WO1997018425A1 - System and procedure for regulating air volume in ovens for painted automobiles - Google Patents

Abstract

System and procedure for regulating air volume in ovens for painted automobiles, that establishes in the intake (1), and exit (15) devices, some butterfly valves (6, 11) lead by electric servomotors (18) that can adopt, simultaneously among themselves, three preestablished positions (7-9, 12-14) in order to change the air volume maintaining the inside pressure, facilitating to realize in the paint cycle, prior to the paint baking, two operations: application of each coat of water-based paint to suitable levels of 11,000 or 14,000 CFM (Cubic Feet per Minute) and drying, increasing for this the air volume to the maximum level of 19,000 CFM. A certain energy save is achieved by reusing part of the warmed air in the intake device (1). The device, in an improved version, incorporates a control system (16-18) in closed loop of the internal pressure that acts on the exit valve position (12-14).

Description

"System and procedure for regulating air volume in ovens for painted automobiles".

The object invention of this Patent consists of a system and procedure usable in conventional ovens for painted automobile vehicles and constitutes a revolutionary development furnishing an onginal regulating system of flow ventilation or air volume circulating in the cited cabin that permits a perfect water-based painted application to the body of automobile vehicles

This invention is inserted in the oven painted automobile vehicles sector, having been especially conceived for water-based paint jobs, that require some very special conditions for its application that are only provided by the system and procedure object of this Patent, given that such suitable work conditions with this type of paint are not actually known in the state-of-the-art At this point one has to realize that, broadly speaking, the paints that are not water-based do not require any air volume regulation inside the cabin due to its well-known chemical characteπstics, reason why in the conventional ovens the air circulates at an only constant velocity On the contrary, the special nature and properties of the water-based paints make very recommendable for a perfect application of the same that this air volume inside the painted cabins is regulated, which is precisely furnished as an absolute development of this Patent

In the expressed state of the art the painted ovens act on an air flow practically constant that using the international CFM measurement ("Cubic feet minute" or cubic feet per minute) can quantify itself at the 19,000 CFM quantity. However, the pressure and velocity that this air volume endures, combined with the density and water-based paint characteristics, determines that the application of this water-based type paint to the bodies of automobile vehicles results complicated and defective, given that the projection of these paints is braked and deviated by the push of this mentioned air volume that provokes an irregular application of the paint.

It has to be explained that because there does not exist an appropriate regulation of air in the present known ovens, the indicated high air volume at 19,000 CFM is adopted necessarily in the painted cycle phase because it is suitable for the ulterior, second and final baking cycle or paint hardening. On the other hand, the water-based paints require that each coat of paint that is applied must be dry before proceeding to apply the second and successive paint layers, which brings with it a notable loss of time, since this type of water-based paint requires a considerable period of time for drying, approximately 1 hour, which multiplies for each water-based paint layer that is applied, which is usually between 2 and 3 coats.

The innovation and original inventive step that bears the present invention lies in the user of the painted oven, by using water-based paints, can regulate willingly the air volume in the painted cycle, with the purpose of applying the paint at appropriate levels so that the water- based paints are applied in a fitting manner, such as 10,000, 1 1 ,000, 13,000 or 14,000 CFM, depending on which is more appropriate for the used water paint characteristics.

At the same time, during this same paint cycle, after applying each paint coat it is not necessary to wait in order to produce drying a period of time that normally is around 1 hour, since it is possible to proceed to dry each one of the same, in about 3 or 4 minutes, by regulating the air volume, elevating it to a maximum of 19,000 CFM, with an obvious and notable save of time that economically assumes an important value.

After producing this brief drying interval of the selected water- based paint layer, the air volume of the oven returns to regulating itself in order to reduce the appropriate levels during its application, during the necessary time for it.

After finishing the application of the diverse water-paint layers, each of them followed by their corresponding drying, always with the speciality that it produces during the same initial paint cycle, it passes to the subsequent and final baking cycle or paint hardening in which the conventional air flow for this phase is of a high value like 19,000 CFM.

With respect to the baking cycle one must specify that during the same t:.ne one „an also regulate the required air volume, which assumes an important save or energy in cold climate zones, given that the reduction of air volume in the inside oven during this baking cycle logically assumes one has to heat until the temperature requires a smaller air quantity, with the consequent saving of time in this phase and, of course, of the required energy for it.

The expressed variations of the air ventilating flow are realized by the invention object of this Patent without bringing about pressure variations in the inside painted ovens that cause turbulence that harm the perfect application of the paint.

In order to achieve the exposed new technical effect, the system and procedure object of this Patent has been foreseen that they can be adapted to any oven for painting automobile vehicles, which generally consists of a closed chamber where it is realized, on the one hand, the painted tasks with the help of the appropriate spray paint to each application in particular and, on the other hand, generally has a ventilating system consisting of a ventilator or compressor that drives the air inside ofthe said closed chamber with the purpose of faciliting drying and also the ulterior baking or hardening of paint.

These mechanisms or chambers for painting automobile vehicles can also have got an appropriate heating system in order to accomplish the so-called final paint baking cycle where the painted surface is submitted to a thermal treatment with the object of obtaining certain mechanical characteristics of the paint which determine its perfect application and fastening to the body of the automobile vehicles.

In the case of the claimed invention in this Patent, the mentioned heating system has been foreseen, that by reason of its new special characteristics, what permits a considerable energy save since part of the heated entered air on its way through the heat exchanger and by effect of the regulating air it results excessive and does not enter the painted chamber, it is recycled another time towards the same admission duct. As a result of this application in the diverse painted and baking cycles, this avoiding unnecessary loss of hot air, it also obtains other additional advantages, how to be able to obtain a greater efficiency of the radiators or heat exchangers that take charge of heating the air introduced in the chamber. What has been stated above is achieved in the present Patent by the use of butterfly valves, one at the entrance or air admission duct at the inside of the painted cabin and another or other similar valves arranged at the exhaust duct or exit of the air from the inside of the painted cabin. These valves or air flow regulating elements have to act in a synchronized form since, in order to avoid pressure alterations in the inside painted cabin, they have to move coordinately in the preestablished positions. That is to say, if the admission air flow in the inside of the painted oven increases, the exit tail should increase and therefore the opening of the valve that regulates the exhaust air flow of the cited cabin or painted chamber, with the purpose of avoiding the mentioned pressure alterations in the inside said cabin, which can redound in a defective finish of the painted operations that were carried out.

The method for developing the system object of this Patent consists of the air that is introduced in the painted oven through a filter, in order to avoid any particle that in case it enters the mentioned automobile vehicles painted chamber it could damage the finish of the paint. Then, this air is introduced in a ventilator or compressor that pushes it, by means of an appropriate pipe to a heat exchanger in order to be heated in its path by the same. With this exit, the already heated air is driven towards the inside chamber of the painted oven, even though at will of the user of the same, part of this air can deviate by means of the already mentioned butterfly valve or regulating device and control of air tail used in the painted chamber of automobile vehicles. So, if it requires less air volume inside of the oven, then the part of hot air not used returns to the entrance duct where it mixes with the air that arrives from the outside and again carries out its itinerary in the admission mechanism, through a ventilator, toward the heat exchanger, this hot air does not enter the painted chamber is recycled instead of being expelled to the outside and lost, achieving with it an evident save of energy. On the other hand said measurement achieves an additional advantage, since for a determined air tail introduced in the inside of the painted chamber of automobile vehicles can be required a smaller dimension heat exchanger thanks to this recirculation from part ofthe hot air, since in the actual state of the art the painted ovens that require to heat a larger air volume what they do is join a bigger dimension heat exchanger, which is avoided by this Patent.

The invention has foreseen the utilization of control elements and presentation of information relative to the different operations that are achieved in the successive paint cycles. Therefore, it can have timing elements in order to set in an automatic form the duration of certain operations, in function of the developed task and used water-based type paints. Likewise, on the outside ofthe chamber 3 bright indicating devices in colours yellow, green and red have been arranged to inform the operator about when he can pass to the following phase or paint cycle. In this sense, during the initial paint cycle, the lights green and yellow are activated alternatively in order to indicate that they are carrying out the operations or paint layer application phases (as much as 1 ,000 to 14,000 CFM, for example) with the colour green, or the drying operation of each one of the water-based paint layers (to 19,000 CFM), which is shown with the bright yellow colour indicator. The bright red colour mechanism will only be activated during the baking cycle. In order to facilitate the handling of the painted oven for the user, the time of the operation or drying phase of the water-based paint layers (yellow colour light), that is produced during the initial paint cycle, can be preestablished by means of a conventional timer. Likewise the activation of these phases, whose lights inform about the phase that crosses the process of developed work in the painted oven, can be carried out by the user by means of a remote control or well by means of simple buttons.

The object invention of this Patent likewise foresees an improvement to the previous described system and method, consisting of the introduction of an automatic pressure controlled system in the inside chamber of the painted oven of automobile vehicles, consisting of a regulating system in closed loop or "feedback" made up of one or various pressure sensors, shared by the inside painted cabin, connected to a regulating element, which after processing the previous signals is capable of generating an exit that leads the movement of a servomotor connected to the butterflies or exit valve blades, producing a variation of the exit air tail opposite the detected pressure variations. Then, is exposed a detailed description of the operation of the object invention of this Patent that is now proposed, with reference to the schematic drawings that are attached, which are represented, by simple way of example, not limitating, a preferred form of realization that is susceptible to all those detail variations that do not assume a fundamental alteration of the essential characteristics of the object invention of this Patent.

The mentioned plan illustrates:

Figure 1 , consisting of lateral elevated view of the entrance or air admission mechanism in the inside of the painted oven of automobile vehicles object of this Patent.

Figure 2, shows a lateral elevation of the exit mechanism or air ventilating evacuation of the painted ovens of automobile vehicles proposed in this Patent.

Figure 3, shows a lateral elevation of the painted oven with both admission and air ventilating evacuation mechanisms.

According to the represented executed example, it has to be specified that in the drawings the cabin work for painting automobile vehicles used with the system and method object of this Patent have not been shown, given that it can be any conventional cabin form for this type of application.

In both indicated figures one can contemplate the entrance to the painted cabin or air intake (1), in which such air crosses a filter, which has not been represented in the attached drawings for constituting an already classic element in this type of device.

The air passes through a duct (2) to a ventilator (3) where it is pushed toward a heat exchanger (4), where it is warmed in its path across the same. Then, it arrives to a place where part or the totality of this hot air tail enters by the entrance (5) to the painted cabin for its ventilation, and another part of this hot air flow that leaves from the mentioned heat exchanger can be diverted by means of a butterfly valve (6), toward the former air entrance duct (2) where it mixes with the new tail that enters through the vent ( 1 ). The mentioned butterfly valve (6) can adopt three positions, previously preestablished by the user of the system, being lead by a servomotor, it manages to regulate the quantity of air introduced in the chamber by means of the entrance duct (5).

Thus, this valve (6) offers a completely closed position (7), determinant that all the air that enters through the vent ( 1 ) and passes through the duct (2), through the ventilator (3) and the heat exchanger (4), is introduced by means of the entrance (5) in the painted chamber, which determines a maximum air volume level tail and 1 ,000 CFM, corresponding to the oven external signal to the air concentration that propels the bright yellow colour mechanism in the paint cycle, indicative of the drying operation subsequent to the application operation of a paint layer that is realized during this firs paint cycle, in the same manner as the colour red in the baking cycle. When the butterfly valve (6) is propelled to its position (8), it establishes a semi-opening that provokes the deviation from part of the circulating air, which reduces the air volume at the selected intermediate level of 14,000 CFM (bright green colour mechanism for the application operation of a paint layer during the initial paint cycle).

The values expressed before are mentioned by way of example and practical realization, given that the greater or lesser variation in the position of the butterfly valve (6) correspondingly would vary the air tail to other concentrations that can be preestablished by the user of the system and can be diverse to the exposed.

Finally, the valve (6) has been foreseen in this way of practical performance that has a third position (9) of total opening that reduces even more the air level at the minimum level of 1 1 ,000 CFM (bright green colour mechanism in the paint cycle). On the other hand, the present invention has foreseen an evacuation system or exit of air from its inside, just as it is illustrated in Figure 2. This system consists of ventilator ( 10) joined to an inside air opening exit of the work enclosure or painted cabin of automobile vehicles. This ventilator (10) pushes the air towards the exterior across a zone in which is established a valve (1 1 ) of various butterflies, similar to the one mentioned before (6), encountering both valves functionally coordinated by some servomotors that secure them in preestablished positions. This valve (1 1 ) also foresees its drive in three preestablished equivalent positions in a coordinated and synchronized way to the fittings of the valve (6).

One first position (12) is an absolute opening and corresponds to the completely closed position (7) of the valve (6), with the purpose of maintaining a balanced and steady pressure in the inside chamber of the oven when the volume or air tail results to be 19,000 CFM maximum. A second position (13) of the valve (1 1 ) is semi-opened and would coincide with this same positioning (8) of the valve (6) from the air entrance mechanism to the oven.

Finally, a third position (14) of the valve (1 1 ) would practically close the oven air exit and would coincide with the minimum air flow level of 1 1 ,000 CFM determined by a smaller air entrance to the chamber due to a great part of the same being diverted by the valve (6) by situating itself in its maximum opening position (9).

An improved form of realization, illustrated in Figuie 5, consists of the introduction of an automatic regulating system in closed loop of the inside pressure of the painted oven. This system acts on the valve ( 1 1 ), placed in the exit device or air ventilating evacuation, which has distinct butterflies that in function of the positions that the adopt permits more or less air flow evacuation across the exit vent ( 15) towards the outside. This valve ( 1 1 ) is lead by a servomotor (18), whose movement is lead by the exit of a regulator (17), that in function of the measured pressure in the inside chamber, by means of a transducer (16) and in function of a command or reference pressure value, calculates the position of the blades or butterflies of the valve (1 1 ), with the purpose of regulating and maintaining the inside pressure in the chamber steady and equal to the command value, avoiding moreover pressure alterations in the inside painted cabin. That is to say, if the admission air flow in the inside painted cabin increases the exit tail should increase and therefore the opening of the valve that regulates the exit air tail of the mentioned cabin, with the purpose of avoiding the mentioned pressure alterations inside of the painted chamber, which can redound in a defective finish of the painted operations that were carried out with the mentioned cabin.

How much has been described constitutes an accurate reflection of the invention object of this Patent, having to consider the characteristics that have been stated in a not restrictive meaning, being indifferent and changeable the secondary character or accessory circumstances, such as the form, materials and dimensions of its practical realization that can be variable if the do not alter the essentialness that is subsequently claimed.

Claims

1 ) System and procedure for regulating air volume in ovens for painted automobiles, conceived for its application to conventional furnished with intake and ventilating air exit devices, likewise also for the heating ofthe same, characterized for having foreseen the installation in both mentioned devices of an air tail regulating system in the inside painted oven, that acts by means of the coordinated drive of some butterfly valves lead by a servomotor, each one of them, simultaneously, can adopt three positions with diverse openings appropriately preestablished.

2) System and procedure, according to the first claim, characterized because the butterfly valve (6) of the ventilating air entrance device in the painted cabin permits the regulation of an air volume that is introduced in the intake mechanism by its vent (1 ) and is warmed in the heat exchanger (4), determining that this air enters in its totality in the inside of the oven situating the butterfly valve (6) in its closed position (7), or can divert a greater or lesser part of this air toward the duct (2), across the flow of air that is introduced by the outside vent (1 ) of the intake device, which is realized by situating this butterfly valve (6) in the semi-opened (8) or complete opened (9) positions.

3) System and procedure, according to previous claims, characterized because the air ventilating device of the inside painted oven foreseen the valve (1 1 ) of the diverse butterflies, which adopts coordinated and synchronized positions with which the butterfly valve (6) of the intake mechanism adopts, establishing a correlation among the three respective positions of these valves: closed (7) arid (12), semi- opened (8) and (13) and opened (9) and (14).

4) System and procedure, according to previous claims, characterized because the regulating possibility that supplies the air volume in the inside oven, without producing alterations in the equilibrium of its pressure by the coordination among the butterfly valves from the intake device (6) and from the air exiting device (1 1 ), determines that during the paint cycle, prior to the successive and final baking cycle, it is possible to regulate at will the volume of air in the inside painted oven, what permits to realize, during the initial paint cycle of the automobile vehicles, with the diverse preselected air volumes the operations of painting and later drying of each coat of paint.

5) System and procedure, according to previous claims, characterized because on the outside ofthe painted oven bright indicators of diverse colours have been arranged to inform about the diverse operations that are realized at each moment in the painted oven, such as the paint operation (bright green colour indicator) and drying (bright yellow colour indicator) of each coat of water-based paint, both during the initial paint cycle, thus the subsequent and final baking cycle (bright red colour indicator). 6) System and procedure, according to previous claims, characterized because the duration time of the drying operations of each of the applied coat of water-based paint, that by means of the claimed system and procedure it is calculated that it can range between 1 to 15 minutes and has been foreseen to take place during the paint cycle, it can be prearranged by means of a connecting timer with any computer or electrical conventional mean to the timer mechanism and driver of the butterfly valves of the intake (6) and exit (1 1 ) devices.

7) System and procedure, according to previous claims, consists of establishing an automatic regulating system in closed loop of the inside pressure, characterized by a regulating element (17) that receives and processes the sent signal by one or various pressure sensors ( 16) shared by the inside cabin of the painted oven, and from the previous regulator (17) it generates a control signal that commands the movement of a servomotor (18) that moves the blades of the butterfly valve (11 ) from the exit or evacuation device from the ventilating air of the painted oven.