JPH09150098A - Hot air leak preventing device of painting drying furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly prevent that hot air is leaked from a painting drying furnace of which the inlet communicates with the outlet of a painting booth fitted with an air feeder through a setting chamber by the collapse of the air supply and discharge balance generated in the painting booth fitted with the air feeder. SOLUTION: When the temp. difference between the inlet 4 and outlet 9 of a drying furnace 3 detected by thermometers 10, 11 is within a definite value, the wind quantity of the variable speed fan 6 of the exhaust hood 7 arranged on the inlet side of the drying furnace of a setting chamber 2 is held to preset standard wind quantity and, when the detected temp. of the outlet 9 becomes higher than that of the inlet 4 by a definite value or more, the wind quantity of the variable speed fan 6 is increased. Contrarily, when the detected temp. of the outlet 9 becomes lower than that of the inlet 4, the wind quantity is reduced. When the temp. on the side of the outlet 5 of a painting booth 1 detected by a thermometer 12 becomes high by a definite value or more, the wind quantity of the variable speed fan 6 is increased regardless of the temp. difference between the inlet 4 and outlet 9 of the drying furnace 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-air leakage prevention device for a coating drying oven, which prevents hot air from leaking out of the inlet and outlet of a tunnel-shaped coating drying oven. The invention relates to a hot-air leakage prevention device for a coating drying furnace, the inlet of which is connected to the outlet of a coating booth with air supply through a settling chamber.

[0002]

2. Description of the Related Art Tunnel type coating drying ovens having openings at both ends are suitable for continuous production by a conveyor, and are therefore widely used as baking ovens for automobile coating. In the oven of this baking / drying oven, high temperature hot air circulated and supplied from the hot air generator keeps the automobile body at 120 ° C.
The coating film formed on the surface of the body is baked by heating to 200 ° C. At that time, organic solvents such as thinner, coating resin and its curing agent evaporate from the coating film, and a large amount of harmful odorous substances Occurs.

When the concentration of harmful odorous substances in the furnace increases,
Since the drying efficiency of the coating film may deteriorate, the coating film may turn yellow, and there is a risk of fire, the exhaust gas inside the furnace is sucked and discharged through the exhaust duct and at the same time corresponds to the exhaust gas volume. The amount of fresh air is supplied to the furnace. At that time, if the supply / exhaust balance between the exhaust gas and the fresh air is disturbed, hot air in the furnace containing harmful odorous substances may leak to the outside from the entrance / exit of the furnace and may deteriorate the environment in the coating factory. For this reason, for example, in a baking oven for electrodeposition coating that performs undercoating for automobile bodies, the hot air leaking from the furnace is forcibly sucked in by the suction force of the fan above the outside of the inlet and outlet. An exhaust hood for exhausting air is provided (Japanese Utility Model Laid-Open No. 63-54477, Japanese Utility Model Publication 5-25).
742).

However, if the intake amount of the exhaust hood is always constant, even if the air supply and exhaust balance inside the furnace is kept uniform and hot air leakage does not normally occur, the hot air inside the furnace will be exposed to the hot air due to the suction force of the fan. May cause heat loss by being sucked into the furnace, or cold outside air may be sucked into the furnace that has become negative pressure due to hot air being sucked in from the inlet and outlet, causing the temperature distribution inside the furnace to collapse and causing uneven drying of the coating film. . Therefore, a detector is installed at the inlet of the exhaust hood to detect the amount of hot air leaked from the furnace by the change in the temperature of hot air sucked into the inlet or the concentration of exhaust gas, and the amount of hot air leak detected by the detector The device has been devised to variably control the air volume of the fan (Japanese Utility Model Laid-Open No. 63-54477). That is, when the amount of hot air leaked from the oven of the drying oven increases and the temperature of the hot air sucked into the suction port of the exhaust hood or the exhaust gas concentration rises, the air volume of the fan increases proportionally, and the exhaust hood There has been proposed a control means for reducing the air volume of the fan in proportion to the decrease in the temperature of the hot air sucked into the suction port or the exhaust gas concentration.

[0005]

By the way, the drying furnace for electrodeposition coating, which bakes the coating film of the automobile body undercoated in the electrodeposition tank, has an inlet open to the outside, but at the air supply coating booth. The drying oven that bakes the coating film of the top-coated car body is not open to the outside of the oven, and the inlet is in communication with the outlet of the air-supplied coating booth through the setting chamber. Even if the supply / exhaust balance is maintained evenly, the hot air in the furnace leaks out from the inlet or outlet of the furnace or is affected by the disruption of the supply / exhaust balance in the air-supplying paint booth. 18 ° C into the furnace
There is a possibility that cold conditioned air in the coating booth with air supply adjusted to -20 ° C may enter or cold outside air may enter the furnace through its outlet.

Moreover, when the air supply / exhaust balance in the air-introducing coating booth is disturbed, hot air leaks out from only one of the inlet and the outlet of the drying oven, and cold air enters into the oven from the other. It will be. That is, when the air supply amount in the air supply coating booth exceeds the exhaust amount and the air pressure inside the coating booth becomes positive, air-conditioning air leaks from the outlet of the coating booth to the setting room and it is discharged from the inlet of the drying furnace. When it enters the furnace, the hot air in the furnace leaks from the outlet of the drying furnace. On the contrary, when the exhaust amount in the air supply coating booth exceeds the air supply amount and the inside of the coating booth is in a negative pressure state, hot air in the oven leaks from the inlet of the drying oven and Cold outside air enters the furnace.

In such a drying oven, hot air leaking from the inlet of the oven enters the coating booth with air supply through the setting chamber and pollutes the air in the coating booth to remarkably improve the coating quality. Since there is a risk of damage, the inlet of the exhaust hood forcibly exhausting the hot air leaking from the inlet of the drying furnace by the suction force of the fan above the interior of the setting room that is located between the inlet of the drying furnace and the outlet of the coating booth. However, the above-described variable control is not performed on the air volume of the fan that sucks the hot air from the suction port, and the air volume is set to be constant.

When the amount of hot air leaking from the inlet of the drying furnace increases due to negative pressure in the coating booth with air supply, the suction amount of the exhaust hood is increased in accordance with the increase in the hot air leakage amount. This is because if the air volume of the fan is controlled, the amount of outside air entering the furnace from the outlet of the drying furnace will significantly increase, the temperature inside the furnace will drop significantly, and the temperature distribution will collapse, resulting in uneven drying. . On the contrary, when the inside of the air supply coating booth becomes positive pressure and the amount of hot air leaking from the inlet of the drying furnace decreases, the suction amount of the exhaust hood should be decreased according to the decrease of the hot air leak amount. This is because if the fan air volume is controlled, it is inevitable that the amount of hot air leaking out of the drying furnace from the drying furnace will remarkably increase and the environment inside the coating factory will be deteriorated.

However, when the air volume of the fan is set to a constant value, it is not possible to reliably prevent hot air leakage or cold air inflow from the inlet / outlet of the drying furnace caused by the imbalance of air supply / exhaust in the air-introducing coating booth. In particular, it is not possible to eliminate the possibility that hot air leaking from the entrance of the drying furnace will enter the coating booth with air supply. In addition, a large amount of cold air entering from the inlet / outlet of the drying furnace condenses the evaporated material in the hot air, and a tar-like substance adheres to the inlet / outlet of the drying furnace, and the tar-like substance is applied to the drying furnace. Since there is a risk of sagging on the film to cause a defective coating film, there is a problem in that the cleaning work of the entrance and exit must be performed frequently, and the running cost of the entire drying furnace increases significantly.

Therefore, the present invention relates to a coating drying oven in which the inlet of the tunnel-shaped oven communicates with the outlet of the air-supplying coating booth through the setting chamber, and it is possible to ensure hot air leakage and cold air intrusion from the inlet and outlet. It is a technical issue to prevent it.

[0011]

In order to solve the above problems, the present invention provides a coating drying oven in which an inlet of a tunnel-shaped oven communicates with an outlet of an air-supplied coating booth through a setting chamber. In the hot air leakage prevention device, the intake port of the exhaust hood for forcibly exhausting the hot air leaked from the inlet of the furnace by the variable speed fan is provided above the inlet side of the furnace in the setting chamber, and the inlet of the furnace is also provided. A furnace inlet side thermometer and a furnace outlet side thermometer for detecting the ambient temperature of the exhaust gas and the outlet, respectively, and an ambient temperature above the setting chamber and located on the outlet side of the air supply coating booth from the suction port of the exhaust hood. When the temperature difference between the detection temperature of the coating booth outlet side thermometer and the temperature detected by the furnace inlet side thermometer and the temperature detected by the furnace outlet side thermometer is within a certain value, the air volume of the variable speed fan is predicted. When a control signal for maintaining the set standard air volume is output and the detected temperature of the furnace outlet side thermometer becomes higher than the detected temperature of the furnace inlet side thermometer and the temperature difference exceeds a certain value, the above A control signal for increasing the air volume of the variable speed fan over the standard air volume is output. Conversely, the temperature detected by the furnace inlet side thermometer becomes higher than the temperature detected by the furnace outlet side thermometer, and the temperature difference exceeds a certain value. In this case, a control signal for reducing the air volume of the variable speed fan from the standard air volume is output, and when the temperature detected by the thermometer on the outlet side of the coating booth reaches a high temperature above a certain level, the above-mentioned control is possible regardless of the temperature difference. A control device for outputting a control signal for increasing the air volume of the variable speed fan is provided.

According to the present invention, the temperature difference between the ambient temperature at the inlet of the drying furnace detected by the thermometer on the inlet side and the ambient temperature at the outlet of the drying furnace detected by the thermometer on the outlet side is a constant value. When it is within the range, the supply / exhaust balance in the drying oven is kept almost even, and there is a steady state that is not affected by the disruption of the supply / exhaust balance in the air supply coating booth. The air volume of the variable speed fan forcibly exhausting from the inlet of the exhaust hood arranged above the setting chamber on the inlet side is maintained at a preset standard air volume.

When the air supply / exhaust balance in the air supply coating booth is disrupted and the inside becomes positive pressure, the conditioned air in the air supply coating booth leaks from its outlet to the setting chamber and from the inlet of the drying furnace. As cool air enters the furnace, hot air inside the furnace leaks from the outlet of the drying furnace, and the temperature detected by the furnace outlet side thermometer becomes higher than the temperature detected by the furnace inlet side thermometer, and the temperature difference is a constant value. When it exceeds, the air volume of the variable speed fan is increased from the standard air volume, the amount of cold air entering the furnace from the inlet of the drying furnace decreases, and the amount of hot air leaking from the outlet of the drying furnace also decreases. Decrease.

When the supply / exhaust balance in the air supply coating booth is disturbed and the inside becomes negative pressure, hot air in the oven leaks from the inlet of the drying oven to the setting chamber and at the outlet of the oven. When cold outside air enters, the temperature detected by the furnace inlet side thermometer becomes higher than the temperature detected by the furnace outlet side thermometer, and when the temperature difference exceeds a certain value, the air volume of the variable speed fan becomes the standard air volume. The amount of hot air sucked from the inlet of the drying furnace and leaking to the setting chamber due to the suction force of the fan is reduced, thereby reducing the amount of outside air entering the oven from the outlet of the drying furnace. .

In the unlikely event that the negative pressure in the air-supply coating booth is excessively high and the amount of hot air leaking from the inlet of the drying oven to the setting room does not decrease even if the air volume of the variable speed fan is reduced. , Part of the hot air flows through the suction port of the exhaust hood without passing through the suction port of the exhaust hood and flows to the outlet side of the air supply coating booth. When the temperature detected by the thermometer on the outlet side of the coating booth located on the outlet side reaches a high temperature above a certain level,
The air volume of the variable speed fan is turned to increase, and hot air is prevented from entering the paint booth with air supply.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a view showing an example of a hot air leak prevention device according to the present invention.

In the figure, reference numeral 1 is a coating booth with air supply for applying an overcoat to an automobile body or the like conveyed by a conveyor, and 2 is a coating film obtained by spontaneously evaporating an organic solvent from the coating film coated in the coating booth 1. A setting chamber 3 for adjusting the temperature is a tunnel-type coating drying oven for baking a coating film, and an inlet 4 thereof communicates with an outlet 5 of a supply booth 1 for supplying air through a setting chamber 2.

In the hot-air leakage prevention device of the present invention, the inlet 8 of the exhaust hood 7 for forcibly exhausting the hot air leaked from the inlet 4 of the drying furnace 3 by the variable speed fan 6 is the inlet of the drying furnace 3 of the setting chamber 2. It is arranged on the 4 side above,
Above the inlet 4 and the outlet 9 of the drying furnace 3, a furnace inlet side thermometer 10 and a furnace outlet side thermometer 11 for respectively detecting the ambient temperature of the inlet and the outlet are arranged, and the suction of the exhaust hood 7 A coating booth outlet-side thermometer 12 for detecting the ambient temperature above the interior of the setting chamber 2 located on the outlet 5 side of the air-supplied coating booth 1 from the mouth 8 is provided,
Further, a control device 13 for variably controlling the air volume of the variable speed fan 6 based on the temperature detection signals output from the thermometers 10, 11 and 12 is provided.
The variable speed fan 6 is configured so that the inverter 14 changes the rotation speed of a motor that rotationally drives the fan according to a control signal output from the control device 13.

Further, in the control device 13, the supply / exhaust balance in the drying furnace 3 is maintained substantially evenly, and the temperature detected by the furnace inlet side thermometer 10 and the temperature detected by the furnace outlet side thermometer 11 are substantially balanced. When the temperature difference is within a certain value (for example, 5 ° C. or less), a control signal for maintaining the air volume of the variable speed fan 6 at a preset standard air volume is output, and the exhaust hood 7 outputs more than necessary. Do not exhaust. In addition, the standard air volume is the harmful odor contained in the hot air leaked from the oven of the drying furnace 3 by the worker who entered the setting chamber 2 in a steady state in which the supply and exhaust balance in the drying oven 3 is kept substantially even. The air volume is set to reduce the exhaust gas concentration in the room to the extent that there is no risk of health damage due to the components.

In this state, the supply / exhaust balance is disturbed in the coating booth 1 with air supply such that the inside becomes a positive pressure, and the outlet 5 of the coating booth 1 enters the setting room 2 from 18 ° C. to 20 ° C. The conditioned air whose temperature has been adjusted to ℃ leaks out, the cold air in the setting chamber 2 enters the inlet 4 of the drying furnace 3, and at the same time, hot hot air leaks from the outlet 9 of the drying furnace 3, so that the furnace outlet side When the temperature detected by the thermometer 11 becomes higher than the temperature detected by the furnace inlet side thermometer 10 and the temperature difference exceeds a certain value, a control signal for increasing the air volume of the variable speed fan 6 from the standard air volume is output from the control device 13. Thus, invasion of cold air into the inlet 4 of the drying furnace 3 is suppressed, and thereby leakage of hot air from the outlet 9 of the drying furnace 3 is also suppressed.

Contrary to the above, the coating booth with air supply 1
The supply / exhaust balance is disturbed such that the inside becomes negative pressure, and hot air in the furnace leaks from the inlet 4 of the drying furnace 3, and at the same time, cool air in the coating factory is discharged to the outlet 9 of the drying furnace 3. If the temperature detected by the furnace inlet side thermometer 10 becomes higher than the temperature detected by the furnace outlet side thermometer 11 due to the intrusion and the temperature difference exceeds a certain value, the air volume of the variable speed fan 6 from the controller 13 becomes standard. A control signal for reducing the air volume is output, and the inlet 4 of the drying furnace 3 by the suction force of the variable speed fan 6 is output.
Leakage of hot air from the inside of the drying furnace 3 is suppressed, and thus cold air is prevented from entering the outlet 9 of the drying furnace 3.

At this time, hot air leakage from the inlet 4 of the drying furnace 3 cannot be suppressed by reducing the air volume of the variable speed fan 6 from the standard air volume to reduce the suction force of the fan. If negative pressure is strong, drying oven 3
There is a case where a part of the hot air leaked from the inlet 4 of the exhaust hood 7 does not get sucked into the inlet 8 of the exhaust hood 7 and flows through the inlet 8 directly toward the outlet 5 of the air-supplying coating booth 1, but in that case, The temperature detected by the coating booth outlet side thermometer 12 reaches a certain temperature or higher due to the high temperature of the hot air passing through the suction port 8, and the control device 13 detects the furnace inlet side thermometer 10 and the furnace outlet side thermometer 11. A control signal for increasing the air volume of the variable speed fan 6 to increase the suction force of the fan regardless of the temperature difference is output, and the hot air leaking from the inlet 4 of the drying furnace 3 is applied to the suction port 8 of the exhaust hood 7. Are sucked in, and the entry of hot air into the coating booth with air supply 1 is reliably prevented.

It should be noted that when the negative pressure in the air-supply coating booth is strong, the air volume of the variable speed fan 6 is increased and the fan 6 is increased.
If the suction power of the air is increased, the inflow of cold air from the outlet 9 of the drying furnace 3 is promoted. However, the hot air containing the harmful malodorous substance leaked from the inlet 4 of the drying furnace 3 enters the air supply coating booth 1. The degree of damage is small compared to the case where the clean atmosphere in the coating booth is polluted.

[0024]

According to the present invention, with respect to a coating drying furnace in which the entrance of a tunnel-shaped furnace communicates with the exit of an air-supplied coating booth through a setting chamber, the air supply in the air-supplied coating booth is improved. It is possible to reliably prevent hot air leaks and cold air intrusions caused by the imbalance of exhaust gas, especially the hot air leaked from the inlet of the drying furnace to be surely prevented from invading the air supply coating booth. There is an effect.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a hot air leak prevention device according to the present invention.

[Explanation of symbols]

 1 ... Air supply coating booth 2 ... Setting room 3 ... Coating drying oven 4 ... Paint drying oven inlet 5 ... Air supply coating booth outlet 6 ... Variable speed fan 7・ ・ ・ Exhaust hood 8 ・ ・ ・ Suction port of exhaust hood 9 ・ ・ ・ Drying furnace exit 10 ・ ・ ・ Furnace inlet side thermometer 11 ・ ・ ・ Furnace outlet side thermometer 12 ・ ・ ・ Painting booth outlet side Thermometer 13 ... Control device 14 ... Inverter

Claims (1)

[Claims] 1. A hot air leak prevention device for a coating drying furnace, wherein a tunnel-shaped inlet of a furnace communicates with an outlet of an air-supplied coating booth through a setting chamber, and leaks from an inlet (4) of the furnace. An inlet (8) of an exhaust hood (7) for forcibly exhausting hot air by a variable speed fan (6) is arranged above the setting chamber (2) on the inlet (4) side of the furnace, and The furnace inlet side thermometer (10) and the furnace outlet side thermometer (11) for detecting the ambient temperature of the inlet (4) and the outlet (9) respectively, and the intake port (8) of the exhaust hood (7) for supplying the gas. A coating booth outlet side thermometer (12) located on the outlet (5) side of the care coating booth (1) for detecting the ambient temperature above the interior of the setting chamber (2), and the furnace inlet side thermometer (10) ) And the temperature detected by the furnace outlet side thermometer (11) When degree difference is within a predetermined value and outputs a control signal to maintain a preset standard air volume air volume of the variable speed fan (6), wherein the furnace outlet side thermometer (11)
When the detected temperature of the variable temperature fan exceeds the detected temperature of the furnace inlet side thermometer (10) and the temperature difference exceeds a certain value, a control signal for increasing the air volume of the variable speed fan (6) above the standard air volume is output. On the contrary, when the temperature detected by the furnace inlet side thermometer (10) becomes higher than the temperature detected by the furnace outlet side thermometer (11) and the temperature difference exceeds a certain value, the variable speed fan (6 ) Output a control signal to reduce the air volume from the standard air volume, and when the temperature detected by the coating booth outlet side thermometer (12) reaches a high temperature above a certain level, the variable speed fan is irrespective of the temperature difference. A hot-air leakage prevention device for a coating drying oven, which is provided with a control device (13) for outputting a control signal for increasing the air volume of (6).