Method and apparatus for controlling dosing of fluid product to container

Abstract

A method and apparatus for controlling dosing of a fluid product to a container. The method (200) for controlling dosing of a fluid product to a container (105) using a device (100) comprising a plurality of filling valves (104) comprises performing, for each filling valve (104), a cycle having the following steps: sending an opening command to the filling valve (104); detecting a volume value and a flow value of the fluid product dispensed by the filling valve (104), the detection occurring at a predetermined sampling interval; calculating a compensation volume (CV) as a difference between a target volume (TV) to be dispensed into the container (105) and a volume filling error (E) detected immediately before the filling step; determining a compensated closing time (CCT) as a time to send a closing command to the filling valve (104); sending a closing command to the filling valve (104) at the compensated closing time (CCT); after closing the filling valve (104), a detected volume filling error value (E2, E3, E4, E5) is received.

Description

Technical Field

[0001] The present invention relates to a method and device for controlling the metered feeding of a fluid product into a container. Background Art

[0002] The proposed present invention is applicable to the food industry, especially the bottling industry, or the chemical, pharmaceutical or cosmetic industries.

[0003] The medium to be filled is usually a liquid, such as a beverage optionally containing solid pieces (i.e., fruits, nuts, etc.), or a non-food liquid, such as mineral oil, etc.

[0004] During the filling process, it is necessary to fill the container with a reliable and reproducible output.

[0005] Several methods for determining the filling volume using sensors are known in the prior art. A scale can be used to directly determine the filling mass, but weighing is not very suitable for fast processes because the movement of the filling machine causes vibrations that limit the filling accuracy.

[0006] An altimeter or level measurement can be used to determine the filling height. However, differences in the containers can lead to errors in the filling volume.

[0007] In addition, closing the filling valve involves a short time. In fact, after receiving the closing command, the actual closing time of the filling valve may fluctuate over time.

[0008] In fact, due to various reasons, the filling valve is not an ideal system. There can be pneumatic and / or physical differences between the filling valves of the filling machine. In addition, the viscosity and temperature of the fluid product and their temporal variations also affect the closing time.

[0009] In addition, the electronic control also introduces an instantaneous time when closing the filling valve.

[0010] A method for metering and filling a flowable medium into a container is known from document DE 102005008041, in which a metering valve is integrated in the filling pipe. This solution is based on a flow meter integrated in the filling pipe for detecting the volume flow rate of the flowable medium passing through the filling pipe. The measured value can be used by an electronic control unit, which actuates the metering valve in a clocked manner based on the stored required filling volume.

[0011] In another solution disclosed in document DE 102005035264B4, the flow rate is determined by a neural network. The neural network can only evaluate the measurement data it receives, such that measurement errors in the flow rate still lead to inaccurate filling volumes. Summary of the Invention

[0012] In this context, the object of the present invention is to provide a method and a device for controlling the metered feeding of a fluid product into a container, which overcome the problems of the above-mentioned prior art.

[0013] Specifically, the object of the present invention is to propose a method and a device for controlling the metered feeding of a fluid product into a container, which provide more precise filling control.

[0014] Said technical task and specific object are substantially achieved by a method for controlling the metered feeding of a fluid product into a container using a device comprising a plurality of filling valves, the method comprising performing a cycle having the following steps for each filling valve:

[0015] - Sending an opening command to the filling valve so that the filling valve fills the corresponding container with the fluid product;

[0016] - Detecting the volume value and the flow rate value of the fluid product dispensed by the filling valve, said detection occurring at a predetermined sampling interval;

[0017] - Calculating a compensation volume which is the difference between the target volume to be dispensed into said container and the volume filling error, wherein the volume filling error is detected immediately before the filling step or is obtained by linear interpolation of points on a plane in which the y-axis is the volume filling error and the x-axis is the detected flow rate;

[0018] - Determining a compensation closing time which is the time to send a closing command to the filling valve, the compensation closing command being the time when the detected dispensed volume value reaches said compensation volume;

[0019] - Sending a closing command to the filling valve at the compensation closing time;

[0020] - After closing the filling valve, receiving the detected volume filling error value, the last flow rate value detected before the compensation closing time and the detected volume filling error value being the coordinates of another point on said plane.

[0021] According to an embodiment of the present invention, the method further comprises the following steps before performing said cycle:

[0022] - Initializing the volume filling error on the plane to an initial filling error;

[0023] - Sending an opening command to the filling valve so that the filling valve performs a first filling of the corresponding container with the fluid product;

[0024] - Detecting the volume value and the flow rate value of the fluid product dispensed by the filling valve, said detection occurring at said predetermined sampling interval;

[0025] - Calculate a first compensation volume that is the difference between a target volume to be dispensed into the container and an initial volume filling error.

[0026] - Determine a first compensation closing time that is the time to send a closing command to the filling valve, the first compensation closing time being the time when the detected dispensed volume value reaches the first compensation volume.

[0027] - Send a closing command to the filling valve at the first compensation closing time.

[0028] - After closing the filling valve, receive a detected first volume filling error value, the last flow rate value detected before the first compensation closing time, and the detected first volume filling error value as the coordinates of another point on the plane.

[0029] Preferably, at each filling in the cycle, the last flow rate value detected before the compensation closing time and the detected volume filling error value are used to update the error curve on the plane, the error curve being a multi-segment curve connecting the currently detected points.

[0030] According to one aspect of the present invention, the step of initializing the volume filling error occurs after changing the format of the container and / or changing the fluid product.

[0031] Preferably, the initialization step is different for the first filling valve to be opened in the filling valve. For the initialization step, the remaining filling valves use the detected first volume error value of the first filling valve as the initial volume error.

[0032] According to a preferred embodiment, the predetermined sampling interval is between 1 and 10 milliseconds.

[0033] More preferably, the predetermined sampling interval is between 4 and 6 milliseconds.

[0034] The technical task and specific purpose are basically achieved by a device for metering a fluid product into a container, the device comprising:

[0035] - A storage tank for the fluid product;

[0036] - A plurality of filling stations, each filling station being equipped with a filling device selectively communicating with the storage tank, each filling device including a filling valve and a flow meter;

[0037] - A control unit, in response to receiving a measurement value from the flow meter, the control unit being configured to execute the method according to the present invention.

[0038] According to a preferred embodiment, the device further includes a memory configured to store a set value file of the filling valve.

[0039] The control unit is configured to also receive set values from the memory. Description of the Drawings

[0040] Further features and advantages of the present invention will emerge more fully from a non - restrictive description of preferred but non - exclusive embodiments of a method and an apparatus for controlling the metered feeding of a fluid product into a container, as shown in the accompanying drawings, in which:

[0041] - Figure 1 is a schematic view of an apparatus for filling a container according to the present invention;

[0042] - Figure 2 shows the variation over time of the filling flow rate and the filling volume of the filling valve of the apparatus in Figure 1 according to the present invention, which uses a method for controlling the metered feeding of a fluid product into a container;

[0043] - Figure 3 shows a flowchart of a method for controlling the metered feeding of a fluid product into a container according to the present invention;

[0044] - Figures 4a to 4f shows Figure 3 the error curves at different steps of the method in Detailed Description of the Invention

[0045] Referring to the accompanying drawings, reference numeral 100 denotes an apparatus for metered feeding of a fluid product (such as a beverage) into a container 105.

[0046] The apparatus 100 includes a plurality of filling stations 102, each filling station being equipped with a filling device.

[0047] Each filling device includes a filling valve 104 for dispensing the fluid product into a corresponding container 105 located therebelow.

[0048] Each filling station 102 further includes a flowmeter 103 operatively acting on the filling device for measuring the amount of fluid product that has flowed through the corresponding filling valve 104.

[0049] The apparatus 100 includes a storage tank 101 for supplying the fluid product to the filling device through a valve arrangement. In fact, the filling device is selectively in fluid communication with the storage tank 101 to receive the fluid product during the filling process.

[0050] The filling valve 104 is part of the valve arrangement of the filling apparatus 100.

[0051] The filling valve 104 can be actuated by pneumatic, magnetic, electric or electromagnetic control.

[0052] In the filling state of the apparatus 100, the filling valve 104 is in an open configuration so that the fluid product can pass through the filling device and be dispensed into the container 105.

[0053] Device 100 includes a control unit 106 that operably acts on a filling valve 104 to control the dispensing of a fluid product into a container 105.

[0054] The control unit 106 is configured to receive measurements from a flowmeter 103 at a filling station 102, and in response to these measurements and based on a filling valve setpoint, the control unit 106 is configured to generate a filling valve control signal 106c that is sent to the filling valve 104.

[0055] In this case, the filling valve setpoint (referred to simply as the "setpoint") is the desired volume dispensed by the filling valve. Device 100 includes a memory 107 configured to store a setpoint profile. Preferably, each setpoint in the setpoint profile has been pre-mapped according to one or more of the following characteristics: the type of fluid product, the type and capacity of the container to be filled.

[0056] According to one embodiment, device 100 is of the rotary turntable type. Thus, the filling station 102 and associated filling devices are distributed along the circumferential extent of the rotary turntable.

[0057] According to another embodiment, device 100 is of the linear type.

[0058] The proposed invention was developed starting from the observation of the behavior of the filling valve 104 during the filling process.

[0059] For illustrative purposes only, with reference to Figure 2 , two superimposed curves of the filling valve 104 over time are shown:

[0060] - The first curve represents the filling flow rate F;

[0061] - The second curve represents the filling volume V.

[0062] It should be noted that the first curve is a simplified example. In reality, there are filling valves where the filling flow rate F has a more complex graph, especially having a high-speed filling step and a subsequent low-speed filling step before closing.

[0063] The opening and closing of the filling valve 104 are controlled by the control unit 106. In particular, the control unit 106 is configured to send a filling valve control signal 106c that can be set to an open value (or open command) or a closed value (or closed command).

[0064] When the filling valve 104 receives an open command, it is forced open such that the filling flow rate F increases. The filling valve 104 starts to dispense the fluid product into the corresponding container 105 at a filling flow rate F, for example, according to Figure 2 the first curve.

[0065] During the filling process, the flowmeter 103 continuously detects the filling flow rate F of the filling valve 104. More precisely, the flowmeter 103 measures the volume of the fluid product dispensed by the filling valve 104 and provides the obtained measurement result as an output, which is the filling flow rate F.

[0066] Theoretically, in response to the dispensed volume reaching a predetermined set value, the control unit 106 should send a closing command to the filling valve 104.

[0067] In this case, it should be noted that the predetermined set value of the filling valve is the desired volume dispensed by the filling valve.

[0068] Ideally, the filling valve 104 should close immediately after receiving the closing command and dispense the theoretical filling volume into the container 105. In this case, the theoretical filling volume is also referred to as the "target volume" and is denoted as TV.

[0069] However, as mentioned above, due to electronic signal delay and mechanical friction, the filling valve 104 does not close immediately after receiving the closing command. Instead, there is a delay between the closing command and the actual closing time of the filling valve 104.

[0070] This delay causes the filling valve 104 to continue dispensing a certain amount of fluid product that is excessive relative to the theoretical filling volume TV. The excessively dispensed fluid product is herein referred to as the "volume filling error" and is labeled as E. This error E is a function of the flow rate.

[0071] To avoid or reduce the volume filling error E of the filling valve 104, it is conceivable to send the closing command to the filling valve 104 in advance.

[0072] In fact, it is desired to send the closing command to the filling valve 104 sufficiently in advance such that the filling valve 104 actually closes when the filling volume dispensed into the container 105 is indeed the theoretical filling volume or the target volume TV, as Figure 2 shown by the second curve.

[0073] Therefore, the closing command should occur when the dispensed volume is TV - E, such that the actual delay in closing the filling valve 104 allows the theoretical filling volume or the target volume TV to be reached.

[0074] Here, the volume CV = TV - E is defined as the "compensation volume", which is the volume at a time referred to as the compensation closing time CCT.

[0075] The compensation closing time CCT is actually the time when the closing command is sent to the filling valve 104 such that the volume dispensed into the container 105 reaches the target volume TV.

[0076] In fact, the filling valve 104 is commanded to close at a time (i.e., the compensation closing time CCT) determined to compensate for the volume filling error E (i.e., the error in volume).

[0077] In other words, due to the inertia of the equipment that does generate an error (volume filling error E), closing the filling valve 104 at the compensation closing time CCT allows the dispensed volume to reach the target volume TV.

[0078] As an example, assume that a target volume TV of 1000 ml is to be dispensed into the container 105, and the volume filling error E caused by the inertia of the equipment is known to be 5 ml.

[0079] Closing the filling valve 104 at the target volume TV will result in an actual dispensed volume of 1005 ml due to the volume filling error E.

[0080] Using the proposed method, the filling valve 104 is commanded to close earlier, i.e., immediately before reaching the compensation volume CV, i.e., CV = TV - E = 1000 ml - 5 ml = 995 ml.

[0081] The flowmeter 103 continuously detects the flow rate F. In this context, the expression "continuously detects" means detecting at a sampling interval within the range of 1 to 10 microseconds.

[0082] More preferably, the sampling interval is within the range of 4 to 6 microseconds.

[0083] The flow rate corresponding to the compensation volume CV (referred to as "flow rate at the closing point" or FCP) is the last sampled value, which refers to the flow rate value sampled before the compensation closing time CCT.

[0084] In other words, the flow rate at the closing point FCP is the flow rate value detected by the flowmeter 103 immediately before the compensation closing time CCT. In this context, the expression "immediately before" means that this value is the sample detected before the compensation closing time CCT.

[0085] Reference Figure 3 , reference numeral 200 denotes a method for controlling the metering feed of a fluid product to the container 105 using the filling valve 104.

[0086] The method 200 includes determining an error curve for each filling valve 104, where the error curve is a characteristic curve of the volume filling error E as a function of the filling flow rate F of the filling valve 104.

[0087] At each filling step, for the same filling valve 104, the flow rate at the closing point (FCP) and the volumetric filling error E detected at the closing time may vary. These values do vary during the filling step. Therefore, the error curve represents the volumetric deviation caused by the flow rate fluctuations due to the non-ideality of the filling valve 104 and the delay introduced by the electronics of the control unit 106.

[0088] Figures 4a to 4f The plane (E,F) in different steps of method 200 is shown, where the y-axis of the plane (E,F) represents the volumetric filling error E in ml and the x-axis represents the filling flow rate F in ml / s.

[0089] According to one aspect of the present invention, method 200 starts with the step of initializing the error curve, represented by 201 and as Figure 4a shown.

[0090] The error curve is initialized with a constant straight line according to the following formula: (1.1)

[0092] E(F) = Ei

[0093] where Ei is the initial volumetric filling error between the minimum acceptable error (referred to as MinE) and the maximum acceptable error (referred to as MaxE).

[0094] The initial volumetric filling error Ei is a predetermined value established after previous tests on a specific fluid product.

[0095] Specifically, the step 201 of initializing the error curve occurs after changing the container format and / or changing the fluid product.

[0096] Method 200 then proceeds to the first filling step, represented by 202. During the first filling step 202, assuming the initial volumetric filling error Ei, the control unit 106 is configured to send a closing command to the filling valve 104 when the detected volume of the dispensed fluid product reaches the compensation volume CV = TV - Ei.

[0097] As previously mentioned, the volume and flow rate of the fluid product dispensed by the filling valve 104 are continuously detected, which means that the volume and flow rate are detected at a sampling interval in the range of 1 to 10 microseconds.

[0098] Therefore, the first flow rate value at the closing point is the last sampled flow rate value before the compensation volume reaches CV = TV – Ei.

[0099] The first flow rate value at the closing point is referred to as FCP1, as Figure 4b shown.

[0100] After closing the filling valve 104, a first volume filling error value E1 is detected, which replaces the initial volume filling error Ei. Thus, according to the following formula, the error curve in the first filling step 202 becomes a constant straight line: (1.2)

[0102] E(F) = E1

[0103] The error curve is as Figure 4b shown.

[0104] Method 200 proceeds to a second filling step, denoted by 204. During the second filling step 204, the control unit 106 is configured to send a closing command to the filling valve 104 at the time (compensation closing time CCT) when it is detected that the volume of the dispensed fluid product has reached the compensation volume CV = TV - E1.

[0105] Immediately before the compensation time CCT, the corresponding flowmeter 103 detects and stores the second flow value at the closing point FCP2. The second flow value at the closing point FCP2 is the flow value sampled before the time when the compensation volume reaches CV = TV - E1.

[0106] After the filling valve 104 is closed, a second volume filling error value E2 is detected.

[0107] Therefore, in the second filling step 204, the error curve becomes a straight line passing through two points with coordinates (FCP1, E1) and (FCP2, E2), as Figure 4c shown.

[0108] Method 200 includes additional filling steps, denoted by 205. During the additional filling steps 205, additional flow values at the closing points (i.e., FCP3, FCP4) are detected immediately before the corresponding compensation closing times, and additional volume filling error values E3, E4, E5,..., E8 are detected after the filling valve 104 is closed.

[0109] In each filling step, the flowmeter 103 measures the flow at the closing time corresponding to the volume filling error predicted by linear interpolation. Then, the volume filling error is actually measured and used to update the curve.

[0110] In fact, in each filling step, the error curve is updated with another pair of detected values of the filling flow and the volume filling error.

[0111] Identify additional pairs of detected values of the filling flow and the volume filling error to obtain more accurate error curve characteristics.

[0112] Preferably, the error curve is a multi-fold curve connecting the measurement points.

[0113] This is shown in Figures 4d to 4f .

[0114] When a volume filling error that has been mapped into the error curve by linear interpolation is retrieved, the mapped volume filling error is replaced by the penultimate volume filling error.

[0115] For ease of understanding, method 200 has been described hereinabove for a single filling valve 104.

[0116] According to an embodiment of the present invention, the same method 200 is used for all filling valves 104.

[0117] According to another embodiment of the present invention, the initial volume filling error of the filling valves 104 other than the opened first filling valve is set to the first volume filling error E1 of the opened first filling valve 104.

[0118] The error curve is continuously updated by obtaining points during successive filling steps throughout the operation of the device 100. This enables a dynamically time-adapted error curve to the actual process instead of using a static predefined curve.

[0119] The features and advantages of the method and device for controlling the metered feed of a fluid product into a container according to the present invention are obvious, as are the advantages.

[0120] Compared to previous solutions, the method enables a higher container filling repeatability. In fact, predicting the volume filling error of the filling valve allows a closing command to be sent to the filling valve in advance in order to get closer to the target volume throughout the filling process.

Claims

1. A method (200) for controlling the dosing of a fluid product into a container (105) using a device (100), the device (100) comprising a plurality of filling valves (104), the method (200) comprising executing, for each filling valve (104), a cycle having the following steps: sending an opening command to the filling valve (104), so that the filling valve (104) performs filling (204, 205) of the corresponding container (105) with the fluid product; Detecting the volume value and flow value of the fluid product dispensed by the filling valve (104), wherein the detection occurs at a predetermined sampling interval; calculating a compensation volume (CV) as the difference between a target volume (TV) to be dispensed into the container (105) and a volumetric filling error (E), wherein the volumetric filling error (E) is detected immediately before the filling step or is obtained by linear interpolation of points on a plane (E, F) having the volumetric filling error (E) on the y-axis and the detected flow rate (F) on the x-axis; determining a compensated closing time (CCT) as the time for sending a closing command to the filling valve (104), the compensated closing time (CCT) being the time at which the detected dispensed volume value reaches the compensation volume (CV); sending the closing command to the filling valve (104) at the compensated closing time (CCT); After the filling valve (104) has been closed, a detected volumetric filling error value (E2, E3, E4, E5) is received, the last flow value (FCP2, FCP3, FCP4) detected before the compensated closing time (CCT) and the detected volumetric filling error value (E2, E3, E4, E5) being the coordinates of another point on the plane (E, F).

2. The method (200) according to claim 1, further comprising the following steps before executing the loop: Initializing (201) the volume filling error (E) on the plane (E, F) as an initial filling error (Ei); sending an opening command to the filling valve (104), so that the filling valve (104) performs a first filling (202) of the corresponding container (105) with the fluid product; Detecting the volume value and flow value of the fluid product dispensed by the filling valve (104), wherein the detection occurs at the predetermined sampling interval; calculating a first compensation volume (CV) as a difference between a target volume (TV) to be dispensed into the container (105) and the initial volumetric filling error (Ei); determining a first compensated closing time (CCT) as the time for sending a closing command to the filling valve (104), the first compensated closing time (CCT) being the time at which the detected dispensed volume value reaches the first compensated volume (CV); sending the closing command to the filling valve (104) at the first compensated closing time (CCT); After closing the filling valve (104), a detected first volume filling error value (E1) is received, the last flow value (FCP1) detected before the first compensated closing time (CCT) and the detected first volume filling error value (E1) being the coordinates of another point on the plane (E, F).

3. Method (200) according to claim 2, wherein the step of initializing (201) the volumetric filling error (E) occurs after changing the format of the container and / or changing the fluid product.

4. A method (200) according to any preceding claim, wherein at each filling point in the cycle, the last flow value (FCP2, FCP3, FCP4) detected before the compensated closing time (CCT) and the detected volume filling error value (E2, E3, E4, E5) are used to update an error curve on the plane (E, F), the error curve being a polyhedral curve connecting the currently detected points.

5. The method (200) according to claim 2 or 3, wherein the initialization step (201) is different for a first filling valve (104) to be opened among the filling valves (104), and for the initialization step (201), the remaining filling valves (104) use the detected first volume error value (E1) of the first filling valve (104) as the initial volume error (Ei).

6. The method (200) according to any preceding claim, wherein the predetermined sampling interval is between 1 millisecond and 10 milliseconds.

7. The method (200) of claim 6, wherein the predetermined sampling interval is between 4 milliseconds and 6 milliseconds.

8. A device (100) for dosing a fluid product into a container (105), the device (100) comprising: A storage tank (101), wherein the storage tank (101) is used for the fluid product; A plurality of filling stations (102), each of which is equipped with a filling device selectively connected to the storage tank (101), and each of which includes a filling valve (104) and a flow meter (103); A control unit (106), in response to receiving a measurement value from the flow meter (103), the control unit (106) being configured to execute the method (200) according to any one of claims 1 to 7.

9. The apparatus (100) according to claim 8, further comprising a memory (107) configured to store a set value profile of the filling valve (104), the control unit (106) being configured to also receive the set value from the memory (107).

10. A computer program having instructions which, when executed by a computer device or system, cause the computer device or system to perform the method according to any one of claims 1 to 7.

Images