JPH0457385B2 - - Google Patents

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, and at the same time forcing air inside the paint booth by an exhaust fan. This invention relates to a supply painting booth configured to suck and discharge paint mist, evaporated organic solvent, etc. from under the floor.

[Prior art and its problems]

For example, a supply paint booth for car painting, which spray paints car bodies etc. that are continuously conveyed by a conveyor, is a long tunnel-shaped paint booth with entrances and exits at both ends. It is interposed between the pre-treatment device and the paint drying oven, and the clean conditioned air supplied to the plenum chamber by an air supply fan is forced into the painting booth and flows down the inside of the booth at a predetermined wind speed, and the booth Paint mist generated by spray painting the air inside,
Paint mist that is sucked and discharged under the floor with an exhaust fan along with evaporated organic solvents, etc., which adversely affects the paint film.
This prevents dust and other particles from flying up and maintains good coating quality, while also maintaining the health of workers preparing for coating or hand-spraying in the coating booth.

By the way, in such a painting booth,
If the intake air volume of the air supply fan and the exhaust volume of the exhaust fan are different, external air containing dust will flow into the painting booth from the entrances and exits opened at both ends of the painting booth, and the quality of the coating on the object to be coated will be affected. In addition, contaminated air containing paint mist, organic solvents, etc. inside the paint booth may leak out to the outside, worsening the surrounding environment of the paint pre-treatment equipment and paint drying ovens installed before and after the booth. Therefore, in the past, the supply air fan and the exhaust fan were arranged so that the amount of conditioned air supplied by the air supply fan and the amount of exhaust air sucked and discharged under the floor of the painting booth by the exhaust fan were the same. is driven at a preset constant rotation speed or blade angle.

However, in a painting booth with a supply air supply system that sucks the air inside the booth to below the floor, the object to be coated, such as a bicycle body, runs continuously over the floor surface, which has many slits that act as air suction ports. Therefore, when the amount of material to be coated is large, the suction port formed on the floor is covered with the material to be coated, reducing the amount of exhaust gas. The amount of air supply increases relatively, and the contaminated air inside the painting booth flows out from the entrance and exit.

In other words, if the rotational speed of the air supply fan and exhaust fan is set constant as in the past, the balance between the air supply amount and the exhaust amount will be disrupted due to an increase or decrease in the amount of material to be coated inside the painting booth. Air may flow in or out from the inlet/outlet.

Therefore, the present inventors detected the wind speed of air flowing into or out of the painting booth from the entrance and exit of the painting booth, and calculated the inflow or outflow amount of the air based on the wind speed. A supply paint booth that prevents air from flowing in and out from the entrance and exit of the paint booth by variably controlling the exhaust volume of the exhaust fan to balance the exhaust volume of the exhaust fan and the supply air volume of the air supply fan. devised a method for driving the vehicle (Patent Application No. 60-63962).

However, in the conventional general supply painting booth, the air from the entire area inside the long painting booth is sucked and exhausted by a single exhaust fan, and the exhaust capacity of the exhaust fan is very large. A new problem has arisen in that it is difficult to finely adjust the exhaust volume to prevent a small amount of air from flowing in and out from the inlet and outlet of the engine.

In other words, in a normal exhaust fan, the minimum change in displacement that can be finely adjusted is about 1% of the exhaust capacity, so it is natural that an exhaust fan with a large exhaust capacity can also finely adjust the displacement in the minimum change. If the size of the painting booth increases and the amount of air flowing in and out from the entrance/exit of the painting booth is extremely small, variable control of the exhaust volume of the exhaust fan may change the wind speed at the entrance/exit more than necessary. It has been found that the inflow and outflow of air cannot be effectively suppressed, and may even be encouraged.

[Purpose of the invention]

Therefore, the present invention provides a plurality of exhaust fans for sucking and discharging the air inside the painting booth, and selects a small exhaust capacity for each exhaust fan to finely adjust the exhaust volume. To provide a paint supply booth that can reliably prevent air from flowing in and out from an entrance and exit of the paint booth.

[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 solvents, etc. In the painting booth where the air supply air is sucked and discharged from under the floor together with the air supply, a plurality of the exhaust fans are arranged so that the sum of the exhaust capacity of each exhaust fan is equal to the air supply capacity of the air supply fans. At the same time, the exhaust volume of each of these exhaust fans is individually variably controlled according to the wind speed of the air flowing in or out from the entrances and exits opened at both ends of the painting booth. It is characterized by being designed to prevent inflow and outflow.

[Action of the invention]

According to the present invention, a plurality of exhaust fans for sucking and discharging air in the painting booth are arranged, and the exhaust capacity of each exhaust fan is set smaller than the conventional one, and the exhaust volume of each of these exhaust fans is set at the entrance and exit of the painting booth. Since it is configured to be individually variable controlled according to the wind speed of the air flowing in or out from the painting booth, even if a small amount of air flows in or out from the entrance and exit of the painting booth, some of the air will follow this and By varying the exhaust volume of the exhaust fan, the amount of exhaust air sucked and discharged from the entire area inside the painting booth can be fine-tuned in a much smaller range than before, and the inflow and outflow of air from the entrance and exit of the painting booth can be reliably suppressed. can.

〔Example〕

Hereinafter, the present invention will be explained based on specific embodiments shown in the drawings.

FIG. 1 is a flow sheet showing a paint supply booth according to the present invention, and FIG. 2 is a block diagram showing an example of its control device.

In the figure, reference numeral 1 denotes a tunnel-shaped paint booth for spray painting bicycle bodies 3, 3, etc., which are continuously conveyed by a floor conveyor 2, etc., and has an inlet and an outlet 4 and an outlet 5 opened at both ends. Each of them is connected to a paint pretreatment device located at the front stage of the painting booth 1 and a paint drying oven located at the rear stage (both not shown).

A plenum chamber 6 is disposed along the ceiling of the painting booth 1 , and conditioned air supplied into the plenum chamber 6 from an air conditioner 8 through an air supply duct 9 by an air supply fan 7 is passed through a filter 10 .
The wind blower is pushed into the coating booth 1 through the blower, and is made to flow down the inside of the booth 1 at a uniform wind speed of about 0.2 to 0.5 m/sec.

Also, inside the painting booth 1 is a painting preparation zone 1a,
It is divided into an automatic painting zone 1b, a setting zone 1c, a hand-sprayed painting zone 1d, etc., and there are mist processing chambers 12a to 12a under the floor surface 11 of each zone.
12d is provided.

Exhaust ducts 14, 14, .
After being sucked downward and separated and removed by gas-liquid contact in the mist processing chambers 12a to 12d, paint mist and the like are discharged to the outside through each exhaust duct 14.

Here, the total exhaust capacity of the exhaust fans 13a to 13d is selected to be comparable to the air supply capacity of the air supply fan 7, and when the air supply capacity of the air supply fan 7 is, for example, approximately 10000 m ³ /min. The exhaust capacity of each of the exhaust fans 13a to 13d is selected to be approximately 2500 m ³ /min.

In this embodiment, the mist processing chambers 12b and 12c provided in the center of the painting booth 1 are
Exhaust fans 13b and 13c that exhaust air inside
The mist processing chambers 12a and 12d are fixed at a predetermined rotation speed set at startup and are always operated with a constant displacement, and are provided on the entrance/exit side of the coating booth 1.
Exhaust fans 13a and 13d that exhaust air inside
Only the displacement amount is variably controlled according to the wind speed at the entrances and exits 4 and 5.

15F and 15R are wind speed sensors that detect the wind speed of air flowing in or out from the inlet 4 and the outlet 5, respectively. For example, when the air is flowing out, the wind speed detection signal is positive, and when the air is flowing in, the wind speed detection signal is negative. is output to the control device 16.

This control device 16 includes samplers 17F and 17R that sample the wind speed detection signals output from the wind speed sensors 15F and 15R at a predetermined period (for example, 0.2 seconds), and digital filters 18F and 18R that have a first-order lag type transfer function. , the signal from the wind speed sensor 15F output from the digital filters 18F and 18R, and the wind speed sensor 15R.
a weighted average processing unit 19 that combines the signals from the
A moving average processing section 20 that performs moving average processing on the output signal of the processing section 19 to determine the wind speed at that point.
and a regulator 21 that performs a predetermined PID calculation based on the output of the processing section 20, and the operation signal output from the regulator 21 is used to control the exhaust fans 13a and 1.
The output signal is outputted to inverters 22 and 23 that variably control the rotation speed of 3d.

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

As shown in FIG. 3a, for example, the wind speed detection signals output from the wind speed sensors 15F and 15R change so as to gradually become smaller as a whole, and a first disturbance wave of about 20 cycl/min occurs.
If a second disturbance wave of about 4 cycl/min is included, the detection signal is first sent to the sampler 17F, 1
The third sampled by 7R at a 0.2 second period
As shown in Figure b, this becomes a digital signal expressed as a pulse train.

Next, when this digital signal is input to the digital filters 18F and 18R, since the digital filters 18F and 18R have a first-order lag type transfer function, their output is as shown in FIG.
The first disturbance wave of 20 cycl/min is removed, and the amplitude is suppressed to a certain extent, resulting in a smoothed signal.

And the digital filters 18F and 18R
The two detection signals that have been shaped are combined into one by a weighted average processing section 19, and then input to a moving average processing section 20 where moving average processing is performed.

Here, the moving average processing is a processing method in which the average value of the values of n input signals sampled at a cycle T/(n-1) within a predetermined moving average time T is the wind speed at that time.

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

That is, if the input signal sampled by the moving average processing unit 20 is Hi, the wind speed V is expressed as V=[ ₁₆ 〓 ⁱ⁼¹ .

Note that since signals are input to the moving average processing section 20 at a cycle of 0.2 seconds, each time a new signal is input, the moving average process is performed and the value is output as the wind speed (FIG. 4).

In this way, since moving average processing calculates the average within a moving average time (for example, 90 seconds) that is sufficiently long compared to the sampling period (0.2 seconds) of the detection signal, caused by fluctuations and turbulence in the airflow.
The signal is shaped into a signal with the second disturbance wave of 4 cycl/min removed (see the lower part of Figure 4).

Next, the digital filters 18F, 18R
A signal from which the first and second disturbance waves caused by fluctuations and turbulence of the airflow have been removed by the moving average processing unit 20 is input to the regulator 21.
PID calculation is performed.

Here, an operation signal is generated using a PID calculation and a three-action controller having proportional action P, integral action D, and differential action I, using the deviation between the measured value and the target value as input, and the detected wind speed. Since it is sufficient to control the wind speed V to be "0", the target value becomes "0" and the detected wind speed V is used as it is as the deviation.

In addition, since differential operation is generally not required in flow rate control, the output M of the regulator 21 in the PID calculation of digital signals as in this embodiment is
If the previous output is MI, the current input (deviation) is E, the previous input is EI, the proportional gain is K, the sampling period is t, and the integration time is Ti, then M=M1+dM=M1+K[E-E1+(t/ Ti) E〕
This will be required.

Then, the output M obtained in this way is output as an operation signal, and the output M is outputted as an operation signal to the exhaust fans 13a and 13d.
The engine speed is increased or decreased and the displacement is variably controlled. For example, when the air is flowing out and the wind speed value is gradually increasing, E>0, E-E1>
0, so dM > 0, and the operation signal becomes larger than the previous output, increasing the displacement. Conversely, when it is in an inflow state and the absolute value of the wind speed is gradually increasing, E < 0, E-E1 < 0. Therefore, dM<0, the operation signal becomes smaller than the previous output, and the displacement is reduced.

In this case, exhaust fans 13a and 13
The exhaust capacity of each of d is about 1/4 of the exhaust capacity of a conventional exhaust fan, and even with two fans it is about 1/2, so the minimum change in the exhaust volume that can be increased or decreased is, for example, 1% of the exhaust capacity.
If this is the case, the total exhaust volume from the entire area inside the painting booth 1 can be finely adjusted by a change range of 1/2 of the conventional amount, that is, 0.5% of the total exhaust capacity, so the amount of exhaust gas from the inlet 4 and outlet 5 can be adjusted by a very small amount. The exhaust amount can be varied in accordance with the inflow and outflow of air, and the inflow and outflow of air from the entrances and exits 4 and 5 can be reliably suppressed.

The above is an example of the configuration of the supply coating booth according to the present invention, and its operation will be explained next.

First, the supply air fan 7 and the exhaust fans 13a to 13
d at a predetermined rotational speed, approximately 9000 m ² /
min conditioned air is supplied and flowed down through the filter 10 into each zone 1a to 1d at a wind speed of about 0.5 m/sec, and the exhaust fans 13a to 1d
At 13d, operation is started by discharging air in an amount comparable to the air supply amount of the conditioned air outside the painting booth 1, and at the same time, the wind speed of the air flow at the entrances and exits 4 and 5 is detected by the wind speed sensors 15 and 15R. do.

When the car bodies 3 are continuously conveyed inside the painting booth 1 by the floor conveyor 2, the floor surface 11 that sucks the air inside the painting booth 1 is covered with the car bodies 3, 3... Exhaust fan 13a
The load of ~13d increases, the exhaust volume decreases relatively, and the air inside the coating booth 1 flows out through the inlet 4 and outlet 5.

At this time, positive detection signals from the wind speed sensors 15F and 15R are input to the control device 16, processed by the digital filters 18F and 18R and the moving average processing section 20, and then input to the regulator 21 for PID calculation. The controller 21 outputs an operation signal to the inverters 22 and 23 to increase the rotational speed of the exhaust fans 13a and 13d.

When the rotational speed of these exhaust fans 13a and 13d increases, the amount of exhaust gas discharged from the painting booth 1 through the exhaust duct 14 increases and becomes equal to the amount of air supplied from the air supply fan 7, so that the amount of air inside the painting booth 1 increases. is maintained in a state where there is substantially no air exchange with the outside via the inlet 4 and outlet 5.

In addition, since the sum of the exhaust capacities of the exhaust fans 13a and 13d is approximately 1/2 of the exhaust capacity of conventional exhaust fans, the minimum amount of change that can be used to finely adjust the exhaust volume is also 1/2 of that of the conventional exhaust fan. Even if the amount of air flowing out from 4 and 5 is very small, the total amount of exhaust air from inside the painting booth 1 can be appropriately varied accordingly, and air outflow can be reliably suppressed.

Conversely, if the number of automobile bodies 3 to be transported in this state decreases, the area covered by the automobile bodies 3 on the floor surface 11 decreases, and the exhaust fans 13a to
Since the load on 13d decreases, the exhaust volume increases relatively, and 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 control device 16
An operation signal is output from the inverter 22 and 23 to the inverters 22 and 23, and the displacement of the exhaust fans 13a and 13d is reduced so that the displacement of all the exhaust fans 13a to 13d becomes equal to the intake air amount of the air supply fan 7. regulated to prevent inflow of external air.

In this way, the amount of discharged contaminated air is automatically adjusted so that outside air containing dust and the like does not flow into the coating gauge 1, and the contaminated air does not flow out to the outside.

Note that in the above embodiment, the detection signals of the wind speed sensors 15F and 15R are combined, and the exhaust fan 13a
Although a case has been described in which the exhaust volume of the airflow fans 13d and 13d is variably controlled, the present invention is not limited thereto. The exhaust fan 13d may be controlled by the detection signal of the exhaust fan 15R.

Further, as a control means in the regulator 21,
The control is not limited to PID calculation control, but may be one that calculates the inflow or outflow amount of air from the wind speed, and increases or decreases the exhaust amount according to the flow rate or outflow amount.

Furthermore, the means for controlling the exhaust volume is not limited to controlling the rotational speed of the exhaust fan, but may also be a means for separately disposing an air volume adjusting damper in the exhaust duct and adjusting the opening/closing angle of the damper.

〔Effect of the invention〕

As described above, according to the present invention, a plurality of exhaust fans are arranged, each exhaust fan is selected to have a small exhaust capacity, and the exhaust volume of some of the exhaust fans is increased or decreased in small increments. It has the excellent effect of being able to finely adjust the total exhaust volume of the paint booth, and can reliably suppress the inflow and outflow of air by following minute changes in the wind speed of air flowing in and out from the entrance and exit of the painting booth. can.

[Brief explanation of drawings]

Fig. 1 is a flow sheet showing a supply coating booth according to the present invention, Fig. 2 is a block diagram showing an example of its control device, and Figs. 3 and 4 show examples of signal waveforms at each point of the control device. FIG. Explanation of symbols, 1...Painting booth, 3...Automobile body, 4...Inlet, 5...Exit, 6...Plenum chamber, 7...Air supply fan, 10...Filter, 11...Floor surface, 12a ~12d...Mist processing chamber, 13a-13d...Exhaust fan, 14...
Exhaust duct, 15F, 15R...Wind speed sensor, 1
6...control device.

Claims (1)

[Claims] 1. Conditioned air supplied to the plenum chamber by an air supply fan is forced into the tunnel-shaped paint booth, and the air inside the paint booth is sucked out from under the floor along with paint mist, evaporated organic solvents, etc. by an exhaust fan. In the supply painting booth configured as above, a plurality of exhaust fans are arranged, and the total exhaust capacity of each exhaust fan is selected so as to be comparable to the air intake capacity of the air supply fan, and each of these exhaust fans is The exhaust volume of the fan is individually variably controlled according to the wind speed of air flowing in or out from the entrances and exits opened at both ends of the painting booth, so as to suppress the inflow and outflow of air from the entrances and exits. A painting booth with a refill.