EP3225315A1 - Method and dispensing device for pressure-regulated metering of a liquid or paste product - Google Patents

Abstract

A method for pressure-controlled dosing of a liquid or pasty product (P), comprising the following steps: dosing (S1) the product (P) by means of a metering pump (2, 3) into a mixing chamber (27); Determining (S2) a product pressure of the product (P) after the mixing chamber (27); Determining (S3) a deviation of the product pressure from a predetermined target pressure; and pressure-responsive opening or closing (S4) of a pressure regulating valve (34) provided at an outlet nozzle (28) of the mixing chamber (27) to equalize the product pressure to the target pressure, reducing product pressure upon opening of the pressure regulating valve (34) and closing of the pressure regulating valve (34) is increased.

Description

The present invention relates to a method and a metering device for pressure-controlled metering of a liquid or pasty product.

In automation technology, dosing pumps with downstream integrated static or dynamic mixers are used for the application of single- or multi-component adhesives and sealants or even paints. For example, these are piston or gear metering devices or metering devices based on the eccentric screw principle, which realize the exact quantity or the volume and the mixing ratio at the input of the mixer by means of a control unit. Static mixing takes place by means of so-called static mixers with mixing spirals, whereby the two components are mixed by multiple throws. Due to the friction in the static or dynamic mixer, pressure losses occur which must be overcome by the metering pumps. Depending on the design, shut-off valves may be arranged both at the inlet and at the outlet of the mixer in order to interrupt the product flow at the start and stop of the dosing and thus prevent dripping or repressing. The amount or volume per component during the dosing process can be influenced by various factors. These include, but are not limited to, the backpressure in the static mixer, the viscosity of the components, the compressibility, and other rheological properties, such as the flow limit of the components. The compressibility of adhesives can take on a significant degree here, for example, by air or gas inclusions. Especially with compressible components, the accuracy of the volume or the amount is not always guaranteed due to the change in volume and the change in pressure conditions in the dynamic and static state, so that there may be partial errors in the mixing ratio as well as in the total.

Against this background, an object of the present invention is to provide an improved method for dosing a liquid or pasty product.

Accordingly, a method for pressure-controlled metering of a liquid or pasty product is proposed. The method comprises the steps of metering the product into a mixing chamber by means of a metering pump, determining a product pressure of the product after the mixing chamber, determining a deviation of the product pressure from a predetermined target pressure, and opening or closing a pressure regulating valve provided at an exit nozzle of the mixing chamber equalize the product pressure to the target pressure, wherein the product pressure is reduced at the opening of the pressure control valve and increased at the closing of the pressure control valve.

In this case, the pressure regulating valve is regulated in particular in such a way, preferably regulated so steadily that the product pressure is equalized to the target pressure.

The method is carried out in particular by means of a dosing device described below. The product can have several components. For example, the product may have two components, each product being associated with a metering pump. The method may then include a step of metering a first component and a second component into the mixing chamber. The product may also have only one component. Preferably, the product is continuously metered into the mixing chamber. That is, throughout the process, the metering pump meters the product into the mixing chamber. The product may be, for example, an adhesive or sealant, water, an aqueous solution, a paint, a suspension, a viscous raw material, an emulsion or a fat. For example, the product may be a two or more component adhesive. A paste or a pasty product is to be understood as meaning a solid-liquid mixture, in particular a suspension, with a high content of solids. For example, the product may have a content Fillers, for example, so-called microballoons have. In particular, the product pressure is raised at least to the target pressure or above the target pressure. The process ensures that the product is always kept at the target pressure. As a result, metering inaccuracies, which could be caused by pressure losses arising in the mixing chamber, are prevented. By adjusting the product pressure to the target pressure, it is understood that the product pressure is raised to the target pressure by the pressure regulating valve, or the product pressure is lowered to the target pressure by the pressure regulating valve. In this case, the product pressure is preferably maintained in a certain pressure range which corresponds to the target pressure plus / minus a predetermined tolerance.

In particular, the pressure regulating valve is not an open-close valve which can only be switched into two switching positions, namely optionally into an open position or into a closed position. Such an open-close valve may also be referred to as a shut-off valve or shut-off valve. In the present case, a regulating valve or pressure regulating valve is to be understood as meaning a valve which can be continuously brought into any, in particular infinite, number of intermediate positions between an open position, that is to say minimum product pressure, and a closed position, that is to say maximum product pressure. This allows any product pressure between the minimum product pressure and the maximum product pressure can be adjusted continuously. For this purpose, the pressure regulating valve preferably has a valve tappet or valve body which can be displaced by means of a drive element, in particular linear. The valve body may be, for example, acicular (needle valve) or spherical (ball valve). The drive element is preferably an electric motor or an electric motor with an adjusting spindle as an actuator. As a result, the valve body can be moved to any position between the open position and the closed position. The pressure control valve is thus steplessly controlled or regulated. The open position may also be referred to as an open or opened state and the closed position may also be referred to as a closed or locked state.

According to a further embodiment, the product is compressible, wherein the product is incompressible from the target pressure.

Compressible may be understood to mean that the product is near or substantially compressible. Incompressible may further be understood to mean that the product is nearly or substantially incompressible. For example, the product may be slightly compressible again when pressurized above the target pressure. In particular, the product may be further compressible at a significantly higher pressure than the target pressure. For example, the product may show a compressibility (volume change) of about 20% at a pressure of about 15 bar. In a range from 15 bar to 30 bar, the compressibility (volume change) can be significantly incompressible relative to a lower pressure range of 0 bar to 15 bar.

A fluid whose density does not depend on pressure is called incompressible - in contrast to compressible fluids. A characteristic of the fluids is the compressibility, which describes the change in the density of a fluid under pressure change and the property of the volume change with temperature change. The compressibility of a fluid is the decision criterion with regard to a distinction between gas (compressible) and liquid (almost incompressible). The terms hydraulics (almost incompressible fluids such as liquids, mostly oil) and pneumatics (compressible fluids such as gases, mostly air) are understood to mean techniques that realize and control "force movements" with fluids. Furthermore, a distinction is made between ideal and real fluids.

Especially with compressible products, especially at the beginning and at the end of a dosing process, different flows and volumes or masses can be established, the determination of which can not be determined by a counter-pressure generated by flow resistances, for example in the mixing chamber. Since from the target pressure the compressibility of the product is almost zero, this effect can be minimized by the product pressure is always maintained in a pressure window greater than the target pressure. Furthermore, it can be prevented by means of the method that sensitive fillers, for example microballoons, which could burst from a certain product pressure, are damaged. For this purpose, the target pressure is limited to a maximum pressure, which is only so high that damage to the fillers is prevented.

According to a further embodiment, at least two different components of the product are metered into the mixing chamber.

The product may also have more than two, for example three or four components. For example, the product may be a two-component adhesive. In this case, one of the components can be filled with one filler and the other component can be unfilled.

According to a further embodiment, the at least two components in the mixing chamber are mixed together by means of a static mixer and / or a dynamic mixer.

By a static mixer is meant a mixer which has no moving parts. For example, in the mixing chamber, mixing elements or mixing helix can be arranged, which are set up to mix the two components by multiple Uberwerfungen. In contrast, a dynamic mixer has a movable mixing element. For example, the mixing element can be moved in rotation via a drive shaft.

According to another embodiment, the product pressure is maintained in a predetermined pressure window.

This ensures that the product is always kept at the target pressure and at the same time, as already mentioned, this can prevent damage to fillers of the product.

According to a further embodiment, the method further comprises a calibration step in which an input in the mixing chamber is closed and the product is passed to a calibration output, wherein a product pressure of the product is determined before the calibration output, wherein a deviation of the product pressure from a predetermined target pressure determined wherein a pressure valve provided at the calibration port is pressure-responsively opened or closed to equalize the product pressure to the target pressure and wherein the product pressure is reduced upon opening of the pressure control valve and increased upon closing of the pressure control valve.

In particular, a first channel for a first component and a second channel for a second component are provided at the entrance of the mixing chamber. The two channels can each be closed and opened by these associated shut-off valves. As with the pressure control of the dosing flow, a stable pressure state, which corresponds to the same pressure state as during the dosing, can be achieved for the calibration step. Since in this calibration step the product flow but each component is dosed individually from the respective component associated calibration opening, can be done very easily a pressurized calibration of each component. For this purpose, the amount of the respective component is measured and can then be used as the measured value of a calibration function of the metering device.

According to a further embodiment, the same product pressure as in the mixing chamber is achieved in the calibration step.

As a result, the values determined during calibration can simply be transferred to the dosing process of the product.

According to another embodiment, the calibration step is performed separately for different components of the product.

For example, the calibration step may be performed separately for the first component of the product and for the second component of the product. The calibration step can also be carried out if the product has only one component.

Furthermore, a metering device for pressure-regulating metering of a liquid or pasty product is proposed. The metering device comprises a mixing chamber, at least one metering pump arranged upstream of the mixing chamber for metering the product into the mixing chamber, a pressure sensor for determining a product pressure of the product in the mixing chamber, a pressure regulating valve for pressure-dependent opening or closing of an outlet nozzle of the mixing chamber and a control device adapted thereto is to control the pressure control valve pressure-dependent, to adjust the product pressure to a target pressure.

The metering pump may be an eccentric screw pump, a gear pump, a piston dispenser or the like. Preferably, the metering pump is an eccentric screw pump. An eccentric screw pump preferably comprises a stator accommodated in a pump housing, which has an elastically deformable elastomer part with a central opening. The breakthrough preferably comprises a helical or helical inner contour. In the stator, a rotatable rotor is preferably provided, which comprises a corresponding to the elastomer part screw or helical outer contour. The rotor can be driven via a drive shaft mounted in a bearing housing of the eccentric screw pump. A drive device, in particular an electric motor, can preferably be connected to the drive shaft. The drive shaft can be fixedly connected to the rotor by means of a flexible shaft, a joint or a flexible shaft. When turning the rotor, the product or the component by the interaction conveyed with the elastomer part of the stator in a longitudinal direction of the eccentric screw pump away from the drive shaft according to the endless piston principle. The mixing chamber is provided in particular in a tubular or rectangular mixing block. For example, a pipe or a hose can be arranged between the mixing chamber and the at least one metering pump so that the mixing chamber can be arranged away from the metering pump. The pressure sensor may be provided directly on the mixing chamber or on a product diverter block.

According to one embodiment, the mixing chamber has a static mixer and / or a dynamic mixer.

Preferably, a static mixer is provided in the mixing chamber. As a result, the metering device is particularly low maintenance. Furthermore, a static mixer is less expensive than a dynamic mixer.

According to a further embodiment, the pressure regulating valve is a needle valve.

A needle valve in particular has a needle-shaped valve body. Preferably, a needle valve is used, which can act as possible dead space directly as dosing tip. Alternatively, the pressure control valve is a ball valve with a spherical valve body. In particular, the pressure control valve has a drive element, preferably a spindle drive or an electric motor with an adjusting spindle as an actuator, and a needle-shaped valve body which is arranged in a bore of a nozzle tube.

According to a further embodiment, a product diversion block for diverting the product is provided on the mixing chamber, the pressure sensor and a drive element of the pressure regulating valve being provided on the product diversion block.

The product diverter block is preferably configured to divert the product twice through an angle of 90 °. The product redirection block is dispensable. By diverting the product into the product diversion block, it can be achieved that the valve body is axially displaceable in a flow direction of the product in order to open and close the pressure regulating valve.

According to a further embodiment, the metering device further comprises a flow block arranged between the at least one metering pump and the mixing chamber, with a channel through which the product can be passed, a pressure sensor for detecting a product pressure of the product in the channel and a shut-off valve for closing the channel in front of the channel mixing chamber.

The flow block may include a mixing head block and a flow shut-off block, wherein the mixing head block is disposed between the flow shut-off block and the metering pump. The channel preferably penetrates both the flow blocking block and the mixing head block. In particular, a first channel for the first component and a second channel, which is fluidically separated from the first channel, for the second component can be provided in the flow block. Each of the channels can be assigned its own pressure sensor. Furthermore, each of the channels can be assigned a shut-off valve. With the help of the shut-off valves, the entrance of the mixing chamber can be closed and opened.

According to a further embodiment, the dosing device further comprises a calibration block with a calibration output and a pressure control valve for pressure-dependent opening or closing of the calibration output, wherein the control device is adapted to control the pressure control valve pressure-dependent to equalize the product pressure with a closed shut-off valve to a desired pressure.

The calibration block is preferably attached to the flow block. The calibration block preferably has a first calibration output and a second calibration output, wherein a first pressure regulating valve is associated with the first calibration output and a second pressure regulating valve is associated with the second calibration output. The calibration outputs are each connected via a bore with their associated channels in the flow block. The control device is preferably set up to control the pressure control valves and the shut-off valves in each case as a function of determined measured values of the pressure sensors assigned to them. The control device can have a computer program with a control algorithm, preferably a PID control.

According to a further embodiment, the metering device has a first metering pump for metering a first component of the product and a second metering pump for metering a second component of the product.

The number of dosing pumps is arbitrary. For example, the metering device may also comprise three or more metering pumps. The metering pumps may be attached to the flow block. Alternatively, the metering pumps and the flow block can be coupled by means of a connecting line.

Further possible implementations of the method and / or the dosing device also include combinations of features or embodiments described above or below with respect to the exemplary embodiments which are not explicitly mentioned. The skilled person will also add individual aspects as improvements or additions to the respective basic form of the method and / or the metering device.

• Fig. 1 zeigt eine schematische perspektivische Ansicht einer Ausführungsform einer Dosiervorrichtung;
• Fig. 2 zeigt eine schematische Schnittansicht der Dosiervorrichtung gemäß Fig. 1;
• Fig. 3 zeigt eine schematische perspektivische Teilschnittansicht der Dosiervorrichtung gemäß Fig. 1;
• Fig. 4 zeigt eine schematische Teilschnittansicht der Dosiervorrichtung gemäß Fig. 1;
• Fig. 5 zeigt eine weitere schematische Teilschnittansicht der Dosiervorrichtung gemäß Fig. 1;
• Fig. 6 zeigt eine weitere schematische Teilschnittansicht der Dosiervorrichtung gemäß Fig. 1;
• Fig. 7 zeigt eine weitere schematische Teilschnittansicht der Dosiervorrichtung gemäß Fig. 1;
• Fig. 8 zeigt eine weitere schematische Teilschnittansicht der Dosiervorrichtung gemäß Fig. 1; und
• Fig. 9 zeigt ein schematisches Blockdiagramm einer Ausführungsform eines Verfahrens zum Betreiben der Dosiervorrichtung gemäß Fig. 1.

Further advantageous embodiments and aspects of the method and / or the metering device are the subject matter of the subclaims and the exemplary embodiments of the method and / or the metering device described below. Furthermore, the method and / or the metering device are based on of preferred embodiments with reference to the accompanying figures.

• Fig. 1 shows a schematic perspective view of an embodiment of a metering device;
• Fig. 2 shows a schematic sectional view of the metering device according to Fig. 1 ;
• Fig. 3 shows a schematic perspective partial sectional view of the metering device according to Fig. 1 ;
• Fig. 4 shows a schematic partial sectional view of the metering device according to Fig. 1 ;
• Fig. 5 shows a further schematic partial sectional view of the metering device according to Fig. 1 ;
• Fig. 6 shows a further schematic partial sectional view of the metering device according to Fig. 1 ;
• Fig. 7 shows a further schematic partial sectional view of the metering device according to Fig. 1 ;
• Fig. 8 shows a further schematic partial sectional view of the metering device according to Fig. 1 ; and
• Fig. 9 shows a schematic block diagram of an embodiment of a method for operating the metering device according to Fig. 1 ,

In the figures, the same or functionally identical elements have been given the same reference numerals, unless stated otherwise.

The Fig. 1 shows a schematic perspective view of an embodiment of a metering device 1 for pressure-controlled metering of a liquid or pasty product P. The Fig. 2 shows a schematic sectional view of the metering device 1 and the Fig. 3 shows a schematic perspective partial sectional view of the metering device 1. Hereinafter, the Fig. 1 to 3 simultaneously referred to.

The product may be, for example, an adhesive or sealant, water, an aqueous solution, a paint, a suspension, a viscous raw material, an emulsion or a fat. The product P may have one or more than one component K1, K2. For example, the product P may be a two-component adhesive. For example, the product may be filled with fillers such as microballoons. Microballoons are hollow glass spheres which are used, for example, as fillers for epoxy and polyester resin systems. Such microballoons may for example have a bulk density of 140 to 150 g / l, a specific gravity of 0.26 g / cm ³ , a particle size distribution of 50 microns and a maximum particle size of 200 microns. A pasty product or a paste is a solid-liquid mixture, in particular a suspension, to be understood as having a high content of solids.

The metering device 1 comprises at least one metering pump 2, 3. The metering device 1, as in the Fig. 1 to 3 shown, two metering pumps 2, 3, in particular a first metering pump 2 and a second metering pump 3, or any number of metering pumps, for example, three metering pumps having. The metering pumps 2, 3 may be, for example, progressing cavity pumps, gear pumps, piston dispensers or the like. Preferably, the metering pumps 2, 3 are designed as eccentric screw pumps.

An eccentric screw pump preferably comprises a stator accommodated in a pump housing, which has an elastically deformable elastomer part with a central opening. The breakthrough preferably comprises a screw or helical inner contour. In the stator, a rotatable rotor is preferably provided, which comprises a corresponding to the elastomer part screw or helical outer contour. The rotor may be driven via a drive shaft of a drive element, in particular an electric motor. The drive shaft may be fixedly connected to the rotor by means of a flexible shaft or flex shaft or propeller shaft. When the rotor is rotated, the product P or the components K1, K2 are conveyed away from the drive shaft according to the endless piston principle by interaction with the elastomer part of the stator in a longitudinal direction of the eccentric screw pump. The delivery volume is dependent on the speed, the size, the pitch and the geometry of the rotor.

The first metering pump 2 and the second metering pump 3 are mounted on a flow head or flow block 4. The metering pumps 2, 3 are arranged V-shaped or parallel. The flow block 4 may for example be made of a steel or an aluminum material. The flow block 4 may be formed in two parts and a mixing head block 5, to which the metering pumps 2, 3 are attached, and a flow blocking block 6 have. The mixing head block 5 is arranged between the flow blocking block 6 and the metering pumps 2, 3.

The flow block 4 comprises a first channel 7 penetrating through the mixing head block 5 and the throughflow blocking block 6, through which the first component K1 can be passed, and a second channel 8 at least partially parallel to the first channel 7, through which the second component K2 can be passed. The flow block 4 further comprises a first pressure sensor 9 for determining a pressure of the first component K1 in the first channel 7 and a second pressure sensor 10 for determining a pressure of the second component K2 in the second channel 8.

Furthermore, the flow block 4 comprises a first shut-off valve 11 for closing the first channel 7 downstream of the first pressure sensor 9. The first Shut-off valve 11 comprises a drive element 12, for example an electric motor, as well as a valve tappet or valve body 13, which is displaceable into it for closing the first channel 7 and can be displaced out of it again to open the first channel 7. Furthermore, the flow block 4 comprises a second shut-off valve 14 for closing the second channel 8 downstream of the second pressure sensor 10. The second shut-off valve 14 also comprises a drive element 15 and a valve stem or valve body 16, which closes and opens the second channel 8 in the second channel 8 in and out of this again verlagerbar.

Furthermore, the dosing device 1 comprises a calibration block 17 fastened to the mixing head block 5. The calibration block 17 can be screwed to the mixing head block 5, for example. The calibration block 17 comprises a first calibration output 18 and a second calibration output 19. Furthermore, the calibration block 17 comprises a first pressure regulating valve 20 for pressure-dependent opening or closing of the first calibration output 18 and a second pressure regulating valve 21 for pressure-dependent opening or closing of the second calibration output 19.

The second pressure regulating valve 21 comprises a drive element 22 and a valve tappet or valve body 23 which is linearly displaceable by means of the drive element 22 in a longitudinal direction L1 of the metering device 1. The drive element 22 is preferably an electric motor with an adjusting spindle as an actuator. With the aid of the valve body 23, the second calibration 19 can be opened or closed. The valve body 23 is preferably needle-shaped. In particular, the second pressure regulating valve 21 is a needle valve.

The valve body 23 of the second pressure regulating valve 21 is arranged in a bore 24 provided in the calibration block 17. The bore 24 may be parallel to the second channel 8. The second channel 8 is connected via a bore 25 passed through the mixing head block 5 and the calibration block 17 the bore 24 fluidly connected. With the help of the second pressure control valve 21, the second calibration output 19 can be closed and opened.

The first pressure control valve 20 also has such a drive element 22 and a needle-shaped valve body 23. With the aid of the first pressure regulating valve 20, the first calibration outlet 18 can be closed and opened. The valve body 23 of the first pressure control valve 20 is provided in a parallel to the first channel 7 arranged bore 24 which is fluidly connected via a further bore 25 to the first channel 7. The first calibration output 18 associated bores 24, 25 and the valve body 23 of the first pressure control valve 20 are in the Fig. 1 to 3 Not shown.

The metering device 1 comprises a mixing block 26, which is fastened on the front side to the flow blocking block 6. The mixing block 26 may be attached directly to the flow blocking block 6, or a pipe or hose may be provided between the flow blocking block 6 and the mixing block 26. The mixing block 26 is tubular and encloses a cylindrical mixing chamber 27, in which the first components K1 and the second component K2 are mixed. For this purpose, a static mixer and / or a dynamic mixer may be provided in the mixing chamber 27.

By a static mixer is meant a mixer which has no moving parts. Such a static mixer has, in particular, mixing helix or mixing body, wherein the two components K1, K2 are mixed through the mixing chamber 27 during conveying thereof by multiple blow-ups. In contrast, a dynamic mixer has one or more movable, for example a rotatable mixing element. In the mixing chamber 27, the components K1, K2 are mixed to the product P. In the event that the product P is not mehrkomponentig, the product P from the metering pump 2, 3, in this case only from a metering pump 2, 3, metered into the mixing chamber 27 and mixed there.

The mixing block 26 has an outlet nozzle 28, which does not necessarily have to be provided directly on the mixing block 26. The exit nozzle 28 is provided on a tapered nozzle tube 29. Between the nozzle tube 29 and the mixing block 26, a Produktumleitungsblock 30 is provided. By means of the product redirection block 30, the product P can be redirected. In particular, the product diverter block 30 is configured to divert the product twice through an angle of 90 °. For this purpose, a coiled channel 31 is provided in the product diversion block 30, which fluidly connects the mixing chamber 27 with a channel 32 provided in the nozzle tube 29. The channels 31, 32 may be part of the mixing chamber 27.

At the product diversion block 30, a drive element 33 of a further, in particular a third, pressure control valve 34 is provided. The drive element 33 is preferably an electric motor with an adjusting spindle as an actuator. With the help of the pressure control valve 34, the output nozzle 28 can be opened or closed depending on the pressure. For this purpose, the pressure regulating valve 34 has a valve tappet or valve body 35 provided in the channel 32 of the nozzle tube 29. The valve body 35 is linearly displaceable in the channel 32, in particular in the longitudinal direction L1. The pressure regulating valve 34 is in particular a needle valve.

The pressure control valves 20, 21, 34 are in particular not designed as open-close valves. An on-off valve can be switched only in two switching positions, namely either in an open position or in a closed position. Such an open-close valve may also be referred to as a shut-off valve or shut-off valve. In the present case, a regulating valve or pressure regulating valve is to be understood as meaning a valve which can be continuously brought into any, in particular infinite, number of intermediate positions between an open position, that is to say minimum product pressure, and a closed position, that is to say maximum product pressure. This allows any product pressure to be set between the minimum product pressure and the maximum product pressure. For this purpose, the respective pressure control valve 20, 21, 34 preferably respectively the previously mentioned valve body 23, 35 which, with the aid of the respective drive element 22, 33, in particular linear, is displaceable. The valve body 22, 33 may be, for example, acicular (needle valve) or spherical (ball valve). The drive element 22, 33 is preferably in each case an electric motor or an electric motor with an adjusting spindle as an actuator. In this way, the respective valve body 23, 35 can be moved to any position between the open position and the closed position. Furthermore, the metering device 1 comprises a pressure sensor 36 for determining a product pressure of the product P after the mixing chamber 27. The pressure sensor 36 may be arranged directly on the mixing chamber 27 or, as in the Fig. 1 to 3 shown on the product redirection block 30 and in particular in the channel 31 of the product redirection block 30th

The metering device 1 further comprises a control device 37, which is set up to detect measured values of the pressure sensors 9, 10, 36 and to control the pressure control valves 20, 21, 34 and the shut-off valves 11, 14. The control device 37 is also set up to compare the measured values recorded with the aid of the pressure sensors 9, 10, 36 with a desired value.

The functionality of the metering device 1 will be described below with reference to FIGS Fig. 4 to 8 explained, each showing detailed views of the dosing device 1 show. The amount or the volume per component K1, K2 during the dosing process can be influenced by various factors. These may include the backpressure in the mixing chamber 27, the viscosity of the product P or the components K1, K2, the compressibility of the product P or the components K1, K2 and other rheological properties, such as the yield point. The compressibility of the product P or the components K1, K2 can in this case take on a considerable degree by air or gas inclusions or by the addition of microballoons.

In particular, with compressible components K1, K2, the accuracy of the metered volume or the amount is not guaranteed due to the change in volume and the changes in pressure conditions both in the dynamic and in the static state, so that there may be partial errors in the mixing ratio and the total amount. In order to prevent this, in the metering device 1, the product P or the components K1, K2 are metered into the mixing chamber 27 with the aid of the respective metering pump 2, 3. The dosing can be done continuously. That is, the metering pumps 2, 3 provide a continuous flow. In normal operation of the metering device 1, the shut-off valves 11, 14 are opened, so that the channels 7, 8 are fluidically connected to the mixing chamber 27. That is, the metering pumps 2, 3 promote into the mixing chamber 27.

With the aid of the pressure sensor 36, the product pressure of the product P after the mixing chamber 27 is measured. This determined product pressure is compared with the aid of the control device 37 with a predetermined target pressure, and the deviation of the product pressure from the target pressure is determined. The control device 37 can for this purpose have a computer program with a control algorithm, preferably with a PID control (English: proportional integral derivative). The target pressure is preferably so high that the product P is no longer compressible and in particular is almost or substantially no longer compressible. However, the product pressure is so low that the product P is not damaged, for example, so small as to prevent microballoons contained in the product P from being crushed. That is, the product pressure is maintained in a predetermined pressure window.

The control device 37 controls the pressure control valve 34 so that the outlet nozzle 28 is opened or closed depending on the pressure. Upon opening of the pressure regulating valve 34, the product pressure is thus lowered because the product P can exit through the outlet nozzle 28. When closing the pressure control valve 34, the product pressure increases in the mixing chamber 27, since no product P can escape from the outlet nozzle 28 more. The Fig. 4 shows For this purpose, the pressure control valve 34 in the closed state and the Fig. 5 shows the pressure control valve 34 in the open state.

With the help of the metering device 1, therefore, the product pressure of the product P can be kept constant during the entire dosing both in the static and in the dynamic state, in order to minimize or completely prevent inaccuracies of the dosage. By means of the control device 37 controlled via the pressure control valve 34 in response to the product pressure measured by the pressure sensor 36, a high pressure state can be kept constant. This is independent of whether the product P flows or does not flow, that is, in both a static and a dynamic state. The product pressure is thus independent of the flow and the back pressure by the static mixer in the mixing chamber 27 and through the outlet nozzle 28th

In addition to the control function of the product pressure, a calibration under pressure can be made possible. For this purpose, an input of the mixing chamber 27 by means of the shut-off valves 11, 14 is closed. In the Fig. 6 When the first shut-off valve 11 is opened, that is, the valve body 13 does not block the first passage 7 provided in the flow block 4. The second shut-off valve 14 is closed, that is, the valve body 16 is displaced into the second channel 8 in order to block it. As with the pressure control of the volume flow of the product P, a stable pressure state is reached via the pressure sensor 10, the control device 37 and the pressure control valve 21, which preferably corresponds to the same pressure state as in the dosage of the product P.

Since in this calibration process the volume flow per component K1, K2 is metered individually from the respective calibration output 18, 19, a pressurized calibration per component K1, K2 can very easily take place. In this case, the amount of component K1, K2 per unit of time is measured and used as the measured value of a calibration function of the dosing device 1. Especially with compressible products P or with compressible components K1, K2, in particular at the beginning and at the end of a dosing process, set up different flows and volumes or masses whose determination can not be determined by a backpressure generated by flow resistances. The Fig. 7 shows the open pressure control valve 21 and the Fig. 8 shows the pressure control valve 21 in a closed state.

But since the product P or the components K1, K2 are no longer compressible and the compressibility is almost zero from the predetermined target pressure, this effect can be minimized by the product pressure is always maintained in a pressure window that is greater than or equal to the target pressure. If the product P or the components K1, K2 contain fillers, such as microballoons, which could burst above a certain pressure, the target pressure can be adjusted so that on the one hand the maximum possible amount of the product P is metered by limiting it to one Maximum pressure but the bursting of the fillers is prevented.

A like in Fig. 9 illustrated method for pressure-controlled dosing of the liquid or pasty product P has several steps. In a step S1, the product P is metered into the mixing chamber 27 with the aid of the metering pump 2, 3. In step S1, at least two components K1, K2 of the product P from different metering pumps 2, 3 can also be metered into the mixing chamber 27. The dosing can be done continuously. That is, throughout the process, the metering pump meters the product P into the mixing chamber 27. In a step S2, the product pressure of the product P after the mixing chamber 27 is determined. For this purpose, the pressure sensor 36 is used, which may be provided directly on the mixing block 26 or also on the product diversion block 30 or on the nozzle tube 29.

In a step S3, a deviation of the product pressure from a predetermined target pressure is determined. The target pressure is in particular so high that the product P or the components K1, K2 are no longer compressible from the target pressure. In a step S4, the at the output nozzle 28th the mixing chamber 27 provided pressure control valve 34 is opened or closed to equalize the product pressure to the target pressure or to raise above the target pressure. In particular, the product pressure is reduced when the pressure regulating valve 34 is opened and increased when the pressure regulating valve 34 is closed.

The method may further include a calibration step S5, in which the channels 7, 8, that is, the input of the mixing chamber 27, are closed and the product P or the individual components K1, K2 are passed to the calibration output 18, 19. In this case, with the aid of the respective pressure sensor 9, 10, the product pressure of the product P or the components K1, K2 is determined before the calibration output 18, 19 and a deviation of the determined product pressure from the predetermined target pressure, which may correspond to the above-mentioned target pressure determined.

The pressure regulating valve 20, 21 provided at the respective calibration output 18, 19 is thereby opened or closed in a pressure-dependent manner in order to equalize the product pressure to the target pressure, the product pressure being reduced at the opening of the respective pressure control valve 20, 21 and at the closing of the respective pressure control valve 20, 21 is increased. The calibration step S5 can be carried out separately for the different components K1, K2 of the product P. In the case that the product P has only one component K1, K2, the calibration step S5 is carried out directly for the product P. The aim here is in particular the pump calibration.

Although the present invention has been described with reference to embodiments, it is variously modifiable.

LIST OF REFERENCE NUMBERS

1

metering

2

metering

3

metering

4

Flow Block

5

Mixing head block

6

Durchflussabsperrblock

7

channel

8th

channel

9

pressure sensor

10

pressure sensor

11

shut-off valve

12

driving element

13

valve body

14

shut-off valve

15

driving element

16

valve body

17

Calibration

18

calibration output

19

calibration output

20

Pressure control valve

21

Pressure control valve

22

driving element

23

valve body

24

drilling

25

drilling

26

mixing block

27

mixing chamber

28

outlet nozzle

29

nozzle tube

30

Product diversion block

31

channel

32

channel

33

driving element

34

Pressure control valve

35

valve body

36

pressure sensor

37

control device

K1

component

K2

component

L1

longitudinal direction

P

product

S1

step

S2

step

S3

step

S4

step

S5

step

Claims (15)

Process for the pressure-controlled dosing of a liquid or pasty product (P), comprising the following steps: Dosing (S1) the product (P) by means of a metering pump (2, 3) into a mixing chamber (27); Determining (S2) a product pressure of the product (P) after the mixing chamber (27); Determining (S3) a deviation of the product pressure from a predetermined target pressure; and pressure dependent opening or closing (S4) of a pressure regulating valve (34) provided at an outlet nozzle (28) of the mixing chamber (27) to equalize the product pressure to the target pressure, reducing product pressure upon opening of the pressure control valve (34) and closing the pressure control valve Pressure control valve (34) is increased. The method of claim 1, wherein the product (P) is compressible and wherein the product (P) is incompressible from the target pressure. A method according to claim 1 or 2, wherein at least two different components (K1, K2) of the product (P) are metered into the mixing chamber (27). Method according to claim 3, wherein the at least two components (K1, K2) in the mixing chamber (27) are mixed together by means of a static mixer and / or a dynamic mixer. The method of any of claims 1-4, wherein the product pressure is maintained in a predetermined pressure window. Method according to one of claims 1-5, further comprising a calibration step (S5), in which an input of the mixing chamber (27) is closed and the product (P) is directed to a calibration outlet (18, 19), wherein a product pressure of the product (P) is determined prior to the calibration output (18, 19), wherein a deviation of the product pressure from a predetermined target pressure is determined Pressure control valve (20, 21) provided on the calibration output (18, 19) is opened or closed in a pressure-dependent manner to equalize the product pressure to the target pressure and the product pressure is reduced during opening of the pressure control valve (20, 21) and at closing of the pressure control valve ( 20, 21) is increased. The method of claim 6, wherein in the calibration step (S5) the same product pressure as in the mixing chamber (27) is achieved. Method according to claim 6 or 7, wherein the calibration step (S5) is carried out separately for different components (K1, K2) of the product (P). Dosing device (1) for pressure-controlled dosing of a liquid or pasty product (P), with
a mixing chamber (27),
at least one of the mixing chamber (27) upstream metering pump (2, 3) for metering the product (P) in the mixing chamber (27),
a pressure sensor (36) for determining a product pressure of the product (P) after the mixing chamber (27),
a pressure regulating valve (34) for pressure-dependent opening or closing of an outlet nozzle (28) of the mixing chamber (27), and
a control device (37) which is adapted to control the pressure regulating valve (34) in a pressure-dependent manner in order to equalize the product pressure to a setpoint pressure. Dosing device according to claim 9, wherein the mixing chamber (27) comprises a static mixer or a dynamic mixer. Dosing device according to claim 9 or 10, wherein the pressure regulating valve (34) is a needle valve. A dosing device according to any one of claims 9 to 11, wherein a product diversion block (30) for diverting the product (P) is provided on the mixing chamber (27) and wherein the pressure sensor (36) and a drive element (33) of the product diversion block (30) Pressure control valve (34) are provided. Dosing device according to one of claims 9 - 12, further comprising a between the at least one metering pump (2, 3) and the mixing chamber (27) arranged flow block (4) with a channel (7, 8) through which the product (P) hindurchleitbar is, a pressure sensor (9, 10) for detecting a product pressure of the product (P) in the channel (7, 8) and a shut-off valve (11, 14) for closing the channel (7, 8) in front of the mixing chamber (27). Dosing device according to claim 13, further comprising a calibration block (17) with a Kalibrierausgang (18, 19) and a pressure control valve (20, 21) for pressure-dependent opening or closing of the Kalibrierausgangs (18, 19), wherein the control device (37) is arranged to actuate the pressure regulating valve (20, 21) in a pressure-dependent manner in order to equalize the product pressure when the shut-off valve (11, 14) is closed to a setpoint pressure. Dosing device according to one of claims 9-14, wherein the dosing device (1) comprises a first dosing pump (2) for dosing a first component (K1) of the product (P) and a second dosing pump (3) for dosing a second component (K2) of the Product (P).

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