EP3317023B1 - Applicator, in particular rotary atomizer - Google Patents

Description

The invention relates to an application device, in particular a rotary atomizer, for applying a coating agent.

Two-component paints (2K paints) are known from the prior art, which consist of two components, namely a hardener (e.g. isocyanate) and a base paint. When such 2K paints are conveyed in a paint shop, needle valves that have a displaceable valve needle are usually used as shut-off valves. The valve needle runs through a valve chamber which is filled with the 2K paint during operation, the valve chamber being sealed off from the valve drive acting on the valve needle by a sealing ring. The inner side of the sealing ring rubs against the outer surface of the valve needle and its outer circumference rests against the inner wall of the valve chamber.

The problem here is the fact that the hardener (e.g. isocyanate) usually reacts with water and then hardens. Even the smallest amounts of water are sufficient to start the curing process, so that, for example, normal humidity already leads to curing. This is problematic because the 2K paint or the hardener used is very capable of creeping and has low viscosity and can therefore infiltrate the sealing ring around the valve needle so that the 2K paint or the hardener can escape from the paint-filled valve chamber into the area of the valve drive.

This can lead to undesired hardening of the 2K lacquer or hardener, especially during longer downtimes (e.g. on weekends). For example, the cured 2K paint can stick the valve needle in the valve seat. In addition, the 2K paint can adhere to the valve needle and then damage the surrounding sealing ring when it has hardened, which leads to a leak. Furthermore, hardened deposits in the valve seat can lead to the valve no longer closing. Hardening can also cause the valve to close more slowly.

A valve failure is particularly problematic if the valve can no longer open, as an overpressure disturbance can then occur upstream in front of the valve, which in extreme cases can lead to the supply hoses bursting, which can cause 2K paint or hardener to escape results in considerable downtimes for cleaning and repair work.

Finally, in the area of the needle tip, a chemical reaction can occur between the medium (2K paint or hardener) on the one hand and the material of the needle tip or the valve seat, which can also lead to sticking, which means that the valve can no longer open.

Reference should also be made to the general technical background of the invention DE 297 19 535 U1 .

Furthermore, the earlier, postpublished European patent application discloses EP 2 990 124 A1 a compressed air operated coating agent valve which controls the coating agent flow to an application device.

The actuation of the coating agent valve takes place here exclusively by compressed air and the coating agent valve is structurally separate from the application device.

Finally revealed DE 27 47 707 A1 an application device according to the preamble of claim 1. Here, however, separate valves are required to control the flow of coating agent and to protect against excess pressure.

The invention is therefore based on the object of providing a correspondingly improved application device which prevents supply lines from bursting in the event of a valve failure (i.e. a valve sticking). In addition, it can be desirable in principle to prevent a valve from failing, which is also advantageous with 1K atomizers.

This object is achieved by an application device according to the invention solved according to the main claim.

The application device according to the invention (e.g. rotary atomizer) initially has, in accordance with the prior art, a first coating agent connection via which a first coating agent can be supplied, such as a base paint of a two-component paint (2K paint).

It should be mentioned here that the term application device used in the context of the invention is not limited to the preferred embodiment of a rotary atomizer, wherein such rotary atomizers can have a rotating bell plate or a rotating disc as the spray element. Other possible exemplary embodiments for application devices according to the invention are air atomizers, strip atomizers (e.g. according to FIG DE 10 2013 002 412 A1 ), Hand guns, disc atomizers, airless atomizers, airmix atomizers and ultrasonic atomizers, to name a few examples.

It should also be mentioned that the invention is not limited to paints or paint components with regard to the applied coating agent. Rather, the coating agent can also be other fluids, such as sealant, insulating material or adhesive, to name just a few examples.

In this context, it should also be mentioned that the invention is not limited to one-component coating agents or two-component coating agents, but can also be used with multicomponent coating agents which, for example, can have three components.

In addition, in accordance with the prior art, the application device according to the invention has a first strand of coating agent, which extends from the first coating agent connection in the application device and guides the first coating agent.

In accordance with the prior art, a controllable first valve which controls the flow of the first coating agent through the first strand of coating agent is arranged in this first strand of coating agent, this first valve being controllable by a first control signal.

The control signal can be, for example, an electrical control signal or a pneumatic control signal, but the invention with regard to the control of the valves is not limited to these examples.

The application device according to the invention is now distinguished from the prior art in that a first pressure relief valve actuated by its own medium is arranged in the first line of coating agent, which opens automatically to avoid an excess pressure disruption when the pressure upstream of the first pressure relief valve exceeds a certain maximum pressure. If there is an overpressure disturbance in the first coating agent strand because a valve in the first coating agent strand fails and no longer opens, the supply lines are prevented from bursting because the first overpressure valve then opens automatically. The first pressure relief valve is therefore a pressure relief valve actuated by its own medium, which opens or closes as a function of the fluid pressure applied on the inlet side.

All fluid lines in the application device that are at risk of overpressure are preferably protected by overpressure valves of this type in order to enable a pressure reduction in the event of overpressure disturbances. This can include all fluid lines in the application device, for example for base paint, hardener, ready-mixed two-component paint, one-component paint, solvent (detergent).

According to the invention, the first pressure relief valve is formed by the controllable first valve. This means that the first valve has two functions. On the one hand, the first valve enables the fluid flow through the first strand of coating agent to be controlled. On the other hand, the first valve also functions as an overpressure valve and opens automatically (actuated by its own medium) when the pressure applied on the inlet side exceeds a certain maximum pressure.

In the preferred exemplary embodiment of the invention, the first strand of coating agent leads to an application element which applies the first coating agent. For example, this application element can be a bell cup or a paint nozzle in a bell cup, but the invention is not limited to this example with regard to the type of application element.

Here, a first main valve is arranged in the first line of coating agent between the first pressure relief valve and the application element, which valve either shuts off or releases the fluid flow in the first line of coating agent. The first main valve is preferably designed as a main needle valve and has a displaceable valve needle which optionally releases or blocks a valve seat.

Such needle valves are known per se from the prior art and therefore do not need to be described in more detail.

In the preferred exemplary embodiment of the invention, the application device has a second coating agent connection in order to supply a second coating agent, such as, for example, a hardener of the 2K paint. A second coating agent line then emanates from this second coating agent connection, with a second pressure relief valve being arranged in the second coating agent line, which is also actuated by its own medium and opens automatically when the pressure upstream of the first pressure relief valve exceeds a certain maximum pressure. The second strand of coating agent preferably opens upstream in front of the first main valve into the first strand of coating agent, which enables the base paint to be mixed with the hardener.

In the first coating agent strand, a mixer is therefore preferably arranged between the junction of the second coating agent strand and the first main valve, which mixer mixes the base lacquer with the hardener to form the 2K lacquer.

The mixer is preferably designed as a static mixer, for example as a grid mixer or as a helical mixer. Such mixers are for example DE 10 2010 019 771 A1 known, so that the content of this publication is to be included in the present description with regard to the structure and mode of operation of the mixer in full.

In addition, the application device according to the invention preferably has a first return connection in order to return fluids (e.g. residues of the base paint) to a first return. Here, a first return line branches off from the first coating agent line upstream in front of the first pressure relief valve and opens into the first return connection. In this case, a third pressure relief valve is preferably arranged in the first return line, which is also actuated by its own medium and opens automatically when the pressure in the first return line upstream of the third pressure relief valve exceeds a certain maximum value.

Furthermore, the application device according to the invention preferably has a first solvent connection in order to supply a first solvent, the first solvent preferably being provided for the base paint. A first solvent line preferably emanates from this first solvent connection, the first solvent line preferably opening into the first coating agent line, namely between the first pressure relief valve and the first main valve. In this case, a first solvent valve, which is controllable and which enables or blocks the flow of solvent, is preferably arranged in the first solvent line.

In addition, the application device according to the invention preferably has a pulsed air connection in order to supply pulsed air for cleaning purposes, which is known per se from the prior art. A pulsed air line preferably emanates from this pulsed air connection and opens into the first coating agent line, namely preferably between the first pressure relief valve and the first main valve, wherein a pulsed air valve can be arranged in the pulsed air line to control the pulsed air.

Furthermore, the application device according to the invention preferably comprises a second solvent connection for supplying a second solvent, which is preferably provided for the hardener is. A second solvent line then preferably emanates from this second solvent connection, which opens into the first coating agent line between the first pressure relief valve and the first main valve, a second solvent valve preferably being arranged in the second solvent line. This second solvent valve is preferably controllable in order to selectively enable or block the flow of solvent.

In the application device according to the invention, the first coating agent connection preferably also emanates a third coating agent strand, wherein a second main valve can be arranged in the third coating agent strand, in particular in the form of a main needle valve, which is known per se from the prior art and is therefore not described in more detail must become. The first main valve and the second main valve are then preferably brought together on the outlet side and lead to the application element (e.g. bell plate). With this type of construction, the application device can be used either to apply a one-component paint or to apply a two-component paint.

Furthermore, the application device according to the invention preferably has a second return connection in order to return fluids (e.g. pulsed air, paint foam) to a second return. A second return line, which opens into the second return connection, then branches off from the third coating agent line, preferably upstream of the second main valve, a return valve preferably being arranged in this second return line. This return valve is preferably operated by its own medium, with the return valve preferably, due to its construction, between liquid coating agent at the inlet on the one hand and compressed air or Foam at the entrance on the other hand is different. The return valve opens automatically when compressed air or foam is present at the inlet of the return valve. In contrast, the return valve closes when liquid coating agent is present at the inlet of the return valve. The return valve can therefore also be referred to as a paint stop valve, as it closes automatically when liquid paint is present at the inlet of the return valve instead of compressed air or foam. The structure and function of such a paint stop valve is detailed in DE 10 2009 020 064 A1 so that the content of this publication can be fully attributed to the present description with regard to the structure and mode of operation of the return valve (paint stop valve).

In addition, the application device according to the invention preferably has at least one short flush connection in order to supply a flushing agent for a short flush of the application device. At least one short rinse line then emanates from the short rinse connection, which can guide the rinsing agent to the application element while bypassing the coating agent lines. In this case, a controllable short flush valve is preferably arranged in the short flush line, which optionally enables or blocks the flow of the flushing agent.

It should also be mentioned that the overpressure valves in the open state preferably have a pressure surge damping function, so that pressure surges arriving on the inlet side are only passed on in a damped manner on the outlet side. This can be achieved, for example, in that the pressure relief valves are designed as diaphragm valves, which will be described in detail below.

The invention also includes the technical teaching that the pressure relief valve is a special needle valve. The needle valve according to the invention initially has, in accordance with the prior art, a valve seat and a displaceable valve needle with a needle shaft and a needle head. The valve needle can be displaced between a closed position and an open position. In the closed position, the needle head of the valve needle closes the valve seat and thereby blocks the flow of fluid. In the open position, on the other hand, the valve needle is lifted from the needle head and thereby releases the fluid flow.

In one variant of the invention, different intermediate positions of the valve needle can be continuously set between the open position and the closed position in order to control the fluid flow not only qualitatively (open / closed) but also quantitatively, i.e. H. with an adjustable flow resistance. In another variant of the invention, however, the needle valve controls the fluid flow only qualitatively in that the fluid flow is either released or blocked.

The invention now provides that the valve space surrounding the valve needle and filled with media during operation is sealed by a flexible membrane which surrounds the valve needle in a ring-shaped and sealing manner upstream of the needle head. The flexible membrane reliably prevents the coating agent (e.g. hardener) from escaping from the media-filled valve chamber in the direction of the valve drive and from hardening there.

In a preferred exemplary embodiment of the invention, the valve needle is arranged displaceably in the valve chamber, the valve chamber being cylindrical at least in sections. The center of the membrane is then preferably in sealing contact with the needle shaft of the valve needle and is attached to the needle shaft of the valve needle. This means that the The membrane does not rub against the valve needle, but participates in the displacement movement of the valve needle between the open position and the closed position. This means that a displacement of the valve needle leads to a corresponding axial deflection of the membrane. Conversely, an axial deflection of the membrane, for example due to one-sided application of pressure to the membrane, also leads to a corresponding displacement of the valve needle. On the other hand, at its peripheral edge, the membrane is attached to the inner wall of the valve chamber in a sealing manner. The diaphragm thus enables an axial stroke in the center which is at least as large as the axial distance between the closed position and the open position of the valve needle, so that the diaphragm does not hinder the movement of the valve needle.

In the preferred embodiment of the invention, the needle valve has a valve drive for moving the valve needle, wherein the valve drive can be designed, for example, as a pneumatic valve drive with a piston, which is known from the prior art and therefore does not need to be described in more detail.

In addition, the needle valve according to the invention preferably has a coating agent inlet in order to supply the coating agent (e.g. 2K paint or hardener), the coating agent inlet preferably opening into the valve chamber on the side of the membrane facing away from the valve drive, so that the membrane is opposite the valve drive seals the valve chamber filled with the coating agent.

Furthermore, the needle valve according to the invention preferably contains a coating agent outlet in order to dispense the coating agent, the coating agent outlet preferably opening into the valve seat, so that the coating agent in the open position of the valve needle can flow through the valve seat to the coating agent outlet.

It has already been mentioned above that the needle valve according to the invention can have a valve drive in order to move the valve needle. In the preferred exemplary embodiment of the invention, this valve drive comprises a displaceable piston which acts on the valve needle in order to move the valve needle. The piston is preferably driven pneumatically. For this purpose, the needle valve preferably has a control air inlet in order to supply control air, the control air acting on the piston in order to move the piston and thus also the valve needle.

Furthermore, the needle valve according to the invention preferably comprises a valve spring which acts with a spring force on the piston or the valve needle. The valve spring on the one hand and the control air on the other hand preferably act in opposite directions.

It should also be mentioned that the spring force of the valve spring is preferably at least 20 N, 40 N or at least 80 N and / or at most 400 N, 200 N or 100 N, which preferably applies to both the closed position and the open position of the valve spring.

In the preferred embodiment of the invention, the valve spring presses the valve needle in the direction of the closed position, whereas the control air presses the valve needle via the piston in the direction of the open position. The valve spring and the needle head are preferably arranged on opposite sides of the piston.

It should be mentioned here that the piston is preferably a has a relatively large piston diameter in order to generate the greatest possible opening force when the valve needle is moved into the open position. It must be taken into account that the opening force depends on the effective piston area and thus also on the piston diameter and the pneumatic pressure of the control air. The piston therefore preferably has a piston diameter of at least 5 mm, 10 mm, 15 mm, 20 mm, 25 mm or even 32 mm. The piston diameter is preferably so large that a sufficiently large opening force can be achieved with a conventional control air pressure of less than 6 bar. This makes sense because the usual 6 bar compressed air networks are usually available in painting systems, which can then also be used to control the needle valve according to the invention. In this way, there is no need for a separate compressed air network for controlling the needle valve.

It has already been mentioned above that the valve spring presses the valve needle preferably in the direction of the closed position, with a certain closing force. The pneumatic valve drive, on the other hand, pushes the valve needle with a certain opening force in the direction of the open position when it is pneumatically activated. In this case, the opening force of the pneumatic valve drive should be a certain excess opening force greater than the closing force in order to be able to reliably open the needle valve when the needle head adheres to the valve seat. The needle valve is therefore preferably designed so that the excess opening force is greater than 20 N, 40 N, 60 N, 80 N, 100 N, 120 N, 130 N or even 180 N.

In the description of the prior art, the risk was already pointed out at the beginning that the coating agent hoses upstream in front of the needle valve in the event of a Overpressure disturbance can also burst due to incorrect operation or misinterpretation of the overpressure disturbance, whereby 2K paint or hardener can escape, which then leads to longer downtimes, since the 2K paint or hardener that has leaked out hardens. After the burst there is no further overpressure disturbance. When the operators start the system again, part or the majority of the paint volume escapes from the burst hose and floods z. B. the entire hand axis area. Usually the error is only discovered when several liters have already leaked and other further malfunctions occur, e.g. B. Speed disruption, as the turbine exhaust air can no longer escape through the paint. The needle valve according to the invention therefore has an overpressure function which, when a certain opening pressure at the coating agent inlet is exceeded, leads to the valve opening automatically. For this purpose, the coating agent located in the valve chamber presses against the membrane, whereby the membrane and thus also the valve needle are pressed from the closed position into the open position when the coating agent pressure is high enough to overcome the opposing force of the valve spring. The membrane therefore preferably has a membrane diameter of at least 3 mm, 6 mm or 9 mm and / or at most 40 mm, 20 mm or 11 mm. The opening pressure of the coating agent at the coating agent inlet is then preferably at least 8 bar, 10 bar, 12 bar, 14 bar or at least 38 bar and / or at most 38 bar, 22 bar, 18 bar or 16 bar. The closing force of the spring must therefore be adapted to the desired opening pressure and the effective cross section of the membrane so that the coating agent pressure in the valve chamber pushes the membrane and thus also the valve needle from the closed position into the open position when the desired opening pressure is exceeded.

It should also be mentioned that the valve seat preferably narrows with a specific seat angle in the direction of flow, just as the needle head also narrows preferably with a specific head angle in the direction of flow. In the preferred embodiment, the seat angle is essentially equal to the head angle. For example, the seat angle can be in the range of 35 ° -50 °, and the head angle is also preferably in the range of 35 ° -50 °, which ensures an optimal seal. A larger head angle improves the flow of the medium in the needle valves according to the invention with an additional membrane, which are equipped with low needle lifts (approx. 1.5 mm instead of 3 mm for conventional needle valves).

In the preferred exemplary embodiment of the invention, an additional sealing element is inserted into the needle head of the valve needle in order to seal the valve seat in the closed position. This additional sealing element can consist of a different material than the needle head of the valve needle, an elastic material preferably being used, such as FFKM (perfluorinated rubber). For example, the additional sealing element can be vulcanized onto the needle head. However, there is also the possibility that the sealing element is inserted into the needle head, for example in an annular groove in the needle head. The needle head itself can consist of titanium or a titanium alloy, for example, so that the needle head is resistant to chemically aggressive hardeners of 2K paints.

It has already been mentioned briefly above that the needle head and the valve seat preferably taper essentially conically in the direction of flow. Here, the needle head can have an annular groove into which the sealing element briefly mentioned above can be inserted. Here can the problem arise that the closing force acting on the valve needle is completely absorbed by the sealing element, which can then lead to mechanical overload and damage to the sealing element. This can be prevented in that the needle head has a rigid stop and is supported in the closed position with the stop on the valve seat. When the valve is closed, the sealing element in the needle head is only subjected to pressure until the valve needle rests with its stop on the valve seat. In this way, the compression of the sealing element in the needle head is limited when the valve is closed, which is beneficial to the service life of the sealing element. In the preferred exemplary embodiment of the invention, this stop is formed by an annular, circumferential support surface which is located in the conical jacket surface of the needle head upstream in front of the sealing element. The problem here can be that the sealing element seals the area of the needle head downstream behind the sealing element, so that this area cannot be reached by the detergent during a flushing process. This problem can be solved within the scope of the invention in that the support surface has at least one axially extending flushing groove through which flushing agent can enter in the axial direction from the valve chamber into the area downstream behind the sealing element. For example, such a flushing groove can have a groove width of 1 mm to 2 mm.

In the context of the invention, there is the possibility that the flexible membrane sealing the valve chamber replaces the sealing ring that is present in conventional needle valves. However, within the scope of the invention there is also the possibility that, in addition to the flexible membrane for sealing, there is also a conventional sealing ring, which is used for the valve needle surrounds ring-shaped and rests on the surface of the valve needle with a drag.

The needle shaft of the valve needle preferably has a diameter which can be in the range from 2 mm to 10 mm, 3 mm to 6 mm or 4 mm to 5 mm. In contrast, the maximum needle lift of the valve needle is preferably less than 3 mm, 2.5 mm, 2 mm or even less than 1.6 mm.

In the context of the invention, different variants are possible which differ in the number of different strands of coating agent within the application device.

A first variant of the invention has already been described above in which two strands of coating agent run within the application device. One strand of coating agent is reserved for a hardener for a two-component paint. The other strand of coating agent, on the other hand, can optionally be used for an associated master paint of the two-component paint or for a one-component paint.

In another variant of the invention, on the other hand, three strands of coating agent run within the application device. Two of the strands of coating material are reserved for the base paint or hardener of a two-component paint. In contrast, the third coating agent strand is reserved for a one-component paint. This variant of the invention thus differs from the variant of the invention described above essentially in that a separate strand of coating agent is provided for the one-component lacquer through which neither the main lacquer nor the hardener flows.

A third variant of the invention is simplified compared to the variant of the invention described at the outset and has only two strands of coating agent, namely one strand of coating agent for a base lacquer of a two-component lacquer and a second strand of coating agent for a hardener of the two-component lacquer. In contrast to the first variant of the invention described at the outset, there is no provision here for a one-component lacquer to be supplied alternatively via the coating agent line for the base lacquer.

A further variant of the invention, however, provides that four strands of coating agent are provided in the application device, namely two strands of coating agent for base lacquer or hardener of a first two-component lacquer and two further strands of coating agent for base lacquer or hardener of a second two-component lacquer.

Figur 1

ein Fluidschaltbild eines erfindungsgemäßen Rotationszerstäubers an einem Lackierroboter,

Figur 2

eine Querschnittsansicht durch ein erfindungsgemäßes Überdruckventil in einer Schließstellung,

Figur 3

eine Querschnittsansicht durch einen Ventilantrieb des Überdruckventils gemäß Figur 2,

Figur 4

eine schematische Darstellung eines konischen Nadelkopfs mit einem konischen Ventilsitz,

Figur 5

eine Abwandlung von Figur 1, wobei in dem Applikationsgerät drei Beschichtungsmittelstränge verlaufen, nämlich für Stammlack, Härter und alternativ einen Einkomponentenlack,

Figur 6

eine Abwandlung von Figur 1, wobei der Stammlackstrang in dem Applikationsgerät für den Stammlack reserviert ist und nicht alternativ zur Zuführung eines Einkomponentenlacks dient, sowie

Figur 7

eine Abwandlung von Figur 1 mit vier Beschichtungsmittelsträngen in dem Applikationsgerät für Stammlack bzw. Zerstäuber von zwei verschieden Zweikomponentenlacken.

Other advantageous developments of the invention are characterized in the subclaims or are explained in more detail below together with the description of the preferred exemplary embodiments. Show it:

Figure 1

a fluid circuit diagram of a rotary atomizer according to the invention on a painting robot,

Figure 2

a cross-sectional view through an inventive pressure relief valve in a closed position,

Figure 3

a cross-sectional view through a valve drive of the pressure relief valve according to Figure 2 ,

Figure 4

a schematic representation of a conical needle head with a conical valve seat,

Figure 5

a variation of Figure 1 , whereby three strands of coating agent run in the application device, namely for base paint, hardener and alternatively a one-component paint,

Figure 6

a variation of Figure 1 , whereby the master paint strand in the application device is reserved for the master paint and does not serve as an alternative to supplying a one-component paint, and

Figure 7

a variation of Figure 1 with four strands of coating agent in the application device for base paint or atomizer of two different two-component paints.

Figure 1 shows a rotary atomizer RZ according to the invention, which is guided by a painting robot and is mounted on the end of a robot arm RA by means of a conventional robot hand axis.

A linear color change LCC (LCC: Linear Color Changer) is located in the robotic arm RA, for example from DE 10 2008 037 035 A1 is known. On the output side, the linear color changer LCC is connected to a master paint connection SL of the rotary atomizer RZ via a metering pump PSL. The metering pump PSL is also arranged in the robot arm RA and can be bypassed by a bypass line By1. The function of the metering pump PSL consists in the metering and delivery of a base paint of a two-component paint (2K paint).

In addition, there is a solvent valve VSV1 in the robot arm RA for supplying a solvent for the Base paint, the solvent valve VSV1 being connected on the output side to a solvent connection VS1 for the base paint.

Furthermore, a metering pump PH is located in the robot arm RA for supplying a hardener for the two-component paint, the metering pump PH being connected on the output side to a hardener connection H of the rotary atomizer RZ. The robot arm RA also contains a solvent valve VHV1 for the controlled supply of a solvent for the hardener, the solvent valve VHV1 being connected on the output side to a solvent connection VH of the rotary atomizer RZ.

The rotary atomizer RZ also contains a pulsed air connection PL for the supply of pulsed air, a return connection RF1 for the return of residual material, a return connection RF2 for the return of pulsed air and paint foam, and short rinsing connections KS1, KS2 for supplying a detergent for brief rinsing of the rotary atomizer.

The base paint connection SL of the rotary atomizer RZ is connected to a base paint line, which consists of line sections L1-L4, which lead to a mixer MIX and finally to a main needle valve HN1, the main needle valve HN1 being connected to an outlet A2 which leads to a bell cup leads.

In the main paint strand, consisting of the line sections L1-L4, there is a membrane overpressure valve SLV1 upstream in front of the mixer MIX, the structure of which will be described in detail below. The diaphragm pressure relief valve SLV1 opens automatically, actuated by the medium itself, when the pressure of the Base paint upstream of the membrane pressure relief valve SLV1 exceeds a certain maximum value. When the diaphragm pressure relief valve SLV1 is opened, the excess pressure can then be discharged via the mixer MIX and the main needle valve HN1. This prevents an overpressure disturbance or even lines bursting upstream in line sections L1, L2 upstream of the membrane pressure relief valve SLV1.

A return line branches off from the line section L2 of the main paint line, which is formed by a line section L5 and opens into the return connection RF1. In the line section L5 of the return line, a diaphragm pressure relief valve RFV1 is also arranged, which can be constructed in the same way as the diaphragm pressure relief valve SLV1. The function of the membrane pressure relief valve RFV1 is to enable a pressure reduction if the main needle valve HN1 is defective and no longer opens. In this case there is namely an increase in pressure in the coating agent strand, which consists of the line sections L1-L4. This pressure increase then leads to an automatic opening of the membrane overpressure valve RFV1 in good time before an overpressure disturbance, so that any overpressure in the main paint line can be reduced through the return line and the return connection RF1.

A hardener strand, which consists of line sections L6, L7, emanates from the hardener connection H. The hardener strand ends upstream in front of the mixer MIX and downstream behind the membrane pressure relief valve SLV1 in the master paint strand. The base paint and the hardener are therefore mixed in the MIX mixer.

A solvent line emanates from the solvent connection VH, which is formed by a line section L8. A solvent valve VHV2 which enables the flow of solvent to be controlled is arranged in the line section L8 of the solvent line.

A pulsed air line, which is formed by line sections L9, L10, emanates from the pulsed air connection PL. A controllable pulsed air valve PLV, which controls the pulsed air flow, is arranged in the line section L9 of the pulsed air line.

Another solvent line, which consists of a line section L11 and the line section L10, starts from the other solvent connection VS1. A solvent valve VSV2, which can control the solvent flow, is arranged in the line section L11 of the solvent line for the base paint.

The hardener valve HV in the hardener line is also designed as a membrane pressure relief valve and therefore also opens, actuated by its own medium, when the pressure of the hardener upstream in front of the hardener valve HV exceeds a certain maximum value. The overpressure in the hardener strand can then be reduced via the line sections L7, L4, L3, the membrane overpressure valve SLV1, the membrane overpressure valve RFV1 and the return connection RF1.

In addition, the rotary atomizer RZ has a further strand of lacquer which is formed from the already mentioned line section L1 and a further line section L12. In the line section L12 of the further main paint line, a main paint valve SLV2 is arranged, which leads to a main needle valve HN2. The two main needle valves HN1, HN2 are connected on the output side to output A2 and thus to the bell cup. Via the main needle valve A one-component paint can be applied to HN2. On the other hand, a two-component paint can be applied via the main needle valve HN1, which is mixed beforehand in the MIX mixer.

A further return line branches off from the line section L12 upstream of the second main needle valve HN2, which consists of a line section L13 which opens into the return connection RF2. In the line section L13 of the second return line, a return valve RFV2 is arranged, which is designed as a paint stop valve. The return valve RFV2 opens, actuated by its own medium, when compressed air or paint foam is present at the input of the return valve RFV2. The return valve RFV2, on the other hand, closes automatically and actuated by its own medium when liquid paint is present at the inlet of the return valve RFV2. The structure of the return valve RFV2 is known per se from the prior art and is for example in DE 10 2009 020 064 A1 described.

From the two short-flush connections KS1, KS2, a short-flush line each starts, which consists of the line sections L14 and L15. A controllable short flush valve KSV1 or KSV2 is arranged in each of the two line sections L14, L15, the two short flush valves KSV1, KSV2 being connected on the output side to an output A1 for short flushing. The two short rinse lines thus bypass both the two main lacquer lines and the hardener line during a rinsing process and thus enable a short rinse, which is known per se from the prior art. A check valve RV is arranged between the output of the two short flush valves KSV1, KSV2 on the one hand and the output of the two main needle valves HN1, HN2 on the other hand.

Regarding the arrangement described above, it should be mentioned that that the membrane overpressure valves SFV1, RFV1 and the hardener valve HV, which is also designed as a membrane overpressure valve, are identified as such by oblique hatching. The return valve RFV2 designed as a paint stop valve, on the other hand, is characterized by a completely black filling as a paint stop valve. The main needle valves HN1, HN2, on the other hand, are identified as needle valves by vertical hatching. The remaining valves are marked with a white filling as conventional needle valves.

The Figures 2-4 show different views of a possible structure of the membrane pressure relief valves SLV1, RFV1 and the hardener valve HV, which is also designed as a membrane pressure relief valve.

The pressure relief valve has an inlet 1 for supplying a fluid (e.g. hardener, base paint) and an outlet 3 for discharging the coating agent.

The flow of the coating agent from the inlet 1 to the outlet 3 is controlled by a needle valve. The needle valve has a displaceable valve needle 4, a needle head 5 being screwed onto the distal end of the valve needle 4. The needle head 5 is made of titanium and tapers conically towards its end, with an annular groove in which a sealing ring 6 made of FFKM (perfluorinated rubber) is inserted in the conically tapering outer surface of the needle head 5.

In the closed position according to Figure 2 If the needle head 5 with the sealing ring 6 rests in a sealing manner on a valve seat 7, the valve seat 7 likewise tapers conically and opens into the outlet 3.

In the open position (not shown), however, the needle head 5 is lifted off the valve seat 7 and thereby releases the flow through the valve seat 7 to the outlet 3.

The setting of the closed position or the open position takes place here by a valve drive 8, which is shown in Figure 3 is shown in detail and works pneumatically.

The pneumatic valve drive thus has an outer housing insert 9 which is screwed into a housing body 10 of the two-component shut-off valve.

An inner housing insert 11 is in turn screwed into the outer housing insert 9.

A piston 12 is arranged displaceably in the pneumatic valve drive 8, the piston 12 being supported by a valve spring 13 in the direction of the closed position according to FIG Figure 1A is biased. The valve spring 13 is supported on the outer housing insert 9 and presses at its opposite end against the piston 12 in order to press it into the closed position. The piston 12 is connected to the valve needle 4 via a piston insert 14 so that the piston 12 acts on the valve needle 4 and thus also on the needle head.

The piston 12 is surrounded by a sealing ring 15, which is arranged in the annular gap between the piston 12 on the one hand and the inner wall of the inner housing insert 11 and, when the piston 12 moves, rubs against the inner wall of the inner housing insert 11.

In addition, a further sealing ring 16 is provided, which rubbing on the outer surface of the displaceable valve needle 4 is applied and thereby causes a further seal. The valve needle 4 runs partially through a valve chamber 17 which is filled with the respective fluid (e.g. hardener, base paint) during operation.

A flexible membrane 18 is provided as a sealing element between the valve drive 8 and the media-filled valve chamber 17 in order to seal the valve chamber 17 with respect to the valve drive 8. The flexible membrane 18 is sealingly fastened with its outer peripheral edge to the lower end of the inner housing insert 11 and has a central bore through which the valve needle 4 is passed. The membrane 18 is fluid-tight and firmly connected to the valve needle 4. On the one hand, the membrane 18 thus takes part in the displacement movement of the valve needle 4 between the closed position and the open position. On the other hand, the membrane 4 also seals the media-filled valve chamber 17 from the valve drive 8, whereby no grinding movement is required as is the case with a sealing ring, so that there is also no risk of the low-viscosity and creeping hardener H being able to penetrate the valve drive 8.

The actual drive takes place here by control air, which can be introduced into a control air space 19 below the piston 12, the control air in the control air space 19 then pushing the piston 12 upwards. The control air is fed into the control air space 19 via a control air connection 20.

The control air can be provided from a conventional 6-bar compressed air network, which is usually available in paint shops anyway. This offers the advantage that there is no need for a separate compressed air supply can. The piston 12 here has a relatively large effective diameter, so that the control air acting on the piston generates a relatively large opening force. When compressed air is applied by the control air, this opening force is greater than the closing force which the valve spring 13 exerts on the piston 12 by a certain excess opening force. In this specific exemplary embodiment, this excess opening force is in the range from 57.4 N to 136 N compared to an excess opening force of only 15 N in a conventional needle valve. This enables the needle head 5 to be “torn loose” from the valve seat 7 even when the needle head 5 adheres to the valve seat 7.

Out Figure 4 it can also be seen that the needle head 5 tapers with a head angle λ = 35 ° -50 ° in the direction of flow, just as the valve seat 7 tapers conically with a seat angle β = 35 ° -50 ° in the flow direction.

The conical outer surface of the needle head 5 upstream in front of the sealing ring 6 here forms a support surface 21, which is in the closed position according to FIG Figure 2 is supported on the valve seat 7. The support surface 21 forms a stop for the axial movement of the needle head 5 into the closed position. This prevents excessive compression of the sealing ring 6, which is beneficial to the service life of the sealing ring 6.

The support surface 21 is interrupted here by a plurality of axially running flushing grooves 22 which are arranged distributed over the circumference of the needle head 5. The flushing grooves 22 enable in the closed position according to FIG Figure 2 that flushing agent can also reach the area downstream behind the support surface 21 from the inlet 1.

Figure 5 shows a modification of Figure 1 so that to avoid repetition, reference is made to the above description, the same reference symbols being used for corresponding details.

A special feature of this exemplary embodiment is that three strands of coating agent run in the rotary atomizer RZ, namely one strand of coating agent for a hardener, one strand of coating agent for a master paint and one strand of coating agent for a one-component lacquer. The coating agent strand for the hardener consists of the line sections L8 and L7. The coating agent strand for the base paint, on the other hand, consists of line sections L1, L3 and L4. The separate line of coating agent for the one-component paint, on the other hand, consists of the line section L12. The difference compared to the embodiment according to Figure 1 consists essentially in the fact that a separate coating agent strand is provided for the one-component paint, whereas with Figure 1 the coating agent strand consisting of the line sections L1, L12 serves either to supply the base paint or to supply the one-component paint.

Figure 6 shows a simplification of Figure 1 so that to avoid repetition, reference is made to the above description, the same reference symbols being used for corresponding details.

A special feature of this exemplary embodiment is that it is only possible to apply a two-component lacquer, so that only two strands of coating agent are provided in order to apply base lacquer or hardener. The coating agent strand for the hardener consists of the line sections L6, L10 and L4. The coating agent strand for the main paint, on the other hand, consists of the line sections L1, L2, L3 and L4. In contrast, it is not possible in this exemplary embodiment to apply a one-component paint as an alternative, as is the case Figure 1 enables.

Finally shows Figure 7 another variation of Figure 6 so that reference is made to the description above to avoid repetition.

A special feature of this embodiment is that a total of four strands of coating agent run in the rotary atomizer, namely for base paint 1 and hardener 1 of a first two-component paint and for base paint 2 and hardener 2 of a second two-component paint. The fluid circuit diagram is therefore essentially in accordance with Figure 4 parallelized and doubled. The components for the first two-component paint are opposite Figure 6 with the addition ".1". The components for the second two-component paint are opposite Figure 6 with the addition ".2". Otherwise, reference can be made to the description above.

The invention is not restricted to the preferred exemplary embodiments described above. Rather, the invention enables a large number of variants and modifications which also fall within the scope of protection.

List of reference symbols:

A1, A2

Exit to the bell plate

By1

Bypass line to bypass the metering pump PSL.1 base paint

By.1

Bypass line to bypass the metering pump PSL.1

By.2

Bypass line to bypass the metering pump PSL.2

H

Hardener connection

H.1

Hardener connection for hardener 1

H.2

Hardener connection for hardener 2

HN1

Main needle valve 1

HN2

Main needle valve 2

HV

Hardener valve

KS1

Short flush connection

KS2

Short flush connection

KSV1

Short flush valve

KSV2

Short flush valve

LCC

Linear color changer

MIX

mixer

P1K

Dosing pump for one-component paint

PH

Dosing pump for hardener

PH.1

Dosing pump for hardener 1

PH.2

Dosing pump for hardener 2

PL

Pulse air connection

PL.1

Pulse air connection

PL.2

Pulse air connection

PLV

Pulse air valve

PLV.1

Pulse air valve

PLV.2

Pulse air valve

PSL

Dosing pump for base paint

PSL.1

Dosing pump for base paint 1

PSL.2

Dosing pump for base paint 2

RA

Robotic arm

RF1

Return port

RF1.1

Return connection for two-component paint 1

RF1.2

Return connection for two-component paint 2

RF2

Return port

RFV1

Return valve as a diaphragm pressure relief valve

RFV2

Return valve as a paint stop valve

RV

check valve

RZ

Rotary atomizer

SL

Base paint connection

SL.1

Base paint connection for base paint 1

SL.2

Base paint connection for base paint 2

SLV1

Main paint valve as a diaphragm pressure relief valve

SLV1.1

Main paint valve as a diaphragm pressure relief valve

SLV1.2

Main paint valve as a diaphragm pressure relief valve

SLV2

Master paint valve as a needle valve

VH

Solvent connection for hardener strand

VHV1

Solvent valve

VHV2

Solvent valve

VS1

Solvent connection for master paint line

VS1.1

Solvent connection for base paint 1

VS1.2

Solvent connection for base paint 2

VSV1

Solvent valve

VSV1.1

Solvent valve

VSV1.2

Solvent valve

VSV2

Solvent valve

VSV2.1

Solvent valve

VSV2.2

Solvent valve

L1-L4

Line sections of the trunk paint strand

L5

Line section of the return line

L6, L7

Line sections of the hardener strand

L8

Line section of the solvent strand for the hardener

L9, L10

Line sections of the pulsed air line

L11

Line section of the solvent line for the base paint

L12

line section of the second trunk paint strand

L13

Line section of the second return line

L14

Line section of the short flush lines

L15

Line section of the short flush lines

1

inlet

3

Outlet

4th

Valve needle

5

Needle head

6th

Sealing ring

7th

Valve seat

8th

Valve drive

9

External housing insert

10

Housing body of the two-component shut-off valve

11

Inner housing insert

12th

piston

13

Valve spring

14th

Piston insert

15th

Sealing ring around the piston

16

Sealing ring around the valve needle

17th

Valve space

18th

membrane

19th

Control airspace

20th

Control air connection

21st

Support surface

22nd

Flushing groove

λ

Head angle

β

Seat angle

Claims (15)

1. Application device (RZ), in particular rotary atomiser, for applying a coating agent, in particular a two-component paint, having

   a) a first coating agent connection (SL) for supplying a first coating agent, in particular a parent paint of the two-component paint,

   b) an application element which applies the coating agent,

   c) a first coating agent line (L1-L4) which leads in the application device (RZ) from the first coating agent connection (SL) and guides the first coating agent to the application element, and

   d) a first valve (SLV1) which is arranged in the first coating agent line (L1-L4) and controls the flow of the first coating agent through the first coating agent line (L1-L4) to the application element, the first valve (SLV1) being controllable by a first control signal,

   e) wherein there is arranged in the first coating agent line (L1-L4) an own-medium-actuated first overpressure valve (SLV1) which, in order to avoid an overpressure fault, opens automatically when the pressure upstream of the first overpressure valve (SLV1) exceeds a specific maximum pressure,
   characterised in

   f) that the first overpressure valve (SLV1) is formed by the controllable first valve (SLV1).
2. Application device (RZ) according to any one of the preceding claims, characterised in that there is arranged in the first coating agent line (L1-L4), between the first overpressure valve (SLV1) and the application element, a first main valve (HN1), in particular in the form of a main needle valve, which either blocks or enables the flow of fluid in the first coating agent line (L1-L4).
3. Application device (RZ) according to claim 2, characterised in that

   a) the application device (RZ) has a second coating agent connection (H) for supplying a second coating agent, in particular a curing agent of the two-component paint,

   b) a second coating agent line (L6, L7) leads from the second coating agent connection (H),

   c) in the second coating agent line (L6, L7) there is arranged a second overpressure valve (HV) which is own-medium-actuated and opens automatically when the pressure upstream of the first overpressure valve exceeds a specific maximum pressure, and

   d) the second coating agent line (L6, L7) joins the first coating agent line (L1-L4) upstream of the first main valve (HN1),

   e) in the first coating agent line (L1-L4), between the point at which the second coating agent line (L6, L7) joins and the first main valve (HN1), there is preferably arranged a first mixer (MIX) which mixes the parent paint with the curing agent to form the two-component paint, and

   f) the first mixer (MIX) is preferably a static mixer, in particular a lattice mixer or a helical mixer.
4. Application device (RZ) according to claim 2 or 3,
   characterised in that

   a) the application device (RZ) has a first return connection (RF1) for returning fluids into a first return system,

   b) a first return line branches from the first coating agent line (L1-L4) upstream of the first overpressure valve (SLV1),

   c) the first return line opens into the first return connection (RF1), and

   d) in the first return line there is arranged a third overpressure valve (RFV1) which is own-medium-actuated and opens automatically when the pressure in the first return line upstream of the third overpressure valve (RFV1) exceeds a specific maximum pressure.
5. Application device (RZ) according to claim 4,
   characterised in that

   a) the application device (RZ) has a first solvent connection (VS1) for supplying a first solvent, in particular for the parent paint,

   b) a first solvent line (L11, L10) branches from the first solvent connection (VS1),

   c) the first solvent line (L11, L10) joins the first coating agent line (L1-L4) between the first overpressure valve (SLV1) and the first main valve (HN1), and

   d) in the first solvent line (L11, L10) there is arranged a first solvent valve (VSV1).
6. Application device (RZ) according to any one of the preceding claims, characterised in that

   a) the application device (RZ) has a pulsed air connection (PL) for supplying pulsed air,

   b) a pulsed air line (L9, L10) leads from the pulsed air connection (PL),

   c) the pulsed air line (L9, L10) joins the first coating agent line (L1-L4) between the first overpressure valve (SLV1) and the first main valve (HN1), and

   d) there is arranged in the pulsed air line (L9, L10) a pulsed air valve (PLV).
7. Application device (RZ) according to any one of the preceding claims, characterised in that

   a) the application device (RZ) has a second solvent connection (VH) for supplying a second solvent, in particular for the curing agent,

   b) a second solvent line (L8, L7) leads from the second solvent connection (VH),

   c) the second solvent line (L8, L7) opens into the first coating agent line (L1-L4) between the first overpressure valve (SLV1) and the first main valve (HN1), and

   d) there is arranged in the second solvent line (L8, L7) a second solvent valve (VHV1).
8. Application device (RZ) according to any one of the preceding claims, characterised in that

   a) there is provided a third coating agent line (L1, L12) which preferably leads from the first coating agent connection (SL),

   b) in the third coating agent line (L1, L12) there is arranged a second main valve (HN2), in particular in the form of a main needle valve,

   c) the first main valve (HN1) and the second main valve (HN2) are brought together on the outlet side and lead to the application element.
9. Application device (RZ) according to claim 8,
   characterised in that

   a) the application device (RZ) has a second return connection (RF2) for returning fluids into a second return system,

   b) a second return line (L13) branches from the third coating agent line (L1, L12) upstream of the second main valve (HN2),

   c) the second return line (L13) opens into the second return connection (RF2), and

   d) a return valve (RFV2) is preferably arranged in the second return line (L13),

   e) the return valve (RFV2) is preferably own-medium-actuated,

   f) the return valve (RFV2) preferably distinguishes, by virtue of its design, between liquid coating agent, on the one hand, and compressed air or foam, on the other hand,

   f1) wherein the return valve (RFV2) opens when compressed air or foam is present at the inlet of the return valve (RFV2),

   f2) whereas the return valve closes when liquid coating agent is present at the inlet of the return valve (RFV2).
10. Application device (RZ) according to any one of the preceding claims, characterised in that

    a) the application device (RZ) has at least one short-flush connection (KS1, KS2) for supplying a flushing medium for a short flushing of the application device,

    b) a short-flush line (L14, L15) leads from the short-flush connection (KS1, KS2),

    c) the short-flush line (L14, L15) guides the flushing medium to the application element, bypassing the coating agent lines,

    d) there is arranged in the short-flush line (L14, L15) a controllable short-flush valve (KSV1, KSV2).
11. Application device (RZ) according to any one of the preceding claims, characterised in that the first overpressure valve (SLV1), the second overpressure valve (HV) and/or the third overpressure valve (RFV1) in the open state have a pressure-surge-damping function, so that pressure surges entering on the inlet side are transmitted on the outlet side only in damped form.
12. Application device (RZ) according to any one of the preceding claims, characterised in that the first overpressure valve (SLV1), the second overpressure valve (HV) and/or the third overpressure valve (RFV1) is a needle valve having

    a) a valve seat (7),

    b) a displaceable valve needle (4) having a needle stem and a needle head (5),

    b1) wherein the needle head (5) closes the valve seat (7) when the valve needle (4) is in a closed position,

    b2) whereas the needle head (5) frees the valve seat (7) when the valve needle (4) is in an open position,

    c) a flexible membrane (18) which surrounds the valve needle (4) upstream of the needle head (5) in an annular and sealing manner.
13. Application device (RZ) according to claim 12, characterised in that

    a) the valve needle (4) is displaceably arranged in a valve chamber (17), wherein the valve chamber (17) is cylindrical at least in part,

    b) the membrane (18) is fixed in the middle to the needle stem of the valve needle (4) in a sealing manner, and

    c) the membrane (18) is fixed by its peripheral edge to the inside wall of the valve chamber (17) in a sealing manner.
14. Application device (RZ) according to claim 13, characterised by

    a) a valve drive for displacing the valve needle (4), in particular in the form of a pneumatic valve drive having a piston (12),

    b) a coating agent inlet (1) for supplying the coating agent, wherein the coating agent inlet (1) opens into the valve chamber (17) on the side of the membrane (18) remote from the valve drive, so that the membrane (18) seals the valve drive with respect to the valve chamber (17) filled with coating agent, and

    c) a coating agent outlet (3) for discharging the coating agent, wherein the coating agent outlet (3) opens into the valve seat (7) so that, when the valve needle (4) is in the open position, the coating agent is able to flow through the valve seat (7) to the coating agent outlet (3).
15. Application device (RZ) according to claim 14, characterised in that the valve drive has the following:

    a) a displaceable piston (12) which acts upon the valve needle (4) in order to displace the valve needle (4),

    b) a control air inlet (20) for supplying control air, wherein the control air acts upon the piston (12) in order to displace the piston (12) and thus also the valve needle (4),

    c) a valve spring (13) which acts upon the piston (12) or the valve needle (4) with a spring force,

    d) wherein the spring force of the valve spring (13) in the closed position and in the open position is preferably at least 20 N, 40 N or 80 N and/or not more than 400 N, 200 N or 100 N.

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