between the openings of the two delivery cylinders. In this position, one of the slide plates 101 and 102 closes the delivery cylinder opening of the delivery cylinder switched from suction to delivery. This enables the piston of this feed cylinder to compress the previously sucked concrete. At the end of this compression stroke, the logic circuit causes the second switching step of the control slide 104 into the respective end position. Thereby the inlet opening 106 of the control slide 104 is aligned with the opening of the conveying cylinder and the previously compacted concrete is pressed into the conveying line 105.

In a first embodiment of the invention, the middle switching position of the control slide 104 is controlled by the directional valve 7. The control hole for the return oil is closed in the middle switch position, causing the control slide to come to a standstill in the middle switch position. Valve 7 is switched on at intervals and moves to the other switching position. This will clear a return control bore at the end of the drive cylinder. Thus, the control spool can be switched to the end position.

In a further embodiment of the invention, the middle switching position of the control slide is determined by the fact that two drive cylinders according to FIG. 5 are connected in series for driving the control slide. With the actuation of the first cylinder 107, the middle position is established. The second cylinder 108 is actuated at intervals, by means of which the control slide 104 reaches its end position. The first cylinder 107 is actuated by the valve 3 and the second cylinder 108 by the valve 31.

In another preferred embodiment of the invention, the switching of the control slide takes place parallel to the compression stroke, which leads to a considerable reduction in the total interruption time between the pumping strokes of the delivery cylinders in accordance with equation (12) t _A = t _Sch + t _K and thus to a reduction in the stroke volume the compensating cylinder V _A and the factors f 4 and f 5 (see Equation 14, 18, 20) and consequently a reduction in the speed of the piston of the pumping delivery cylinder. This possibility arises from the fact that at the beginning of the compression stroke there is still no discharge of thick matter into the delivery line, because initially no pressure builds up due to the equalization of vacuum and air and by then the control slide has quickly reached its central position while subsequently in the time range , in which the compressing delivery piston effectively compresses the thick matter, i.e. builds up pressure, the control spool passes through its central position range more or less delayed until the compression is almost complete and then the control spool accelerates the rest of its switching path again (Fig. 6).

For practical reasons of construction, namely to keep the compensating cylinder as small as possible, but also for reasons of adjusting the control system when idling, it makes sense to limit the compression stroke. The extent of the limitation results from the minimum volumetric efficiency η _vol , which corresponds to the general level of knowledge of the concrete flow behavior, i.e. the concrete's suction ability. With η _vol = 0.85 the predominant range of all pumped concrete and other thick materials is covered.

3, the required limitation of the compression stroke is done with a cylinder 33 in which a piston 38 is arranged. The stroke volume 40 corresponds to the selected compression stroke limitation. A valve 51 controls the cylinder in such a way that in the phase of the compression stroke the valve 51 is switched by one of the sensors a, b. As a result, pressure oil from a reservoir 60 acts on the side 36 of the piston 38 via the line 35. The amount of oil displaced by the piston side 37 becomes via a line 34, 28 to the compressing feed cylinder until the piston 38 has reached its end position. The switching back of the valve 51 by a sensor acts on the accumulator side 37 of the piston 38. The oil displaced from the side 36 flows out to the tank. The piston 38 can thus be returned in its starting position for the next compression.

In the embodiment according to FIG. 4 it is provided that during the compression stroke of one delivery cylinder the piston in the other delivery cylinder stands still, i. H. its suction stroke does not start yet. The compression stroke limitation takes place with a multi-chamber cylinder 41. This corresponds in terms of stroke limitation in terms of dimension, function and control to the cylinder 33 according to FIG. 3. However, it has a further chamber 42 which is dimensioned in such a way that it does so during the compression stroke of the drive cylinder of the compressing delivery cylinder displaces hydraulic oil displaced into the bridge line via line 43 and feeds it back into the bridge in the course of the following delivery stroke and thus restores the synchronization of the running of the delivery cylinders.

A continuous concrete flow is achieved in that the same piston area ratios as well as the same hydraulic quantities for the delivery stroke are available for the different cylinders L, R and A. The hydraulic pump P1 ensures the continuity of the concrete delivery. It is therefore advantageous to provide one or more separate other drive sources for all other drives of the valves or control slides, the suction stroke of the compensating cylinder A, etc. A second hydraulic circuit, which has a reservoir 60 fed by a pump P2, is used for this purpose.

It is provided with a safety and pressure shut-off valve 70.

For the suction stroke of the compensating cylinder, an auxiliary pump P3 is provided, which is switched so that in the phase in which the compensating cylinder conveys the concrete, the pump P3 is not switched off, but the hydraulic medium supplied by it via line 9 additionally to the reservoir 60 is supplied.

Instead of the auxiliary pump P3, a correspondingly enlarged pump P2 can be provided in connection with a larger working volume storage.

It is also advisable to use all hydraulic switching valves with the shortest response time. When the valve 2 is hydraulically actuated via the sensor control point (e) by means of the pump medium P1, the switching time is reduced to a minimum by replacing the valve 2 including the check valve 30 with the aid of a hydraulic unlockable check valve.

Claims (15)

1. A pump for viscous materials having delivery cylinders (R, L), in particular a two cylinder concrete pump with a viscous material flow control between a filling hopper, the delivery cylinders (R, L) and a delivery pipeline (105), together with a linking switch system controlling the drive mechanisms of the delivery cylinders (R, L) and the viscous material flow, wherein the viscous material flow runs through a control slide valve (104) which is connected continuously to the delivery pipeline (105) by means of its outlet aperture and is provided with at least one inlet aperture which alternates in position in front of the apertures of the delivery cylinder, wherein a compensating cylinder (A) prevents interruptions to the viscous material during the switching over of the control slide valve (104) and the linking switch is constructed in such a way that the compensating cylinder (A) forces viscous material into the delivery pipeline during the switching over of the control slide valve (104) and, during the subsequent delivery stroke of one of the delivery cylinders (R, L), is filled with viscous material, and wherein slide valve plates arranged to each side respectively of the inlet aperture of the control slide valve are aligned along a plane to fit onto a surface between the delivery cylinder apertures in such a way that, in the intermediate switching position of the control slide valve (104), the apertures of the delivery cylinders (R, L) are sealed off by the slide valve plates from the inlet apertures within the control slide valve (104) along the surface between the delivery cylinders (R, L), characterised in that the linking switch system causes the drive mechanism of the respective delivery cylinder (R, L) during delivery to convey its load more quickly depending on the mass of the quantity of viscous material taken up by the compensating cylinder (A) and delays the switching over of the control slide valve (104) in such a way that one of the slide valve plates (101, 102), closes off the aperture of the delivery cylinder associated with it in order for a partial stroke to be carried out by the delivery cylinder piston as it compacts the induced viscous material.
2. A pump for viscous materials according to claim 1, characterised in that the compensating cylinder (A) is connected continuously to the delivery pipeline (105) by means of its outlet aperture and is filled with viscous material from said delivery pipeline.
3. A pump for viscous materials according to one of the claims 1 and 2, characterised in that the linking switch system comprises control elements in the form of position-identifying sensors and valves controlled by these sensors, wherein the switching signals are capable of being conveyed electrically, hydraulically, mechanically or pneumatically.
4. A pump for viscous materials according to one of the claims 1 to 3, characterised in that, in order to accelerate the drive mechanisms of a particular delivery cylinder (R, L) in its delivery operation, hydraulic medium can additionally be supplied to the piston of a drive cylinder of the delivering cylinder from the return flow from a drive cylinder of the compensating cylinder (A).
5. A pump for viscous materials according to one of the claims 1 to 4, characterised in that ratio of the surface areas of the drive piston of the compensating cylinder and the delivery piston of the compensating cylinder is the same as for the delivery cylinders (R, L).
6. A pump for viscous materials according to one of the claims 1 to 5, characterised in that, in order to establish the intermediate position of the control slide valve (104), a piston of the control slide valve drive mechanism (B) closes off an associated control orifice for reflux oil and brings the control slide valve (104) to a standstill in the intermediate switching position, whereby, by means of an additional and, after an interval, subsequently performed switching of the valve (7) into a further switching position, a return flow control orifice is made available at the end of the drive cylinder and the switching of the control slide valve (104) into the terminal position is effected.
7. A pump for viscous materials according to one of the claims 1 to 5, characterised by the establishment of the intermediate switching position of the control slide valve (104) by means of a control slide valve drive mechanism (B) having two consecutively switched drive cylinders (107, 108) which, on actuation of the first cylinder, effect the intermediate position and, subsequently, after an interval, on actuation of the second cylinder, effect the terminal position of the control slide valve (104), wherein a respective switching valve (3, 31) is associated with each drive cylinder for the control of the drive cylinders.
8. A pump for viscous materials according to one of the claims 1 to 5, characterised in that the positions of the control slide valve (104) for compressing and conveying are established in such a way that, at a high initial speed of operation of the control slide valve (104), it is retarded throughout the intermediate phase and, towards the end of the control slide valve movement, the control slide valve (104) is accelerated once more to its initial speed, wherein the intermediate phase retardation is effected by locating throttle valves in the return flow of the control slide valve drive cylinder in order to perform the compression stroke.
9. A pump for viscous materials according to one of the claims 1 to 8, characterised in that the control slide valve drive (B) is effected with differential, synchronising or plunger cylinders.
10. A pump for viscous materials according to one of the claims 1 to 9, characterised in that, for limiting the compression stroke, a cylinder (33) is used having a stroke volume (40) suitably matched to the selected compression stroke limitation, said cylinder being controlled by means of a valve (51) in such a way that, in the compression phase, the valve (51) is actuated by means of one of the sensors (a, b) and reservoir oil then impinges on one side (36) of a piston (38) in the cylinder (33) by way of the pipeline (35), whereby the volume of hydraulic medium displaced from the other side (37) of the piston flows by way of pipelines (34, 39, 8) to the compressing delivery cylinder until the piston (38) has reached its terminal position, and that, by reverse switching of the valve (51), the reservoir oil impinges on the side (37) of the piston (38) and the displaced hydraulic medium from the side (36) flows away to the tank and the piston (38) returns to its initial position for the following compression.
11. A pump for viscous materials according to one of the claims 1 to 9, characterised in that, for limiting the compression stroke, the delivery piston is stopped in the adjacent delivery cylinder and the induction stroke is delayed with the aid of a multi-chamber cylinder (41) which comprises an additional chamber (42) that is of such dimensions that it can contain, during the compression stroke, hydraulic medium equivalent to the compression stroke and which has been displaced from the drive cylinder of the compressing delivery cylinder into a bridging pipeline, and feed it back into the bridge again in the course of the subsequent delivery stroke so that the synchronisation of the operational cycle of the delivery cylinder piston can be re-established.
12. A pump for viscous materials according to one of the claims 1 to 11, characterised in that, in order to carry out the delivery stroke of the delivery cylinder pistons and the delivery stroke of the compensating cylinder piston, an hydraulic pump (P1) is provided.
13. A pump for viscous materials according to one of the claims 1 to 12, characterised in that, for the drive (B) of the control slide valve (104), for performing the compression stroke and for switching the valves, a separate hydraulic circuit is provided, for which a pump (P2) and a reservoir supplied by said pump, together with a security and pressure disengagement valve, are also provided.
14. A pump for viscous materials according to one of the claims 1 to 13, characterised in that, for carrying out the induction stroke of the compensating cylinder (A), an additional auxiliary pump (P3) is provided which is switch operated in such a way that, during the delivery stroke of the compensating cylinder, it conveys the hydraulic medium which is supplied by said pump by means of a pipeline (29, 9) to the reservoir.
15. A pump for viscous materials according to one of the claims 1 to 14, characterised in that, in order to reduce the switching time of the compensating cylinder (A), an hydraulically operated non-return valve is used to reduce to a minimum the switching time of the drive mechanism of the compensating cylinder.

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