ES2272593T3 - VALVE UNIT FOR AN ELECTROSTATIC COATING INSTALLATION. - Google Patents

Abstract

A main needle valve for an electrostatic sprayer has an optoelectronic sensor device with light wave conductors (20,21) with their front surfaces facing a reflex element (12) for a structural link (10) moved by the valve needle (1), which is remotely controlled to slide between two indexing positions. The optoelectronic sensor senses an indexing position and generates a corresponding sensing signal.

Description

Valve unit for an installation of electrostatic coating

The present invention relates to a unit of valves according to the preamble of claim 1, in particular for a sprayer which during operation is subjected at high voltage for series cladding for example of auto vehicle bodies.

In rotating electrostatic sprayers or known air sprayers of this type (DE 4306800 A or Dürr / Behr "EcoGun ESTA") opens and closes the driving of color at the entrance to the spray organ with a valve colored needle, the so-called main needle valve, whose valve needle is carried by the piston of a drive pneumatic valve, under control by the control system by upper range program of the cladding installation, from the closed position, against the force of a spring of recoil, to the opening position.

For control of the higher range installation, an execution control of at least one and preferably of the two switching positions of the main needle valve or colored needle valve is desirable. For example, in non-electrostatic air sprayers it was possible and usual to generate the switching position signals with sensors
Hall or inductive sensors arranged in the valve drive. However, dielectric sensors cannot be used in electrostatic sprayers which, during operation, are subject to high voltage. Although an interrogation about the switching position would also be important here, there has been no feasible possibility up to now.

Registration of the switching position of a Valve needle for color flow control takes place, on the one hand, for monitoring the switching operation through execution control and, on the other, also for the valve control By recording the elapsed time between the control signal of a valve needle and the control of execution of the switching position variation and the comparison with a predetermined theoretical value can be recognized variations conditioned by operation (eg because of wear of construction parts) and compensated by technique of control. Thanks to this it is possible, particularly in varnishing, which work with high varnish speeds and Frequent connections / disconnections of valve needles, better proof of process developments.

However, there are also pneumatic sensors for interrogation of the valve switching position, which are, however, too slow for the processes dynamic that are considered here.

For the document EP-A-0 846 498 is known as for example, an electrostatic sprayer, for example, with a sensor optical for the valve position of the sprayer. The sensor is arranged on a movable sensor pin with the valve needle Sprayer The sensor signal should indicate positions of open-closed as well as intermediate positions of the mobile valve body and can be used with the help of a signal processing apparatus for purposes of diagnosis.

For the document GB-A-2 159 942 a sensor is known Optical switching position with waveguides for valves of fluid, in which the value of the light sent by an emitter to a receiver varies with the switching position.

For the document US-A-4 356 397 is also known a device for monitoring the switching position of valves, in which a magnet, arranged in a valve stem movable, rotates a polarization device and analyzer that It is in the path of light between two waveguides.

The invention poses the problem of proposing a valve unit whose switching position can be consult, also subjected to high voltage, as quickly possible.

This problem is solved by characteristics of claim 1.

Through the invention a switching position signaling, potential free and by this is also suitable for electrostatic sprayers, for example for interrogation of the main needle. I also know you can interrogate, in the manner described here, the position of switching of other valves, which are in a sprayer electrostatic or other components of an installation of high voltage coating. In the case of the valve it can be, for example, also a membrane valve.

The invention is explained below with greater detail from the rotation sprayer represented in the drawing as an exemplary embodiment for direct loading of the coating material. In the drawing:

Fig. 1 shows the rotation sprayer with the valve unit; Y

Fig. 2 and Fig. 3 show two ways of Modified realization

The sprayer shown in Fig. 1 has the usual main needle valve with valve needle 1 for open and close the color channel 2 that flows into the hood of the sprayer 4. The valve needle is movable, along of its axis, in the coaxial color tube 3 that contains the channel of color 2. For valve operation, a pneumatic valve drive with a plunger 6, which stops the Main needle valve opening is loaded in 7 with air to pressure and, as a consequence, pulls the valve needle 1 attached to it, against the force of a compression spring 8, which crimp on its back side, in the drawing to the right in the remote direction of the spray hood 4. In this measure The sprayer is itself known. During operation the whole of the color driving system of the sprayer can be at a high voltage potential with an order of magnitude of for example 100 kV.

On its back side, away from the needle of valve 1, a plug or tap element is spliced in plunger 6 rod 10 which may be arranged, for example, with the same shaft with the valve needle 1, for example, inside the compression spring 8. Suitably at the perimeter of your end part 11 away from the plunger 6, the rod element 10 it has, according to the representation, a surface element 12 optically reflective The reflective surface of element 12 it can be flat and spread, for example, around the entire perimeter of the final piece of the rod that in section Transverse is, for example, quadrangular.

The final piece 11 provided with element 12 reflective is represented, in the drawing, in the two positions of switching the main needle valve. In 11, 12 you can see in the left closing position, at 11 ', 12' in position valve opening (right). The rise of the needle H between these two switching positions can value for example approximately 5 mm

The stem 10 can be moved to a recess 14 of the coaxial valve housing with respect to the shaft of the needle, in which it conducts an opening 15 that runs radially, that is to say transverse with respect to the needle axis, to through the housing. In the opening 15 a body of clamping and positioning 17 for two waveguide units 20 and 21, whose optical front surfaces are aligned with the interior wall of the recess 14 in the two positions, in which in which the reflective element 12, 12 'is found in the Two switching positions. The reflective element is located therefore, when the main needle valve is closed, closely adjacent to the front surface of the unit waveguide 20 and, when the valve is open, facing the front surface of unit 21. The opposite distance of the central axes of units 20, 21 corresponds to the rise of the Valve needle H. As a result, the two positions of switching can be indicated by light signals, which they are formed when light is supplied from outside through the corresponding waveguide unit, is reflected by the element 11, 11 'and is driven back, through it waveguide unit (or, eventually, another waveguide) towards an optoelectronic sensor (not shown), which can be Find out of the high voltage zone.

The guidance systems of sensor waves suitable for the purpose described They are themselves known and do not require further explanation.

Instead of the represented provision of the surface element 12 reflective on different or all parts of the perimeter at the end of the rod element 10, which allows discretionary spindle positions with respect to to the waveguide 20, 21, a reflective surface is sufficient only in the part of the perimeter facing the guides of wave.

The interrogation about the position of switching can also take place at other points of the needle valve itself or one of the construction elements that They can move with it.

In addition, in some cases, it may be sufficient with a single waveguide unit for interrogation of only one of the two switching positions.

Instead of the radial arrangement of the guides waveform of the embodiment shown is also possible arrange a waveguide axially along the element of rod, whose switching position is recognized by a reflection of different intensity.

Another possibility of use is the provision of at least one optoelectronic light barrier, by example, in the stem element 10 for interrogation, free of potential, one or both switching positions. Fig. 2 shows an implementation guide with two waveguides LWL1 and LWL2 arranged radially, aligned with each other, on opposite sides of the rod element. In the switching position represented The LWL2 driver can drive light pulses sent by the LWL1 driver to the optoelectronic converter while in the other position the end of the rod element closes the light barrier In the embodiment according to Fig. 3 they can be interrogated, on the contrary, the two positions of switching actively, since there is a drill 30 here leading radially through the rod element, positioned in each case between two waveguides LWL1, LWL2 or LWL1 ', LWL2' aligned with each other.

According to another possibility (not represented), the main needle valve represented in the drawing can be modified in the sense that next to or in the rod element 10 at least one magnetically emitting element is disposed active, for example instead of the reflective element 12 in Fig. 1 or of hole 30 in Fig. 3. As a sensor device arranged for interrogation of the switching position in the scrollable rod element serves, in this modification, so less a sensor element that takes advantage of the Faraday effect magentooptic or Kerr effect, which contains a device Optical polarization with an analyzer. The sender element can be a permanent magnet, or also an element made of iron or other material with ferromagnetic properties, with which you can vary the magnetic field of a magnetic element contained in the sensor element By approximating the emitter element that moves with the rod element 10 you can turn the polarization direction of the light conducted through the device  of polarization in the sensor element for the generation of a light signal A waveguide arrangement connected to the polarization device leads to an electronic device remote, which is outside the high voltage zone, for the generation of an electrical signal corresponding to the signal of light. The sensor element may contain a reflector, which brings the light from the device back to the analyzer polarization, being between the polarization device and the reflector an element of refraction (effect element Faraday) or a prism and being connected to the device polarization a light conductor for the light supplied to the sensor element and in the analyzer a light conductor for the light supplied to the remote electronic device. This type of optical sensors are known per se and can be obtained in the Commerce. In the case described herein they have, without However, the special and surprising advantage that they can work No problems under high voltage. Depending on the convenience, one or two sensors may be arranged for it, for example at the points of the waveguides 20 and / or 21 in the Fig. 1.

Especially when in the rod element 10 movable only one waveguide unit is available and, for example, the following waveguide 21 in Fig. 1 or the second unit with waveguides LWL1 ', LWL2' in Fig. 3 must saved, it may be appropriate that in the rod element 10 Two signal generating elements are provided, distanced from each other in the direction of travel of which the first element emits a binary signal from the device sensor. when the valve needle 1 is in one of its switching positions while the second element of signal generation emits a binary signal from the device sensor, when the valve needle 1 is in its other switching position In correspondence with Fig. 1 or Fig. 3, the two signal generation elements can be formed by reflective surfaces, among which is its non-reflective surface, or through barrier openings of spaced light. An embodiment is also possible with two permanent magnets or magnetically emitting elements assets, distanced in the rod element 10, for the purpose Faraday described above or for the effect sensor system Kerr

The binary signals emitted in each case by the sensor in the two switching positions have, so adequate, the same binary value. Binary signals are generated. by the electronic sensor device, which is in a position away from the valve outside the high voltage zone and which is connected to the valve unit through the waveguide arrangement. When the rod element 10 is shifted between its two positions, the sensor signal varies due to to the area between the two signal generation elements, first, to the opposite binary value, before, upon reaching another valve position, the first value is generated again binary. With the help of an electronic control device, you can determine if, for example, after the generation of a signal from control for valve switching (and after disappearance of the first binary value), in the course of a prescribed time, the first binary signal is generated again as an indication of the Other valve position. If this is not the case, there is a fault, the which is indicated by an alarm signal.

Claims (13)

1. Valve unit for an installation electrostatic for serial coating of parts job a remotely controlled switchable valve, whose mobile valve element (1) can be moved between two switching positions and in one of the switching positions opens the way for a medium that circulates through the valve, while the valve is closed, when the valve element (1) is in its other switching position, particularly for a sprayer that during the operation is subject to high voltage, being planned for interrogation of the valve switching position and for generating a corresponding interrogation binary signal a device Optoelectronic sensor with at least one waveguide (20, 21) in a constructive element (10) that can be moved with the valve element (1) or that forms a part of the element of valve, characterized in that by means of an electronic control device it is determined whether the binary signal appears in the interval of a predetermined time after the generation of a control signal to switch the valve and because, otherwise, an alarm signal is generated. 2. Valve unit according to claim 1, characterized in that the movable construction element (10) has at least one optically reflective surface (12), which is opposite the sensor surface of the waveguide (20, 21) , when the valve element (1) is in its switching position that must be indicated. 3. Valve unit according to claim 1 or 2, characterized in that for each of the switching positions, in each case, an electronic sensor device is provided in each case with at least one waveguide (20, 21) . 4. Valve unit according to one of claims 1 to 3, characterized in that the mobile valve element (1) is the valve needle of a needle valve. 5. Valve unit according to claim 4, characterized in that the mobile construction element (10) is a rod element, positioned on the same axis with the valve needle (1) in the piston (6) of the pneumatic valve drive, which can be moved in a recess (14) of the valve housing, to which a radial opening (15) leads, relative to the axis of the needle, for the waveguide (s) (20, 21). 6. Valve unit according to one of claims 1 to 3, characterized in that the mobile valve element is connected to the membrane of a membrane valve. 7. Valve unit according to claim 1, characterized in that the waveguides (LWL1, LWL2) form at least one light barrier for the construction element (10). 8. Valve unit according to claim 1, characterized in that a magnetically active emitter element is arranged on the construction element (10) therein, because a sensor element is provided, the which contains an optical polarization device, because by approximation of the element of emitter the polarization of the light conducted through the device polarization is modified in the sensor unit magnetooptically for the generation of a light signal, and because the polarization device is connected a waveguide arrangement which leads to a remote electronic device for signal generation electric corresponding to the light signal. 9. Valve unit according to claim 8, characterized in that the sensor element contains a reflector which brings the light from the polarization device back to an analyzer of the polarization device, an element being between the polarization device and the reflector of refraction or prism that rotates the direction of polarization, and because in the polarization device a light conductor for the light supplied to the sensor element and a light conductor for the light supplied to the electronic device are connected. 10. Valve unit according to one of the preceding claims, characterized in that in the movable construction element (10) two signal generating elements are provided, spaced apart from each other in the direction of travel, of which the first element emits a binary signal of the sensor device, when the valve element (1) is in one of its switching positions, while the second signal generating element emits a binary signal from the sensor device, when the sensor element (1) is found in its other switching position. 11. Valve unit according to claim 10, characterized in that the two signal generating elements of the movable construction element (10) are formed by optically reflective surfaces. 12. Valve unit according to claim 10, characterized in that the two signal generating elements are formed by light barrier openings. 13. Valve unit according to one of claims 10 to 12, characterized in that the two binary signals have the same binary value and because the sensor signal of the sensor device is switched to the opposite binary value, when the construction element (10) movable It is shifted between its two positions.