Metering device for variably metering a powder

Abstract

The invention relates to a powder metering device (10) for variably metering a quantity of powder, having a metering chamber (1) with a defined metering volume, which is connected on the inlet side to a powder feed line (2) and on the outlet side to a discharge line (4), to which a negative pressure can be selectively applied, wherein the metering chamber (1) is formed by a line section (5), which has an inlet valve (6), an outlet valve (7) opposite the inlet valve, and a vent valve (8) interposed therebetween, and a control unit (41) of the device (10) is designed to selectively control the valves (6, 7, 8) for carrying out a preferably variable quantity metering process in the line section (5).

Description

[0001] The present invention relates to a metering device and a powder metering method, which can variably transport powder through a metering chamber having a predetermined volume by means of a vacuum.

[0002] Devices and systems for metering powders or powdered substances are known to exist in industrial applications. The design of conventional devices for metering powdered substances or media often makes determining the amount delivered cumbersome and only possible with relative accuracy. This is particularly true for metering systems targeting smaller quantities, such as those required in the chemical industry or battery manufacturing. In particular, it is difficult to ensure the required consistency in dispensing or metering using known devices. Deviations and the resulting inaccurate dosages are common, which can lead to several problems.

[0003] Furthermore, known systems and devices are generally inflexible or have only limited flexibility. For example, devices designed for relatively precise delivery and metering of powders exist, but they typically have only relatively low delivery rates per unit time. While devices or systems exist for rapidly delivering larger quantities of powder, they are clearly not accurate enough in determining delivery rates or dosages.

[0004] Another requirement for equipment used for conveying is the ability to design it as a sealed system. This is especially necessary when conveying hazardous materials, such as lithium compounds used in battery manufacturing. Additionally, the equipment and devices used for conveying typically must be easy and quick to clean, which places additional demands on their design.

[0005] EP 0 937 004 B2 discloses an apparatus and method for pneumatically conveying powder, wherein the apparatus includes a cylindrical chamber associated with a collection container and serving as a metering chamber, into which powder is drawn in via a powder supply line in a vacuum manner, and a vacuum is applied to the metering chamber through a membrane. The fixed membrane serves to prevent powder from being drawn into the vacuum line. During the intake phase prior to evacuation, the chamber is not completely filled with powder. The powder in the metering chamber is evacuated into the collection container by applying compressed air to the chamber via a separate supply line and conveying the powder to the collection container through a lower outlet opening. A weighing system may be associated with the collection container, thereby enabling the measurement of the amount of powder conveyed or collected.

[0006] EP 0 789 230 A1 discloses a complex metering device for metering powder, wherein the metering volume of the metering chamber can be adjusted by an adjustable metering needle extending into the chamber. During metering, a vacuum is applied to a vacuum connector on the metering chamber to draw the powder to be metered into the chamber via the inlet space. After the filling process, the metering chamber is emptied by generating positive pressure and opening a shut-off flap valve.

[0007] EP 3 184 971 A1 discloses a complex metering device for minute quantities, comprising a metering chamber into which powder can be drawn in by vacuum. The metering chamber includes a filter for retaining the powder, which is in the form of an intake opening formed on the peripheral wall. The powder is ejected from the metering chamber by means of an ejector plunger rather than compressed air, in order to minimize the risk of dispersion of minute quantities of powder.

[0008] DE 10 2010 054 649 B3 discloses a powder metering device comprising a metering chamber with a variable volume, wherein the metering chamber can be evacuated to draw powder from a powder supply line through a membrane defining the metering chamber. The membrane is adjustable relative to an outlet opening to set the powder metering volume and empty the metering chamber.

[0009] For applications in metering methods in battery manufacturing, screw conveyors known in the art, such as those from Coperion K-Tron GmbH, are also known.

[0010] Known devices and systems have the following drawbacks: they cannot provide optimal solutions in terms of conveying efficiency and accuracy while maintaining a simple design.

[0011] Based on the aforementioned prior art, the object of the present invention is to provide a powder metering device with a simple structure, particularly for pharmaceutical and / or chemical applications, which can achieve relatively accurate powder metering and preferably has flexibility in terms of feed rate per unit time. Furthermore, the object of the present invention is to provide a correspondingly improved powder metering method.

[0012] This objective is achieved by the powder metering apparatus and powder metering method according to the independent claims. The dependent claims describe advantageous embodiments of the invention.

[0013] In a first aspect, the present invention relates to a powder metering device for variably metering powder quantities, the metering device comprising a metering chamber having a predetermined metering volume, the metering chamber being connected at an inlet side to a powder supply line and at an outlet side to a discharge line, the discharge line being selectively subject to a vacuum, wherein the metering chamber is formed by a pipeline section including an inlet valve, an opposing outlet valve, and a fluidizing valve inserted between the two, and wherein a control unit of the device is configured to selectively control these valves for preferably achieving variable metering within the pipeline section.

[0014] Compared to known devices, the metering device according to the invention is simple and effective in design, enabling efficient, reliable, and accurate metering, and is easier to operate and maintain. Furthermore, the design of the powder metering device according to the invention advantageously allows for variable metering or flow control of powder within the pipeline section, thus enabling flexible and application-specific metering. In addition, the device can safely transport the conveyed material, particularly for example, in the manufacture of batteries comprising lithium compounds.

[0015] In this context, "vacuum-applicable" means that the feed line can be connected to or be connected to a vacuum source or a unit for generating a vacuum. The vacuum source can be part of the device or part of a system that includes the device.

[0016] In this context, "variable metering" means that the amount of powder delivered per unit time via the metering chamber is adjustable. In particular, at least two—more preferably at least three—different operating modes should be selectable by controlling or operating the valve, and these modes advantageously differ in the corresponding amount of powder delivered per unit time.

[0017] In a preferred embodiment, the metering chamber has a constant metering volume, and in the remaining continuous closed-loop piping section, the metering volume is defined only by the inlet valve, outlet valve, and fluidizing valve. That is, the metering chamber or piping section preferably does not have any other supply and / or discharge piping besides the aforementioned valves.

[0018] More preferably, the metering chamber contains no moving and / or fixed components, especially no powder retention membrane. This allows for an optimized design of the metering chamber, providing accurate metering volume while maintaining the simplest possible structure.

[0019] The fluidizing valve is preferably designed to provide a connection between the metering chamber and ambient air, thus serving as an air inlet for the metering chamber. In a preferred embodiment, the fluidizing valve is connected to an air filter only on its inlet side. This means that the fluidizing valve has no other connections, particularly no compressed air connections. Furthermore, the fluidizing valve or the associated air inlet and / or air filter advantageously does not contain an associated powder-retaining membrane. The membrane disposed in or contained in the air filter is advantageously designed only for coarse filtration of the air passing through it.

[0020] The pipeline segment preferably has a cross-sectional shape and / or cross-sectional area corresponding to the downstream discharge pipeline, and more preferably, to the upstream supply pipeline. In particular, there is preferably no significant change in cross-section between the pipeline segment and the upstream supply pipeline and / or downstream discharge pipeline. This particularly optimizes the conveying of powder through the metering chamber. In a preferred embodiment, the pipeline segment extends along a longitudinal axis, preferably has a circular cross-sectional profile, and inlet and outlet valves are located at opposite ends.

[0021] In a more preferred embodiment, the piping section includes a T-shaped element connecting the fluidizing valve to the inlet valve and the outlet valve, the T-shaped element preferably being positioned in the center of the metering chamber. The T-shaped element preferably connects three piping elements, which preferably have a substantially uniform cross-sectional shape and / or area.

[0022] In a preferred embodiment, the device includes a collection container connected to a discharge line of the device. The collection container preferably includes a weighing system connected to or integrated therewith, or a scale associated therewith, for determining the amount of powder stored or collected therein. In this context, the device is preferably configured to continuously monitor the conveying rate to the collection container and to stop conveying via a metering chamber when a predetermined amount is reached in the collection container.

[0023] The apparatus preferably also includes a powder container connected specifically via a hopper to a powder supply line, the powder container holding a larger quantity of powder to be conveyed. Powder can flow from the container into the hopper under gravity and from the hopper into the powder supply line. The hopper and powder container may also be integrally formed. The hopper and powder container are advantageously designed to provide a larger quantity of powder to be conveyed. The hopper and / or powder container are preferably closed or closable. Furthermore, it preferably includes a connected or integrated weighing system for determining weight, particularly in the form of one or more weighing sensors. This allows the amount of powder conveyed to be determined based on weight loss detected at the hopper and / or powder container. The apparatus is preferably configured to continuously monitor the amount of powder to be conveyed contained in the hopper and / or container and stop conveying when a predetermined conveying volume is reached.

[0024] Preferably, the inlet and outlet valves are adjustable and controllable pinch valves. Each valve can be selectively switched to at least an open position and a closed position. Preferably, the fluidizing valve can be switched between at least an open state and a closed state, and is preferably a shut-off valve with adjustable opening.

[0025] In a preferred embodiment, the control unit is configured to control the valve of the metering chamber in a variable timing manner to achieve different metering rates or to meter different amounts of powder conveyed per unit time. The control unit is preferably configured to operate the valve in at least two, preferably at least three, different conveying modes to convey different metering amounts within a predetermined time. The conveying modes preferably include at least a coarse conveying mode and a fine conveying mode. Furthermore, the conveying modes advantageously include a medium-fine conveying mode.

[0026] The control unit can be configured to operate the valves in a first coarse conveying mode, in which the inlet and outlet valves are preferably held in the fully open position, a vacuum is applied to the discharge line, and the fluidizing valve is repeatedly opened and closed at predetermined time intervals to convey powder from the powder supply line to the powder discharge line. The conveyed mass flow rate can be adjusted in the coarse metering mode by controlling the opening and closing of the fluidizing valve. In the coarse conveying mode, high conveying speeds are advantageously achieved, for example, conveying the maximum amount of powder within a predetermined time period. For example, in conjunction with a collection container associated with the device, the container can be rapidly filled in the initial stage.

[0027] The control unit can also be configured to operate the valve in a second intermediate-fine conveying mode, in which the outlet valve remains in the open position while a vacuum is applied to the discharge line, the fluidizing valve is repeatedly opened and at least partially closed at predetermined time intervals to convey powder from the powder supply line to the powder discharge line, and the inlet valve is optionally closed and reopened at predetermined time intervals to limit the amount of powder conveyed. By opening and closing the inlet valve, the mass flow rate can be controlled based on the corresponding opening and / or closing times. The opening duration is preferably between 1 and 5 seconds. The closing duration is preferably between 3 and 10 seconds. Additionally, the fluidizing valve can be used to control the mass flow rate conveyed. This also allows for relatively high conveying speeds while selectively limiting the conveying rate, thereby limiting the conveying velocity. For example, in conjunction with a collection container associated with the device, the intermediate-fine conveying mode can provide a more moderate filling rate after an initial rapid filling via the coarse conveying mode, especially as the filling process in the collection container nears its end. This allows for more significant control over the flow rate during the filling process. For example, a weighing system or scale associated with a collection container and / or hopper can monitor the amount of powder collected in the collection container and / or discharged from the hopper with significantly greater accuracy.

[0028] The control unit can also be configured to operate the valves in a third precision delivery mode, in which the inlet and outlet valves are opened and closed sequentially while a vacuum is applied to the discharge line to precisely deliver one metering volume of the metering chamber in a single metering operation. This makes powder metering exceptionally accurate. This is particularly advantageous in pharmaceutical and / or chemical applications where only small or zero deviations are permissible.

[0029] In this process, the control unit preferably controls the components of the device to first create a vacuum in the metering chamber. For this purpose, the inlet valve and fluidizing valve are closed, the outlet valve is opened, and a vacuum is generated in the discharge line by the vacuum generating unit. Advantageously, the vacuum generation lasts for 1 to 5 seconds.

[0030] Subsequently, the outlet valve also closes, thus maintaining a continuous vacuum in the closed metering chamber. Advantageously, the valve remains closed for 1 to 2 seconds.

[0031] In another step, the inlet valve of the metering chamber is opened, allowing sufficient powder to fill the metering chamber to be drawn in due to the existing vacuum. During this process, the outlet valve and fluidization valve remain closed. This process preferably lasts 1 to 3 seconds.

[0032] Subsequently, the inlet valve—and thus the metering chamber, whose metering volume is filled with powder—is closed again, and the outlet valve and fluidization valve are opened, allowing the powder contained in the metering chamber to be conveyed through a discharge line under vacuum. This process preferably lasts 2 to 10 seconds.

[0033] The operation can be repeated multiple times in the described sequence to deliver a precise amount of powder via the metering chamber of the device to, for example, a collection container connected to the device. An associated weighing system at the collection container and / or hopper continuously measures and monitors the amount of powder delivered or collected.

[0034] In a preferred embodiment, the control device can be configured to provide different vacuum levels in the metering chamber. Thus, the control device can generate a weaker vacuum or a lower vacuum level by briefly activating the corresponding vacuum generating device or vacuum generating system. A stronger vacuum or a higher vacuum level can be generated by running the vacuum generating device for a correspondingly longer time. Alternatively, the vacuum level can be adjusted by regulating the vacuum in the collection container connected to the discharge line and / or the upstream pre-chamber. Even more alternatively, the vacuum level can also be adjusted by regulating the re-suction phase used to generate a vacuum in the collection container and / or its associated pre-chamber. This eliminates the need for a vacuum control unit in the collection container.

[0035] Furthermore, in conjunction with the collection container associated with the device, after an initial rapid filling using coarse and / or medium-fine conveying modes, precise conveying can be performed near the end of the filling process in the collection container—particularly to more accurately reach the predetermined total amount in the collection container. This allows for a high degree of accuracy in conveying volume during the filling process of the collection container. For example, a weighing system or scale associated with the collection container and / or hopper can accurately monitor the amount of powder collected in the collection container and / or discharged from the hopper.

[0036] On the other hand, the present invention relates to a system comprising a powder metering device as described above and a collection container connected thereto, the collection container preferably having an associated weighing system, wherein the collection container has a vacuum generating unit connected thereto, the vacuum generating unit being configured to selectively generate a vacuum in or in a region of the collection container and in the discharge line of the powder metering device connected thereto. This enables the selective generation of a vacuum in the discharge line of the device by the vacuum generating unit, thereby enabling the powder to be delivered to the collection container as described above. The system preferably also includes a hopper and / or powder container connected to a supply line. The hopper and / or powder container is preferably closed or closable and includes an associated weighing system for determining weight, particularly in the form of one or more weighing sensors.

[0037] In another aspect, the present invention relates to a powder metering method, particularly for operating a powder metering device and / or system as described above, wherein powder is drawn from a supply line into a metering chamber by means of a vacuum, the metering chamber being formed by a pipeline section and including an inlet valve, an opposite outlet valve and a fluidizing valve inserted between the two, and the powder is conveyed by means of a vacuum through a discharge pipeline connected to the metering chamber by selectively controlling the valve in at least two different conveying modes, the conveying modes preferably including at least a coarse conveying mode and a fine conveying mode.

[0038] In a preferred embodiment, the method includes the step of controlling the valve in a coarse conveying mode as described above with reference to the apparatus. In this step, the control unit associated with the valve may control the valve, for example, in such a manner that the fluidizing valve is closed for a predetermined first time period t1, preferably 2 seconds, and then opened for a predetermined second shorter time period t2, preferably 1 second, while a vacuum is applied to the discharge line to form a certain amount of powder or powder plug in the metering chamber.

[0039] In a preferred embodiment, the method includes the step of controlling the valve in a medium-fine conveying mode as described in the reference apparatus above. In this step, control can be performed in substantially the same manner as in the coarse conveying mode; however, the inlet valve additionally closes and reopens at predetermined intervals to limit the amount of powder conveyed.

[0040] In another preferred embodiment, the method includes the step of controlling the valve in a fine delivery mode as described in the reference apparatus above. Particularly advantageously, the control is performed in such a manner that: first, a vacuum is created in the closed metering chamber; then, while the outlet valve and fluidization valve remain closed, the inlet valve is opened to allow powder to enter the metering chamber; then, the inlet valve is closed again; subsequently, while the inlet valve remains closed, the outlet valve and fluidization valve are opened.

[0041] In a preferred embodiment, the method includes using a coarse conveying mode, a medium-fine conveying mode, and a fine conveying mode for the above-mentioned control, such that the powder is first conveyed in a coarse conveying mode—preferably conveyed to a collection container connected to the device—and when approaching a predetermined target amount of powder, the powder is conveyed in a medium-fine conveying mode and / or a fine conveying mode.

[0042] To avoid repetition, the features and advantages described above for the apparatus of the present invention should be regarded as equally applicable to the features and advantages of the method of the present invention and may be claimed, and vice versa.

[0043] Details of the invention, further beneficial effects and specific contents will be described below with reference to the purely illustrative and explanatory drawings.

[0044] Figure 1a and 1b The images show a side view and a partially sectional side view of a preferred embodiment of the measuring device according to the present invention.

[0045] Figures 2a to 2c Schematic diagrams of the apparatus and system according to the invention in various conveying states; and Figure 3 This is a schematic diagram of the cumulative amount of powder delivered over time by the apparatus and system according to the present invention.

[0046] The following text refers to Figure 1a and 1b A preferred embodiment of the powder metering device 10 according to the present invention is described. The metering device includes a metering chamber 1 having a predetermined metering volume. A powder supply line 2 is provided on the inlet side of the metering chamber 1 and connected to a powder supply source (arrow A), particularly a powder container, etc. (not shown). A hopper 3 may be provided to connect the powder supply source to the supply line 2. Powder can be conveyed by gravity into the hopper 3 and then to the connected supply line 2.

[0047] On the outlet side, the metering chamber is connected to the discharge line 4, which can be selectively vacuumed so that the discharge line 4 can deliver powder from the metering chamber (see...). Figure 1a Arrow B in the image.

[0048] Metering chamber 1 comprises a predetermined, constant metering volume and is formed by a piping section 5, which includes an inlet valve 6, an opposing outlet valve 7, and a fluidizing valve 8 inserted between them. Piping section 5 comprises a straight pipe sub-segment extending longitudinally L and positioned between supply line 2 and discharge line 4. Advantageously, the cross-sectional profile of piping section 5 is similar to that of supply line 2 and discharge line 4 to which it is connected. In particular, piping section 5 includes an internal tubular section for powder conveying, which preferably has a cross-sectional shape and dimensions substantially identical to those of supply line 2 and discharge line 4 to which it is connected. Piping section 5 can be selectively isolated from supply line 2 and discharge line 4 by opposing valves 6 and 7. Valves 6 and 7 are advantageously designed as adjustable and controllable pinch valves.

[0049] The metering volume is advantageously defined solely by the inner walls of the aforementioned valves 6, 7, 8 and pipeline section 5, and in particular, it does not have any other supply and / or discharge pipelines. Furthermore, the metering chamber 1 or the metering volume of the metering chamber 1 is advantageously free of any movable and / or fixed components, and in particular, it does not contain a powder retention membrane.

[0050] The fluidizing valve 8 is preferably disposed in the circumferential surface of the pipe section 5. The fluidizing valve 8 may be disposed in a preferably straight pipe sub-section connected to the axial pipe section via a T-joint or T-element. The fluidizing valve 8 is advantageously designed as a shut-off valve capable of switching between at least an open and closed state, more preferably an adjustable-opening shut-off valve. This allows control of the delivered mass flow rate—particularly in coarse delivery mode—by appropriately opening or closing the fluidizing valve 8. An air filter 9 is disposed on the inlet side of the fluidizing valve 8. The air filter 9 is preferably used only to filter ambient air drawn into the fluidizing valve 8.

[0051] Device 10 also includes control unit 41 (see Figures 2a to 2c The control unit is configured to control valves 6, 7, and 8 of metering chamber 1 in a variable timing manner to achieve different metering speeds. Specifically, the control unit 41 is designed to control valves 6, 7, and 8 in different operating modes, preferably differing in the amount of powder delivered per unit time. In particular, the control unit 41 may include a position controller 20 connected to valves 6, 7, and 8.

[0052] Control unit 41 is preferably configured to operate valves 6, 7, and 8 in a first coarse conveying mode, in which inlet valve 6 and outlet valve 7 are preferably held in the fully open position, while a vacuum is applied to the discharge line 4. As a result, powder is continuously conveyed from powder supply line 2 and its connected powder container through metering chamber 1 to discharge line 4, and, for example, to collection container 30 connected thereto (see...). Figure 2aThe fluidizing valve 8 is repeatedly opened and closed at predetermined time intervals to establish a sufficient vacuum in chamber 1 and ensure that each powder plug is continuously and rapidly delivered through metering chamber 1 to discharge line 4. In a preferred embodiment, the fluidizing valve 8 may, for example, be completely closed for 2 seconds to deliver a predetermined amount of powder from supply line 2 to metering chamber 1 to form a powder plug, and then opened for, for example, 1 second to deliver the powder plug through discharge line 4. This control process may, for example, last for 9 seconds, so that within the specified 9-second time period, device 10 forms and delivers 3 powder plugs, each powder plug being delivered for 2 seconds.

[0053] The control unit 41 is also advantageously configured to operate valves 6, 7, and 8 in a second intermediate-fine conveying mode, in which outlet valve 7 remains in the open position while a vacuum is applied to discharge line 4, fluidizing valve 8 is repeatedly opened and at least partially closed at predetermined time intervals to convey powder from powder supply line 2 to powder discharge line 4, and inlet valve 6 is optionally closed and reopened at predetermined time intervals to limit the amount of powder conveyed. In this case, fluidizing valve 8 can be opened to less than 100%, for example, only 50%, while inlet valve 6 can be continuously switched between open and closed positions.

[0054] In a preferred embodiment, the fluidizing valve 8 can, for example, be completely closed for 1 second to deliver a predetermined amount of powder from the supply line 2 into the metering chamber 1, thereby forming a powder plug, and then, for example, can be completely opened for 1 second to deliver the powder plug through the discharge line 4. This control can, for example, be performed for 20 seconds, so that within a specified 20-second period, the device 10 forms and delivers 10 powder plugs, each powder plug being delivered for 1 second.

[0055] The control unit 41 is also advantageously configured to operate valves 6, 7, and 8 in a third precision conveying mode, in which inlet valve 6 and outlet valve 7 are opened and closed sequentially, while a vacuum is applied to the discharge line 4 to precisely convey one metering volume of metering chamber 1 in each metering operation—thus conveying a very precise amount of powder. The following is in conjunction with... Figures 2a to 2c The control of valves 6, 7, and 8 for this purpose in the fine delivery mode is described by way of example.

[0056] Figures 2a to 2c A system 40 according to the invention is shown, which includes a device 10 and a collection container 30 connected thereto, the collection container being connected to the discharge pipe 4 of the device 10 and designed to receive the amount of powder conveyed by the device 10.

[0057] In addition to the collection container 30, the system 40 also includes a weighing system 33 connected thereto for determining the weight of the powder collected in the container 30. The weighing system 33 is preferably connected to the control unit 41 of the device 10, thereby enabling selective activation of valves 6, 7, and 8 based on the detected amount of powder in the container 30.

[0058] System 40 also includes a vacuum generating unit 31 designed to selectively generate a vacuum in the collection container 30, in region 32 of the collection container 30, and in the associated discharge line 4 of the powder metering device 10. Region 32 may be a pre-chamber of the collection container 30, which may be selectively opened via a lower outlet 34, allowing powder collected therein to be transported or conveyed into the collection container 30 by gravity. Alternatively or additionally, the contents of the pre-chamber 32 may be conveyed into the collection container 30 by introducing pressure while opening the outlet 34. The collection container 30 may be configured as a device similar to that described in EP 0 937 004 B2. For this purpose, the pre-chamber may include a supply line 35 for compressed air or nitrogen.

[0059] like Figure 2a As shown, a vacuum is first generated in the metering chamber 1. For this purpose, the inlet valve 6 and the fluidizing valve 8 are closed, the outlet valve 7 is opened, and a vacuum is generated in the discharge line 4 by the vacuum generating unit 31. At the same time, the vacuum generating unit 31 can generate a vacuum in the pre-chamber 32, while the intermediate valve 36 located between the pre-chamber 32 and the discharge line 4 is open.

[0060] Subsequently, as Figure 2b As shown, outlet valve 7 and preferably intermediate valve 36 are also closed, thereby maintaining a continuous vacuum within the enclosed metering chamber 1. Another intermediate valve 37 may also be closed, through which vacuum generating unit 31 is connected to pre-chamber 32. Simultaneously or subsequently, inlet valve 6 of metering chamber 1 is opened, such that the existing vacuum draws in sufficient amount of powder to fill metering chamber 1. Then inlet valve 6—and thus metering chamber 1, whose metering volume is now filled with powder—is closed again.

[0061] like Figure 2c As shown, while the inlet valve 6 remains closed, the outlet valve 7 and fluidizing valve 8 are opened, allowing the vacuum present in the discharge line 4 to convey the powder to the collection container 30. Simultaneously, the intermediate valve 36 between the discharge line 4 and the pre-chamber 32 is opened. This process can be repeated multiple times to deliver a precise amount of powder to the collection container 30 via the metering chamber 1 of the device 10. The weighing system 33 can continuously measure and monitor the amount of powder 38 delivered or the amount of powder 38 collected in the collection container 30.

[0062] The powder collected in the pre-chamber 32 can be delivered at predetermined intervals through the outlet opening 34 and advantageously using compressed air introduced through the supply line 35, which connects the chamber 32, for example, to a high-pressure generating system 35a or a low-pressure generating system 35b.

[0063] Figure 3 A schematic diagram of the amount of powder 38 collected in the collection container 30 within a predetermined time period t is shown. As shown in graph 39, to ensure the most accurate and fastest possible filling, the control unit 41 now controls the device 10 in such a way that the powder amount is initially conveyed into the collection container 30 in a coarse conveying mode (graph segment 39a). This allows for the fastest possible conveying while maintaining sufficient accuracy. The collected conveyed amount is continuously measured via the weighing system 33 and / or a weight measuring device 42 (e.g., in the form of a load cell) associated with the hopper 3.

[0064] When approaching the predetermined target powder quantity or target conveying volume M T At this time, the device 10 is operated in the medium-precision conveying mode (curve segment 39b) as described above. In this mode, the amount of powder conveyed per unit time is significantly reduced.

[0065] As it approaches the predetermined target powder quantity or target conveying volume M T In the final step, the device 10 is operated in a precision delivery mode (curve segment 39c). This ensures very accurate measurement of the amount delivered into the collection container 30, thereby enabling the target amount delivered into the collection container 30 to be achieved with high precision.

[0066] Figure Labels 1 Metering chamber 2 Powder supply pipeline 3. Hopper / Container 4. Discharge Pipeline 5 pipeline sections 6. Inlet valve 7. Outlet valve 8 Fluidizing valve 9. Air Filter 10. Powder Metering Device 20 Position Controller 30 Collection Containers 31 Vacuum Generating Unit 32 Pre-existing chamber 33 Weighing System 34 Exports 35 Supply pipeline 35a, 35b High-pressure / low-pressure piping 36. Intermediate valve in the discharge pipeline 37 Vacuum intermediate valve 38. Amount of powder in the collection container 39 shows a graph of the conveying volume. 39a Coarse conveying mode 39b Medium-precision conveying mode 39c Precision delivery mode 40 System 41 Control Unit 42 Weighing system at hopper / container Arrows A and B indicate the direction of transport. L (vertical direction) t time M T Target powder amount

Claims

1. A powder metering device (10) for variably metering powder quantity, the powder metering device (10) comprising a metering chamber (1) having a predetermined metering volume, the metering chamber (1) being connected at an inlet side to a powder supply line (2) and at an outlet side to a discharge line (4), the discharge line (4) being selectively subject to a vacuum, characterized in that, The metering chamber (1) is formed by a pipeline section (5) including an inlet valve (6), an opposite outlet valve (7) and a fluidizing valve (8) inserted between them, and characterized in that the control unit (41) of the device (10) is configured to selectively control the valves (6, 7, 8) for preferred implementation of variable metering in the pipeline section (5).

2. The powder metering device according to claim 1, characterized in that, The metering chamber (1) has a constant metering volume. In the remaining part of the pipeline section (5) which is a continuous closed structure, the metering volume is defined only by the inlet valve (6), the outlet valve (7) and the fluidizing valve (8).

3. The powder metering device according to claim 1 or 2, characterized in that, The metering chamber (1) contains no movable and / or fixed components, and in particular, no powder retention membrane.

4. The powder metering device according to any one of the preceding claims, characterized in that, The fluidizing valve (8) is connected only to the air filter (9) on its inlet side, and in particular does not contain an associated powder trapping membrane.

5. The powder metering device according to any one of the preceding claims, characterized in that, The pipeline section (5) extends along the longitudinal axis (L) and the cross-sectional profile is preferably circular. The inlet valve (6) and the outlet valve (7) are located at opposite ends.

6. The powder metering device according to any one of the preceding claims, characterized in that, The pipeline section (5) includes a T-shaped element that connects the fluidizing valve (8) to the inlet valve and the outlet valve (6, 7), and the T-shaped element is preferably located in the center of the metering chamber (1).

7. The powder metering device according to any one of the preceding claims, characterized in that, The inlet valve (6) and the outlet valve (7) are adjustable and controllable pinch valves.

8. The powder metering device according to any one of the preceding claims, characterized in that, The fluidizing valve (8) is preferably an adjustable shut-off valve that can switch between at least an open state and a closed state.

9. The powder metering device according to any one of the preceding claims, characterized in that, The control unit (41) is configured to control the valves (6, 7, 8) of the metering chamber (1) in a variable timing manner to achieve different metering speeds.

10. The powder metering device according to claim 9, characterized in that, The control unit (41) is configured to operate the valves (6, 7, 8) in at least two, preferably at least three, different delivery modes, the delivery modes preferably including at least a coarse delivery mode and a fine delivery mode, to deliver different metering quantities within a predetermined time.

11. The powder metering device according to any one of the preceding claims, characterized in that, The control unit (41) is configured to operate the valves (6, 7, 8) in a first coarse conveying mode, in which the inlet valve (6) and the outlet valve (7) are preferably held in the fully open position, while the discharge line (4) is subjected to a vacuum, and the fluidizing valve (8) is repeatedly opened and closed at predetermined time intervals to convey powder from the powder supply line (2) to the powder discharge line (4).

12. The powder metering device according to any one of the preceding claims, characterized in that, The control unit (41) is configured to operate the valves (6, 7, 8) in a second intermediate-fine conveying mode, in which the outlet valve (7) is held in the open position while the discharge line (4) is subjected to a vacuum, the fluidizing valve (8) is repeatedly opened and at least partially closed at predetermined time intervals to convey powder from the powder supply line (2) to the powder discharge line (4), and the inlet valve (6) is optionally closed and reopened at predetermined time intervals to limit the amount of powder conveyed.

13. The powder metering device according to any one of the preceding claims, characterized in that, The control unit (41) is configured to operate the valves (6, 7, 8) in a third precision delivery mode, in which the inlet valve and the outlet valve (6, 7) are opened and closed in sequence, while the discharge pipeline (4) is subjected to a vacuum in order to accurately deliver one metering volume of the metering chamber (1) in a single metering operation.

14. The powder metering device according to any one of the preceding claims, characterized in that, The discharge pipe (4) is connected to a collection container (30), which is preferably closed or closable, and the collection container (30) has a weighing system (33) connected thereto for determining the weight of the powder stored therein.

15. The powder metering device according to any one of the preceding claims, characterized in that, The supply line (2) is connected to a hopper (3), which is preferably closed or closable, for providing the amount of powder to be conveyed and has a weighing system (42) connected thereto for determining the weight, particularly in the form of one or more weighing sensors.

16. A system (40) comprising a powder metering device (10) according to any one of the preceding claims and a collection container (30) connected thereto, characterized in that, The collection container (30) has a vacuum generating unit (31) connected thereto, the vacuum generating unit (31) being configured to selectively generate a vacuum in the collection container (30) or in a region (32) of the collection container (30) and in the discharge line (4) of the powder metering device (10) connected thereto.

17. A powder metering method, particularly for operating a powder metering device and / or system according to any one of the preceding claims, characterized in that, Powder is drawn from the supply line (2) into the metering chamber (1) by means of vacuum. The metering chamber (1) is formed by a line section (5) and includes an inlet valve (6), an opposite outlet valve (7) and a fluidizing valve (8) inserted between the two. The powder is conveyed from the metering chamber (1) through the discharge line (4) connected thereto by means of vacuum by selectively controlling the valves (6, 7, 8) in at least two different conveying modes. The conveying modes preferably include at least a coarse conveying mode and a fine conveying mode.

18. The powder metering method according to claim 17, characterized in that, In the first coarse conveying mode, the control unit (41) associated with the valves (6, 7, 8) controls the valves (6, 7, 8) in such a way that the fluidizing valve (8) is closed for a predetermined first time period t1, preferably 2 seconds, and then opened for a predetermined second shorter time period t2, preferably 1 second, while the discharge line (4) is vacuumed to form a powder plug in the metering chamber (1).

19. The powder metering method according to claim 18, characterized in that, The inlet valve (6) is also closed and reopened at predetermined time intervals to limit the amount of powder conveyed.

20. The powder metering method according to any one of claims 17 to 19, characterized in that, In the fine delivery mode, the control unit (41) associated with the valves (6, 7, 8) controls the valves (6, 7, 8) in the following manner: first, a vacuum is generated in the closed metering chamber (1), then the inlet valve (6) is opened while the outlet valve (7) and the fluidization valve (8) are kept closed to allow powder to enter the metering chamber (1), then the inlet valve (6) is closed again, and then the outlet valve (7) and the fluidization valve (8) are opened while the inlet valve (6) is kept closed.

21. The powder metering method according to any one of claims 17 to 20, characterized in that, The control unit (41) controls the valves (6, 7, 8) in such a way that it first delivers the powder in a coarse conveying mode, preferably to a collection container (30) connected to the device (10), and delivers the powder in a fine conveying mode when the powder amount approaches the predetermined target amount.

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