JP2007212095A - Air temperature control method and control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely control the temperature of air to be supplied to a clean room. <P>SOLUTION: Air 25 is moved through an inlet 11A to an air-conditioner 11. The temperature of the air 25 at a dry coil outlet 12B is measured by a thermometer 17 and the air 25 is passed through a low pass filter 33, and then an air temperature signal W1 is formed. The signal W1 is transmitted to a main loop PID computer 31. A main loop current value or controlled variable Z2 having a difference from an air temperature set value D1 is transmitted to a sub loop PID controller 32. The temperature of cold water to be supplied to a dry coil 12 is measured by a thermometer 18 to form a cold water temperature signal W2 which is transmitted to a computer 32. The computer 32 calculates a sub loop operation variable Z1 from the value and transmits it to a heater 15. In accordance with the result, the heater 15 precisely controls the temperature of the cold water to keep the temperature of the dry coil 12 constant. The temperature of the air 25 is set constant in heat exchange with the dry coil 12, and then the air 25 is supplied through the outlet 11B to the clean room. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an air temperature control method and control system, and more particularly to an air temperature control method and control system for air supplied to various chambers used in the field of precision machining and measurement.

  With the integration of semiconductors on a large scale, there is an increasing demand for a precision environment chamber (for example, a clean room) that highly controls the air temperature, which is an environmental factor for precision processing and measurement accuracy. In these air temperature controls, it is necessary to cool or heat the air in order to remove the heat load in the chamber and absorb changes in the outside air temperature introduced into the chamber. As a cooling method, a method of circulating cold water through a heat exchanger having a dry coil using cold water is often used. However, the chilled water temperature and flow rate fluctuations at that time are one of the major causes of air temperature fluctuations. Therefore, in the advanced control of the air temperature, high performance of the cold water control or the temperature control by the dry coil is one of the problems (for example, see Non-Patent Document 1).

  One method generally employed in air temperature control using a dry coil is an air temperature control system 100 shown in FIG. In the air conditioner 101, a dry coil 102, a fan 103, a thermometer 107, and the like are provided. The air conditioner 101 is connected with a cold water production apparatus 104 for producing cold water circulating in the dry coil 102 via a pump (not shown) and a three-way valve 110. Then, air 115 is sent into the air conditioner 101 from the air conditioner inlet 101A. Then, in order to control the temperature fluctuation of the air 105 at the air conditioner outlet 101B caused by the air temperature change or the temperature fluctuation of the chilled water in the chilled water production apparatus 104, the flow rate of the chilled water flowing into the dry coil 102 is adjusted by the three-way valve 110. ing. In the adjustment, the temperature of the air 115 at the dry coil outlet 102B is measured by a thermometer 107. The measured value is input to the controller 109 as the air temperature signal S1. The controller 109 also receives an air temperature set value S2. An opening value S3 of the three-way valve 110 is obtained from the difference between S1 and S2 by the PID calculator 109A. The procedure of transmitting the opening degree value S3 as a signal to the three-way valve 110 and adjusting the opening degree of the three-way valve 110 is repeated.

As another air conditioning system, an optimization controller is used to control the power required for the cold water production apparatus, the power of the fan, and the power required for air conditioning such as a pump for circulating the cold water through the dry coil. Are known. This air conditioning system is provided with a local controller, which controls the dry coil temperature and the chilled water temperature to be optimum target values (see, for example, Patent Document 1).
Published by the Society for Air Conditioning and Sanitation Engineering, “Air Conditioning and Hygiene Engineering Vol. 65, No. 9”, August 1991, pages 557-561 JP 2004-0669134 A

  FIG. 4 schematically shows the temperature fluctuation of the air 115 by the air temperature control system 100 of FIG. The air temperature at the air conditioner outlet 101B (see (c)) can be controlled within a certain range regardless of the temperature change at the air conditioner inlet 101A (see (a)). However, it turns out that it is influenced by the temperature fluctuation (refer to (b)) generated in cold water. Such a change in the air temperature due to the chilled water temperature fluctuation has a short cycle and is difficult to control with an electric heater or the like, which is a fatal problem in facilities that require high-accuracy temperature control. This problem is not necessarily improved because the air conditioning system described in Patent Document 1 aims to minimize the power required for air conditioning.

  The objective of this invention is providing the air temperature control method and control system which improve the control performance of the air temperature by the heat exchanger using a heat medium.

  In order to achieve the above object, the invention according to claim 1 is the air temperature control method in which the temperature of the air supplied to adjust the room temperature is controlled by heat exchange using a heat exchanger. The air temperature is the current value or control amount of the main loop, and the heat medium temperature in the heat exchanger defined based on the current value or control amount of the main loop is the target value of the sub-loop. The temperature of the air is controlled by a cascade control method so that the temperature of the heat medium flowing into the exchanger becomes a target value of the sub-loop.

  According to the first aspect, the temperature fluctuation of the air at the inlet side of the heat exchanger can be suppressed in the main loop, and the temperature fluctuation of the heat medium can be suppressed in the sub loop, so that the air temperature control performance is improved.

  In the invention of claim 2, the heat exchanger preferably includes a dry coil.

  In a third aspect of the invention, the temperature adjustment of the heat medium flowing into the heat exchanger is performed by passing the heat medium through a mixing tank, passing the heat medium through a heater or a cooler, and adjusting the temperature of the heat medium. It is preferable to measure and control the temperature of the heater or the cooler based on the temperature of the heat medium. According to claim 3, it is possible to precisely control the temperature of the heat medium.

  According to a fourth aspect of the present invention, it is preferable that the temperature of the air subjected to the heat exchange is measured, and the result is passed through a low-pass filter to reduce noise to obtain the current value or control amount of the main loop. . According to the fourth aspect, it is possible to remove the noise of the sensor and the rapid temperature change that cannot be followed by this control method, and to stabilize the control.

  According to a fifth aspect of the present invention, there is provided an air temperature control system for controlling the temperature of air supplied for adjusting a room temperature by heat exchange using a heat exchanger, in order to achieve the above object, the temperature control of the heat exchanger. In order to perform the above, the main loop having the air temperature heat exchanged by the heat exchanger as a current value or a controlled variable, and the temperature of the heat medium in the heat exchanger as the current value or the controlled variable, the target temperature is the A cascade control system having a sub-loop defined by an operation amount of the main loop, and a heat medium temperature control means for controlling the temperature of the heat medium flowing into the heat exchanger. According to the fifth aspect, the temperature fluctuation of the air on the inlet side of the heat exchanger can be suppressed in the main loop, and the temperature fluctuation of the heat medium can be suppressed in the sub loop, so that the air temperature control performance is improved.

  ADVANTAGE OF THE INVENTION According to this invention, the control performance of the air temperature of the air supplied into the room | chamber interior (for example, clean room) for the environmental chambers for precision processing / measurement etc. can be improved, for example.

  Hereinafter, preferred embodiments of an air-conditioning air temperature control method and control system according to the present invention will be described in detail with reference to the accompanying drawings.

  An air temperature control system 10 according to the present invention is shown in FIG. The air conditioner 11 in the air temperature control system 10 is connected to a chilled water production apparatus 14 via a pipe or the like, and is further connected to a controller 19. The controller 19 includes a main loop PID calculator 31, a sub-loop PID calculator 32, and a low pass filter 33. In the air conditioner 11, a dry coil 12, a fan 13, and a thermometer 17 that are part of a heat exchanger are provided. In addition, although the heat exchanger provided in the air conditioner 11 is not specifically limited, It is preferable to use the thing provided with a dry coil. The air 25 that has entered the air conditioner 11 from the air conditioner inlet 11A is cooled by the dry coil 12 and sent out from the air conditioner outlet 11B to a room (not shown) for, for example, an environmental chamber for precision processing and measurement. .

  The cold water production apparatus 14 is connected to the dry coil 12 by a cold water mixing tank 16, a heater (heater) 15, a thermometer 18, piping, and the like, and supplies cold water as a heat medium into the dry coil 12. In the present invention, the heat medium is not limited to cold water. Further, a cooler may be used for temperature adjustment instead of the heater. Furthermore, the thermometers 17 and 18 are not particularly limited, and various sensors may be used.

  The flow rate of cold water flowing into the dry coil 12 is always constant, but the cold water temperature is controlled by the cold water mixing tank 16 and the heater 15. After the cold water is produced by the cold water production apparatus 14, the cold water is mixed in the cold water mixing tank 16 and the temperature becomes substantially constant. Further, precise temperature control is performed by the heater 15.

  The method for controlling the temperature of the cold water is as follows. The temperature of the air 25 at the dry coil outlet 12 </ b> B is measured with the thermometer 17. The measurement result is transmitted to the low-pass filter 33 as an air temperature signal W1 '. After the noise of the air temperature signal W <b> 1 ′ is removed by the low-pass filter 33, it is transmitted to the main loop PID controller 31 as the noise-removed air temperature signal W <b> 1. In the present invention, the arrangement of the low-pass filter 33 in the controller 19 can be omitted. However, it is preferably provided in the controller 19 in order to remove noise of the temperature of the air 25 at the dry coil outlet 12B or to remove the influence of an exceptionally rapid change in air temperature.

  In the controller 19, the difference between the noise-removed air temperature signal W <b> 1 and the air temperature set value D <b> 1 supplied to the room is input to the main loop PID controller 31. Then, the target value of the cold water temperature is calculated by the main loop PID controller 31 and transmitted to the PID controller 32 of the sub loop. The value output from the main loop PID controller 31 is set as the current value of the main loop or the control amount Z2. Further, the temperature of the cold water supplied to the dry coil 12 is measured by the thermometer 18. The measurement result is defined as a cold water temperature signal W2. The difference between the main loop current value or control amount Z2 and the chilled water temperature signal W2 that is the current value of the sub loop is input to the sub loop PID controller 32. Then, the sub-loop operation amount Z <b> 1 transmitted to the heater 15 is calculated by the sub-loop PID controller 32. The operation amount Z1 of the auxiliary loop is transmitted to a controller (not shown) of the heater 15, and the controller adjusts the temperature of the heater 15 based on the value. The temperature of the cold water supplied to the dry coil 12 by the heater 15 is controlled to be a desired temperature and maintained at a constant value.

  The schematic diagram of the result of the temperature control of the air 25 by the air temperature control system 10 which concerns on this invention is shown in FIG. The chilled water temperature is controlled by the sub-loop PID controller 32 by sending a precise temperature to the heater 15 as the sub-loop current value or the control amount Z1, so that the air conditioning as seen in FIG. There is no sudden temperature fluctuation of the air 25 at the machine outlet 10B (see (c)). Further, it can be seen that the chilled water temperature is changed so as to suppress the fluctuation of the air temperature at the air conditioner inlet 11A (see (a)) by the main loop control by the main loop PID controller 31 (see (b)). That is, when the air temperature at the air conditioner inlet 11A rises, the cold water temperature is controlled to be lowered. As a result, the temperature of the air 25 at the air conditioner outlet 11B is controlled with high accuracy (see (c)).

  In the air temperature control system 10 according to the present invention, the temperature fluctuation of the air 25 at the air conditioner inlet 11A targeted by the main loop PID controller 31 and the cold water production apparatus 14 targeted by the sub loop PID controller 32 are output. The period of the dominant temperature fluctuation is greatly different from the cold water temperature fluctuation. Therefore, the temperature control of the cold water by the sub-loop PID controller 32 targets a temperature fluctuation with a short cycle. Further, the heat medium temperature control means constituted by the cold water mixing tank 16, the heater 15, and the thermometer 18 has a sufficiently high speed and can sufficiently control the cold water temperature fluctuation. The main loop current value or the control amount Z1 is changed by the main loop PID controller 31, but the change is sufficiently slow in the sub loop PID controller 32, and the change of the sub loop (signal; W2 to Z1). Does not adversely affect control performance. Therefore, it becomes possible to suppress the temperature fluctuation of the air 25 at the air conditioner inlet 11A in the main loop (signals; W1 'to Z2). Moreover, it becomes possible to suppress a chilled water temperature fluctuation | variation by a subloop (signal; W2-Z1).

It is the schematic of the air temperature control system which concerns on this invention. It is a schematic diagram which shows the change of each temperature in the case of using the air temperature control system which concerns on this invention. It is the schematic of the conventional air temperature control system. It is a schematic diagram which shows the change of each temperature in the case of using the conventional air temperature control system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Air temperature control system, 12 ... Dry coil, 14 ... Cold water manufacturing apparatus, 15 ... Heater, 16 ... Cold water mixing tank, 19 ... Controller, 31 ... Main loop PID controller, 32 ... Sub loop PID controller, 33 ... Low pass filter

Claims (5)

In the air temperature control method in which the temperature control of the air supplied to adjust the room temperature is performed by heat exchange using a heat exchanger,
The air temperature that has undergone the heat exchange is the current value or control amount of the main loop,
When the heat medium temperature in the heat exchanger defined based on the current value or control amount of the main loop is the target value of the sub-loop,
An air temperature control method, wherein the temperature of the air is controlled by a cascade control method so that the temperature of the heat medium flowing into the heat exchanger becomes a target value of the sub-loop.   The air temperature control method according to claim 1, wherein the heat exchanger includes a dry coil. The temperature adjustment of the heat medium flowing into the heat exchanger is as follows:
The heating medium is passed through a mixing tank, the heating medium is passed through a heater or a cooler, the temperature of the heating medium is measured, and the temperature of the heating machine or the cooler is controlled based on the temperature of the heating medium. The air temperature control method according to claim 1 or 2.   4. The temperature of the air subjected to the heat exchange is measured, and the result is passed through a low-pass filter to reduce noise, thereby obtaining the current value or control amount of the main loop. The air temperature control method according to claim 1. In an air temperature control system that controls the temperature of air supplied to adjust the indoor temperature by heat exchange using a heat exchanger,
In order to perform temperature control of the heat exchanger, a main loop having a current value or a control amount as an air temperature heat-exchanged by the heat exchanger;
A cascade control system having a secondary loop having a value defined based on a current value or a control amount of the main loop as a target temperature of the heat medium in the heat exchanger,
An air temperature control system comprising heat medium temperature control means for controlling the temperature of the heat medium flowing into the heat exchanger.

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