THICK MATERIAL PUMP AND METHOD FOR OPERATING A THICK MATERIAL PUMP

Description

TECHNICAL FIELD

The present invention relates to a thick material pump and a method for operating a thick material pump.

DESCRIPTION OF THE STATE OF THE ART

In the case of a mobile thick material pump, especially a concrete pump, a pre-assembled mounting frame is usually provided that is placed on and connected to the running gear of a truck chassis. The mounting frame is designed, among other things, to accommodate a core pump with material feed container or hopper and a drive assembly for controlling the functional units. A two-cylinder piston pump is usually used as the core pump which has two hydraulic drive cylinders and conveying cylinders connected to one another in pairs, the pistons of which are connected in pairs via a common piston rod passing through a water chamber and can be driven in push-pull operation via a hydraulic control system. For this purpose, the drive cylinders are alternately pressurized with hydraulic oil at their one end and are hydraulically coupled to each other at their other end via a connecting line using so-called rocking oil (also referred to as balancing oil). The concrete is fed through the hopper in which, in particular, a transfer tube (S-valve or rock valve) is arranged. The transfer tube is alternately pivoted on the inlet side in front of the front openings of the two conveying cylinders and opens on the outlet side into a conveying pipe that is guided over a distribution boom. Accordingly, the common piston rods with drive pistons and conveying pistons are moved back and forth in opposite directions in the longitudinal direction of the running gear during operation. Such an arrangement is described, for example, in DE 38 34 678 A1 and EP 2 867 531 B1.

SUMMARY OF THE INVENTION

Based on this, the invention proposes a thick material pump having the features of claim 1 and a method for operating a thick material pump having the features of claim 6. Furthermore, according to the invention, a computer program having the features of claim 11 and a control device for a thick material pump having the features of claim 13 are proposed.

The invention is based on the finding of providing a cleaning operating mode for a thick material pump of the type described above in which the conveying cylinders jointly assume an end position on the hopper side and an alternating switching of the transfer tube between the two conveying cylinders takes place. The invention involves a reverse pumping process for emptying the conveying cylinders and the conveying pipe. By withdrawing (in the case of a bottom-side drive of the drive cylinders) or adding (in the case of a rod-side drive of the drive cylinders) rocking oil, the stroke of the conveying cylinders is shortened so that they can jointly assume the end position on the hopper side.

Further advantages and embodiments of the invention emerge from the dependent claims, the description and the accompanying drawings.

The invention also relates to a computer program with program code means that are suitable for carrying out a method according to the invention when the computer program is run on a computer. Both the computer program itself and the program saved on a computer-readable medium are claimed.

It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case but also in other combinations or on their own without departing from the scope of the present invention.

The invention is schematically represented in the drawings using an exemplary embodiment and is described in detail below with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic, partially sectional, perspective representation of a thick material pump according to the invention with a core pump and material feed container.

FIG. 2 shows a schematic representation of the thick material pump of FIG. 1 in a partially transparent top view with a bottom-side drive.

FIG. 3 shows a more schematic top view of FIG. 2.

FIG. 4 is a schematic top view of the thick material pump during a sequence of cleaning and operation mode comparable to FIG. 3.

FIG. 5 is a schematic top view of the thick material pump during a sequence of cleaning and operation mode comparable to FIG. 3.

FIG. 6 is a schematic top view of the thick material pump during a sequence of cleaning and operation mode comparable to FIG. 3.

FIG. 7 shows an embodiment variant of the representation in FIG. 3 with a rod-side drive.

FIG. 8 is a schematic top view of the thick material pump during a variant of the cleaning operation mode of FIG. 7.

FIG. 9 is a schematic top view of the thick material pump during a variant of the cleaning operation mode of FIG. 7.

FIG. 10 is a schematic top view of the thick material pump during a variant of the cleaning operation mode of FIG. 7.

DETAILED DESCRIPTION

Identical and similar features depicted in the individual figures are designated by the same reference signs.

FIGS. 1 and 2 show a thick material pump 10 according to the invention, which comprises a core pump 12 and a material feed container or hopper 14. The core pump 12 has a first conveying cylinder 16 and a second conveying cylinder 18, the front openings 20, 22 of which open into the hopper 14 and can be alternately connected to a conveying pipe 22 via a transfer tube (S-valve) 24 during the pressure stroke and are open towards the hopper 14 during the suction stroke while the material 24 is sucked in.

The conveying cylinders 16, 18 are driven in counter-phase mode (push-pull operation) via respective corresponding first and second hydraulic drive cylinders 26, 28. For this purpose, conveying pistons 34, 36 of the conveying cylinders 16, 18 are connected to pistons 38, 40 of the drive cylinders 26, 28 via a common piston rod 30, 32. In the area between the conveying cylinders 16, 18 and the drive cylinders 26, 28 there is a water chamber 42 through which the piston rods 30, 32 extend.

In the depicted exemplary embodiment, the drive cylinders 26, 28 are alternately pressurized with hydraulic oil on the bottom side via pressure lines 44, 46 with the aid of a hydraulic pump. At their rod-side end, the drive cylinders 38, 40 are hydraulically coupled to each other by a connecting line 48. Via this connecting line 48, the so-called rocking oil is pumped back and forth between the drive cylinders 26, 28 during the alternating pressure and suction stroke movements of the pistons 38 and 40.

A 3/3-directional control valve 50 is connected to the connecting line 48 and enables the controlled supply and withdrawal of rocking oil in the manner described below. The inlet and outlet connections 52, 54 of the directional control valve 50 can be pressurized with high pressure via a pump P or connected to a tank T at low pressure level.

If, in the case of a conveying operating mode shown in FIGS. 2 and 3, hydraulic oil is supplied to the first drive cylinder 26 via the line 44 on the bottom side (bottom-side drive) and the returning oil from the second drive cylinder 28 is returned to the low-pressure level or tank level via the line 46, the first piston arrangement 34, 38 moves in the direction of the arrow P1 and the piston arrangement 32, 40 in the direction of the opposite arrow P2. At the same time, thick material, in particular concrete, located in the first conveying cylinder 16 is conveyed in the direction of the arrows P3 via the transfer tube 24 under appropriate pressure into a conveying pipe 56, while material 58 is sucked from the hopper 14 in the direction of the arrow P4 into the second conveying cylinder 18 by means of the second conveying piston 36.

After carrying out the described pressure and suction stroke movement, the pressure application to the pressure lines 44, 46 is reversed, and the transfer tube 24 is switched to the front opening 22 of the second conveying cylinder 18 so that by means of the second conveying piston 36 the previously sucked thick material from the second conveying cylinder 18 can be conveyed via the transfer tube 24 under appropriate pressure into the conveying pipe 56, and material 58 can be sucked from the hopper 14 into the first conveying cylinder 16 by the first conveying piston 34.

After completion of the pumping process, not only the hopper 24 but also the conveying cylinders 16, 18 as well as their front openings 20, 22 and conveying pistons 34, 36 must be cleaned in order to prevent hardening of the residues of thick material. For this purpose, the machine operator can initiate a cleaning operating mode according to the invention, for example by pressing a button provided on a control device of the thick material pump. The sequence of the cleaning operating mode according to the invention is illustrated using an exemplary embodiment in FIGS. 4 to 6.

In a first step, reverse pumping of the core pump is initiated. In this case, the connection of the transfer tube 24 to the conveying cylinders 16, 18 is operated asynchronously, i.e., the transfer tube 24 is assigned to or connected to the conveying cylinder which next performs a suction stroke (instead of the conveying cylinder which next performs a pressure stroke, as in regular pumping operation). This situation is illustrated in FIG. 4. The reverse pumping enables the emptying of the conveying cylinder (in the illustration of the figure, the second conveying cylinder 18) filled with thick material 58 (from the last pumping process) into the hopper 14 as well as the emptying of thick material remaining in the transfer tube 24 or the conveying pipes 56 by the corresponding other conveying cylinder (in the illustration of the figure, the first conveying cylinder 16).

Simultaneously with the reverse pumping, rocking oil 60 is withdrawn into the tank T via the connecting line 48, for example via the directional control valve 50 described in connection with FIG. 2 (which is not reproduced in the illustration of FIGS. 3 to 6 for the sake of clarity).

The reverse pumping according to the invention is carried out by a plurality of alternating piston strokes until a short stroke, i.e., a shortening of the possible stroke of the drive cylinders 38, 40, has ceased (i.e. has been established) by reducing the amount of rocking oil 60 located in the cylinders 26, 28, as is illustrated in FIG. 5. At this moment, the pump is switched off. The size of the short stroke at which the reverse pumping movement of the conveying pistons 16, 18 ceases (i.e., stops) can, for example, be parameterizable, i.e., adjustable or preset. In this situation, the difference or offset between the two cylinder positions is significantly smaller, and the amount of rocking is already significantly reduced.

In a next step, rocking oil 60 is further withdrawn into the tank T until both conveying pistons 34, 36 come to lie in an end position on the hopper side, i.e., close to their front openings 20, 22, as is illustrated in the illustration in FIG. 6.

After reaching the described hopper-side end position of the conveying pistons 34, 36, the transfer tube 24 is reactivated so that it switches back and forth between the two front openings 20, 22. This is illustrated in FIG. 6 by the two transfer tube positions superimposed by dashed lines. According to the invention, the activation of the transfer tube 24 can be time-controlled, wherein the duration of the switching intervals can be parameterized, i.e., adjustable or preset.

During this time, the machine operator can clean the conveying cylinders, for example by spraying water under sufficient pressure onto the front openings and the cylinder interior between the front openings and the conveying pistons, which are opened alternately by the transfer tube in a time-controlled manner. Due to the end position of the conveying pistons, according to the invention only a very small space behind the front openings has to be cleaned, which saves time and water and also ensures optimized cleaning of the conveying piston front sides.

After ending cleaning, the machine operator can stop the cleaning operating mode by pressing a corresponding button or by re-pressing the button already pressed to initiate the cleaning operating mode, whereupon rocking oil 60 is fed back in via the inlet connection 52 until the regular opposite piston positions are reached again.

FIGS. 7 to 10 illustrate an embodiment variant of the invention with a rod-side drive.

According to the exemplary embodiment depicted in FIG. 7, the drive cylinders 26, 28 are alternately pressurized with hydraulic oil via rod-side pressure lines 44, 46 with the aid of a hydraulic pump. At their bottom end, the drive cylinders 38, 40 are hydraulically coupled to each other by a connecting line 48. Via this connecting line 48, the rocking oil is pumped back and forth between the drive cylinders 26, 28 during the alternating pressure and suction stroke movements of the pistons 38 and 40.

A directional control valve (not shown) is connected to the connecting line 48 and enables the controlled supply and withdrawal of rocking oil in the manner described below. The inlet and outlet connections of the directional control valve can be pressurized, for example, by a pump or connected to a tank or to the rod-side pressure lines 44, 46.

FIG. 7 shows the thick material pump 10 in the conveying operating mode with the first conveying cylinder 16 in an end position on the hopper side after it has previously conveyed thick material contained therein via the transfer tube 24 under appropriate pressure into a conveying pipe 56, while the conveying piston 36 of the second conveying cylinder 18 has sucked material 58 from the hopper 14. Next, in this position, the transfer tube 24 (assigned to the first conveying cylinder 16) is switched from the position shown in FIG. 7 to the position shown in FIG. 8 in which the transfer tube 24 is assigned to the second conveying cylinder 18 filled with material 58.

Subsequently, in the conveying operating mode, hydraulic oil is supplied to the rod side of the first drive cylinder 26 via the line 44 (rod-side drive), and the returning oil from the second drive cylinder 28 is returned to the low-pressure level or tank level via the line 46, and the first piston arrangement 34, 38 moves in the direction of the arrow P5, and the second piston arrangement 32, 40 moves in the direction of the opposite arrow P6. At the same time, material 58 is sucked from the hopper 14 into the first conveying cylinder 16 via the first conveying piston 34, white thick material located in the second conveying cylinder 18 are conveyed via the transfer tube 24 under appropriate pressure into a conveying pipe 56 (see end position of FIG. 8).

As already described above, after completion of the described pumping process, not only the hopper 24 but also the conveying cylinders 16, 18 as well as their front openings 20, 22 and conveying pistons 34, 36 must be cleaned in order to prevent hardening of the residues of thick material. For this purpose, the machine operator initiates a cleaning operating mode according to the invention, for example by pressing a button provided on a control device of the thick material pump.

The sequence of the cleaning operating mode according to the invention with a rod-side drive is illustrated using the illustration in FIGS. 8 to 10.

In a first step, reverse pumping of the core pump is initiated. In this case, the connection of the transfer tube 24 to the conveying cylinders 16, 18 is operated asynchronously, i.e., the transfer tube 24 is assigned to or connected to the conveying cylinder which next performs a suction stroke (instead of the conveying cylinder which next performs a pressure stroke, as in regular pumping operation), therefore in the situation shown in FIG. 8, to the second conveying cylinder 18.

The reverse pumping enables the emptying of the conveying cylinder (in the illustration in FIG. 8, the first conveying cylinder 16) filled with thick material 58 (from the last pumping process) into the hopper 14 as well as the emptying of thick material remaining in the transfer tube 24 or the conveying pipes 56 by the corresponding other conveying cylinder (in the illustration of FIG. 8, the second conveying cylinder 18).

Simultaneously with the reverse pumping, rocking oil 60 is fed via the connecting line 48, for example via a directional control valve 50 (not shown). For this purpose, the directional control valve can be connected to a tank with a rocking oil reservoir, or the supply can be effected by connecting the connecting line 48 to the pressure lines 44, 46 (as is known in principle to a person skilled in the art and is described, for example, in EP 2 867 531 B1).

The reverse pumping according to the invention is carried out by a plurality of alternating piston strokes until a short stroke, i.e., a shortening of the possible stroke of the drive cylinders 38, 40, has ceased by increasing the amount of rocking oil 60 located in the cylinders 26, 28, as is illustrated in FIG. 9. At this moment, the pump is switched off. The size of the short stroke at which the reverse pumping movement of the conveying pistons 16, 18 ceases (i.e., stops) can, for example, be parameterizable, i.e., adjustable or preset. In this situation, the difference or offset between the two cylinder positions is significantly smaller, and the amount of rocking is already significantly reduced.

In a next step, rocking oil 60 is further fed into the drive cylinders 26, 28 until both conveying pistons 34, 36 come to lie in an end position on the hopper side, i.e., close to their front openings 20, 22, as is illustrated in the illustration in FIG. 10.

After reaching the described hopper-side end position of the conveying pistons 34, 36, the transfer tube 24 is reactivated so that it switches back and forth between the two front openings 20, 22. This is illustrated in FIG. 10 by the two transfer tube positions superimposed by dashed lines. According to the invention, the activation of the transfer tube 24 can be time-controlled, wherein the duration of the switching intervals can be parameterized, i.e., adjustable or preset.

During this time, the machine operator can undertake cleaning of the conveying cylinders as described above in connection with FIG. 6.

After ending cleaning, the machine operator can-also as described above-stop the cleaning operating mode by pressing a corresponding button or by re-pressing the button already pressed to initiate the cleaning operating mode, whereupon rocking oil 60 is withdrawn again via the inlet connection until the regular opposite piston positions are reached again.

LIST OF REFERENCE SIGNS

• • 10 thick material pump
  • 12 core pump
  • 14 material feed container or hopper
  • 16 first conveying cylinder
  • 18 second conveying cylinder
  • 20 first front opening
  • 22 second front opening
  • 24 transfer tube
  • 26 first hydraulic drive cylinder
  • 28 second hydraulic drive cylinder
  • 30 common piston rod
  • 32 common piston rod
  • 34 first conveying piston
  • 36 second conveying piston
  • 38 piston of the first drive cylinder, drive piston
  • 40 piston of the second drive cylinder, drive piston
  • 42 water chamber
  • 44 pressure line
  • 46 pressure line
  • 48 connecting line, rocking-oil line
  • 50 3/3-directional control valve
  • 52 inlet connection
  • 54 outlet connection
  • 56 conveying pipe
  • 58 material, thick material
  • 60 rocking oil
  • P pump
  • P1 arrow
  • P2 arrow
  • P3 arrows
  • P4 arrow
  • P5 arrow
  • P6 arrow
  • T tank