EP1222968B9 - Ventilation system for a paint spray booth - Google Patents

Abstract

The device has an input air fan for subjecting the spray cabin to input air, an output air fan for sucking the used air from the cabin, filters for preventing impurities from entering the cabin and paint particles from leaving the cabin, fan drives, a heater and a controller. The controller specifies a temperature level for the cabin adapted to intermediate drying of a base paint layer on the component in the cabin. Independent claims are also included for the following: a ventilation method for a spray cabin of a painting system.

Description

The invention relates to a ventilation device for a spray booth a Lackierbetriebs, with a Zuluftventilator for acting on the spray booth with supply air, an exhaust fan for extracting the exhaust air from the spray booth, filter means by which the ingress of contaminants in the spray booth and the escape of paint particles the spray booth can be prevented, drive means by means of which the supply air and the exhaust fan can be driven, a heater by means of which the temperature in the spray booth is changeable, and a control device by means of which the drive means of Zuluft- and the exhaust fan can be controlled.

In the operation of the spray booths mentioned above, a component to be painted is introduced into the spray booth. Subsequently, this component is provided with at least one basecoat film. Before applying the component with a further basecoat film or with an outer or clearcoat film, the basecoat film initially used must first be pre-dried or cured in an intermediate drying process. This pre-drying or pre-hardening takes place in known spray booths at about that temperature, in which also the injection process, which serves to carry out this pre-hardening or -drying Intermediate drying process is interrupted takes place.

EP-A-0 584 638 discloses such a ventilation device for a spray booth of a painting operation. The preamble of claim 1 is derived from this document. The revelation EP-A-0 584 638 does not disclose an intermediate drying curtain.

The invention has the object of developing the above-described ventilation device for a spray booth a Lackierbetriebs such that the time and energy consumption for the painting process of a component can be further reduced.

This object is achieved in that the heating of the spray booth by means of the control device is controllable and that the control device is designed so that by means of her for the heater of the spray booth, a temperature level can be predetermined, which is to intermediate drying of a basecoat layer to be painted in the spray booth Component is adapted, and that by means of a control device, the supply air and the exhaust fan during an intermediate drying operation are automatically operated at a low speed. In this embodiment according to the invention results in addition to a reduction in the time consumption for the intermediate drying and a total of the painting a considerable energy savings. The reduction of the time consumption and, correspondingly, the resulting energy saving is all the greater, the greater the number of basecoat films with which the component to be painted must be provided. Particularly advantageous effects arise in Wasserbasislakken.

A further reduction of the energy expenditure can be achieved if the control device is designed so that by means of her the Zuluft- and the exhaust fan during an intermediate drying operation are automatically operated at a lower speed, so that a higher temperature level is possible even at a given burner power. Furthermore, it is possible, the cost of the temperature change for the purpose of initiating the intermediate drying operation in that the control device is designed so that the supply air and the exhaust fan are operated during recirculation operation in an intermediate drying operation. Once heated by means of the heater air is then reintroduced into the spray booth due to the recirculation mode, which only needs to be further heated according to the temperature difference to the predetermined temperature for the intermediate drying operation. The dissipated heat loss to the environment is considerably reduced in this approach.

In order to prevent Staubaufwirbelungen occur, it is advantageous if the control device is designed so that a speed change of both the Zuluft- and the exhaust fan is performed by means of a speed jump-free, continuous speed change phase.

Advantageously, the control device has a switching element by means of which an adjustable desired value for the temperature level adapted to the intermediate drying can be predetermined on the control device. This setpoint can be different depending on the requirement profile for the intermediate drying process or for the quality of the basecoat film.

Appropriately, the ventilation device according to the invention has a temperature sensor which is arranged in the supply air duct of the spray booth and connected to the control device. As a result, the temperature level in the supply air flow can be suitably used as a basic variable for controlling or regulating the temperature within the spray booth.

Of course, according to a further embodiment of the ventilation device according to the invention, the control device be designed so that by means of it for the heating of the spray booth, a second temperature level can be predetermined, which is adapted to a taking place in the spray booth injection process.

In addition, according to a further embodiment of the invention, the control device be designed so that by means of it for the heating of the spray booth, a third temperature level can be predetermined, which is adapted to a performed for an outer or clear coat layer burning process.

The temperature level provided for the intermediate drying process is usually between the temperature level adapted to the spraying process and the firing process.

In such ventilation devices, the supply-side and the exhaust-side filter means are exchanged at regular intervals to ensure that tolerable operating conditions prevail within the spray booth, and that the environment of the spray booth is not inadmissible with paint particles or the like. is contaminated. In the course of the period of use increasingly occurs a burden of the two filter devices with impurities or paint particles and thus decreases the permeability of the mutual filter devices with increasing useful life.

In order to further reduce the energy consumption of the ventilation device, the drive device of the exhaust fan adjustable according to the pollution of the exhaust air side filter device. This is given the possibility with little effort, the exhaust fan depending on the degree of contamination of the exhaust-side filter device set differently, so that without any flap adjustment or the like. an adaptation of the exhaust air side filter device by flowing air quantity is possible. It is thus avoided that the drive device of the exhaust fan operates virtually during the entire useful life of the replaceable exhaust-side filter device with that power output, which is actually only required in the event that the exhaust-side filter device at the end of their period of use more or less strongly with paint particles or the like , is acted upon, which affect the permeability of the exhaust air side filter device.

A further energy saving can be achieved if a drive device of the supply air fan is adjustable according to the contamination of the supply-side filter device. As a result, a corresponding energy saving in the operation of the drive device of the supply air fan is achieved analogously to the manner described above for the exhaust fan.

According to an advantageous embodiment of the ventilation device according to the invention is in the control device as an input variable for polluting the exhaust-side filter device proportional parameters and possibly a for polluting the supply-side filter device proportional parameters entered. By means of the control device is the drive means of the discharge fan and possibly the supply air fan according to the pollution of the exhaust-side or supply-side filter device adjustable. As a result, a quasi-continuous adjustment of the two drive means for the exhaust and the supply air fan is possible, so that in each case the part of the two drive means, the optimal output power is provided. A manual adjustment of the drive means and the associated error sources are thereby completely avoided.

The ventilation device according to the invention can be realized with a comparatively small technical and design effort, if in the spray booth a pressure gauge is arranged, by means of pressure in the spray booth as to pollute the exhaust air side or supply-side filter device proportional parameters can be entered into the control device. According to the course of the pressure in the spray booth, the drive device of the exhaust fan or that of the supply air generator is then tracked in such a way that the amount of air flowing through the two filter devices is constant.

As a pressure gauge diaphragm pressure switch have proven to be particularly advantageous.

If the two drive means are formed as usual as electric motors, their power output can be controlled in an appropriate manner by means of a respective arranged between the drive means and the control means frequency converter. By means of the frequency converter, which act practically as an automatic transmission, the electric motors can be controlled exactly as needed according to the given by the degree of contamination of the filter devices power requirements. Furthermore When using frequency converters for controlling the electric motors, the load peaks caused by the startup of such electric motors are avoided.

In an advantageous embodiment of the ventilation device according to the invention, the control device is associated with a tap changer, by means of which different power output ranges can be specified for each drive device, within which each drive device can be adjusted or regulated according to the contamination of the exhaust air and possibly supply air side filter device.

The tap changer can advantageously be configured as a three-stage switch, with its first stage corresponding to a standby mode, its second stage to a partial load stage and its third stage to a full load mode of the spray booth. Standby mode can always be used when there are work interruptions. For example, in standby mode, the frequency converter is set to 40% of the maximum power of the supply air fan or extractor fan. In partial load operation, which can occur with short paint finishes and with full paint jobs depending on the spray mist accumulation, it is possible to set the power of the supply air fan and exhaust fan to approx. 60% of the maximum power. In full-load operation, the maximum power of the supply and extract air fans is then set on the three-step switch.

The achievable with the above-described ventilation device according to the invention advantages also result in a ventilation method for a spray booth Lakkierbetriebs in which the spray booth charged with supply air and exhaust air is sucked out of the spray booth, entering the spray booth incoming air and from the Spray booth exhausted exhaust air are filtered, the supply air and the exhaust air flow are controlled separately, and the temperature in the spray booth is varied when an intermediate drying of a base coat layer to be painted in the spray booth component is adjusted to the intermediate drying temperature level.

In this case, the supply air and the exhaust air flow can be reduced during the intermediate drying process.

Furthermore, it is possible to interconnect the supply air and the exhaust air flow during the intermediate drying process to a circulating air flow.

To avoid Staubaufwirbelungen it is expedient to perform changes in the supply and exhaust air flow steadily and smoothly.

The temperature of the supply air flow can be measured and advantageously used as a basis for regulating the temperature in the spray booth.

Furthermore, it is possible to set a temperature level adapted to this injection process in the case of an injection process taking place in the spray booth.

The same naturally also applies to a firing process taking place in the spray booth.

Advantageously, the exhaust air flow is kept constant or changed independently of the pollution exhaust air side filter means.

The same naturally also applies to the supply air flow according to a further advantageous embodiment of the method according to the invention.

In the following the invention with reference to an embodiment will be described in more detail with reference to the drawing, in which essential components of the ventilation device according to the invention are shown for the present invention.

A spray booth, not shown in the figure has on its supply air side a supply air fan 1, by means of the ambient air into the spray booth can be inserted. In order to avoid contaminants from getting into the spray booth with the ambient air, the supply air fan 1 is assigned an inlet-side filter device 2, to which an exchangeable filter cover, mat or the like expediently. belongs.

In the spray booth sits a pressure gauge 3, which may be designed as a membrane pressure switch. By means of the pressure gauge 3, the pressure in the spray booth is measured.

The supply air fan 1 is driven by means of a first electric motor 4, which may be e.g. can act around a three-phase motor.

The power output of the first electric motor 4 and thus the speed and flow rate of the supply air fan 1 is controlled by a control device 5 and a frequency converter 6, wherein the control device 5 pre-processed by the pressure gauge 3 in it, the pressure curve in the spray booth corresponding pressure measurement signal and to the first Frequency converter 6 passes, so that the power output of the first frequency converter 6 associated first electric motor 4 is controlled according to the pressure profile in the spray booth and thus according to the degree of contamination of the supply-side filter device 2.

An exhaust fan 7, which is arranged on the exhaust side of the spray booth, not shown in the figure, serves to carry air from the spray booth into the environment. In order to avoid that paint particles and similar impurities from the spray booth reach their environment, the exhaust fan 7 is associated with an exhaust-side filter device 8. Like the supply-side filter device 2, the exhaust-air-side filter device 8 also has filter covers, mats or the like to be exchanged in specific periodic periods.

The Druckmeßsignal entered by the pressure gauge 3 is preprocessed by the control device 5 and forwarded to a second frequency converter 9, which in turn controls a the exhaust fan 7 driving second electric motor 10. The regulation of the second electric motor 10 also takes place as a function of the pressure variation in the spray booth and thus depending on the degree of contamination of the exhaust-air-side filter device 8.

The two electric motors 4, 10 are adapted in terms of their energy consumption to the degree of contamination of the two filter devices 2, 8, so that it is no longer - as in the prior art - required to operate each with the required at the highest degree of contamination of the filter devices energy.

In the illustrated embodiment, the control device 5 is assigned a three-step switch 11, by means of which for each electric motor 4, 10 different power output ranges can be predetermined; Within these predetermined power output ranges, the two electric motors 4, 10 are regulated as a function of the degree of soiling of the supply-side and exhaust-air-side filter devices 8. In this case, it is possible for the predefinable power output ranges to overlap or overlap at their edges. The predeterminable power output ranges may correspond, for example, to a standby, a part load and a full load operation of the spray booth.

In the spray booth, not shown in the single figure, a heating device 12, e.g. preferably in the form of a burner. By means of the heater 12, the temperature can be varied within the spray booth. For this purpose, the heating device 12 is connected to the control device 5.

In order to provide an output variable for the control or regulation of the heating device 12, a temperature sensor 13 is arranged in the supply air duct of the spray booth, not shown in the single figure, by means of which the temperature of the inlet air entering the spray booth can be detected. This temperature serves as an output variable for the control of the heating device 12 in order to achieve the respectively required or desired temperature level within the spray booth as quickly as possible.

In the spray booth to be painted components are provided with at least one basecoat film, wherein after application of each basecoat film initially an intermediate drying process carried out in which no further paint is sprayed onto the component.

By means of the heating device 12 and a reduction in the air flow rate, the temperature level within the spray booth can be set or increased at the beginning of such an intermediate drying process so that the optimal temperature for the intermediate drying process is created as quickly as possible.

Of course it is also possible, both for the injection process as well as for the firing process, with which the clearcoat or exterior coating is cured, each set the optimum temperature within the spray booth for a short time.

Thus, for each occurring in a painting of a component in the spray booth process step each optimal temperature level is controlled within the spray booth, so that overall results in a shortening of the painting process with a concomitant reduced technical and economic effort.

For this purpose, further, the control device 5 is designed so that both the supply air fan 1 and the exhaust fan 7 are automatically operated at the initiation of an intermediate drying operation at a lower speed. The energy required for the operation of the two fans 1, 7 is thereby significantly reduced.

As indicated by the double arrow 14 in the basic figure in the single figure, it is possible by a line adaptation or switching not shown in the single figure to drive the supply air fan 1 and the exhaust fan 7 during an intermediate drying operation in the recirculation mode. As a result, the temperature increase within the spray booth required for carrying out the intermediate drying operation after an injection process can be brought about within a shorter period of time, wherein, moreover, the energy expenditure for heating the air in the spray booth can be further reduced.

To u.dgl in any case unwanted dust turbulence. to avoid, the control device 5 is designed so that by means of a speed change of the supply air fan 1 or the exhaust fan 7 is performed in a gradual transition, so that speed jumps are avoided in any case.

The control device 5 is associated with a switching element 15, by means of which on the control device 5 a variable according to the respective requirement profile variable setpoint is adjustable. This setpoint corresponds to the adapted to the intermediate drying process temperature level, which is to be maintained within the injection chamber.

Claims (24)

1. A ventilation device for a paint spray booth of a paint operation, including a supply air fan (1) for introducing supply air into the paint spray booth, an exhaust air fan (7) for evacuating the exhaust from the paint spray booth, filter devices (2, 8), via which contaminants can be prevented from getting into the paint spray booth and paint particles can be prevented from getting out of the spray booth, drive devices (4, 10), via which the supply air fan (1) and the exhaust air fan (7) are driveable, a heating device (12), via which the temperature in the paint spray booth can be changed, and a control device (5), via which the drive devices (4, 10) for the supply air fan (1) and the exhaust air fan (7) and the heating device (12) can be controlled, and via which a temperature level can be preset for the heating device (12) of the spray booth, which level is adapted to a spraying operation taking place inside the spray booth, characterised in that an additional temperature level can be preset via the control device (5) for the heating device (12) of the spray booth, and this temperature level is adapted to an intermediate drying stage of a base paint layer on a component to be painted in the spray booth, and that the supply air fan (1) and the exhaust air fan (7) can be operated at a lower speed automatically during an intermediate drying stage via the control device (5).
2. The ventilation device in accordance with claim 1, wherein the control device (5) is designed such that the supply air fan (1) and the exhaust air fan (7) are operable in circulating mode during an intermediate drying operation.
3. The ventilation device in accordance with either of claims 1 or 2, wherein the control device (5) is designed such that it is possible to change the speed of both the supply air fan (1) and the exhaust air fan (7) via a non-incremental, constant speed changing phase.
4. The ventilation device in accordance with any of claims 1 to 3, wherein the control device (5) has a switching element (15), via which an adjustable setpoint value for the temperature level that is adapted to the intermediate drying operation can be preset at the control device (5).
5. The ventilation device in accordance with any of claims 1 to 4, including a temperature sensor (13) that is disposed in the supply air duct to the paint spray booth and to which the control device (5) is connected.
6. The ventilation device in accordance with any of claims 1 to 5, wherein the control device (5) is designed such that it can be used to preset a second temperature level for the heating device (12) of the paint spray booth, which temperature level is adapted to a spraying operation taking place in the paint spray booth.
7. The ventilation device in accordance with any of claims 1 to 6, wherein the control device (5) is designed such that it can be used to preset a third temperature level for the heating device (12) of the paint spray booth, which temperature level is adapted to a curing operation for a top coat or clear varnish layer that is carried out in the paint spray booth.
8. The ventilation device in accordance with claim 7, wherein the temperature level that is adapted to intermediate drying is between the temperature level that is adapted to the spraying operation and the temperature level that is adapted to the curing operation .
9. The ventilation device in accordance with any of claims 1 to 8, wherein the drive device (10) of the exhaust air fan (7) is adjustable according to the contamination of the exhaust side of the filter device (8).
10. The ventilation device in accordance with any of claims 1 to 9, wherein the drive device (4) of the supply air fan (1) is adjustable according to the contamination of the supply side of the filter device (2).
11. The ventilation device in accordance with either of claims 9 or 10, wherein a parameter proportional to the contamination of the exhaust side filter device (8) and/or a parameter proportional to the contamination of the supply side filter device (2) can be entered at the control device (5) as input variables, and wherein the drive device (1) of the exhaust air fan (7) and/or the drive device (4) of the supply air fan (1) can be regulated via the control device (5) according to the contamination of the exhaust side and/or supply side filter device(s) (8, 2).
12. The ventilation device in accordance with claim 11, wherein a pressure gauge (3) is situated inside the paint spray booth, via which the pressure in the paint spray booth can be entered in the control device (5) as a proportional parameter for the contamination of the exhaust side and/or the supply side filter device(s) (8, 2).
13. The ventilation device in accordance with claim 12, wherein the pressure gauge (3) is constructed as a membrane pressure monitor.
14. The ventilation device in accordance with any of claims 1 to 13, wherein each drive device (4, 10) has the form of an electric motor, the drive power of which can be regulated via a frequency converter (6, 9) disposed between the motor and the control device.
15. The ventilation device in accordance with any of claims 11 to 14, wherein a step switch (11) is assigned to the control device (5), and via which different power output ranges can be preset for each drive device (4, 10), within which each drive device (4, 10) can be adjusted and regulated according to the contamination of the supply side and when necessary the exhaust side filter device(s) (2, 8).
16. The ventilation device in accordance with claim 15, wherein the step switch (11) is configured as a three-stage switch, of which the first stage corresponds to a standby mode, the second stage corresponds to a partial load mode, and the third stage corresponds to a full load mode of the paint spray booth.
17. A ventilation method for a paint spray booth of a paint operation, in which supply air is fed into the paint spray booth and exhaust air is evacuated from the paint spray booth, the flow of air is filtered as it enters the paint spray booth and as it is evacuated, the supply air and exhaust air flows are controlled separately, and the temperature in the paint spray booth is varied, characterised in that during an intermediate drying operation of a base paint layer on a component to be painted in the paint spray booth, a preset temperature level adapted to the intermediate drying is set, and that the supply air and exhaust air flows are reduced during the intermediate drying operation.
18. The ventilation method in accordance with claim 17, wherein the supply air and exhaust air flows are merged in a circulating air flow during the intermediate drying operation.
19. The ventilation method in accordance with either of claims 17 or 18, wherein changes to the supply and exhaust air flows are made constantly and smoothly.
20. The ventilation method in accordance with any of claims 17 to 19, wherein the temperature of the supply air flow is measured and used as the basis for regulating the temperature in the paint spray booth.
21. The ventilation method in accordance with any of claims 17 to 20, wherein a temperature level adapted to the spraying operation is set in the paint spray booth when a spraying operation is taking place inside the paint spray booth.
22. The ventilation method in accordance with any of claims 17 to 21, wherein a temperature level adapted to the curing operation is set in the paint spray booth when a curing operation is taking place inside the paint spray booth.
23. The ventilation method in accordance with any of claims 17 to 22, wherein the exhaust air flow is kept constant or changed regardless of the contamination of exhaust side filter devices (8).
24. The ventilation method in accordance with any of claims 17 to 23, wherein the supply air flow is kept constant or changed regardless of the contamination of supply side filter devices (2).

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