EP0808422A1

EP0808422A1 - Process and device for feeding concrete or other thick materials

Info

Publication number: EP0808422A1
Application number: EP96901313A
Authority: EP
Inventors: Gerhard Hudelmaier
Original assignee: Hudelmaier Gotz; Hudelmaier Ulrike
Current assignee: Hudelmaier Gotz; Hudelmaier Ulrike
Priority date: 1995-02-07
Filing date: 1996-01-19
Publication date: 1997-11-26
Anticipated expiration: 2016-01-19
Also published as: KR19980702057A; JPH10505647A; JP3081923B2; EP0808422B1; CN1177393A; US5993181A; WO1996024767A1; KR100264234B1; DE19503986A1

Abstract

A process and device are disclosed for feeding concrete and other thick materials from a container into a feeding pipe by means of two feeding cylinders that can be alternatively connected to the container or to the feeding pipe by a switching device. The feeding pistons of the feeding cylinder alternatively carry out a suction and a compression stroke. The average piston speed during the suction hub is at least temporarily higher than during the compression stroke. In order to achieve a continuous feeding flow, both feeding cylinders are at least temporarily separated from the container, short-circuited together and connected to the feeding line during the switching period tu of the switching device. One of the feeding pistons finishes its compression stroke in this condition and at the same time the other feeding piston starts its compression stroke. The corresponding feeding piston starts its suction stroke only when the short-circuit is again substantially cancelled and only the appropriate feeding cylinder is connected to the container.

Description

Method and device for conveying concrete or others

Thick matter

The present invention relates to a method for conveying concrete or other sealants from a container into a delivery line by means of two through one

Conversion device alternately connectable to the container or the delivery line conveyor cylinder, the

Conveyor pistons alternately perform a suction and a pressure stroke, the average

Piston speed during the suction stroke is at least temporarily greater than during the pressure stroke, as well as a

Device for performing the method.

A corresponding procedure and a corresponding one

Device are known from DE-PS 3525003. The

The essence of the known method is that the first feed cylinder has not yet completed its pressure stroke, while the second feed cylinder already begins the pressure stroke at a lower conveying speed. After the first delivery cylinder has finished its pressure stroke, the changeover process of the changeover device begins, while the second delivery cylinder continues to deliver at a lower delivery speed. This procedure ensures that the concrete is already advanced in the second feed cylinder, so that after switching the

Switching device can not spring back the concrete column in the delivery pipe too much. On the whole, this method and the device used for it have proven themselves very well. In technology, however, there have recently been calls for ever more efficient processes for concrete conveyors. There are serious efforts to increase the length of the delivery pipe and, in particular, the delivery head. Since in the known method during the switching period with a smaller one

Conveying speed is pumped, there is a low Pulsation in the flow. This could be neglected under the usual funding conditions, but leads to vibrations at the end of the conveyor pipe due to the now required delivery heights and thus large overhangs, for example with an arm of a concrete conveyor vehicle.

It is therefore the object of the present invention to provide a method and a device for conveying concrete from a container into a delivery line, by means of which irregularities in the flow rate are further reduced.

This object is achieved according to the invention by a generic method in which, during the changeover period t _{u of} the changeover device, the two delivery cylinders are at least temporarily essentially separated from the container and short-circuited to one another with a common connection to the delivery line, and in this state the delivery piston has its pressure stroke still ended and at the same time the other delivery piston already begins its pressure stroke, the corresponding delivery piston only executing its suction stroke when the short circuit has essentially been removed again and the associated delivery cylinder is connected to the container.

The method according to the invention avoids that during the changeover period t _u only a conveying takes place at a lower conveying speed. This is achieved by short-circuiting the two delivery cylinders, which can be replaced in the short-circuited state without loss of changeover times in delivery at full delivery speed. Short-circuiting also automatically compresses the concrete column in the delivery cylinder that begins the pressure stroke. Pulsation beats are avoided by this procedure due to the continuous flow provided. The method according to the invention is particularly advantageously suitable for concrete pumps with a single changeover device (for example a single swivel tube) which works simultaneously with both delivery cylinders. In an advantageous variant of the method, the properties of the material to be pumped are taken into account even more. This is done in that the delivery piston, which has ended the suction stroke, already begins the pressure stroke during a time period Δ t of the changeover time period t _u , while the other delivery piston has not yet ended its pressure stroke. This measure can already precompact the concrete column in one of the

Delivery cylinders take place, for example

Gas inclusions or not completely filled

Delivery cylinders do not lead to unwanted fluctuations in delivery. In a further variant, it is quite sufficient if the speed of the pressure stroke in the

Time period Δ t beginning conveyor cylinder is less than the average speed during the remaining pressure stroke. The beginning of the pressure stroke of one

The delivery time and speed of the delivery cylinder can be selected so that all losses to be taken into account and thus fluctuations are compensated for by, for example, the material to be delivered. In a further variant of the method, both delivery pistons can be moved substantially at half the average speed V _{1 of} the remaining pressure stroke during the time period. This has the advantage that the switch from one to the other delivery piston can take place almost in stages since the partial delivery flows add up to the continuous total delivery flow.

The method according to the invention is advantageously carried out by a device which has at least two conveying cylinders which can be alternately connected to a container or a delivery line by a changeover device

has, the delivery piston alternately perform a suction and a pressure stroke, the

Switching device is pivotable along the open end regions of the feed cylinders with its inlet opening Swivel tube is. The device is characterized in particular by the fact that the inlet opening and the closure regions of the swivel tube surrounding it are designed in such a way that the conveying cylinders in the

essentially short-circuited with the delivery tube, but are essentially separated from the container.

This device has the advantage that known devices can be used in principle, in which only the changeover device in the form of a swivel tube has to be configured differently. With its inlet opening, the swivel tube must ensure, according to the invention, that a short-circuit of the two delivery cylinders is produced at least temporarily during the swiveling process or changeover event.

Advantageously, the inlet opening can be designed in the form of an elongated hole which is essentially bent around the pivot axis of the pivot tube and have a length which corresponds approximately to the outer distance of the two feed cylinder openings. To achieve a safe separation of the feed cylinder from the container, the closure areas in

Extension of the elongated hole may be arranged and have a width which is substantially the diameter of the

Delivery cylinder openings corresponds. This will

avoided that a short circuit between a delivery cylinder carrying out the pressure stroke and the container is produced.

The device is preferably controlled hydraulically, for which purpose a cylinder-piston unit can be provided in a first embodiment, in which an optionally switchable line into the piston-side space of each

Cylinder leads, with an additional pump to the other

Pressure medium supply of the two pressure chambers of the second cylinder-piston units is arranged, whereby

a connecting strand of the connecting piston-side pressure chambers of the cylinder-piston units Hydraulic system extends in which one over a

Change-over valve optionally with the additional pump or with a pressure medium return connectable line opens, the sections of the line between each cylinder and the mouth of the line each by the pressure of the

Cylinder lockable check valve included, and wherein the cylinders of the cylinder-piston units in the end region of their piston rod side have a line connecting them, which is also selectively connectable to the pressure medium return or the auxiliary pump via the changeover valve. The additional pump for supplying pressure to the cylinder-piston unit starting the pressure stroke ensures that no drive energy has to be extracted from the still pressing delivery piston. The energy supply to the piston, which is in

Movement should be switched on in a timely and accurate manner in a simple manner. Since the pressure of the hydraulic pump, which exceeds the pressure from the auxiliary pump, is present at the cylinder-piston unit in the pressure stroke, and thus at the associated check valve, this can only act on the other piston to be set in motion. This also applies to the downtime of the piston that has ended the pressure stroke. The additional pump also ensures a higher pressure stroke

Speed of the piston in the suction stroke.

Independent control of the cylinder-piston units is achieved in a second embodiment in that the cylinder-piston units are each supplied with pressure medium via a separate pump. In such an embodiment, speed and switching cycles can be dependent on the control of the pumps used

to be provided.

The process sequence according to the invention can also be achieved in a third embodiment of the device

achieve that a cylinder-piston unit is provided for driving the delivery piston, in which one optionally switchable line of a first pump with the piston rod-side space of each cylinder can be connected or separated from that a second pump for

Pressure medium supply to the two piston ends

Pressure spaces can be connected individually or together with the pressure spaces via a switchable line, and that the piston rod-side spaces of each cylinder can be connected together with a pressure medium return. The pump control and the area ratio of piston to piston rod determine whether the different piston speeds are reached. Furthermore sees this

Embodiment before that the two pistons move at the same speed in the pressure stroke, the

Control usually takes place so that one piston ends its pressure stroke in this state and the other begins it. If the second pump provides a constant flow rate, the pressure medium flow is halved and divided between the two cylinders, so that they each travel at half the speed, but still produce a constant flow rate together.

In a third embodiment, a cylinder-piston unit is provided for driving the delivery pistons, in which an optionally switchable line of a first pump is connected to the piston-side pressure chamber of each cylinder and the piston rod-side chamber of each other cylinder via an adjustable flow divider

is connectable or separable from these, a second pump for supplying pressure medium to the piston-side pressure chambers via a switchable line can be connected individually or jointly to the pressure chambers, the flow dividers in each case being able to be connected or blocked together to the strands that can be connected to the piston-side pressure chambers of the cylinder, and wherein the current dividers, if they are separated from the first pump, together with one

Pressure medium return are connectable. With this arrangement, the different control is essentially through to regulate the pumps. This device is fine-tuned by the second pump.

In order to dispense with a second pump in a fifth embodiment, a cylinder-piston unit is provided for driving the delivery pistons, in which one

optionally switchable line of a pump with the

piston rod-side space of each cylinder can be connected or separated from this, a second optionally

Switchable line of this pump with the piston-side pressure chambers of the cylinders can be connected together or separated from them, the piston-side

Pressure chambers of the cylinders with a rocker line

are interconnected, and wherein the

piston-side pressure chambers via an optional

switchable line can be connected to or separated from a pressure medium return. With this

Hydraulic circuit ensures that in one

Volume displaced on the piston end side so that the other piston is moved accordingly. Since the

Swing line is optionally connectable to the pressure medium return, the volume flow pressed through the swing line can be influenced.

Furthermore, each cylinder can advantageously have a piston at its piston end via a control line to the control connection side of the other cylinder

associated check valve connected. The

Swivel tube can be moved by means of a slide

Controlled two-way valve can be actuated, which is connected to a pump and / or a pressure accumulator.

An embodiment of the invention is explained below with reference to a drawing. It shows:

Fig. 1 is a schematic, partially cut away

View of a conveyor for concrete,

Fig. 2 shows a first embodiment of a simplified

hydraulic circuit diagrams for driving the device,

Fig. 3 is a schematic circuit diagram of the

Delivery cylinder facing end of the

Swivel tube,

Fig. 4 is a path-time diagram of the two delivery pistons according to the first method variant of the present invention

5 shows five working positions of the piston-cylinder units according to the diagram from FIG. 4,

Fig. 6 is a path-time diagram of a second

Process variants according to the present invention,

7 five working positions of the piston-cylinder units according to the second method variant from FIG. 6,

Fig. 8 shows a second embodiment of a simplified

hydraulic circuit diagrams for driving the device,

Fig. 9 shows a third embodiment of a simplified

hydraulic circuit diagrams for driving the device,

Fig. 10 shows a fourth embodiment of a simplified

hydraulic circuit diagrams for driving the device, and Fig. 11 shows a fifth embodiment of a simplified hydraulic circuit diagram for driving the

Contraption.

The conveyor device shown in FIG. 1 shows a plan view of an approximately funnel-shaped container 1 for receiving concrete, for example from ready-mixed concrete mixers. The concrete is in a delivery line 2 only indicated above

Swivel pipe 3 and a pipe bend 4 promoted. This is done by means of two delivery cylinders 5, the delivery pistons 6

alternately perform one suction and one pressure stroke. The swivel tube 3 can be swiveled hydraulically into its desired position with respect to the mouth of the two delivery cylinders 5 by means of a slide 7. In Fig. 1, the mouth of the suction feed cylinder 6 to the container 1 is open, so that the cylinder fills from there (see the arrow shown in dashed lines).

The delivery pistons 6 are moved by means of cylinder-piston units 8, of which only the cylinders 9 are indicated schematically in FIG. 1. At the junction between the

Delivery cylinders 5 and the cylinder-piston units 8 are

Housing 10 arranged. As will be described further below, the swivel tube 3 is in this

Embodiment funnel-shaped, so that both

Delivery cylinder 5 can be connected to the delivery line 2 at least temporarily at the same time.

2 shows a first embodiment of a

simplified diagrams of a hydraulic system for actuating the cylinder-piston units 8 and thus

coupled delivery piston 6. A delivery cylinder 5 and

Delivery pistons 6 are fragmentary and schematized in

Connection to one of the cylinder-piston units 8

indicated. The slide 7, which is likewise actuated by the hydraulic system, is also indicated schematically. Each cylinder-piston unit 8 has a piston 11, the sequence of movements of which is via its piston rod 12

Transfer piston 6 transmits.

The drive for the cylinder-piston units in the pressure stroke takes place essentially by means of a hydraulic pump 13. An additional pump 14 supplies additional delivery flow for certain movement sections of the pistons. The hydraulic pipeline network has the following sections:

A line 15 leads from the hydraulic pump 13 to a branch point 16 and from there a line 17 to a two-way valve 18 and a line 19 to a changeover valve 20. From the two-way valve 18, a line 21 leads into the area of a cylinder 9 ₁ on the piston side. the index designations 1 and 2 are used below for the two piston-cylinder units when describing their movement sequences

A line 22 leads from the two-way valve 18 into the

piston-side pressure chamber of the cylinder 9 ₂ . The strands 2 and 22 can thus be optionally connected to the hydraulic pump 13 by the two-way valve 18.

From the changeover valve 20, a line 23 leads to one side, a line 24 to the other side of a piston 7a in the slide 7. In addition, a line 25 leads from the switch valve 20 to the return 26 in such a way that, depending on the valve position, one side of the slide with the hydraulic pump 13 and the other with the

Return 26 is connected.

A wiring harness 27 connects the two

Piston end faces of the cylinders 9 ₁ and 9 ₂ with each other. Between the two branches 28 to a switch valve 29. Before the end of the branch 28 into the cylinders 9 ₁ and 9 ₂ , the branch 27 each contains a check valve 30 or 31, each with the closing direction towards the branch 28. From the changeover valve 29, a line 32 leads to the return 26 and a line 33 to the additional pump 14

Changeover valve 29 a line 34 in the area of the cylinder-piston units, where it opens into a line 35 connecting the rod-side areas of the cylinders 9 ₁ and 9 ₂ . This line contains no valves.

A runs between the piston-side area of the cylinder 9 ₁ and the control connection side of the check valve 31

Control line 36. The cylinder 9 _{2 is also} via a

Control line 37 connected to the check valve 30.

The hydraulic pump 13 is assigned a pressure relief valve 38, the auxiliary pump 14 a pressure relief valve 39.

With the described device and an additional controlled switching system for the changeover valves 20, 29 and the two-way valve 18, a movement sequence of the pistons 11

achievable, based on Figures 3 to 7 below

is described. The sequence of movements applies in the same way to the delivery pistons 6 and thus determines the delivery of concrete from the container 1 into the delivery line 2.

The following is a first with reference to Figures 3 to 5

Process variant according to the present invention under

Use of the device described above described in more detail.

In particular in Fig. 3 it can be seen that the

Delivery cylinder 5 facing end 40 of the swivel tube 3 is essentially kidney-shaped. In the end face 40 there is an arcuate inlet opening 41, the width B of which essentially corresponds to the diameter D of the orifice opening 42, 43 of the feed cylinder 5. The length L of the inlet opening 41 corresponds to the outer distance A of the two orifices 42, 43. The inlet opening 41 thus has the shape of a curved elongated hole, the center of which is in the pivot axis 44 of the pivot tube 3. Furthermore, the end face 40 in each case at the end of the inlet opening 41, closure areas 45, 46, the smallest distance C from the inlet opening 41 to the outer edge corresponding to the diameter D of the orifices 42, 43. Starting from the end face 40 of the swivel tube 3, it runs funnel-shaped to its second with the

Supply line 2 connected end to. The inlet opening 41 is also reduced in a funnel shape to the

corresponding opening at the opposite end. Apart from the transition states, the five states shown in FIG. 3, which are of crucial importance for the control of the system, can essentially be achieved by the configuration of the swivel tube 3 according to the invention.

In the following description, the corresponding position of the swivel tube 3 is shown in FIGS. 3 to 5

Positions of the pistons 11 ₁ and 11 ₂ assigned.

The starting position for phase I is the position of the pistons and the swivel tube, as shown in FIGS. 3 and 5. The hydraulic pump 13 acts on the cylinder 9 ₁ via the branch 15, the valve 18 and the branch 21 with a pressure P ₁ .

At the same time, the hydraulic pump 13 holds the slide 7 in its position on the right in the figure via the strands 15, 19 and 23 and the valve 20. The right side of the slide is connected to the outlet 26 via the changeover valve 20. The

rod-side regions of the cylinders 9 ₁ and 9 ₂ are connected to the return 26 via the strands 35, 34 and the changeover valve 29. The auxiliary pump 14 is connected via the strands 33, 34 and 35 and the valve 29 to the end of the pistons 11 ₁ , 11 _{2 on} the piston rod side. By switching the

Switching valve 29 now acts on the auxiliary pump 14 in each of the cylinders 9 ₁ and 9 ₂ in their region on the piston rod side with a pressure P ₂ . The pressure P ₂ is less than the pressure P ₁ . Therefore, the piston 11 ₁ presses the pressure to be displaced by the pressure P ₂ into the strand 35. The piston 11 ₁ thus receives an additional one on the rod side Pressurization to effect the pump 14. Its return stroke takes place at the speed V ₃ . This stroke movement corresponds to the suction stroke of the associated delivery piston 6.

Because the speed V _{3 is} greater than that

At the speed V ₁ , the piston 11 ₁ has not yet completed its pressure stroke when entering phase II, while the piston 11 _{2 is} already finished with its suction stroke. In the corresponding time-distance diagram in FIG. 4 it can be seen that the changeover time range t _u begins with phase II. During one

Time period Δt of the changeover time range tu, the piston 11 ₂ and thus the corresponding delivery piston 6 are stationary. The advantage is in particular that the closure area 46 of the end face 40 is not unnecessarily under high pressure

is applied. The pivot tube 3 pivots in phase II by switching the valve 20 so far that the orifice 42 is separated from the container 1.

When phase III is reached, both mouth openings 42, 43 and thus both delivery cylinders 5 are now short-circuited with the inlet opening 41 and thus the delivery line 2. In this state, the two-way valve 18 switches. As a result, the hydraulic pump 13 with the area of the cylinder 9 at the piston end is ₂

_connected. The piston 11 ₂ now carries out a pressure stroke at the speed V ₁ until the end of phase IV is reached. In phase IV, the swivel tube 3 pivots further in such a way that the outflow region 45 gradually sweeps over the mouth opening 43. The piston 11i stands still during this time. When the mouth opening 43 is completely separated from the inlet opening 41 and a connection to the container 1 again

is produced, the additional pump 14 is now via the strands 33, 34, 35 and the changeover valve 29 now with the piston rod-side regions of the cylinders 9 ₁ and 9 ₂ in

Connection so that the piston 11 ₂ against the pressure P ₂ presses the liquid to be displaced during the pressure stroke into the strand 35, the piston 11 ₁ thus receiving an additional pressurization on the rod side for the action of the pump 14. Its return stroke takes place at the speed V ₃ see phase V. This stroke movement corresponds to the suction stroke of the associated one

Delivery piston 6. At the end of phase III, ie at the beginning of phase IV, the pistons 11 ₁ and 11 _{2 have} exchanged their starting position exactly. The rest of the procedure corresponds to the procedure described, only with the pistons swapped accordingly and the pressurization swapped accordingly.

The movement sequence of the swivel tube 3 shown in FIG. 3 thus takes place between the end of phase I and the beginning of phase V, that is to say during the changeover period of the t _u . The switching positions assigned to the travel-time diagram during the pivoting movement of the pivoting tube 3, see FIG. 3, can be designed variably and do not have to be exactly according to this

Embodiment take place. Overlaps of the phases may even be desirable depending on the operating conditions. 4 clearly shows that the pressure strokes Cylinder 11 ₁ and 11 ₂ onne loss of time at the end of the time interval Δt with the same conveying speed V ₁ , and thus provide a continuous conveying flow. According to the invention, it is important here that the orifices 42, 43 of the feed cylinder 6 are short-circuited with the inlet opening 41 and thus the delivery line 2 in this state. Another important point is that both mouth openings 42, 43 are separated from the container 1 and, accordingly, do not begin their suction stroke until the short circuit again

is canceled.

Using the displacement-time diagram for the pistons of the

Hydraulic device, which essentially corresponds to the stroke sequence of the delivery pistons for the conveying of concrete, can be seen that the entire pressure stroke of a delivery piston takes a longer period, namely t ₁ , than the suction stroke with the duration t ₃ . The total time of suction and pressure stroke, t ₁ + t ₃ , however, always remains the same, so that the reciprocity of the two sides

Piston movements is obtained.

A second method variant according to the present invention is explained in more detail in particular with reference to FIGS. 3, 6 and 7. It will only focus on the essentials

Differences to the previous embodiment discussed in more detail. For the same and similar procedures and

Components are therefore given the same reference numbers.

The device shown in Fig. 2 is in particular by the changeover valve 29, the check valves 30, 31, and their control lines 36, 37 in a position to let one of the cylinders 9 already begin its pressure stroke, while the other cylinder 9 noen its pressure stroke has ended. This is particularly advantageous if possible losses, e.g. due to insufficient filling or air pockets in the concrete,

must be balanced.

Starting from the end of phase I, i.e. at the beginning of phase II, the additional pump 14 is via the strands 33, 28, 27 and Valves 29, 31 with the end of the piston 9 ₂

connected. The auxiliary pump 14 thus acts on the piston 11 ₂ with a pressure P ₂ from the beginning of phase II to the beginning of phase III during the period Δt. The piston 11 ₁ ends the pressure stroke at the speed V ₁ . The piston 11 ₂ already begins its pressure stroke under the action of the pressure P ₂ at a speed V ₂ which is less than the speed V ₁ . When phase III is reached, the changeover valve 18 switches over, and the additional pump 14 is separated from the end of the piston P ₂ . Due to the pressure stroke with reduced speed V ₂ in the time interval Δt, the concrete column is already pre-compacted in this feed cylinder, so that, for example, material-related

Pressure losses can be compensated. Thus, both pistons press during the period Δt. The one delivery piston, which continues via the swivel tube 3 with the delivery line 2

is connected, stops its pressure stroke during this period and then stops during the changeover time t _u . At the end of its suction stroke, the other delivery piston is slowly set in motion again in the direction of the pressure stroke with the aid of the additional pump 14. The just in

Concrete sucked into the cylinder in the opposite direction thus also already receives an initial movement in the direction of the mouth opening 42. After completing the

Time interval Δt, that is, after establishing the short circuit between the two orifices 42, 43 and the

simultaneous switching to a larger oil flow through the hydraulic pump 13, the speed of the changes

Delivery piston. The concrete is transferred from the delivery cylinder to the

Delivery line 2 pressed without the risk of a sudden transition, a stall or even a return caused by poor filling. After completing the

Changeover process, that is after the time t _u , the other delivery piston is moved in the direction of its suction stroke, and faster than in the pressure stroke. The increase in speed is made possible by the additional pump 14. It ensures that the suction stroke ends at the moment when

corresponding switching operations, a new pressure stroke is initiated before the other piston has completely completed its pressure stroke. It is essential in the present invention that the described speed differences between the suction and pressure stroke of each piston and the timing of the stroke sequence of the other delivery piston, as well as the

at the corresponding times, the required position of the end face of the suction pipe are coordinated with one another.

In the following, 8 to 11 will be used with reference to FIGS

Embodiments of simplified schemes one

Hydraulic system explained in more detail. In the following, however, only essential differences from the diagram shown in FIG. 2 will be dealt with, which is why the same reference numbers are used for the same and similar components.

It should be emphasized at this point that the diagrams are only the most important ones that are required to fulfill their functions

Include components.

The scheme shown in FIG. 8 has two essentially equivalent variable displacement pumps 13, 14 for control purposes. The first variable pump 13 is connected via line 15, a 4/2-way valve 45 and a line 21 to the

piston-side pressure chamber of the cylinder 9 ₁ in

Connection. The directional valve 45 ensures in its other

Switch position for that the variable displacement pump 13 via the

Line 15 and the strand 46 is connected to the piston rod-side space of the cylinder 9 ₁ . Likewise, the variable displacement pump 14 is connected via the line 33, a 4/2-way valve 47 and the line 22 to the pressure chamber of the cylinder 9 ₂ on the piston side. In the other

Shift position of the directional control valve 47 communicates the variable displacement pump 14 through the strand 48 to the piston rod side chamber of the cylinder 9 ₂ in connection. The variable pumps 13, 14 are matched to one another. From the circuit it can be seen that each cylinder 9 ₁ , 9 ₂ separately on the assigned

Variable pump 13, 14 can be controlled and operated. It follows that the control of the

Variable pumps 13, 14 and the directional valves 45, 47 for that Extending and retracting the cylinder 9 ₁ , 9 _{2 is} responsible and their control must take place accordingly. Of

another is an additional pump 49 with a

subsequent pressure accumulator 50 is provided, which are connected to the slide 7 via the line 19 and the 4/2-way valve 20. The pressure accumulator 50 ensures that the pump 49 does not have to be in continuous operation. In this

However, an embodiment is also conceivable in which the pressure accumulator 50 is filled by one of the variable displacement pumps 13, 14 during the idle period of one of the pistons 11 ₁ , 11 ₂ .

The diagram shown in Fig. 9 comprises a variable displacement pump 13, which is connected via a line 15, a 4/3-way valve 51 and the branches 46, 48 to the piston rod-side spaces of the cylinders 9 ₁ , 9 ₂ . The directional control valve 51 has a position in which the strands 46, 48 are separated from the pump 13 and via the strand 25 to the

Pressure medium return 26 are connected. Furthermore, a second variable displacement pump 14 is provided, which is optionally connected via the line 33, a 4/3-way valve 52 and the lines 53, 54 to the pressure chambers of the cylinders 9 ₁ and 9 ₂ on the piston side. In the position shown in FIG. 9, the directional control valve 52 connects both pressure chambers of the cylinders 9 ₁ and 9 ₂ to the pump 14. By means of the control via the two variable pumps 13, 14, one of which is the pressure stroke and the other is the respective suction stroke causes, the speed ratio between the pressure and suction stroke can be kept constant by precisely controlling the directional control valves 51, 52 and the pumps 13, 14. This is the case in this embodiment in particular when both cylinders 9 ₁ and 9 _{2 have a} short pressure stroke

execute (see valve position in Fig. 9) and both

Piston rod sides of cylinders 9 ₁ and 9 ₂ are connected to the tank during this time. At the same time, the slide 7 is then actuated. This means that when the short circuit is produced on the swivel tube 3, both of them Delivery cylinders 5 in the pressure stroke are at essentially half the average speed V ₁ . The gradual changeover from one to the other cylinders 9 ₁ and 9 ₂ had no effect on the overall flow rate due to the adjustment of the speeds.

The embodiment shown in Fig. 10 differs from the previous one in that in the line 46, 48 after the 4/3-way valve 51 each one adjustable

Current divider 55, 56 is arranged, each of which

Strands 46, 48 to the piston rod-side rooms of the

Cylinders 9 ₁ and 9 _{2 are} continued and in each case a second line 57, 58 is connected via a 4/2-way valve 59 to the piston-side pressure chambers of the cylinders 9 ₁ and 9 ₂ . In this embodiment, the pressure or suction stroke can be generated by the variable pump 13. During the changeover process of the swivel tube 3, however, the 4/3-way valve 51 connects the lines 46, 48 to the pressure medium return 26 and the 4/2-way valve 49 blocks the lines 57, 58, so that no oil volume from the piston-side pressure chambers of the cylinders 9 ₁ and 9 ₂ can escape. In this state, the variable displacement pump 14 is simultaneously connected to both pressure chambers of the cylinder 9 ₁ and 9 _{2 on} the piston side. These then lead to

Depending on the delivery volume of the variable displacement pump 14, a pressure stroke at the same speed.

During this process, one cylinder is usually shortly before its end position and the other at the beginning of its pressure stroke. The delivery volume of the variable displacement pump 14 is usually chosen so that none

Flow fluctuations occur. In this process, the parts ratio of the current dividers 55, 56 and the

Area ratio of the piston face and the

Piston rod side of the cylinder 9 ₁ and 9 _{2 be} designed to a reasonable relationship between pressure stroke or

To obtain suction stroke speed. The device is fine-tuned by the variable displacement pump 14 correspondingly for generating larger or smaller ones

Speeds can be adjusted.

Finally, a fifth embodiment of a hydraulic scheme for driving the delivery cylinders 5 is shown in FIG. 11. The line 15 from the variable displacement pump 13 is in turn connected via a 4/3-way valve 51 and the branches 46, 48 to the piston rod-side spaces of the cylinders 9 ₁ and 9 ₂ . In addition, a line 59 branches off from line 15 before directional valve 51 is reached. The line 59 connects the line 15 and thus the pump 13 to a rocking line 61 via a 3/2-way valve 60

Rocking line 61 is connected directly to both pressure chambers 9 ₁ and 9 _{2 on the} piston side. A line 62, which is also connected to the 3/2-way valve 60, leads via a further 3/2-way valve to the pressure medium return 26

Pressure medium return 26 passed. The piston rod-side space of this cylinder is then in with the pump 13

Connection. The oil volume from the cylinder starting the suction stroke is now in the swing line 61 minus the small amount of hydraulic fluid in the

piston-side pressure chamber of the other cylinder pressed. The small amount of hydraulic fluid discharged through the directional control valves 62, 63 ensures a temporary

Speed difference between the suction and pressure stroke. Then after closing the directional control valve 63, both cylinders 9 ₁ and 9 ₂ move with the same one

Speed until the cylinder in the suction stroke reaches the end position. The one in the pressure stroke

Cylinder has not yet reached the end position due to the speed differences just mentioned at the start of the movement. At this time, the 4/3-way valve switches to the position shown in FIG. 11 and the 3/2-way valve 60 also switches to the position shown in FIG. 11. The pump 13 is thus via the line 15, the line 59 and the Rocking line 61 connected to the piston-side pressure chambers of the cylinders 9 ₁ and 9 ₂ . This leads both

Pistons 11 ₁ and 11 _{2 have} a pressure stroke with the same

Speed off until the cylinder in the pressure stroke from the beginning has reached its end position. During this time, the slide 7 is actuated via the directional valve 20. The counter stroke then takes place in reverse

Sequence. The embodiment shown in FIG. 11 offers the possibility of controlling the entire process with only a single pump 13.

Claims

Expectations

1. Process for conveying concrete or other thick matter

from a container (1) into a delivery line (2) by means of two through one

Conversion direction (3) alternately with the container (1) or the delivery line (2) connectable delivery cylinder (5), the delivery piston (6) alternately perform a suction and a pressure stroke, the average

Piston speed V _{3 is} at least temporarily greater during the suction stroke than during the pressure stroke, as a result

characterized in that during the changeover period t _{u of} the changeover device (3) the two delivery cylinders (5) at least temporarily essentially separate from the container (1) and in common connection with the

Supply line (2) are short-circuited to one another and in this state one of the delivery pistons (6) ends its pressure stroke and at the same time the other delivery piston (6) already begins its pressure stroke, the corresponding delivery piston (6) only executing its suction stroke when the

Short circuit essentially canceled and the

associated delivery cylinder (6) is connected to the container (1).

2. The method according to claim 1, characterized in that the

Delivery piston (6) that has completed the suction stroke during a

Period Δt of the changeover period t _u already begins with the pressure stroke while the other delivery piston (6) has not yet ended its pressure stroke.

3. The method according to claim 2, characterized in that the

Velocity V ₂ of the delivery piston (6) starting the pressure stroke in the time interval Δt is lower than that

average speed V ₁ during the remaining pressure stroke.

4. The method according to claim 2 or 3, characterized

characterized in that during the time interval Δt both delivery pistons (6) are essentially half

average speed V _{1 of} the rest

Pressure strokes are moved.

5. Device for performing the method according to one of the

Claims 1 to 4, with at least two by one

Conversion device (3) alternately with a container (1) or a delivery line (2) connectable delivery cylinder (5), the delivery piston (6) alternately perform a suction and a pressure stroke, the

Changeover device (3) along the open one

End regions (42, 43) of the feed cylinder (5) with its

Inlet opening (41 pivotable swivel tube (3), characterized in that the inlet opening (41) and this

surrounding closure areas (40, 46) of the swivel tube (3) are designed such that the conveying cylinder (5) essentially together with the during a changeover process

Delivery tube (2) short-circuited, but are essentially separated from the container (1).

6. The device according to claim 5, characterized in that the inlet opening (41) in the form of a substantially to the

Swivel axis (44) of the swivel tube (3) is bent and has a length L which is approximately the outer distance A of the two orifices (42, 43)

corresponds.

7. The device according to claim 5 or 6, characterized in that the closure regions (45, 46) in extension of

Elongated hole (41) are arranged and have a width C which corresponds essentially to the diameter D of the mouth openings (41, 43).

8. Device according to one of claims 5 to 7, characterized

characterized in that a cylinder-piston unit (8) is provided, from which an optionally switchable line (17) leads into the piston-side space of each cylinder (9), that an additional pump (14) for the further supply of pressure medium to the two pressure chambers of the two Cylinder-piston units (8) is arranged so that it extends between the piston-side pressure chambers of the cylinder-piston units (8), a connecting line (27) of the hydraulic system, in which a switch valve (29) optionally with the auxiliary pump (14) or with a pressure medium return (26) connectable strand (28) that the sections of the

Strands (27) between each cylinder (9) and the mouth of the strand (28) each contain a check valve (30, 31) which can be closed by the pressure in the cylinder (9), and that the cylinders (9) of the cylinder-piston units (8) have a strand (35) connecting them in the end region of their piston rod side, which is also connected via the changeover valve (29)

either with the pressure medium return (26) or the

Additional pump (14) can be connected.

9. Device according to claim 8, characterized in that

Each cylinder (9) is connected at one end to the piston end via a control line (36, 37) to the control connection side of the check valve (31, 30) assigned to the other cylinder (9).

10. Device according to one of claims 5 to 7, characterized

characterized in that a cylinder-piston unit (8) is provided for driving the delivery pistons (6), each with the separate pump (13, 14)

Pressure medium can be supplied.

11. Device according to one of »claims 5 to 7, characterized in that in each case a cylinder-piston unit (8) for driving the delivery piston (6) is provided, in which an optionally switchable line (15) of a first pump (13th ) with the piston rod-side space of each cylinder (9) connectable or separable therefrom that a second pump (14) for

Pressure medium supply to the piston-side pressure chambers of the cylinders (9) can be connected individually or jointly to the pressure chambers via a switchable line (33), and that the piston rod-side chambers of each cylinder (9) together with one

Pressure medium return (26) can be connected.

12. The device according to one of claims 5 to 7, characterized in that in each case a cylinder-piston unit

(8) for driving the delivery pistons (6) is provided, in which an optionally switchable line (15) of a first pump (13) is in each case adjustable

Current divider (55.56) together with the

piston-side pressure space of each cylinder (9) and the piston rod-side space of every other cylinder

(9) can be connected or separated from this in that a second pump (14) for supplying the pressure medium

piston-side pressure chambers can be connected individually or jointly to the pressure chambers via a switchable line (33) such that the flow dividers (55, 56) with the piston-side pressure chambers of the cylinders (9) are connectable or blockable strands (57, 58), and that the

Flow divider (55, 56), if these are separated from the first pump (13), together with one

Pressure medium return (26) can be connected.

13. Device according to one of claims 5 to 7, characterized in that in each case a cylinder-piston unit

(8) for driving the delivery pistons (6) is provided, in which an optionally switchable line (15) of a pump (13) can be connected to or separated from the space on the piston rod side of each cylinder (9) such that a second optionally switchable line ( 59) of this pump (13) can be connected to or separated from the piston-side pressure chambers of the cylinders, that the piston-side pressure chambers of the cylinders

(9) with a rocker line (61) are connected to each other, and that the piston-side pressure chambers via an optionally switchable line (63) with a

Pressure medium return (26) can be connected or separated from this.

14. Device according to one of claims 5 to 13, characterized in that the swivel tube (3) can be actuated by means of a slide (7) via a controlled two-way valve (20), which with a pump and / or a

Pressure accumulator is connected.