Patent Application
20070196219
The invention concerns a device and a process for controlling a two cylinder thick matter pump with two conveyor cylinders communicating via end openings in a material supply container operable in counter stroke by means of a hydraulic reversible pump and via hydraulic drive cylinders controlled by the pump, with a hydraulic actuated pipe switch provided within the material supply container, of which the inlet side is alternatingly connectible to one of the openings of the conveyor cylinders leaving open the respective other opening and on the outlet side is connected with a conveyor line, wherein at each conveyor stroke the passing-by of the piston is detected at least two sensor positions spaced a predetermined distance from each other and from the rod and/or bottom side end of the drive cylinder, and upon ending of the conveyor stroke initiates a switching process of the reversible pump and the pipe switch, wherein respectively upon conclusion of the one advance stroke a reversal process of the pipe switch is initiated, wherein further the drive cylinders, forming a closed hydraulic circuit, are hydraulically connected with respectively one connection at one of their ends to the reversible pump and to each other via an oscillating hydraulic line at their other end, and wherein hydraulic pressure branched or tapped out of the hydraulic lines leading from the reversible pump to the drive cylinders is used for reversing the pipe switch.
A device for control of a two cylinder thick matter pump of this type is known (DE 195 42 258), in which the end position of the piston of the drive cylinder can be determined by means of cylinder switch sensors for producing end position signals. The flow-through reversal of the reversible pumps is there initiated by the end position signal of the drive cylinder. As a rule the end position signal is conventionally triggered via the two cylinder switch sensors located at the rod end of the cylinder. It often happens that the cylinder switch sensors fail. In such a case it is necessary to switch to manual operation or to turn off the machine.
Beginning therewith it is the task of the present invention to develop a device and a process, with which, even in the case of failure of the hitherto conventional cylinder switch sensors, a reliable pump operation can be ensured with continuous flow of concrete.
For the solution of this task the combination of characteristics set forth in the main patent claims is proposed. Advantageous embodiments and further developments of the invention can be seen from the dependent claims.
The inventive solution is based primarily upon the recognition, that in consulting a computer control, supplemental operating data can be derived from the hydraulic circuit for control of the reversible pump and the pipe switch.
A first variation of the solution envisions that the reversing device includes a computer assisted device for determining the predicted stroke duration and for the registration thereof in a memory device as well as for monitoring the time during each piston stroke and for initiating a pipe switch control and a reversal of the flow in the reversible pump according to the measure of the defined stroke time, with comparison to an anticipated elapsed stroke duration. Preferably the reversal device therein exhibits a time monitoring routine, which includes an algorithm for determining a comparison value from actual stroke time and predicted stroke duration and to their conversion, upon exceeding a predetermined value, into a reversal signal for the pipe switch and/or the reversible pump. One advantageous embodiment of the invention envisions therein that the reversing device includes an input routine for recording in memory the stroke duration measured during a calibration of the concrete pump with at least one specific defined conveyance amount. Since the conveyed amount can be varied in computer-controlled concrete pumps, for example via a remote control device, it is of particular advantage when the reversing device includes a computer routine for variably converting the registered stroke duration based upon the conveyance amount input from the remote control device.
According to a preferred or alternative embodiment of the invention a sensor is provided for monitoring the hydraulic pressure on the hydraulic pressure side of the reversible pump, which output signal can be evaluated by a pressure monitoring routine of the reversing device for initiating a pipe switch reversal and flow-through reversal of the reversible pump. For this purpose an average pump pressure can be determined and stored in memory during each pressure stroke. The pressure monitoring routine then provides an algorithm for determining the pressure increase occurring at the end of each pressure stroke in the concerned drive cylinder relative to the average pressure value and for the translation thereof into a reversal signal for the pipe switch and/or reversible pump.
If one cylinder switch sensor responsive to the pistons as they pass by is provided respectively spaced apart from the rod end and bottom end of the drive cylinders, then the reversing device can, besides this, include a path monitoring routine responsive to the output signal of the selected cylinder switch sensor for initiating the pipe switch reversal and/or flow-through reversal of the reversible pump. The reversal device can in this case supplementally include a measurement routine for determining the stroke duration from the initiation signals of the cylinder switch sensors and to their recordation. The stroke durations recorded in a memory in this manner can, in emergency cases, be employed for controlling the time of the flow-through reversal.
One preferred embodiment of the invention envisions that on the path monitoring routine corresponding to the selected cylinder switch sensors, the pressure monitoring routine responsive to the pressure measurement values, and the time monitoring routine responsive to the stroke time, can form a, preferably hierarchical structured, redundant program sequence for controlling the pipe switch and/or reversible pump.
The inventive control, in normal operation, switches the reversible pump upon reaching the base side cylinder switch and insures therewith a continuous flow of concrete. At the same time, during operation the respective stroke duration is calculated and the average high pressure at the pressure outlet of the reversible pump is determined and stored in the data storage.
In the case that at least one of the rod side cylinder switch sensors fails, the control for the further operation of the pump can automatically be switched to one of the base side cylinder switch sensors. The rod side cylinder switch sensors are on the one hand given priority. During operation however the rod and the base side cylinder sensors are monitored, and can be activated independently of each other for the above mentioned measuring processes.
In the case that three or all four cylinder switch sensors fail, it is possible with the inventive supplemental measures to monitor the stroke time from the last reversal process and to compare this with the registered stroke duration. The expected stroke duration can be calculated from the conveyed amount, the RPM and the viscosity of the conveyed material. If the stroke time has approximately elapsed, then the high pressure at the pump output is compared with the average stored high pressure of the actual stroke. In the case of an increase of the pressure beyond the predetermined threshold, in this case an override reversal can be initiated.
In so far as the measured stroke time exceeds the registered stroke time and during this time no increase in pressure was determined, a forced or override reversal can occur on the basis of the time measurement alone. Therewith it is ensured that also in the case of a loss of a pressure sensor an automatic further operation of the concrete pump can continue.
For simplification of the pump control the present described measures can also be employed individually for switching over the pipe switch and the reversible pump.
In the following the invention will be described in greater detail on the basis of the illustrative embodiment shown in schematic manner in the figures. There is shown
The control arrangement shown in
In the shown illustrative embodiment the drive cylinders 5, 5′ are acted upon with hydraulic pressure on their base side via hydraulic lines 11, 11′ of the hydraulic circulation with the aid of the reversible pump 6 and are on their rod side end connected hydraulically with each other via an oscillating oil line 12. The direction of movement of the drive pistons 8, 8′ and therewith the common piston rods 9, 9′ are reversed when the flow-through direction of the reversible pump 6 is reversed via a reversing device 18 comprising a computer 14 and a switch mechanism 16. The reversible pump 6 has, for this purpose, a slant disk 62, which for reversing is pivoted through its zero position, so that the oil pressure in the hydraulic lines 11, 11′ is reversed. The amount conveyed via the reversible pump 6 can be varied, while keeping constant a predetermined rotational speed of a not shown drive motor, by changing the pivot angle of the slant disk 62. The pivot angle of the slant disk 62 can therein be adjusted via a remote control device 64 with support of a computer 14.
The reversing of the reversible pump and the pipe switch 56 occurs as soon as the piston 8, 8′ of the drive cylinders 5, 5′ reach their end position. The reversing control device 18 exhibits for this purpose multiple redundant control routines, which are integrated with each other to form a hierarchical structured program sequence (See
The reversing device evaluates output signals of the respective cylinder sensors 20, 22 and 20′, 22′, located respectively a distance from the rod side and base side ends of the two drive cylinders 5′, 5′, which on the output side are connected with the computer 14 of the control device 18. The cylinder switch sensors react to the drive pistons 8, 8′ passing by during operation of the pump, and signal this occurrence to the computer input 66, 68. Upon occurrence of the output signals a reverse signal 76 is initiated in the reversing device, which reverses the reversible pump 6 via the actuating mechanism 16. In the course of the reverse process there is initiated, besides this, a switching of the pipe switch 56 via the directional valve and the plunger cylinder 72, 72′. In normal operation it is primarily the signals of the rod side cylinder switch sensors 20, 20′ which are employed for producing a reverse signal. For this, the computer 14 includes a path monitoring routine 40, in which the output signal of the rod side cylinder switch sensors 20, 20′ are evaluated with formation of a switching or reversing signal 76 for the reversible pump 6 and/or the pipe switch 56. In the case that at least one of the rod side cylinders switch sensors 20, 20′ fails, at least one of the base side cylinder switch sensors 22, 22′ is activated in the place of the failed sensor for forming the reverse signal 76 via the monitoring routine 40.
The switching or reversing device 18 further includes a pressure sensor 24, which is connected on the high pressure side 78 of the reversible pump 6 and of which the output signal is evaluated in the computer 14 with the aid of a pressure monitoring routine 80. The pressure monitoring routine 80 determines in the course of a stroke displacement an average high pressure and includes an algorithm for determining a pressure increase occurring at the end of each conveyance stroke and for the conversion thereof into a reverse signal 76′ for the reversible pump 6 and/or the pipe switch 56. This reversing signal is preferably used for reversing in the case of a failure of the cylinder switch sensors 20, 20′; 22, 22′.
Further, in the case of the calibration of the concrete pump, a stroke duration can be determined depending upon the conveyed amount and drive RPM of the reversible pump 6, and this information be recorded in the memory or data storage of the computer 14. Also, during the pump operation the stroke duration can be measured and recorded via the rod side and base side cylinder switch sensors 20, 20′; 22, 22′ depending upon the input amount to be conveyed and the motor RPM. If, in addition thereto, after each reversal process the stroke time is monitored and compared with the recorded stroke duration, a reverse signal 76″ for the reversible pump 6 and/or the pipe switch 56 can be derived therefrom, via a stroke monitoring routine 82 of the computer 14. The comparison routine 82 preferably includes an algorithm, which also makes possible a conversion of the stored stroke duration in the case of a change in the conveyed amount and/or the motor RPM. With the therefrom derived reversal signal 76″ it is ensured, that also in the case of a failure of the cylinder switch sensors 20, 20′; 22, 22′ and pressure sensor 24 or, in the case of the absence of these sensors, an automatic reversing of the reversible pump 6 and the pipe switch 56 can be initiated.
In the described reversing device there can be interconnected with each other to form a redundant, priority structured program sequence (
In summary the following can be concluded: The invention relates to a device and a method for controlling a two-cylinder thick matter pump comprising conveyance pistons that are actuated in a push-pull manner by means of a hydraulic reversible pump 6 and hydraulic drive cylinders controlled by said pump. For each pressure stroke, the conveyance cylinders 50, 50′ are connected to a conveyance conduit 58 by means of a pipe switch 56. At the end of each conveyance stroke in the conveyance cylinders 50, 50′, a reversal process of the pipe switch 56 and the reversible pump 6 is triggered. The aim of the invention is to ensure a reliable operation of the pump, even in the event of a breakdown of switch and pressure sensors 20, 22, 24. To this end, during the calibration of the concrete pump and/or during the operation of the pump, the actual length of the stroke of the pistons 8, 81 in the drive cylinders 5, 5′ is measured and recorded as expected value, the stroke time of each conveyance stroke is monitored and compared with the expected stroke duration, and the reversible pump 6 is respectively pivoted, reversing the flow, and/or the pipe switch 56 is reversed, when the stroke time exceeds the expected stroke duration by a pre-determined value. The output signals of a pressure sensor 24 connected to the reversible pump 6 or cylinder switching sensors 20, 20′ arranged on the working cylinders can also be evaluated in order to trigger a reversal process.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 015 415.5 | Mar 2004 | DE | national |
This application is a national stage of PCT/WO2005/093252 filed Mar. 18, 2005 and based upon DE 10 2004 015 415.5 filed Mar. 26, 2004 under the International Convention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/02895 | 3/18/2005 | WO | 9/8/2006 |
