EP0584638B1 - Ventilation device for spraying booths or similar - Google Patents

Description

The invention relates to ventilation devices for paint booths or the like. According to the preamble of claim 1.

In painting booths, which are understood here to mean all rooms for surface coating processes in which larger amounts of a coating material, solvents or the like get into the air, certain air sinking speeds of the vertically-horizontally or diagonally guided air are prescribed, which are used to remove the liquid that gets into the air , solid and gaseous components during the painting process, especially to protect the health of the people working in them. Since such air sink speeds are, for example, 0.35 m / s, calculated over the entire painting area, enormously high fan outputs result.

A ventilation device according to the preamble of claim 1 has become known from JP-A-59 123 569. An air volume control is mentioned therein, which is used to control the ventilation fan works simultaneously or with a delay in relation to the ventilation fan.

The object of the invention is an essential without impairing the health and quality aspects To achieve a reduction in the energy requirement for the ventilation of paint booths while maintaining a constant pressure.

This is achieved according to the invention by claim 1.

So there are separate fans for ventilation and ventilation, which can be controlled synchronously. With such high air conversions as are required during the work of paint booths, a significant pressure surge would occur if the volume was increased or decreased if the regulation were not carried out in such a way that both fans are controlled synchronously and at the same time change the quantity. A pressure ratio control is provided which maintains a substantially constant pressure, namely preferably an overpressure in the painting booth, both before and after the change in quantity and during the change in quantity. This ensures that dust can never be sucked into the paint booth from outside.

Identical fans are selected, preferably within the type group in terms of both their performance and their run-up behavior (so-called twins). In this case, pole switching can also be used if it is ensured that the exhaust air and supply air flows are changed in the same way. In this case, special means for fine regulation, for example throttle valves adjustable by an automatically operating pressure regulator, can be arranged in the supply or exhaust air duct. This also ensures the necessary fine-tuning in the event that, for example, the filters located in the exhaust air flow between the painting booth and the blower become increasingly clogged, thereby shifting the pressure conditions.

It has been found that the high air throughput is only necessary during the actual painting process, because it primarily serves to prevent the spray mist created during the painting process, provided that it is not deposited on the object to be painted, and the resulting increased margins Dissipate solvent vapors. As soon as the painting process, for example the atomization of the paint, has ended, a substantially smaller amount of air is sufficient to remove the solvent vapors or the like which arise when the paint is vented. It has been found that about a third of the high amount of air is sufficient for this, so that a down regulation or downshifting to a quarter to half, preferably a third of this amount is possible.

A switch on a suspension hook for the spray gun can be used, for example, as a command transmitter which can be actuated as a function of the readiness to work for the painting process. If it is hung there, it is not ready for use and the amount of air can be reduced. As a command for such a reduction or re-increase signal can also be a manually operated signal generator or z. B. the operation of the spray gun can be used immediately. In this case, the signal that actuates a solenoid valve for the compressed air supply to the spray gun could also be the corresponding relay for changing the pole of the fan motors actuate. In this case, the signal is given in an even closer coupling to the painting process. In order to prevent the air volume control or regulation from responding immediately in the event of a brief interruption in the painting process, a time delay circuit can be provided which maintains the high air output for a predetermined period of time (run-on time) and only then initiates a reduction. For example, when the command is given by the solenoid valve of the spray gun, a run-on time of 10 to 30 seconds can be set in order to bridge a brief suspension of the painting process, for example when the painter changes position.

The reduction in the amount during painting breaks also has the advantage that the high air speed, which is often troublesome during intermediate activities, and which could otherwise blow away covering materials or the like or blow onto freshly painted surfaces, is reduced.

The air volume can preferably be reduced by reducing the speed of the fans. This can be done by frequency switching, pole switching, in the case of multi-pole electric motors or by other known control options for electric motors, also by means of stepless speed control. It is also possible to bring about a reduction when using several fans by switching off individual fans or groups of fans. Several switching stages, for example for a multi-stage decrease in the quantity depending on the interruption time of the painting process, are also possible.

Although the power that the fans consume is very high and a considerable amount of energy can be saved by reducing the amount of air, this saving is significantly increased if you take into account that the air in painting booths is limited to one certain temperature must be brought, which is usually significantly above the outside temperature.

Heat recovery systems have already been designed here, but despite high system costs and susceptibility to faults as well as enormously high cleaning costs, only comparable energy savings were achieved. The invention, on the other hand, makes it possible to directly reduce the heating energy requirement by reducing the amount of air that is passed through. The respective adjustment can take place automatically without control intervention by regulating the temperature of the air thermostatically, so that it regulates itself automatically when the quantity is reduced. The only thing that should be ensured is that the regulation is sufficiently quick to access.

Intensive investigations in many paint shops have shown that of the gross operating time of a paint booth, the actual painting process, during which a paint job is carried out, is only 30 to 40%. The rest of the time, especially in the case of individual lacquering, is required for the preparation, transportation to and from the site, cleaning and ventilation of the parts. This results in enormous energy savings, which are up to 50% in the area of the fan output and about 40% in the area of the heating. In particular, the high savings rate in the high-quality and expensive form of energy required for the fans (electrical energy) is of great importance both for the profitability of the individual company and for the economy as a whole. In addition, attention should be drawn to the reduction in sound emissions, which is reduced from 12 dB (A) from 79 to 67 dB (A) in economy mode.

Fig. 1

einen schematischen Schnitt durch eine Lackierkabine mit den zugehörigen Belüftungseinrichtungen,

Fig. 2

einen Draufsichtsplan auf die Lackierkabine nach Fig. 1 und

Fig. 3

einen schematischen Plan der Belüftungseinrichtung.

These and other features emerge from the description and the drawings in addition to the claims, wherein the individual features can be implemented individually or in groups in the form of sub-combinations in one embodiment of the invention and in other fields and can represent advantageous and protectable versions for which protection is claimed here. An embodiment of the invention is shown in the drawings and are explained in more detail below. The drawings show:

Fig. 1

2 shows a schematic section through a painting booth with the associated ventilation devices,

Fig. 2

a plan view of the painting booth according to Fig. 1 and

Fig. 3

a schematic plan of the ventilation device.

The drawings show a painting booth 11 which can be integrated or set in a building 12 or can also be portable. A drying booth 13 is provided parallel to it and is separated from it, for example, by a roller door 14, so that the painted objects can be transported more easily from the painting booth 11 into the drying booth 12. Both cabins have gates 15.

The painting booth has a ventilation device 16 which is separate from the ventilation device 17 of the drying chamber. It contains one or more fans 18 and an air heater 19 with a gas or oil burner 20. In a conventional manner, the ventilation system can be switched between pure fresh air supply and recirculation mode, with a partial air flow of air enriched with exhaust gas vapors in the exhaust air chimney during recirculation mode via a separate evaporation line 21 22 can be initiated. The fresh air is drawn in via an intake line 23 and the air heater discharges its exhaust gas via a separate chimney 24.

The air that flows through the painting booth 11 is fed in via an inlet air duct 25 running above the booth, then sinks as evenly as possible in the booth and exits again via an exhaust air duct 26, which is arranged below a grating 27 in the floor of the booth. This feeds the air back to the central ventilation device 16, where, depending on whether it is a recirculation or fresh air operation, it is filtered and returned or exits via the exhaust air chimney 22.

The devices belonging to the ventilation device 16, such as fans and heating devices, are located in a separate room 28 outside the painting booth. There is also a control cabinet 29 in which the switches, regulators, etc. which control or regulate the ventilation device are combined.

In the paint booth, a command transmitter 30 is mounted on a wall which contains a switch or signal transmitter which is actuated when a spray gun 31, which can be hung on a hook 33 connected to the switch, is removed or hung up again. If several spray guns are stationed in the room, there should be a command transmitter for all of them. The command transmitter is in connection with the control cabinet 29, where it actuates the control of the fan (s) 18 so that it releases the full power of the fan when the spray gun 31 is removed, while with the spray gun attached the power is reduced to about 1/3 of the speed by means of the spray gun Air volume throttles.

Fig. 3 shows schematically the ventilation devices. The fresh air intake line 23 leads into a changeover chamber 40 in which a changeover flap 41 can be pivoted between a fresh air position (solid line) and a return air position (dash-dotted line). From there, the air flows via a pre-filter 42 to the fresh air blower 18a, from which it is conveyed through the air heater 19 into the supply air duct to the painting booth 11. The air flows through the grating of the painting booth into the exhaust air duct 26, passes through a filter 43 and in turn flows to the switchover chamber, where it is guided to the inlet of the exhaust air fan 18b when the flap position (fresh air mode) is shown and is conveyed outside via the exhaust air chimney 22.

It should be noted that fans 18a, 18b should be absolutely identical. They should not only be the same in terms of blower and motor type and type and power, but also, if possible, selected so that they have absolutely identical performance in all control stages produced by pole changing and the same ramp-up times between these stages.

It can be seen that control devices in the form of blind-like switch flaps 44 are provided at the outlet in the exhaust air chimney or at the entry into the switchover chamber, which are operated manually or preferably automatically by control or regulating devices 45 and together with these form pressure ratio regulating means . The regulation can take place depending on a pressure transmitter (not shown) in the painting booth or elsewhere in the air circuit. The flaps are controlled so that a slight overpressure is constantly maintained in the painting booth. They are mainly for fine adjustment This overpressure is provided, while during the switchover between the work output and the reduced output, which is described below, and vice versa, the pressure ratio is automatically maintained by the identical design of the fans and appropriately dimensioned duct cross sections, etc. The corresponding control elements could also be provided elsewhere in the ventilation system or could be designed differently, for example by slight power shifts between the fans.

The ventilation device works as follows:

The objects to be painted, for example motor vehicles, machines or racks with small parts, are placed in the painting booth 11 and the gate 15 is closed. The ventilation device 16 is put into operation, since the spray gun 31 is attached to the commanding device hook 33, only with reduced power. After the object to be painted is correctly positioned and prepared accordingly for painting, the painter removes the spray gun 31. As a result, the signal for increasing the ventilation output is given and the fan 18 is now driven, for example by pole switching, to its full speed, which is reached in a few seconds. The air heater previously running at a lower output, which had maintained the pre-selected temperature thermostatically, is now driven higher because the increased air output threatens to lower the temperature and in turn maintains the set temperature. Due to the high amount of air conveyed, the spray mist which arises during painting and the solvent vapors evaporating therefrom are immediately lowered and are drawn off via the exhaust air duct 26. In this case the spray booth is switched to fresh air, ie it sucks Fresh air via the fresh air intake 23 and leads the exhaust air via the exhaust air chimney 22 to the outside.

When the painting process has ended or is interrupted, the painter hangs the spray gun back on the hook 33 and, if necessary with an adjustable time delay, the air output is set again to the reduced amount. At the same time, the ventilation device could also be switched to recirculation mode, in which only a relatively small percentage of the circulated air is discharged to the outside via the evaporation line 21.

In addition to the design described, the signal or command could also be given by a corresponding foot actuation, a proximity switch, the triggering of the spray gun, etc.

After painting and first venting, the painted objects can be brought into the drying chamber after opening the roller door 14, where they are finally dried, essentially with circulating air.

Claims (7)

1. Ventilation device for spraying booths (11) or the like with air feed and optionally air conditioning devices, which ensure an air passage through the booth with a quantity predetermined for the spraying process, with at least one instruction generator (30) for reducing or re-increasing the quantity to the predetermined quantity and which is operable as a function of the readiness for the spraying process, the air feed or delivery devices having speed regulatable or controllable fan motors and preferably separate fans (18) are provided for ventilation and exhausting, which are simultaneously regulatable, characterized in that for ventilation and exhausting fans of the same type and size are provided and that in particular for the synchronous, fine regulation of an overpressure regulator adjustable throttle flaps or valves, e.g. Venetian blind-type flaps, are located in the fresh air and/or exhaust air duct.
2. Ventilation device according to claim 1, characterized in that pressure ratio regulating means are provided, which maintain in the spraying booth (11) before and after the quantity reduction or increase and during the quantity change a substantially constant pressure, preferably a small over-pressure.
3. Ventilation device according to claim 1 or 2, characterized in that the reduced air quantity is between 1/4 or 1/2 (preferably 1/3) of the predetermined quantity.
4. Ventilation device according to one of the preceding claims, characterized by several fans (18), whereof at least one is stopped in the case of reduced air quantity.
5. Ventilation device according to one of the preceding claims, characterized in that a time delay circuit is provided, which maintains the predetermined air quantity for a predetermined time period following the actuation of the instruction generator (30) which has taken place for quantity reduction purposes.
6. Ventilation device according to one of the preceding claims, characterized in that the instruction generator (30) cooperates with a spraying tool (spray gun 31) or the storage means (33) provided for it.
7. Ventilation device according to one of the preceding claims, characterized by a thermostatic control device, which brings about the air conditioning of the air quantity corresponding to the quantity reduction.

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