JPS62152568A - Method for operating painting booth with air supply mechanism - Google Patents

Abstract

PURPOSE:To suppress the inflow and outflow of air at an entrance and exit, by a method wherein effect due to a disturbance wave is removed from a wind velocity detection signal and the inflow and outflow state of air from the entrance and exit of a painting booth is accurately detected to variably control the exhaust amount of an exhaust fan. CONSTITUTION:Wind velocities at the exit 5 and/or entrance 4 opened at both ends of a tunnel shaped painting booth 1 are measured by wind velocity sensors 15R, 15F. The detection signal from each sensor is sampled, for example, at a cycle of 0.2sec to receive first averaging processing and a first disturbance wave is removed from said signal. The signal subjected to first averaging processing is sampled, for example, at a cycle of 6sec to receive second moving averaging processing and a second disturbance wave caused by the feed in and out of a car body is removed from said signal. The wind directions and wind velocities at the entrance and exit 5, 4 are discriminated by the obtained signal and the number of rotations of an exhaust fan 11 are increased and decreased so as to set said wind velocities to an objective value 0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to forcing conditioned air supplied to a plenum chamber by an air supply fan into a tunnel-shaped paint booth through a filter at a predetermined wind speed, and This invention relates to a method of operating a painting booth with a supply air supply system in which the air inside the booth is sucked and discharged under the floor together with paint mist, evaporated organic solvent, etc. by an exhaust fan.

[Prior art and its problems]

For example, in a relatively large supply paint booth that paints automobile bodies that are continuously transported by a conveyor, conditioned air supplied to a plenum chamber by an air supply fan is connected between a paint pretreatment device and a paint drying oven. The air inside the paint booth is sucked and discharged under the floor together with paint mist, evaporated organic solvents, etc. by an exhaust fan, and paint mist and evaporated organic solvents that have a negative impact on the paint film are removed. This prevents dust and other particles from flying up to maintain good coating quality, and also maintains the health of workers preparing for coating or hand-spraying in the coating booth.

By the way, in such a painting booth, if the air intake amount of the supply fan and the exhaust amount of the exhaust fan are different, external air containing dust etc. may enter the painting booth from the entrances and exits opened at both ends of the booth. The paint quality of the car body may be damaged by the inflow, or the contaminated air containing paint mist, organic solvents, etc. inside the paint booth may flow out to the outside, causing paint pre-treatment equipment and paint drying ovens installed before and after the paint booth. Conventionally, the amount of conditioned air supplied by the air supply fan and the amount of exhaust air sucked and discharged to the bottom of the paint booth by the exhaust fan were made to be the same amount. The air supply fan and the exhaust fan are driven at a preset constant rotation speed or blade angle.

However, the supply paint booth is designed to suck the air inside the paint booth below the floor, and the car body is continuously conveyed over the floor, which has many slits that serve as air suction ports. Therefore, when a large number of car bodies are transported, the suction port formed on the suction floor is covered by the car body, reducing the exhaust volume and increasing the relative intake air volume. The contaminated air inside the paint booth will flow out from the entrance and exit.

In other words, when the rotation speed or blade angle of the air supply fan and exhaust fan is set constant in advance as in the past, the amount of air supply changes depending on the number of objects to be painted, such as automobile bodies, conveyed in the painting booth. The balance of exhaust volume may be disrupted and air may flow in or out from the entrance and exit of the painting booth.

Therefore, the inventors of the present invention have developed a method to detect the wind speed of air flowing in or out from the entrance/exit of a painting booth, and to variably control the exhaust volume of the exhaust fan according to the amount of air flowing in or out of the air, which is calculated based on the wind speed. devised a method of operating a supply paint booth that balances the exhaust volume of the exhaust fan and the supply air volume of the supply fan to prevent air from entering and exiting from the entrance and exit of the paint booth. -63962).

According to this operating method, even if air does not flow in or out from the entrance and exit of the coating booth due to an increase or decrease in the number of objects to be conveyed and the balance between the supply air volume and the exhaust volume is disrupted, the exhaust fan will be activated according to the wind speed. The amount of exhaust gas is increased or decreased, and the inflow and outflow of the air is prevented.

However, subsequent experiments have shown that at the entrance and exit of the painting booth, fluctuations and turbulence of air flow occur due to the influence of outside air and the ratio of the objects to be coated, and in some cases, eddy currents may occur. was found to fluctuate irregularly.

In other words, when the wind speed at an entrance/exit is continuously measured with a wind speed sensor, the measurement signal may include the characteristics of the wind speed sensor itself or the turbulence of the air flow caused by the air flow coming into contact with the wind speed sensor1. It includes a first disturbance wave with a period of ~4 seconds and a 20th disturbance wave with a period of 10 to 30 seconds, which is thought to be caused by loading and unloading of the object to be coated, etc. Alternatively, if a gust of wind temporarily flows in or out from the entrance/exit of the coating booth, the measurement signal will fluctuate rapidly.

This means that, for example, if the wind speed on the outflow side is detected as positive and the wind speed on the inflow side is detected as negative, the wind speed value will not only change due to turbulence in the airflow (or even change the wind direction to the positive side). The signal that was fluctuating in the negative direction may momentarily shift to the negative side.

In this case, the exhaust amount of the exhaust fan will not only follow changes in the wind speed of the air flowing in or out from the entrance/exit due to the imbalance between the supply air amount and the exhaust amount in the painting booth, but also follow changes in the wind speed due to external disturbances. The amount of air is increased and decreased regularly and frequently, and instead of preventing the inflow and outflow of air from the entrance and exit of the painting booth, there is a risk that this will be encouraged.

[Purpose of the invention]

Therefore, the present invention is designed to prevent irregular changes in the wind speed detection signal of the wind speed sensor due to fluctuations or turbulence in the air flow at the entrance/exit of the painting booth, or when gusts of wind momentarily or temporarily enter or exit from the entrance/exit. Even if there is a sudden change in the wind speed detection signal from the sensor, or if the wind speed detection signal from the wind speed sensor contains pulsations, the flow from the entrance/exit of the painting booth is not affected by these fluctuations. It is an object of the present invention to provide a method of operating a paint booth for air supply, which can accurately detect the state of air inflow or outflow, variably control the exhaust amount of an exhaust fan, and reliably prevent air inflow or outflow at the entrance/exit. .

[Structure of the invention]

To achieve this objective, the present invention forces the conditioned air supplied to the plenum chamber by an air supply fan into a tunnel-shaped paint booth, and the air inside the paint booth is removed by an exhaust fan to remove paint mist, evaporated organic matter, etc. In a method of operating a supply painting booth in which air is sucked and discharged under the floor together with solvent, etc., a wind speed sensor detects the wind speed of air flowing in or out from an outlet and/or an inlet opened at both ends of the painting booth. Then, the wind speed detection signal is sampled at a fixed sampling period and subjected to first averaging processing, and the signal subjected to this first averaging processing is further sampled at a fixed sampling period and subjected to second averaging processing. , the wind direction at the outlet and/or the inlet is determined based on the second averaged signal, and at the same time the wind speed is measured, and the exhaust volume of the exhaust fan is variably controlled according to the wind direction and wind speed, so that the air flow from the inlet to the outlet is determined. It is characterized by suppressing the inflow and outflow of air.

[Action of the invention]

According to the method of the present invention, the first disturbance wave having a period of 1 to 4 seconds, which is considered to be caused by the characteristics of the wind speed sensor itself, is added to the wind speed detection signal detected at the exit and/or entrance of the coating booth. If disturbance waves having a period of 10 to 30 seconds are included, which are thought to be caused by the loading and unloading of painted car bodies, etc., or if rapid fluctuations due to gusts of wind during FF4 are included. Even if the wind speed detection signal is sampled at a constant sampling period and subjected to the first averaging process, the influence of the disturbance wave 10 is eliminated, and then the averaged signal is By sampling at the sampling period and performing the second averaging process, the influence of the 20th disturbance wave is eliminated, so the direction of the air at the entrance and exit of the painting booth can be reliably determined without being affected by the disturbance wave. At the same time, the wind speed can be accurately measured, and the exhaust amount of the exhaust fan can be variably controlled accordingly to reliably prevent the inflow and outflow of air from the entrance and exit of the painting booth.

〔Example〕

Hereinafter, the present invention will be specifically described based on embodiments shown in the drawings.

FIG. 1 is a flow sheet showing an example of a supply coating booth using the method of the present invention, and FIG. 2 is a diagram showing an example of its control means.

In the figure, ■ indicates an automobile body 3. :3- A tunnel-shaped painting booth for spray painting, with an inlet 4 and an outlet 5 opened at both ends communicating with the coating pre-treatment device at the front stage of the painting booth 1 and the drying oven at the rear stage, respectively. has been done.

A plenum chamber 6 is arranged along the ceiling of the painting booth 1, and conditioned air supplied from an air conditioner 8 to the plenum chamber 6 through an air supply duct 9 by an air supply fan 7 passes through a filter 10 to the painting booth. 1.

The conditioned air pushed into the painting booth 1 is
The paint mist generated in the painting booth 1 is blown down at a uniform wind speed of about 0.2 to 0.5 m/sec, and the paint mist generated in the painting booth 1 is evaporated together with organic solvents, etc. by the exhaust fan 1) into the mist treatment chamber below the floor 12. 13, and after the paint mist is separated and removed by gas-liquid contact within the mist processing chamber 13, it is discharged to the outside through an exhaust duct 14.

In addition, the entrance 4 and the exit 5 of the painting booth 1 are
Wind speed sensors 15F and 15R are arranged to detect the wind speed of the air flowing in or out from the wind speed sensors 15F and 15R. has been completed.

The control device 16 receives the detection signals output from the wind speed sensors 15F and 15R at a predetermined sampling period (for example, 0.
samplers 17F and 17R that sample at 2 seconds); and a digital filter 18 having a -order lag transfer function.
R and 18F, and the digital filters 18R and 18F
A weighted average processing unit 19 performs a weighted average of the signals from the entrance 4 side and the signals from the five exits outputted from the inlet 4, and the output signal of the processing unit 19 is sampled at a predetermined sampling period (for example, 6 seconds) and subjected to moving average processing. It consists of a moving average processing unit 20 that determines the wind speed at that point in time, and a regulator 21 that performs a predetermined PID calculation based on the output of the processing unit 20. An operation signal is output to an inverter 23 that controls the engine 22 to increase or decrease the displacement.

3 and 4 are explanatory diagrams showing examples of signal waveforms at each point of the control device 16.

The detection signal output from the wind speed sensor 15F (15R) gradually decreases as a whole as shown in FIG. When the wind speed detection signal includes a disturbance wave of approximately 4 cycles/min and a second disturbance wave of approximately 4 cycles/min, the wind speed detection signal is first sampled at a period of 0.2 seconds by the sampler 17F (17R), and then This results in a digital signal represented by a pulse train as shown in Figure (b).

Next, this digital signal is passed through the digital filter 18F (
18R), the digital filter 18F(
18R) has a transfer function 1/(1+Ts) of a -order lag system, so its output is 20 as shown in Figure 3 (C1).
The first disturbance wave of cycle/min is removed and the amplitude is slightly suppressed, resulting in a smoothed signal.

Thereafter, the two detection signals from the wind speed sensors 15F and 15R are weighted averaged in a weighted average processing section 19 and combined into one signal, and then input to a moving average processing section 20 where moving average processing is performed. Ru.

Here, the moving average processing is a processing method in which the average value of the values of n input signals sampled at a period T/(n-1) within a predetermined moving average time T is the wind speed at that point, This is done in order to eliminate shadows 8 when the airflow in the painting booth 1 is swayed or disturbed.

Now, if the moving average time T is 90 seconds and the sampling period in the moving average processing section 20 is 6 seconds, the number of sampled signals is n-90/6+1=16, and as shown in FIG. 4, the sampling period is 6 seconds. The wind speed is determined by the average value of the values of the 16 input signals sampled.

That is, assuming that the input signal sampled by the moving average processing unit 20 is Hi and the calculated wind speed is ■, it is expressed as follows.

Note that since signals are input to the moving average processing section 20 at a period of 0.2 seconds, each time there is a new input, the moving average processing is performed and the resulting value is output (see FIG. 4).

In this way, the moving average process uses a moving average time that is sufficiently long (for example, 90 seconds) compared to the sampling period (6 seconds) of the detection signal.
Since the average within seconds) is calculated, the output signal of the moving average processing section 20 is averaged even if there are fluctuations in the airflow due to disturbances or turbulence that could not be removed by the digital filters 18F and 18R. /min
The signal becomes a signal from which the disturbance wave No. 20 has been removed, and the displacement is prevented from increasing or decreasing due to the influence of the wave (No. 5
(See figure below).

Next, the signal from which the 10th disturbance wave and the second disturbance wave have been removed by the digital filters 18F, 18R and the moving average processing section 20 is input to the regulator 21 and subjected to PID calculation processing.

Here, PrD calculation processing is a process in which the deviation between the measured value and the target value is input, and an operation signal is generated using a three-action controller with proportional action P, integral action, and differential action (■).
In the present invention, since it is sufficient to control the detected wind speed V to become O, the target value becomes O and the detected wind speed V
is used as is as the deviation.

Also, since differential operation is generally not required in flow rate control, the PTD of digital signals? The output M of the regulator 21 in the J calculation is the previous output as Ml, the current input (deviation) as E, and the previous input as El.

Let the proportional gain be, the period of the input signal be t, and the integration time be Ti.
Then, M=M1 +dM =M1 +K (E-El + (t/Ti) E)
This will be required.

Then, the output M obtained in this way is outputted to the inverter 23 as an operation signal, and the rotation speed of the exhaust fan 1) is increased or decreased to variably control the exhaust volume.For example, when air is flowing out and the wind speed value gradually changes When it is getting bigger, F,
>O, E−El >O, so dM>O is guaranteed,
The operation signal also becomes larger than the previous output and the displacement is increased, and conversely, when it is in an inflow state and the absolute value of the wind speed is gradually increasing, E<O, E-El<O, so dM< 0, the operation signal becomes smaller than the previous output, and the displacement is reduced.

The above is an example of the configuration of a supply coating booth using the method of the present invention, and the operating method thereof will now be described.

First, the motor 22 of the exhaust fan 1) and the motor 24 of the air supply fan 7 are set to predetermined rotational speeds and started, and the air supply fan 7 is moved from the air supply fan 7 into a painting booth l having a width of, for example, 6 m, with a rotation speed of approximately 7.5 m per 50 m in length. 200rr? / min of conditioned air is supplied and the same amount of air is discharged outside the painting booth 1 by the exhaust fan 1.
Detected by 5F and 15R.

When the car body 3.3- is continuously conveyed into the paint booth 1 by the floor conditioner 2, the floor surface 12 that sucks the air inside the paint booth 1 is covered with the car body 3.3-. As a result, the load on the exhaust fan 1) increases and the exhaust volume decreases relatively, causing the air inside the coating booth 1 to flow out through the inlet 4 and outlet 5.

At this time, the wind speed sensors 15F and 1 at the inlet 4 and outlet 5
A positive detection signal is outputted from 5R to the control device I6, sampled by samplers 17F and 17R at a 0.2 second period, and subjected to signal processing by digital filters 18F and 18R1, weighted average processing section 19 and moving average processing section 20. After the current wind speed is determined every 2 seconds, the wind speed is input to the controller 21, a predetermined PID calculation is performed, and an operation signal is output to the inverter 23 to rotate the motor 22 of the exhaust fan 1). The number will be raised.

When the rotational speed of the motor 22 that drives the exhaust fan 1) is increased, the amount of exhaust gas discharged from the painting booth 1 through the exhaust duct 14 increases and becomes equal to the supply air 9 from the supply air fan. Thus, the coating booth 1 is maintained in a state of equilibrium with substantially no air exchange with the outside via the inlet and outlet 5.

Conversely, if the number of conveyed car bodies 3 decreases in this state, the area of the floor 12 covered by the car bodies 3 decreases, and the load on the exhaust fan 1) decreases, which in turn reduces the displacement. A relatively increased amount of external air flows into the coating booth 1 from the inlet 4 and the outlet 5.

At this time, negative detection signals are output from the wind speed sensors 15F and 15R, and the signals are similarly processed and an operation signal is output to the inverter 23 to reduce the rotation speed of the motor 22.

Then, when the rotational speed of the motor 22 is reduced, the amount of exhaust gas discharged from the inside of the painting booth 1 to the outside via the exhaust duct 14 decreases and becomes equal to the amount of air supply, thereby suppressing the inflow of outside air.

In addition, in the embodiment, the PI is used as a control means for obtaining the operation signal.
Although the case where the D-control regulator 21 is used has been described, the present invention is not limited to this. For example, the inflow or outflow amount of air is calculated based on the determined wind speed, and the exhaust The exhaust air 9 of the fan may be variably controlled.

In addition, the means for variably controlling the exhaust amount is not limited to controlling the rotation speed of the motor 22 of the exhaust fan 1), but may also include, for example, disposing a damper separately in the exhaust duct 14 and adjusting the opening/closing angle of the damper. You can do it like this.

Further, in the embodiment, a case has been described in which the wind speed sensors 15R and 15F are arranged at the outlet 5 and the inlet 4 of the painting booth 1, respectively, but in the method of the present invention, the wind speed sensor is arranged at either the outlet 5 or the inlet 4. This may be the case.

〔Effect of the invention〕

As described above, according to the present invention, the wind speed at the exit and/or entrance opened at both ends of a tunnel-shaped painting booth is measured by a wind speed sensor, and the wind speed detection signal from the sensor is measured at a fixed sampling period. Since the wind speed detection signal includes 10 disturbance waves with a period of 1 to 4 seconds due to the characteristics of the wind speed sensor itself, , the influence of the waves can be completely removed, and the signal that has been subjected to the first averaging process is sampled at a fixed sampling period and subjected to the second averaging process, so wind speed detection is possible. l caused by the loading and unloading of car bodies at traffic lights, etc.
Of course, it is completely unaffected by fluctuations and turbulence in the air that occur momentarily or temporarily in the coating booth 1, as well as when a second disturbance wave with a period of 30 seconds is included. By accurately determining the inflow or outflow direction of air from the entrance/exit of the painting booth at that time, and accurately measuring the wind speed, the exhaust volume of the exhaust fan is variably controlled according to the condition. This has a particularly excellent effect of reliably suppressing the inflow and outflow of air.

[Brief explanation of drawings]

Fig. 1 is a flow sheet showing an example of a supply painting booth using the method of the present invention, Fig. 2 is a block diagram showing an example of its control device, and Figs. 3 and 4 show each point of the control device. FIG. 2 is an explanatory diagram showing an example of a signal waveform. Explanation of symbols 1-painting booth, 3-car body, 4-population, 5-・
- outlet, 6 - plenum chamber, 7 - supply air 7 am, 1
) -- Exhaust fan, 15F, 15R-Wind speed sensor, 1
6-control device, 18R, 18F---digital filter having a first-order lag system transfer function, 20-moving average processing unit, 22.24-motor. Patent applicant Trinity Industries Co., Ltd. Toyota Motor Corporation Deshiro Engineering Service Co., Ltd.

Claims (7)

[Claims] (1) The air supply fan forces the conditioned air supplied to the plenum chamber into the tunnel-shaped painting booth, and the exhaust fan sucks and discharges the air inside the painting booth to the floor below along with paint mist, evaporated organic solvents, etc. In the method of operating a supply coating booth, a wind speed sensor detects the wind speed of air flowing in or out from an outlet and/or an inlet opened at both ends of the coating booth, and the wind speed detection signal is adjusted to a certain level. The signal is sampled at a sampling period and subjected to first averaging processing, and the signal subjected to this first averaging processing is further sampled at a constant sampling period and subjected to second averaging processing, and this second averaging processing is performed. The wind direction at the outlet and/or the inlet is determined based on the signal, and at the same time the wind speed is measured, and the exhaust volume of the exhaust fan is variably controlled according to the wind direction and wind speed to suppress the inflow and outflow of air from the inlet and outlet. A method of operating a supply coating booth, characterized in that: (2) The method of operating a pre-filling paint booth according to claim 1, wherein the sampling period of the first averaging process is 2 seconds or less. (3) The sampling period of the second averaging process is 15
A method of operating a paint booth for supplying air supply according to claim 1, wherein the charging time is less than seconds. (4) The supply coating booth according to any one of claims 1 to 3, wherein the first averaging process is performed by a digital filter having a temporary delay type transfer function. (5) The method of operating a supply coating booth according to any one of claims 1 to 3, wherein the first averaging process is performed by a moving average process having a moving average time of 2 to 30 seconds. (6) The method of operating a supply coating booth according to any one of claims 1 to 5, wherein the second averaging process is performed by a moving average process having a moving average time of 10 to 180 seconds. (7) The above-mentioned claim, wherein the moving average processing is defined as the average value of the values of n input signals sampled at a period T/(n-1) within an average averaging time T defined by the following formula: Scope: How to operate the supply coating booth described in item 1. V=[Σ^n_i_=_1Hi]/n V: Signal obtained by moving average processing Hi: Sampled input signal