EP2107184B1 - Method for the operation of a mixing device for liquid concrete - Google Patents

Description

The invention relates to a method for operating an arrangement for mixing and pumping of liquid concrete, in which liquid concrete mixed in a mixing drum and fed via a buffer tank of a motor-driven concrete pump and is supported by this via a feed line to a concreting, wherein the drive of the concrete pump over a remote control unit on and off and the level in the buffer tank is automatically monitored, the speed of the mixing drum is varied according to the capacity of the concrete pump, the amount of liquid concrete in the buffer tank in accordance with the level in the buffer tank and depending on the drive state of the concrete pump is controlled, wherein the level of the liquid concrete is monitored in the buffer tank at an upper limit position, and wherein upon reaching the upper limit position, an upper limit signal is emitted.

In a known method of this type ( JP-2002-206343A ) liquid concrete is mixed in the mixing drum and fed through the buffer memory of a hydraulically driven concrete pump and conveyed by this over the delivery line to a concreting. During pumping, enough concrete must always be added to the buffer tank to prevent air from being sucked in. Conversely, care must be taken to ensure that the mixer drum does not introduce too much concrete into the buffer tank so that it does not overflow. The overflow has hitherto been prevented by the fact that a level probe was provided in the buffer tank, which turns the mixing drum on and off in the manner of a black and white circuit. Otherwise, the mixing drum and the concrete pump are controlled separately by the concrete pump driver. In particular, this applies to the quantity control the concrete pump and for the speed control of the mixing drum. The faster the mixing drum turns, the more concrete is added to the buffer tank and vice versa. The volume and quantity removal must be coordinated. In the previous procedure, in which the mixing drum was always turned on and off, it came to dynamic load peaks and thus to wear. Further, the abrupt stopping and starting of the mixing drum leads to jerky movements in the chassis and to vibrations in the distribution boom, which are perceived as disadvantageous.

Proceeding from this, the present invention seeks to improve the known method of the type mentioned in that the material supply and removal is better coordinated and that jerky movements when switching on and off the mixing drum are reduced and damped.

To solve this problem, the feature combination specified in claim 1 is proposed. Advantageous embodiments and modifications of the invention will become apparent from the dependent claims.

The solution according to the invention is based primarily on the fact that the drive of the concrete pump is switched on and off via a remote control that the level in the buffer memory is automatically monitored and that the amount of liquid concrete in the buffer tank in accordance with the level in the buffer tank and depending on Drive state of the concrete pump is controlled. In order to be able to harmonize the inflow and outflow of the concrete in and out of the buffer tank, an additional information about the delivery rate of the pump to the drive of the mixing drum must be passed on. In order to make this possible, according to the invention, the delivery rate of the concrete pump is adjusted by a setpoint input to a remote control unit, wherein the amount of liquid concrete added per unit time from the mixing drum at Absence of the upper limit signal higher and in the presence of which is set lower than the capacity of the concrete pump. An important application of these precautions is that the addition of liquid concrete to the buffer tank is reduced to a predetermined intermediate value when the upper limit signal is given and the concrete pump is driven at the same time, and that it is interrupted while the concrete pump is not operating. Another important application is that the quantity addition of liquid concrete in the buffer tank is reduced to an intermediate value when the concrete pump is not driven and is interrupted after the upper limit signal is issued. In both cases, it is ensured that the level of liquid concrete in the buffer tank is kept at a sufficient level, without causing overflow of the buffer tank or an abrupt shutdown of the mixing drum.

Further, it is possible that the level is monitored at a lower limit position, giving a lower limit signal. An important application case is that the quantity addition of liquid concrete is increased at the occurrence of the lower limit signal to an adjustable maximum value, so that sufficient liquid concrete is available for removal. In order to avoid the risk of air suction, which could lead to disturbances in the conveying process, the drive of the concrete pump can be interrupted briefly when the lower limit signal is delivered. The quantity addition of liquid concrete can be increased or reduced by changing the speed of the mixing drum. In particular, the addition of liquid concrete can be interrupted by switching off the mixing drum drive.

In order to better coordinate the concrete inlet and outlet, according to a preferred embodiment of the invention, the delivery rate of the concrete pump is adjusted by a setpoint input on the remote control unit, while the speed of the mixing drum according to specification the set flow rate is varied. In conventional mixing drums, the speed can continuously between 0 and about 13 revolutions per Minute be varied. In order to always ensure a sufficient level and still avoid overflow can be achieved with the provisions of the invention that the amount of liquid concrete per unit time from the mixing drum in the absence of the upper limit signal is higher and in its presence lower than the capacity of the concrete pump. A further improvement in this regard is achieved by reducing the quantity addition of liquid concrete at a predetermined delivery driven concrete pump and delivery of an upper limit signal by a predetermined amount and increases upon delivery of a lower limit signal by a predetermined amount until the respective threshold signal disappears ,

Fig. 1a

und b eine Seitenansicht und eine Rückseitenansicht einer Fahrmischerpumpe im Transportzustand;

Fig. 2

ein Ablaufdiagramm für eine Betriebsoftware der Fahrmischerpumpe;

Fig. 3

ein Mischerdrehzahl/Zeitdiagramm bei vorbekannter Ansteuerung;

Fig. 4

ein Mischerdrehzahl/Zeitdiagramm bei patentgemäßer Ansteuerung.

In the following the invention will be explained in more detail with reference to an embodiment shown schematically in the drawing. Show it

Fig. 1a

and b is a side view and a rear view of a truck mixer pump in the transport state;

Fig. 2

a flow chart for a driving mixer pump operating software;

Fig. 3

a mixer speed / time diagram in previously known control;

Fig. 4

a mixer speed / time diagram with patented control.

The truck mixer pump shown in the drawing consists essentially of a four-axle elongated chassis 10, a rotatably mounted in the central region of the chassis about the axis 12, with its feed and outlet opening 14 obliquely rearwardly facing up mixing drum 16, one with liquid concrete from the mixing drum Chargeable buffer container 18, one connected to the buffer tank, by means of a non-illustrated drive mechanism with variable capacity drivable concrete pump 20 and one in the vicinity of the cab 24,22 'in the vicinity of the cab 24 on a bearing block 26 about a vertical axis rotatably mounted, from a plurality of mutually pivotable mast arms 28,28', 28th Compound boom 30. The concrete pump 20 is formed in the embodiment shown as a rotor hose pump (see. DE 42 04 330 B4 ), to the pressure outlet of which a delivery line 32 is connected, which consists of a plurality of pipe branches connected to the boom arms 28, 28 ', 28 "of the transfer boom 30, which are articulated to each other via rotary joints and which open into a flexible end hose 34 Concrete pump 30 is driven by a hydraulic motor, not shown, with continuously variable speed, so that the flow rate can be controlled continuously Fig. 1b can be seen, the buffer tank 18 is placed laterally next to the eccentrically mounted on the chassis 10 concrete pump 20. Likewise, the concrete boom 30 is arranged laterally offset on the chassis 10 in the folded and resting on the chassis condition.

The mixing drum 16 can be charged with liquid concrete from above via a feed funnel 36 opening into the feed and outlet opening 14. At the bottom of the feed and outlet opening 14 is a Auslasshose 38, which opens with its lower free end in an obliquely downwardly pointing discharge chute 40. The outlet chute 40 opens with its outlet end into the buffer container 18th

The mixing drum 16 is drivable by means of a rotary drive 42 with variable speed.

In addition, the truck mixer pump shown has a microprocessor-controlled control device 44 which in turn is connected to the rotary drive 42 of the mixing drum and the drive mechanism of the concrete pump 20 is and with an operable by the concrete pump driver remote control device 46 is actuated.

In mixer pumps with combined mixer and pump control, the concrete supply via the mixing drum 16 in the buffer tank 18 and the concrete removal via the concrete pump 20 from the buffer tank 18 are coupled together. This means that always sufficient liquid concrete must be refilled during the pumping process, so on the one hand no air is sucked in and on the other hand, the buffer tank does not overflow. It should be noted that the contents of the buffer tank 18 is pumped at maximum capacity of the concrete pump 20 in just a few seconds, so that constantly liquid concrete must be refilled via the mixing drum 16 in sufficient quantity.

A special feature of the invention is that the concrete supply and the concrete removal are coordinated so that a hard braking and restarting the mixing drum 16 is largely avoided. Wear and vibration due to dynamic stress can be effectively reduced.

To enable this, an upper level sensor 48 and a lower level sensor 50 are arranged in the buffer tank 18, which are responsive to the liquid level and which are coupled to the microprocessor-controlled controller 44 and depending on the level emit an upper and a lower limit signal. The controller 44 includes software routines 60 responsive to the presence of the upper and lower limit signals for this purpose. The upper limit signal 62 ensures that when filling the buffer tank 18 overflow is avoided, while the lower limit signal ensures that no air is sucked in via the concrete pump 20. If the control device 44 additionally has a software routine 64 that responds to the operating state of the concrete pump 20 or its delivery capacity, further parameters can be used be taken into account in the control of the liquid concrete supply via the control device. In particular, it is thus possible to match the delivery rate of the concrete pump and the amount of liquid concrete from the mixing drum to each other. The concrete supply is controlled via an adjustable at the rotary drive 42 of the mixing drum discharge speed, while the capacity of the concrete pump by the concrete pump driver can be adjusted continuously via the setpoint generator 45 of the remote control device 46. With the continuity equation, a corresponding emptying speed can be calculated in a software routine 66 on the basis of the delivery rate of the concrete pump set via the remote control device 46.

Since the flow rates during operation are subject to fluctuations, which are dependent on the concrete consistency, for example, differences in the precalculated level can occur despite exact calculations. In order to be able to eliminate these differences in terms of regulation, various strategies are possible:

In the buffer tank 18 there is an upper level sensor 48. According to a first strategy, a little more concrete is always supplied from the mixing drum to the buffer tank 18 than it is conveyed away by the concrete pump 20 to ensure that there is sufficient concrete and no air is drawn. Once the level reaches the upper level probe 48, depending on the operating state of the concrete pump, the concrete supply must be reduced or switched off.

A second strategy is that a lower level probe 50 is additionally arranged in the buffer container 18. In this case, it can be determined metrologically whether the level is too low. In this case, starting from a starting state, the rotational speed of the mixing drum 16 can be increased until the supply quantity corresponds exactly to the discharge quantity. When the pumping process is running, the following applies: In the case of a signal 62 of the upper probe 48 is to reduce the mixer speed, at a signal of the lower probe 50 is to increase the mixer speed.

A third strategy provides that the loading condition of the mixing drum 18 and / or the delivery rate of the pump 20 are continuously measured in order to achieve better matching.

In Fig. 2 FIG. 3 is a typical flowchart of the operating software 44 'arranged in the control device. At the start 68 of the program, liquid concrete is supplied to the buffer tank 18 by emptying the mixing drum 16. Depending on the operating state 64 of the concrete pump 20 (switched on or off) and after scanning the upper probe 48, the emptying speed D of the mixing drum 16 is selected. In the exemplary embodiment shown, when the pump 20 is switched on and the upper limit signal 62 is not output, an emptying speed D = D _{ber is} calculated according to the equation of continuity 66 and the rotary drive 42 of the mixing drum 16 is actuated at this emptying speed: Routine 70. Does the upper probe 48, 60 say 61 by delivering an upper limit signal 62, so with the pump switched on 20.64 (yes) to a reduced discharge speed D = D _{red is} switched: routine 72. When simultaneously deactivated pump 20,64 (no) in this case, the emptying stopped (D = 0): Routine 73. This should prevent overflow of the buffer tank 18.

In addition, if a lower level probe 50 is provided, can with the same flowchart according to Fig. 2 be worked, the lower level probe 50 then acts correctively on the calculation of the emptying speed D _over .

In order to point out the differences in the operating procedure according to the prior art and with the control device 44 according to the invention, reference is made to the in 3 and 4 illustrated diagrams.

In the diagram according to Fig. 3 is a speed curve D (t) of the mixing drum 16 shown in conventional control. The solid line D shows the set by the pump driver discharge speed of the mixing drum 16. The dashed line indicates the delayed over the mixing drum 16 in the buffer tank 16 delivered concrete supply BZ (t), while the dotted line indicates when the liquid level reaches the upper level probe 48 and the upper limit signal 62 is output. After switching on the rotary drive 42, the mixing drum 16 is raised by the concrete pump driver via a starting ramp to the speed D _max . In this case, it comes with a time delay to an addition of liquid concrete BZ in the buffer tank 18. As soon as the liquid level reaches the upper level sensor 42 by issuing the limit signal 62, the rotary drive 42 of the mixing drum 16 is switched off abruptly to avoid an overflow. This leads to a wake of liquid concrete until the mixing drum 16 comes to a standstill due to their inertia. When the level subsequently drops below the upper level probe 42, the upper limit signal 62 disappears and the mixing drum is ramped abruptly to the maximum discharge speed D _max . The concrete supply BZ follows the drum movement with a corresponding delay. In this operating strategy is felt to be disadvantageous that the switching on and off of the mixing drum 16 at the occurrence of the upper limit signal 62 jerky takes place, with the result of increased bearing wear and the excitation of vibrations in the chassis and in the distribution boom.

To avoid these disadvantages, the in the diagram according to Fig. 4 shown operating strategy can be applied. In this case, the mixing drum 16 with a calculated speed D _ber with a reduced speed D _red and in the off state (D = 0) can be controlled. The reversal between the various rotational drive states is in accordance with the presence or absence of the upper limit signal 62 (dot-dashed) and the operating state BF of the concrete pump (Dashed). The rotary drive 42 of the mixing drum 16 is switched in each case via a switch-on and a Ausschalttrampe between the various states. Over time, the following operating states are recognizable:

A short time after starting the mixing drum 16, the concrete pump 20 is turned on. When switched concrete pump 20, the mixing drum 16 moves up to its calculated speed D _over . After the first shutdown of the concrete pump (BF = 0), the speed is reduced to D _red . If the level in the buffer tank 16 reaches the upper level sensor 42, the limit value signal 62 is emitted, which triggers a shutdown of the rotary drive 42 (D = 0) when the concrete pump 20 is switched off. The shutdown state lasts until the concrete pump 20 is switched on again (BF ≠ 0). Since the upper limit signal 62 is output here, the rotary drive 42 of the mixing drum 16 moves to the reduced speed D _red . When the level at the upper filling level sensor 48 is subsequently dropped below, the limit value signal 62 disappears, so that after a short delay time the rotary drive 42 of the mixing drum 16 is raised to the calculated speed D _over . The calculated speed D _ber leads to a flow rate BZ of liquid concrete per unit time, which slightly exceeds the concrete flow BF discharged via the concrete pump 16. Therefore, after a certain time, the upper level 48 is reached again. With the delivery of the fill level signal 62, the mixer speed is reduced again to the value D _red until, when the concrete pump 20 is running, the upper limit signal 62 disappears again and the mixer speed is raised again to D _over . As long is pumped, the mixer speed remains at its calculated value D _over if not at the same time the upper limit value of signal 62 occurs.

This mode of operation leads to a quiet conveying operation within the truck mixer pump and thus to less wear and less vibration phenomena.

In summary, the following should be noted: The invention relates to a mixer pump for liquid concrete, in which liquid concrete mixed in a mixing drum and fed via a buffer memory 18 of a motor-driven concrete pump 20 and is conveyed by this via a feed line 32 to a concreting. It is essential that the drive of the concrete pump 20 via a remote control unit 46 is turned on and off, that the level in the buffer tank 18 is automatically monitored and that the amount of liquid concrete in the buffer tank 18 in accordance with the level in the buffer tank and in dependence on the drive state Concrete pump 20 is controlled.

Claims (9)

1. Method for operating an arrangement for mixing and pumping liquid concrete, in which liquid concrete is mixed in a mixing drum (16) and is fed via a buffer container (18) to a motor-driven concrete pump (20) and is delivered from there via a delivery line (32) to a concreting location, wherein the driver of the concrete pump (20) is switched on and off by means of a remote control unit (46), and the filling level in the buffer container (18) is monitored automatically, wherein the rotation speed (D_ber) of the mixing drum (16) is varied in accordance with the delivery capacity of the concrete pump, wherein the amount of liquid concrete fed into the buffer container (18) is controlled in accordance with the filling level in the buffer container (18) and as a function of the drive state of the concrete pump (20), wherein the filling level of the liquid concrete in the buffer container (18) is monitored at an upper limiting position (48), and wherein, when the upper limiting position is reached, an upper limiting value signal (62) is output,
   characterized
   in that the delivery capacity of the concrete pump (20) is set by means of a setpoint value prescription (45) at a remote control unit (46), and in that the amount of liquid concrete fed in per time unit from the mixing drum (16) is set to a higher value when the upper limiting value signal (62) is not present, and to a lower value when it is present, than the delivery capacity of the concrete pump (20).
2. Method according to Claim 1, characterized in that the quantity of liquid concrete fed into the buffer container (18) when the upper limiting value signal (62) is being output, together with simultaneous driving of the concrete (20), is reduced to a predefined intermediate value (D_red), and is interrupted in the case of simultaneous non-driving of the concrete pump (20).
3. Method according to Claim 1 or 2, characterized in that the amount of liquid concrete fed into the buffer container (18) in the case of non-driving of the concrete pump (20) is reduced to an intermediate value (D_red), and is interrupted after the upper limiting value signal has been output.
4. Method according to one of Claims 1 to 3, characterized in that the filling level is monitored at a lower limiting value position (50) by outputting a lower limiting value signal.
5. Method according to Claim 4 characterized in that the amount of liquid concrete which is fed in when the lower limiting value signal is output is increased to an adjustable value (D_ber).
6. Method according to Claim 4 or 5, characterized in that the driving of the concrete pump (20) is interrupted when the lower limiting value signal is output.
7. Method according to one of Claims 1 to 6, characterized in that the amount of liquid concrete fed in is increased or reduced by changing the rotational speed of the mixing drum (16).
8. Method according to one of Claims 1 to 7, characterized in that the amount of liquid concrete fed in is interrupted by switching off the rotational drive of the mixing drum (16).
9. Method according to one of Claims 1 to 8, characterized in that the amount of liquid concrete fed in when the concrete pump (20) is being driven with a predefined delivery capacity and when an upper limiting value signal (62) is being output is reduced by a predefined quantity, and when a lower limiting value signal is being output it is increased by a predefined quantity, until the respective limiting value signal disappears.

Images