JPH0324265B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to forcing air 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 paint booth with a supply system in which the air inside the booth is suctioned 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 conveyed by a conveyor, conditioned air supplied to the plenum chamber by an air supply fan is used 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. using an exhaust fan, and the paint mist that has a negative impact on the paint film is removed. In addition to maintaining good coating quality by preventing dust and dirt from flying up, the system also aims to maintain the health of workers preparing for coating or hand-spraying in the coating booth.

By the way, when it comes to this kind of paint 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 paint booth from the entrances and exits opened at both ends of the booth, impairing the quality of car body painting. In addition, the contaminated air containing paint mist, organic solvents, etc. inside the painting booth will flow out to the outside, worsening the environment around the painting pre-treatment equipment and paint drying oven installed before and after the booth. Conventionally, the air supply fan and the exhaust air are arranged so that the amount of conditioned air supplied by the air supply fan and the amount of exhaust air sucked and discharged to the underfloor of the painting booth by the exhaust fan are the same. The fan is driven at a preset constant rotation speed or blade angle.

However, the paint supply booth, which is designed to suck the air inside the paint booth below the floor, is designed to be continuously conveyed to the car body or the like over the floor, which has a number of advantages that serve as air suction ports. Therefore, when a large number of car bodies are transported, the suction port formed in the suction floor is covered so that the car body is blocked, 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 rotational 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 coated, 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 present inventors have developed a method to detect the wind speed of air flowing in or out from the entrance/exit of the 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 calculated from the wind speed. devised a method for operating a supply paint booth that balances the exhaust volume of the exhaust fan and the supply air volume of the supply air fan to prevent air from entering and exiting from the entrance and exit of the paint booth. -Refer to No. 63962).

According to this operating method, even if the balance between the supply air amount and the exhaust amount is disrupted due to an increase or decrease in the number of objects to be transported, and air does not flow in or out from the entrance and exit of the coating booth,
The exhaust amount of the exhaust fan is increased or decreased depending on the wind speed, 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 occur in the airflow due to the influence of outside air and the loading and unloading of objects to be coated, and in some cases, vortices can occur. It was found that the detected wind speed fluctuated irregularly.

In other words, when the wind speed at the entrance and exit is continuously measured using a wind speed sensor, there may be some differences in the measurement signal due to the characteristics of the wind speed sensor itself or turbulence in the airflow caused by the airflow coming into contact with the wind speed sensor. The first disturbance wave has a period of 1 to 4 seconds, and the second disturbance wave has a period of 10 to 30 seconds, which is thought to be caused by loading and unloading of the object to be coated. If a gust of wind momentarily or temporarily flows in or out from the entrance/exit of the coating booth, the measurement signal will also fluctuate rapidly.

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, not only will the wind speed value change due to turbulence in the airflow, but the wind direction will also change and become positive. A fluctuating signal may momentarily shift to the negative side.

In this case, the exhaust volume of the exhaust fan not only follows changes in the wind speed of air flowing in or out from the entrance/exit due to the imbalance between the supply air volume and the exhaust volume in the painting booth, but also follows changes in wind speed due to external disturbances. This increases or decreases irregularly and frequently, and rather than inhibiting 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 disturbances in the air flow at the entrance/exit of the painting booth, or when gusts of wind momentarily or temporarily flow in or out from the entrance/exit. Even if there is a sudden change in the wind speed detection signal from the wind speed sensor, or if the wind speed detection signal from the wind speed sensor contains pulsations, it can be easily detected from the entrance/exit of the painting booth without being affected by these fluctuations. An object of the present invention is to provide a method of operating a paint booth for supply and air supply that can accurately detect the inflow or outflow state of air and variably control the exhaust amount of an exhaust fan to reliably prevent air inflow or outflow at the entrance/exit. do.

[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 pumped into the paint mist by an exhaust fan. In a method of operating a supply coating booth in which air supply is sucked and discharged under the floor together with evaporated organic solvents, etc., the wind speed is defined as the wind speed of air flowing in or out from the outlets and/or inlets opened at both ends of the coating booth. Detected by a sensor, the wind speed detection signal is sampled at a fixed sampling period and subjected to first averaging processing, and the signal subjected to the first averaging processing is further sampled at a fixed sampling period to obtain a second averaging signal. The wind direction at the outlet and/or the inlet is determined based on the second averaged signal, the wind speed is measured at the same time, and the exhaust volume of the exhaust fan is variably controlled according to the wind direction and wind speed. A feature of the present invention is that air is prevented from flowing in and out from the entrance/exit.

[Action of the invention]

According to the method of the present invention, the outlet of the paint booth and/or
Or, the first disturbance wave having a period of 1 to 4 seconds, which is thought to be caused by the characteristics of the wind speed sensor itself, in the wind speed detection signal detected at the entrance, and the fact that it is caused by the loading and unloading of the automobile body, which is the object to be coated. seems 10~30
Even if a second disturbance wave with a period of seconds is included, or even if rapid fluctuations due to instantaneous gusts are included, the wind speed detection signal is first detected at a constant sampling period. The influence of the first disturbance wave is eliminated by sampling and performing first averaging processing, and the second disturbance wave is removed by sampling the averaged signal at the sampling period and performing second averaging processing. Since the influence of waves is eliminated, the wind direction of the air at the entrance and exit of the painting booth can be reliably determined without being affected by the disturbance waves, and the wind speed can also be accurately measured.
Accordingly, the exhaust amount of the exhaust fan can be variably controlled to reliably prevent air from flowing in and out 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 block diagram showing an example of its control means.

In the figure, reference numeral 1 denotes a tunnel-shaped paint booth for spray painting automobile bodies 3, 3, etc., which are continuously conveyed by a floor conveyor 2, etc., and has an entrance 4 and an exit 5 opened at both ends. are connected to a coating pretreatment device located at the front stage of the painting booth 1 and a drying oven located at the rear stage, respectively.

A plenum chamber 6 is disposed along the ceiling of the painting booth 1, and conditioned air is supplied into the plenum chamber 6 from an air conditioner 8 through an air supply duct 9 by an air supply fan 7 to a filter 10.
It is configured to be pushed into the coating booth 1 through the housing.

The conditioned air pushed into the painting booth 1 flows down inside the booth 1 at a uniform wind speed of about 0.2 to 0.5 m/sec, and is exhausted together with the paint mist, evaporated organic solvent, etc. generated inside the painting booth 1. The mist is sucked into the mist processing chamber 13 under the floor 12 by the fan 11,
After the paint mist is separated in the mist processing chamber 13 by gas-liquid contact, it is discharged to the outside through the exhaust duct 14.

In addition, wind speed sensors 15F and 15R are installed at the inlet 4 and outlet 5 of the painting booth 1 to detect the wind speed of air flowing in or out from the inlets 4 and 5. It is configured to output the wind speed on the side as a negative signal to the control device 16.

The control device 16 includes wind speed sensors 15F and 15R.
samplers 17F and 17R that sample the detection signal output from the digital filters 17F and 17R at a predetermined sampling period (for example, 0.2 seconds); digital filters 18R and 18F having a first-order lag type transfer function; A weighted average processing unit 19 weighted averages the signal on the entrance 4 side and the signal on the exit 5 side, 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. A moving average processing unit 20 that determines the wind speed at a point in time. The processing section 2
A controller 21 performs a predetermined PID calculation based on the output of the exhaust fan 1.
An operation signal is output to an inverter 23 that controls one motor 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 a first disturbance wave of approximately 1 cycl/min and a second disturbance wave of approximately 1 cycl/min are included, the wind speed detection signal is first sampled at a period of 0.2 seconds by the sampler 17F (17R). The result is a digital signal represented by a pulse train as shown in .

Next, when this digital signal is input to the digital filter 18F (18R), the output is as shown in FIG. Then, the first disturbance wave of 20 cycl/min is removed, and the vibration is slightly suppressed, resulting in a smoothed signal.

Thereafter, the two detection signals from the wind speed sensors 15F and 15R are weighted averaged by the weighted average processing section 19 and combined into one signal.
The signal is input to the moving average processing section 20 and subjected to moving average processing.

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, Painting booth 1
This is done to eliminate the effects of swaying or turbulent airflow within the interior.

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 and the calculated wind speed is V, then V=[ ₁₆ 〓 ⁱ⁼¹ Hi]/16.

Note that since signals are input to the moving average processing unit 20 at a cycle of 0.2 seconds, each time there is a new input, the moving average processing is performed and its value is output (fourth
(see figure).

In this way, in the moving average processing, the average is calculated within a sufficiently long moving average time (for example, 90 seconds) compared to the sampling period (6 seconds) of the detection signal, so the output signal of the moving average processing section 20 is processed by a digital filter. Even if there are fluctuations in the airflow due to disturbances or turbulence that could not be removed with 18F and 18R, they are averaged out, and the second disturbance wave of 4 cycl/min becomes a signal that has been removed, and the signal is affected by this wave. This prevents the displacement from being increased or decreased (see the lower diagram in Figure 5).

Next, the digital filters 18F, 18R
The signal from which the first disturbance wave and the second disturbance wave have been removed by the moving average processing unit 20 is sent to the regulator 21.
is input and PID calculation processing is performed.

Here, PID 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 of proportional action P, integral action D, and differential action I. In the invention, since it is sufficient to control the detected wind speed V to become 0, the target value becomes 0 and the detected wind speed V is directly used as the deviation.

Furthermore, since it is generally considered that differential operation is not necessary in flow rate control, the output M of the regulator 21 in PID calculation of digital signals is the previous output M1,
The current input (deviation) is E, the previous input is E1, the proportional gain is K, the period of the input signal is t, and the integration time is
If Ti, then M=M1+dM=M1+K[E-E1+(t/Ti)E].

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 11 is increased or decreased to variably control the exhaust volume.For example, when air is in an outflow state and the wind speed value gradually increases When it is warm, E>0, E-E1>0
Therefore, 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- Since E1<0, dM<0 is sure to hold, 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 11 and the motor 24 of the air supply fan 7 are set to a predetermined rotation speed and started, and from the air supply fan 7, for example, about 7200 m ³ / 50 m in length is delivered into the painting booth 1 with a width of 6 m. When the operation is started by supplying the conditioned air of min min and discharging the same amount of air to the outside of the painting booth 1 by the exhaust fan 11, the wind speed of the air flow at the entrances and exits 4 and 5 is detected by the wind speed sensors 15F and 15R. Detected by

Then, when the car bodies 3, 3... are continuously conveyed by the floor conveyor 2 into the painting booth 1,
The floor surface 12 that sucks the air inside the painting booth 1 is covered with the car bodies 3, 3..., which increases the load on the exhaust fan 11 and relatively reduces the exhaust volume. are inlet 4 and outlet 5
leaks to the outside through

At this time, the wind speed sensor 15 at the inlet 4 and outlet 5
A positive detection signal is output from F and 15R to the control device 16, and the sampler 17F and 17R outputs a positive detection signal to the control device 16.
After being sampled at a period of 0.2 seconds and subjected to signal processing by the digital filters 18F and 18R, the weighted average processing section 19, and the moving average processing section 20 to determine the wind speed at that point every 0.2 seconds, the wind speed is sent to the regulator 21. Upon input, a predetermined PID calculation is performed, and an operation signal is output to the inverter 23 to increase the rotation speed of the motor 22 of the exhaust fan 11.

A motor 22 that drives the exhaust fan 11
When the rotation speed of the paint booth 1 is increased, the amount of exhaust gas discharged from the paint booth 1 through the exhaust duct 14 increases and becomes equal to the amount of air supplied from the air supply fan, and the paint booth 1 is discharged through the inlet and outlet 5. It is maintained in an equilibrium state with almost no air exchange with the outside.

Conversely, if the number of automobile bodies 3 to be conveyed decreases in this state, the area of the portion of the floor 12 covered by the automobile body 3 decreases, and the exhaust fan 11
Since the load on the painting booth 1 decreases, the exhaust volume increases relatively, and external air flows into the painting 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 rotation speed of the motor 22 is reduced,
The amount of exhaust gas discharged from inside the painting booth 1 to the outside via the exhaust duct 14 decreases and becomes equal to the amount of air supply, thereby inhibiting the inflow of outside air.

In the embodiment, a case has been described in which a PID-controlled regulator 21 is used as a control means for obtaining an operation signal, but the present invention is not limited to this. For example, the inflow or outflow amount of air may be calculated based on the obtained wind speed. However, the exhaust amount of the exhaust fan may be variably controlled depending on the inflow amount or outflow amount.

In addition, the means for variably controlling the exhaust volume is not limited to controlling the rotation speed of the motor 22 of the exhaust fan 11; for example, a damper may be provided separately in the exhaust duct 14 and the opening/closing angle of the damper may be adjusted. You may also do so.

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 exits and/or
Alternatively, the wind speed at the entrance is measured with a wind speed sensor, and the wind speed detection signal from the sensor is sampled at a constant sampling period and subjected to the first averaging process, so the wind speed detection signal is not affected by the characteristics of the wind speed sensor itself. If the first disturbance wave with a period of 1 to 4 seconds caused by Since the wind speed detection signal is sampled at a sampling period of , and subjected to second averaging processing, the wind speed detection signal includes a second disturbance wave with a period of 10 to 30 seconds caused by loading and unloading of the car body, etc. It is completely unaffected by air fluctuations and turbulence that occur momentarily or temporarily in the painting booth 1, as well as by
By accurately determining the inflow or outflow direction of air from the entrance/exit of the painting booth at that point in 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. 3 is an explanatory diagram showing an example of a signal waveform. Explanation of symbols, 1... Paint booth, 3... Car body, 4... Inlet, 5... Outlet, 6... Plenum chamber, 7... Air supply fan, 11... Exhaust fan, 15F, 15R... Wind speed Sensor, 16...
Control device, 18R, 18F...Digital filter having a first-order lag type transfer function, 20...Moving average processing unit, 22, 24...Motor.

Claims (1)

[Claims] 1. Conditioned air supplied to the plenum chamber by an air supply fan is forced into a tunnel-shaped paint booth, and the air inside the paint booth is pumped through an exhaust fan to produce paint mist, evaporated organic solvents, etc. In a method of operating a paint booth in which supply air is sucked and discharged under the floor together with the air supply, 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, 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 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 to remove the air from the outlet. 1. A method of operating a supply coating booth, characterized in that the inflow and outflow of water is inhibited. 2 The sampling period of the first averaging process is
A method of operating a paint booth for supplying air supply according to claim 1, wherein the charging time is 2 seconds or less. 3 The sampling period of the second averaging process is
A method of operating a paint booth for supplying air supply according to claim 1, wherein the charging time is 15 seconds or less. 4. The supply paint booth according to 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 paint booth according to 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 paint booth according to 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 scope of the above claims, 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: A method of operating the supply coating booth described in paragraph 1. V=[ _o 〓 ⁱ⁼¹ Hi]/n V: Signal obtained by moving average processing Hi: Sampled input signal