METHOD AND DEVICE FOR FILLING A CONTAINER WITH A FILLING PRODUCT

Description

Technical field

[0001] The present invention relates to a method and a device for filling a container with a filling product by means of a continuously openable filling valve in combination with a device for determining an actual volume flow rate. State of the art

[0002] Methods for filling a container with a product are known from the prior art, in which the product is fed into the container by means of a filling device. It is known to vary the volumetric flow rate of the product into the container over the filling period. For example, it is known to start the filling process with a low volumetric flow rate to reduce the initial tendency of the product to foam due to the high drop height into the container and the impact of the product on the container bottom. Subsequently, the volumetric flow rate is maximized in such a filling process to achieve the fastest possible filling of the container.Once a certain fill level, filling time, or volume is reached, the flow rate introduced into the container is reduced to minimize foaming and ensure the filling process is completed. The filling process then ends—depending on the specific filling method—when a certain fill level, weight, time, or volume is reached. The shut-off mechanisms used for this purpose are generally known.

[0003] For filling containers with a product, for example in a beverage bottling plant, it is known to use filling devices which are usually arranged above the containers to be filled and which, among other things, control the volume flow into the container by means of a product valve. A product valve, which is, for example, incorporated into a filling device, typically comprises a valve body movable relative to a valve seat, which, when fixed in the valve seat, blocks the flow of the product and, when lifted out of the valve seat, allows the product above the product valve to flow out.

[0004] The movement of the valve body relative to the valve seat is typically pneumatically controlled. Conventional pneumatic actuators allow only two switching positions: fully closed and fully open. Accordingly, the flow rate into the container can only be either switched on or off. Varying the flow rate when filling the container with the product can be achieved, for example, by means of a throttle valve installed upstream of the actual filling valve. This upstream throttle valve allows the flow rate to be reduced or increased according to switching points defined by a target flow rate.

[0005] Alternatively, to vary the flow rate, a filling valve that can be opened essentially continuously is known. In this way, the flow rate flowing into the container to be filled can be varied by continuously adjusting the opening of the filling valve itself. Such a continuously opening filling valve enables proportional control of the flow rate, especially when coupled with a flow meter. The actual flow rate is measured by the flow meter, and a control system adjusts the continuously opening filling valve to the flow rates specified by a target flow rate.

[0006] EP 1 762 539 A1 describes a method and a device for filling containers with a specific quantity of liquid. EP 2 915 775 A1, published after the priority date of the present application, describes a device and a method for filling a container with a product. WO 2004 / 051200 A1 describes a method for controlling the flow rate in filling plants. WO 2008 / 126119 A1 describes a filling valve and a method for filling a container. Description of the invention

[0007] Starting from the known state of the art, it is an object of the present invention to provide a method and a device for filling a container with a filling product which exhibits a further improved filling behavior.

[0008] This problem is solved by a method with the features of claim 1. Advantageous further developments result from the dependent claims.

[0009] Accordingly, a method for filling a container with a product is proposed using a continuously adjustable filling valve and a device for determining the actual volume flow rate, wherein a target volume flow rate is specified. According to the invention, a pre-stored opening position of the filling valve is controlled for a predetermined value of the target volume flow rate, the pre-stored opening position being determined by a prior control process for the specified target volume flow rate.

[0010] By controlling a pre-stored opening position for a predetermined target flow rate, the actual flow rate can reach the target flow rate more quickly without excessive overshoot in the continuously variable filling valve. In particular, the overshoot that would occur in a purely control-based process can be reduced or even eliminated by controlling the pre-stored opening position. Using the pre-stored opening position, the filling valve can therefore be moved so quickly to an opening position that correlates with the target flow rate because the pre-stored opening position was determined in a previous control process and thus achieved for this specific filling valve and the respective ambient conditions.

[0011] In this way, it is possible to use the opening position of the filling valve, which was already reached in a previous filling process via a control loop encompassing the device for determining the actual flow rate, as a pre-stored opening position in one, several, or all subsequent filling processes. Accordingly, the filling valve can immediately move to the opening position that was determined in the previous filling process to be the closest possible opening position to the target flow rate. This allows a constant flow rate corresponding to the target flow rate to be established quickly or achieved in a subsequent control process.

[0012] Preferably, the pre-stored opening position is the one reached in the previous control process immediately before a change in the target volume flow rate. This ensures that the control process is as smooth as possible and that the pre-stored opening position corresponds as closely as possible to the specified target volume flow rate.

[0013] As a preferred refinement, the pre-stored opening position can be determined as the average of the opening positions for a given target flow rate, in order to eliminate any oscillations at the end of the control process. Particularly preferably, the average is calculated over a predetermined segment of the target flow rate, preferably a predetermined time segment, to achieve different weighting of different control segments. These methods of determining the pre-stored opening position make it possible to average out any transient responses that occur when the target flow rate is changed again, thus providing an improved pre-stored opening position for the filling valve during the subsequent filling process, even if the control system has not yet fully settled.

[0014] Preferably, the pre-stored opening position is defined as the starting point for a subsequent control process. Accordingly, the pre-stored opening position of the filling valve is first approached for the respective target flow rate, and then, starting from this opening position, the control process is carried out again, taking into account the measured actual flow rate. This direct control of the opening position avoids initial overshoot, and the subsequent control can be performed from an improved starting point, namely the pre-stored opening position. The control system allows for further refinement of the opening position and can also accommodate changing conditions, such as changes in temperature or the level of the product being filled.

[0015] It is particularly advantageous for the control process to begin only after a delay following the reaching of the pre-stored opening position. Depending on the spring constant of the system, the subsequent control process can thus only commence after a predetermined time has elapsed, such that a constant actual volume flow is first established at the pre-stored opening position, calming the system which was excited to oscillation by the switching process, and only then is the control process carried out starting from this constant actual volume flow.

[0016] In a preferred alternative, the opening position is controlled from a pre-stored opening position only for selected filling processes, preferably only for every second, fifth, tenth, or fiftieth filling process. This allows for a particularly efficient filling process, and a separate control process for each individual filling process is not necessary. Depending on the rate of change of the operating parameters, such as the temperature and the fill level of the product upstream of the filling valve, the frequency of the control process can be specified as more or less frequent.

[0017] Accordingly, the system learns with each filling process, so that after a finite number of filling cycles, the pre-stored opening position essentially or exactly achieves the specified target flow rate, and even when a subsequent control process is initiated, no further control takes place in principle. Thus, a virtually overshoot-free, precise filling process can be achieved by controlling the respective pre-stored opening position of the continuously variable filling valve.

[0018] The respective pre-stored opening position is preferably controlled via a ramp, which preferably corresponds to the ramp of the target volume flow. In this way, the specified target volume flow can be followed as closely as possible without causing excessive control movements or overshoot.

[0019] The proposed method is preferably carried out separately for each filling valve, so that mechanical tolerances in the filling valves as well as different positioning and different flow characteristics of the individual filling valves can be compensated for.

[0020] The problem set out above is also solved by a device having the features of claim 11.

[0021] Accordingly, a device for filling a container with a filling product is proposed, comprising a continuously adjustable filling valve, a device for determining an actual volume flow rate, and a control system for regulating the opening position of the filling valve based on a predetermined target volume flow rate and the actual volume flow rate, and further comprising a control device. According to the invention, the control device is designed and configured to carry out the method described above. Brief description of the characters

[0022] Preferred further embodiments and aspects of the present invention are explained in more detail by the following description of the figures. These show: Figure 1 is a schematic representation of a filling process during a preceding filling process; Figure 2 is a close-up of a section of the filling process. Figure 1 Figure 3 is a schematic representation of a filling process during a downstream filling process; and Figure 4 is a close-up of a section of the filling process. Figure 3 . Detailed description of preferred embodiments

[0023] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are designated with identical reference numerals, and repeated descriptions of these elements are sometimes omitted in the following description to avoid redundancy.

[0024] In Figure 1 The graph shows schematic curves where the time t of a filling process is represented on the X-axis and different parameters are plotted on the Y-axis.

[0025] The solid line represents the specified target volume flow rate 1, which is required for the [unclear text]. Figure 1 The filling process shown schematically is specified by the plant operator for the respective product. The target volume flow rate 1 is usually specified differently by the plant operator for each container type and each product to ensure gentle yet efficient filling. The foaming tendency of the product plays a particularly important role in determining the target volume flow rate 1, as a higher foaming tendency necessitates a lower volume flow rate earlier in the filling process to prevent overflow and subsequent over-foaming.

[0026] Accordingly, a target flow rate 1 is initially set to a high target flow rate 10 for rapid filling of the container, which is then reduced to a lower target flow rate 12 towards the end of the filling process. It is taken into account that, at least from a fluid dynamics perspective, a product valve should not be switched abruptly to avoid unnecessarily exciting vibrations in the overall system. Therefore, the target flow rate 1 is switched from the high target flow rate 10 to the lower target flow rate 12 via a ramp 14.

[0027] The dashed curve in the figures represents the measured actual volume flow rate 2 of the filling product through the filling valve, which is measured, for example, by means of a flow meter or another measuring method.

[0028] A control system continuously compares the target volume flow 1 with the actual volume flow 2 to determine a control variable, which regulates the opening position 3 of the filling valve.

[0029] The dotted curve shown in the figures represents the opening position 3 of the filling valve. As can be seen from the figures, the opening position 3 is correlated with the actual volume flow rate 2, because at a given opening position 3, a corresponding actual volume flow rate 2 is reached after a settling-in period.

[0030] The total volume of product 4 flowing into the container throughout the entire filling process is shown by the dash-dot curve. This product volume 4 is the time integral of the actual volume flow rate 2. The filling valve shuts off at time 40, at which point the desired filling volume for the respective container is reached. At time 40, the filling valve closes, thus ending the filling process.

[0031] Conventional methods for filling a container with a product using a continuously variable filling valve typically employ a PD controller or a PID controller to perform the control operations. Accordingly, the respective PD or PID controller is parameterized identically for all filling valves, resulting in less than optimal control outcomes, as the individual filling valves or filling points usually differ slightly. Consequently, the control variables with respect to the target flow rate cannot be optimally determined, and individual adaptation to each specific filling valve or filling device is not possible.

[0032] Accordingly, the results, for example, from the Figures 1 and 2Recognizable overshoots 30 in the opening position 3 of the filling valve result in corresponding overshoots 20 of the actual volume flow rate 2. These overshoots 20 of the actual volume flow rate 2 also depend on the respective spring constant of the system, which is set into oscillation anew each time the filling valve switches.

[0033] Such overshoots 20, 30 occur, for example, when the target volume flow rate 1 is reduced from the high target volume flow rate 10 to the lower target volume flow rate 12 towards the end of the filling process. The overshoot 20, 30 occurs here both with respect to the opening position 3 and with respect to the actual volume flow rate 2.

[0034] From the Figures 1 and 2It follows that after the target flow rate 1 is reduced to the lower target flow rate 12, a stable state is not reached until the shutdown point 40. Instead, the actual flow rate 2 oscillates around the lower target flow rate 12, causing the opening position 3 of the filling valve to oscillate accordingly. The overshoot 20, 30 during the switching process of the filling valve from the high target flow rate 10 to the lower target flow rate 12, as well as the oscillation until the shutdown point 40, is due, among other things, to a suboptimal parameterization of the PD controller. Consequently, a completely stable control state for the opening position 3 of the filling valve cannot be achieved at the lower target flow rate within the available time. At the shutdown point 40, before the actual closing, the filling valve assumes an opening position 32, which can vary for each individual filling process.

[0035] The in the Figures 1 and 2 The curves shown for the actual volume flow rate 2 and the opening position 3 are fully controlled curves, in which a PD controller is only supplied with the target volume flow rate 1 and the actual volume flow rate 2, and the corresponding manipulated variable for controlling the opening position 3 is determined from this. The overshoot 20, 30 and the ringing result, among other things, from the parameterization of the control system not being optimized for the respective application.

[0036] To promote the achievement of a steady state and thus reduce the overshoot and after-oscillation of the actual volume flow rate 2 and the opening position 3, it is proposed that, in a control process such as the one described in the Figures 1 and 2 shown, the opening position 32 at the shutdown time 40 is to be stored as a pre-stored opening position 32 for the corresponding lower target volume flow 12 for a subsequent filling process.

[0037] In a subsequent filling process, such as that which occurs, for example, in the Figures 3 and 4 As shown, the pre-stored opening position 32 is then directly approached for the specified lower target volume flow rate 12, so that the pre-stored opening position 32 is adopted as the starting position for the further control process at the lower target volume flow rate 12. Accordingly, this can be implemented in the Figures 1 and 2 The excessive overshoot shown 20, 30 of the opening position 3 and the actual volume flow 2 can be reduced, since the pre-stored opening position 32 is activated at the specified target volume flow 12.

[0038] The control process then continues as before, such that, starting from the pre-stored opening position 32, the opening position 3 is again adjusted to the lower target volume flow 12 specified via the target volume flow 1, based on the actual volume flow 2 detected by the flow meter.

[0039] For example, as can be seen from Figure 4 This results in a quasi-static level for the opening position 3 being reached at the switch-off time 40 in the second pass, which is then stored as a new pre-stored opening position 32' for the subsequent filling process. Accordingly, in the illustrated embodiment, a quasi-stable state or a quasi-stable opening position 3 for a lower target volume flow 12 specified via the target volume flow 1 can be reached after only two passes.

[0040] This newly pre-stored opening position 32' will again be the first position reached in the next filling process in order to achieve the specified lower target volume flow rate 12. If the external conditions, for example the pressure of the product in the filling valve, have not changed or have not changed significantly between the two filling processes, it is possible that the specified lower target volume flow rate 12 will be reached immediately as the actual volume flow rate 2 simply by using this second pre-stored opening position 32'.

[0041] The procedure described above can be used for any desired change in the target volume flow rate 1, not only for reducing the high target volume flow rate 10 to the lower target volume flow rate 12. For this purpose, the opening position of the controller prior to the change is stored for this target volume flow rate and, in a subsequent filling process, is directly used as the starting point for the subsequent control.

[0042] Accordingly, once the opening position of 32' has been stored, under the same conditions, no further or no significant adjustments can be made, making the control process quick and simple. However, if the conditions change, a new control process takes place, such that an optimized starting position can be reached again during the subsequent filling process using the then pre-stored opening position.

[0043] In the case of a target volume flow curve 1 that repeatedly reaches the same target volume flow values ​​during a filling process, the opening position stored when the value was previously reached can be used as the starting value when the desired value is subsequently reached.

[0044] The pre-stored opening position 32, 32' for the specified target volume flow 1, which is in the respect of the Figures 1 and 2The point at which the specified target volume flow is reached at the switching-off time 40 in the illustrated embodiment, or at which a change in the specified target volume flow occurs, can also be determined in other ways.

[0045] In particular, it is also possible here to calculate an average value for opening position 1 either over a predefined time window, for example, the last second before the change in the target volume flow rate 1, or over the entire period, starting from the change in the target volume flow rate 1 and continuing until a further change in the target volume flow rate 1. When calculating the average value, for example, the oscillation processes or decay processes, which are particularly noticeable in Figure 2which are clearly recognizable, can be better balanced, so that the pre-stored opening position determined in this way can meet the predetermined target volume flow 12 even better than a simple determination of the opening position 32 when reaching the switch-off time 40.

[0046] Furthermore, the control process following the attainment of the pre-stored opening position 32, 32' can be started either immediately after reaching the pre-stored opening position or only after a certain delay. Depending on the spring constants of the system, it may be advantageous to first reach the pre-stored opening position 32, 32', then wait for the system to stabilize, and only then begin the further control process. For example, a time delay of 100 milliseconds to 500 milliseconds can be provided after reaching the pre-stored opening position 32, 32', after which the control process resumes via a PD controller or PID controller.

[0047] The speed of approaching the pre-stored opening position 32, 32' from the previous opening position 1 preferably results from the ramp 14 specified via the target volume flow rate 1. Here, as for example in Figure 2 schematically shown, a ramp 14 is specified for changing the opening position 3 from the high target volume flow 10 to the lower target volume flow 12, which is then also used as a specification for the movement of the filling valve to the pre-stored opening position 32, 32'.

[0048] In this way, it remains possible to enable optimized approach to opening positions for each individual filling valve of a filling system, regardless of the originally specified parameter set of a PD or PID control.

[0049] Regarding the target volume flow rate 1, it should be noted that the overshoots shown 20, 30 occur with conventional PD or PID controls particularly when steep ramps have to be driven, as can be seen from the Figures 1 and 2 This also results directly. In normal filling operation, these respective steep ramps are usually followed by plateaus in which the target volume flow rate 1 is to be kept constant. The opening position 3 of the filling valve reached at the end of the respective plateau of the target volume flow rate 1 is the one that should ideally have been reached at the beginning of the control process, i.e., at the beginning of the respective plateau. Accordingly, this opening position 3, reached at the end of the respective plateau, can then be stored as a pre-stored opening position 32, 32', essentially as "Experience value", used for the subsequent filling process.

[0050] If the system has learned the different opening positions 32, 32' for all target volume flows 1, the entire filling process can be carried out simply by approaching the respective pre-stored opening position 32, 32' without subsequent control.

[0051] Furthermore, it is possible to carry out the following procedure not with every filling process, but only, for example, with every second, third, tenth, fiftieth, etc. filling process, and to carry out the filling process at other times simply by moving to the pre-stored opening positions 32, 32'.

[0052] To carry out the aforementioned method, a device with a continuously adjustable filling valve is preferably provided, which can be moved to the respective predetermined opening position 3 by means of a suitable actuator. Using a control system known per se, for example a PID controller or a PD controller, the opening position 3 of the filling valve can be adjusted according to a predetermined target flow rate 1, based on a flow meter connected to the controller. Accordingly, the opening position 3 of the filling valve is adjusted so that the predetermined target flow rate 1 is reached as quickly as possible.

[0053] Additionally, a control device is provided which is designed and configured to store an opening position 32, 32' of the filling valve for each predetermined target volume flow rate 1 for the next filling cycle or for a subsequent attainment of a value of the previous target volume flow rate 1. In particular, an opening position 32, 32' of the filling valve is stored here, which is reached in the widest possible swing state of the control system for the respective predetermined target volume flow rate 1. This is the case, for example, at the end of a plateau of the target volume flow rate 1, whereby the pre-stored opening position 32, 32' can also be calculated from the control curve and the corresponding opening positions 3 assumed.

[0054] By means of the control device, the corresponding pre-stored opening position 32, 32' can then be approached during the next filling process for the respective specified value of the target volume flow 1, in order either to carry out the filling process with this pre-stored opening position 32, 32', or to provide a starting point for a new control process.

[0055] The corresponding control device is preferably configured to perform the procedure described above and to drive each filling valve separately, so that an optimized filling process can be provided for each individual filling valve of a filling system.

[0056] Where applicable, all individual features shown in the individual embodiments can be combined and / or exchanged without leaving the scope of the invention. Reference symbol list

[0057] 1 Target volume flow 10 High target volume flow 12 Lower target volume flow 14 Ramp 2 Actual volume flow 20 Overshoot 3 Opening position 30 Overshoot 32, 32' Pre-stored opening position 4 Fill product volume 40 Shutdown time

Claims

1. Method for filling a container with a fill product by means of a filler valve which can be opened steplessly and a device for determining an actual volume flow (2), wherein a required volume flow (1) is specified, characterized in that for a specified value of the required volume flow (12) the filler valve is controlled to adopt a pre-stored open position (32, 32'), wherein the pre-stored open position (32, 32') was determined by a prior control process for the specified required volume flow (12).

2. Method according to claim 1, characterized in that the open position (3) that is stored as the pre-stored open position (32, 32') is that which was reached in the previous control process prior to a change in the value of the required volume flow (1), preferably shortly prior to a change.

3. Method according to claim 1 or 2, characterized in that the pre-stored open position (32, 32') is determined as the mean value of the open positions (3) for a specified required volume flow (1).

4. Method according to claim 3, characterized in that the mean value is calculated over a specified segment of the required volume flow (1), in particular a specified time segment.

5. Method according to one of the previous claims, characterized in that the pre-stored open position (32, 32') is set as the starting point for a subsequent control process.

6. Method according to claim 5, characterized in that the control process is begun only following a delay after the pre-stored open position (32, 32') is reached.

7. Method according to one of the previous claims, characterized in that the open position (3) is controlled based on a pre-stored open position (32, 32') for every filling process.

8. Method according to one of claims 1 to 6, characterized in that the open position (3) is controlled based on a pre-stored open position (32, 32') only for selected filling processes, preferably for every second, fifth, tenth or fiftieth filling process.

9. Method according to one of the previous claims, characterized in that the pre-stored open position (32, 32') is adopted via a ramp (14).

10. Method according to one of the previous claims, characterized in that every filler valve of a beverage filling plant is individually controlled.

11. Device for filling a container with a fill product, comprising a filler valve which can be adjusted steplessly, a device for determining an actual volume flow (2), and a controller for controlling the open position (3) of the filler valve based on a specified required volume flow (1) and the actual volume flow (2), further comprising a control device, characterized in that the control device is designed and configured to carry out the method described in one of the previous claims.