JPH0796233A - Air volume control method for coating booth - Google Patents

Abstract

(57) [Summary] [Purpose] To speed up tracking of the conditioned air volume to the target value while stabilizing the conditioned air supply volume during painting work. [Structure] Air conditioner 27 to coating room 22 of coating booth 20
In the air volume control method of the coating booth, in which the air volume of the conditioned air A supplied to the air conditioning system is continuously changed in proportion to the deviation F _E between the target value F ₀ and the control amount F, the operation amount in the proportional control operation. Is made variable by the variable gain x, and the target value F
_When the deviation F _E between ₀ and the control value F is larger than a predetermined value, the variable gain x is set large, and when the deviation F _E is smaller than the predetermined value, the variable gain x is set small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for controlling the air volume of conditioned air supplied into a coating chamber of a coating booth, and more particularly to a air volume control method for a coating booth capable of reducing air conditioning energy.

[0002]

2. Description of the Related Art Painting of an automobile body is carried out in a painting booth in which a conveyor for conveying the body is laid, and the painting room of the painting booth is air-conditioned to keep the painting quality constant. When the amount of conditioned air supplied to the coating chamber fluctuates, the coating quality varies, so the amount of conditioned air from the air conditioner to the coating booth is controlled to be constant by automatic control. As an example of the prior art relating to the air volume control of conditioned air, for example, Japanese Patent Publication No. 60-3898.
No. 0 publication is known.

FIG. 6 shows an example of a conventional air volume control method for a coating booth. The air volume control is performed by proportional control, but in order to obtain a better control result, integration,
Used in combination with differential action. In block 1 of FIG. 6, a deviation is calculated from the relationship between the target value (target air volume) and the control amount (measured air volume), and the proportional control operation is performed in block 2 based on this deviation. Next, the block 3 performs the integration operation and the block 4 performs the differentiation operation. Block 5
Is an automatic or manual mode switching of air volume control, and is normally switched automatically. Therefore, the rotation speed of the blower is controlled based on the output signal from the block 5, and the air is supplied to the coating room of the coating booth. The air volume of the conditioned air is controlled so as to follow the target value.

[0004]

However, the air volume control method by proportional control shown in FIG. 6 has the following problems. The amount of conditioned air supplied to the coating room of the coating booth is controlled by the proportional operation calculation of block 2 in FIG. 6 based on the deviation between the target value and the control value, but the gain in this proportional operation calculation is fixed. Therefore, if the gain is increased, the control becomes too sensitive to the disturbance, and the vertical movement of the air volume of the conditioned air becomes large, and the waviness phenomenon shown by the broken line in FIG. 7 occurs. Further, when the gain of the proportional operation calculation is made small in order to suppress the waving phenomenon, the control becomes dull, and as shown in FIG. 7, the follow-up times T ₁ , T ₂ , T ₃ to the target value F ₀ of the conditioned air flow rate. Becomes longer.

As shown in FIG. 7, when the follow-up time T ₁ to the target value F ₀ of the conditioned air becomes long, if the coating work is started at 8:00 am, the conditioned air will start from 6:00 am. Air volume control must be started, and conditioned air that is not related to painting work will be supplied. Also, the supply of conditioned air should be reduced or stopped during the lunch break when the painting work is not performed, but after that, it takes a long time to return to the predetermined target air volume. It cannot be reduced or stopped. As described above, conventionally, since the follow-up time of the air volume of the conditioned air to the target value F ₀ is long, there is a problem in that wasted conditioned air is supplied only during that time and air conditioning energy is wasted.

It is an object of the present invention to provide an air volume control method for a coating booth, which makes it possible to quickly follow the target value of the air volume of the conditioned air while stabilizing the supply air volume of the conditioned air in the coating work. To do.

[0007]

A method for controlling the air volume of a coating booth according to the present invention for achieving the above object is to control the air volume of conditioned air supplied from an air conditioner to a coating room of a coating booth.
In the air volume control method of the coating booth that is continuously changed in proportion to the deviation between the target value and the control amount, the operation amount in the proportional control operation is made variable by the variable gain, and the deviation between the target value and the control value is When the difference is smaller than a predetermined value, the variable gain is set large, and when the deviation is smaller than the predetermined value, the variable gain is set small.

[0008]

In the air volume control method for the coating booth thus constructed, the manipulated variable in the proportional control operation is made variable by the variable gain based on the deviation between the target value and the control value. Here, when the deviation between the target value and the control value is larger than the predetermined value, the variable gain is made large, so that the sensitivity of control becomes sensitive and the follow-up of the air volume of the conditioned air becomes faster. Therefore, by shortening the follow-up time, the supply of useless conditioned air is reduced, and the air conditioning energy can be reduced.
On the contrary, when the deviation between the target value and the control value is smaller than the predetermined value, the variable gain is set to be small, so that the control sensitivity becomes dull. Therefore, the fluctuation range of the conditioned air supply air quantity with respect to the disturbance becomes small, and it becomes possible to stabilize the conditioned air supply air quantity during the coating work.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the air volume control method for a coating booth according to the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of the present invention, particularly when applied to a painting booth for painting a body of an automobile. First, an air volume control device for a coating booth to which the present invention is applied will be described. In FIG. 1, 20 indicates a coating booth. Painting booth 2
0 has an air supply chamber 21, a coating chamber 22, and an exhaust chamber 23. The vehicle body 15 is transferred into the coating chamber 22 by a transfer conveyor (not shown).

An air supply duct 25 is connected to the air supply chamber 21 of the coating booth 20. The other side of the air supply duct 25 is
It is connected to the blower 26. The upstream side of the blower 26 is
It is connected to the air conditioner 27. The air conditioner 27 has an intake port 2
It has a function of adjusting the temperature and humidity of the air sucked from 7a. The conditioned air A whose temperature and humidity have been adjusted by the air conditioner 27 is supplied to the blower 26 and the air supply duct 2
It is designed to be supplied to the air supply chamber 21 of the coating booth 20 through 5. The conditioned air A flowing into the air supply chamber 21 is
It is supplied to the coating chamber 22 via a ceiling filter (not shown).

The conditioned air A supplied to the coating chamber 22 is exhausted to the exhaust chamber 23 via the scaffolding 28 having a saw-like shape. An exhaust duct 29 is connected to the exhaust chamber 23. The conditioned air A discharged into the exhaust chamber 23 is sucked by the air exhaust device 30 provided in the middle of the exhaust duct 29 and discharged to the outside. Here, the conditioned air A discharged into the exhaust chamber 23 is forcibly sucked by the air blower 30 because the conditioned air A containing the paint mist in the coating chamber 22.
This is because it does not leak to the outside.

The blower 26 has an AC motor 26a which functions as a variable speed motor. The exhaust fan 30 also has an AC motor 30a having a function as a variable speed motor. The rotation speed of the AC motor 26a of the blower 26 is controlled by the inverter 31. Similarly, the rotation speed of the AC motor 30a of the exhaust fan 30 is controlled by the inverter 32. The inverters 31 and 32 are connected to the control unit 40 described later.

An air flow meter 35 for measuring the amount of conditioned air A supplied from the blower 26 into the coating chamber 22 of the coating booth 20 is provided in the middle of the air supply duct 25. The airflow meter 35 has a function of converting the airflow rate (flow rate) of the conditioned air A into an electric signal. The air volume signal of the conditioned air A measured by the air volume meter 35 is input to the control unit 40.

FIG. 2 shows a schematic structure of the control unit 40. As shown in FIG. 2, the control unit 40 is provided with a deviation calculating means 41, a P operation calculating means 42, a gain varying means 43, an I operation calculating means 44, a D operation calculating means 45, and a mode switching means 46. . The deviation calculation means 41 is input with the target value F ₀ of the air volume of the conditioned air A and the control value F of the air volume of the conditioned air A measured by the air flow meter 35. The deviation calculation means 41 has a function of calculating a deviation F _E between the target value F ₀ and the control value F.

The P operation calculation means 42 is the deviation calculation means 41.
It has a function of outputting a manipulated variable B proportional to the deviation F _E calculated by Gain changing means 43 is connected to the P operation calculating means 42. Gain varying means 43
Stores a map of the variable gain x shown in FIG. When the deviation F _E between the target value F ₀ and the control value F is larger than a predetermined value, the variable gain means 43 increases the variable gain x so that the change F _E between the target value F ₀ and the control value F is smaller than the predetermined value. If it is small, it has a function of increasing the variable gain x. In the P operation calculation means 42, the operation amount B is changed by the variable gain x.

The I operation calculation means 44 performs integral control, and the D operation calculation means 45 performs differential control. The integral control is a control for accumulating deviations and performing a correcting operation, and the differential control is a control for outputting a manipulated variable proportional to a change in the deviation and suppressing fluctuations in the controlled variable as much as possible. In this embodiment, a better control result is obtained by combining the proportional control operation with the integral and derivative operations.

The mode switching means 46 performs automatic or manual switching of air volume control, and is normally switched to automatic. The output signal from the mode switching unit 46 is input to the inverter 31 that controls the rotation speed of the AC motor 26a of the blower 26 and the inverter 32 that controls the rotation speed of the AC motor 30a of the exhaust fan 30. The present invention is
Since the purpose is to control the air volume of the conditioned air A supplied into the coating room 22 in the coating booth 20, it is not necessary to control the number of revolutions of the exhaust fan 30, but as described above, the paint mist in the coating room 22 is not required. The blower 26 and the exhaust fan 30 are controlled to have the same rotational speed so as not to leak the conditioned air A containing the air to the outside.

FIG. 4 is a proportional product in the control unit 40 of FIG.
It shows the system of partial differential control, P ₁, P₂, P₃Is the ratio
It is an example term, I is an integral term, and D is a differential term. M
Is an AC motor of the blower 26, and F is an air flow meter 35.
It

Next, the method of controlling the air volume of the coating booth according to the present invention and its operation will be described. FIG. 5 shows changes in the air volume of the conditioned air A due to the rotation control of the blower 26. In this embodiment, when the deviation F _E is ± 5%, the variable gain x is 1.0, so the control becomes sensitive. Therefore, the air volume of the conditioned air A can quickly follow the target value, and the conditioned air A can reach the target value F ₀ from the start of the blower 26.
The time T ₄ required to reach is significantly shortened.

Even when the target air volume is reduced from one target air volume to another target air volume, as shown at time T ₅ in FIG.
Since the target value F ₀ is quickly tracked, the air volume of the conditioned air A can be remarkably reduced in a short time during the lunch break when the painting work is not performed. Then, even when returning to the original target air volume, it is possible to follow the target value F ₀ in a short time as shown at time T ₆ . In this way, by shortening the follow-up time, the useless supply of the conditioned air A is reduced, and the air conditioning energy can be significantly reduced.

When the deviation F _E between the target value F ₀ of the conditioned air A and the control value F is 0%, the variable gain x becomes 0.1, so the control becomes insensitive. Therefore, the fan 26 does not react sensitively to disturbances such as variations in blade angle and flow path resistance, and the waving phenomenon of air volume as shown in FIG. 7 does not occur. Therefore, during the coating operation, the air volume of the conditioned air A in the coating chamber 22 can be stabilized, and the coating quality can be maintained constant.

[0023]

According to the present invention, the manipulated variable in the proportional control operation is made variable by the variable gain, and when the deviation between the target value and the control value is larger than the predetermined value, the variable gain is increased so that the deviation is the predetermined value. When it is smaller than the above, the variable gain is set to be small, so that it is possible to quickly follow the target value of the conditioned air volume while stabilizing the conditioned air supply air volume during the coating work. Therefore, it is possible to eliminate useless supply of conditioned air by shortening the follow-up time, and it is possible to reduce air conditioning energy. In addition, since it is possible to change the setting of the supply volume of conditioned air during breaks and lunch breaks, it is possible to significantly reduce the supply volume of conditioned air or to stop the supply of conditioned air, further reducing air conditioning energy. You can

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an air volume control device to which an air volume control method for a coating booth according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram of the air volume control of FIG.

FIG. 3 is a map showing the relationship between the deviation and the variable gain stored in the gain changing means of FIG.

FIG. 4 is a control system diagram of proportional-plus-integral-derivative control in the control unit of FIG.

5 is a characteristic diagram showing a change in the amount of conditioned air in the device of FIG.

FIG. 6 is a control block diagram showing an example of a conventional air volume control method for a coating booth.

FIG. 7 is a characteristic diagram showing a change in the amount of conditioned air in the control of FIG.

[Explanation of symbols]

20 coating booth 22 coating room 26 blower 27 air conditioner 35 air flow meter 40 control unit A conditioned air F ₀ target value F control value (measured value) F _E deviation

Claims (1)

[Claims] 1. A method for controlling the amount of air in a coating booth, wherein the amount of conditioned air supplied from an air conditioner to a coating room of a coating booth is continuously changed in proportion to a deviation between a target value and a control amount. , The operation amount in the proportional control operation is made variable by a variable gain, and if the deviation between the target value and the control value is larger than a predetermined value, the variable gain is increased, and if the deviation is smaller than the predetermined value, the variable gain is changed. An air flow control method for a coating booth, which is characterized by a small size.