Title of Invention:
CONTROL SYSTEM AND CONTROL DEVICE
Technical Field
The present invention relates to a control system and a control device. Background Art
Compressors installed in factories are facilities that consume a large proportion of electric power in the factories. Therefore, energy saving for the compressors is strongly demanded. In many factories, a plurality of compressors are connected in parallel so as to supply compressed air to production lines through a receiver tank that is a pressure buffer. An amount of the compressed air used fluctuates in accordance with change in consumption based on production activities. Therefore, supply pressure is stabilized by the receiver tank. In addition, a volume rate of flow to the receiver tank is controlled with adjustment in supplied amounts of the compressed air by the compressors.
In a technique disclosed in Patent Literature 1, a plurality of compressors in which at least one is different in operation efficiency characteristic from the others are connected in parallel. An operation schedule from which compressors with poor energy efficiency are preferentially excluded is made up through, monitoring of the volume rate of flow and the pressure in the receiver tank, temperatures of intake air for the compressors, and operational status of the compressors, correction of the operation efficiency characteristics of the compressors in accordance with the temperatures of the intake air. Citation List

Patent Literature
[0004] Patent Literature 1: JP 2012-67626 Summary of Invention Technical Problem
[0005] When air is compressed in a compressor, temperature of the air is increased through agency of thermodynamics. Such heat is added to heat generated by rotation of a motor. Consequently, temperature of the compressor itself and ambient temperature of the compressor are increased. Heated air expands and thus decreases in density. In order to continue supplying a constant quantity of compressed air, therefore, the compressor needs to compress a greater volume of air per unit time. In an environment in which the temperature has been increased, consequently, an operation load on the compressor increases. That is, operation of the compressor involves decrease in energy efficiency due to heat generation in the compressed air. With the operation in an environment with a high temperature, additionally, deterioration of a main unit of the compressor is accelerated by increase in motor load and adverse effects on oil. Consequently, a life of the compressor may be decreased and costs for maintenance may be increased.
[0006] As a measure against heat in the compressor, introduction of a water-cooling mechanism is conceivable. The introduction of the water-cooling mechanism, however, entails great costs. Besides, a degree of freedom for installation of the compressor may be lowered and ensuring of an installation site for the water-cooling mechanism and maintenance of the water-cooling mechanism may be necessitated. Air-cooling makes it possible to avoid such problems with the water-cooling. As a measure against heat with use of the air-cooling, conventionally, a method of continuously ventilating or cooling a room where the compressor is installed has been

adopted.
[0007] As a whole space where a plurality of compressors are installed, a temperature distribution is prevented from being uniform by various factors such as operating capacity, operational status, and installation sites of the individual compressors, even if the measure against heat with use of the air-cooling is taken. That is, high-temperature regions are locally generated. In prior art techniques, however, existence of such high-temperature regions is not considered in relation to operation control for compressors. Therefore, compressors having high operational efficiency characteristics even in the environment with high temperature are made to continue operating with high operation intensity even when being located in the high-temperature regions. Consequently, temperatures in the high-temperature regions are further increased so that the temperature distribution is made less uniform. As a whole, optimal control over the plurality of compressors is made unattainable. [0008] As an operational environment for compressors, an environment of 40°C or lower temperature is generally recommended. In low-latitude areas such as Asia, however, many areas have a hot and humid climate. Even in Japan, outside air temperatures exceeding 35°C have been observed in summer months in recent years. In factories located in such areas, it may be difficult to maintain temperatures in the operational environments at 40°C or lower temperatures only by ventilation or cooling. In the local high-temperature regions as described above, particularly, there is a high possibility that the recommended temperatures may not be maintained. Therefore, the temperatures in the high-temperature regions need to be lowered by the operation control over the compressors. In the prior art techniques, however, there is a fear that the temperatures in the high-temperature regions may be increased on the contrary. By contrast, the temperatures in the high-temperature regions may be lowered simply by

stoppage of the operation of the compressors located in the high-temperature regions.
With use of only such a method, however, the supplied amount of the compressed air
that satisfies a demand may not be maintained.
[0009] The present invention mainly aims at lowering the temperatures in the
high-temperature regions produced in a space where a plurality of compressors are
installed, while maintaining a supplied amount of compressed air that satisfies a demand,
through operation control over the compressors.
Solution to Problem
[0010] A control system according to one aspect of the present invention includes:
a plurality of compressors installed in a room and to compress and discharge gas;
a supply mechanism to deliver the gas, discharged from the plurality of compressors, to a common supply destination;
a detection mechanism to detect a temperature distribution in the room; and
a control device to respectively identify a region with high temperature and a region with low temperature in the room as a high-temperature spot and a low-temperature spot, based on the temperature distribution detected by the detection mechanism, and to exercise control over the plurality of compressors, the control including lowering operation intensity of a compressor installed in the high-temperature spot and heightening operation intensity of a compressor installed in the low-temperature spot while maintaining a pressure of the gas delivered from the supply mechanism in a setting range. Advantageous Effects of Invention
[0011] In the invention, as the operation control over the compressors, the control is exercised in which the operation intensity of the compressor installed in the

high-temperature spot is lowered and the operation intensity of the compressor installed
in the low-temperature spot is heightened while maintaining the pressure of the gas,
delivered from the supply mechanism, in the setting range. Thus the temperature in
the high-temperature region produced in a space where the plurality of compressors are
installed may be lowered while a supplied amount of compressed air that satisfies a
demand is maintained.
Brief Description of Drawings
[0012] Fig. 1 is a block diagram illustrating a configuration of a control system
according to Embodiment 1.
Fig. 2 is a block diagram illustrating transmission and reception among elements of the control system according to Embodiment 1.
Fig. 3 is a block diagram illustrating a configuration of a control device according to Embodiment 1.
Fig. 4 is a flowchart illustrating operation of the control system according to Embodiment 1.
Fig. 5 is a diagram illustrating examples of a temperature distribution and a humidity distribution.
Fig. 6 is a block diagram illustrating a configuration of a control device according to Embodiment 2.
Fig. 7 is a flowchart illustrating operation of a control system according to Embodiment 2.
Fig. 8 is a graph illustrating a relationship among power consumption by a plurality of compressors, power consumption by an air conditioner, and setting temperature for the air conditioner. Description of Embodiments

[0013] Hereinbelow, embodiments of the present invention will be described with use of the drawings. In the drawings, identical parts or corresponding parts are provided with identical reference characters. In description of the embodiments, description of the identical parts or the corresponding parts will be omitted or simplified appropriately. Note that the present invention is not to be limited by the embodiments to be described below but may be modified in various manners as appropriate. For instance, two or more out of the embodiments to be described below may be embodied in combination. Alternatively, one of the embodiments to be described below or a combination of two or more out of the embodiments to be described below may be partially embodied. [0014] Embodiment 1.
The present embodiment will be described with use of Figs. 1 to 5. [0015] *** Description of configuration ***
With reference to Fig. 1, a configuration of a control system 100 according to the embodiment will be described.
[0016] The control system 100 includes a control device 101, a plurality of compressors 102, a supply mechanism 103, and a detection mechanism 104. [0017] The control device 101 is a device to control the plurality of compressors 102. The control device 101 according to the embodiment is a server to collect and analyze various types of sensor information and to individually control the compressors 102 and an air conditioner 109 to be described later.
[0018] Though the compressors 102 may be installed in any place as long as the place is indoor, the compressors 102 in the embodiment are installed in a factory. The compressors 102 are equipment to compress and discharge gas. Though the compressors 102 have only to be adjustable for operation intensity, the compressors 102 in the embodiment are compressors of inverter type. The compressors 102 according

to the embodiment are connected in parallel to one another. Though a number of the compressors 102 may be any number as long as the number is plural, the number is six in the embodiment including the compressors CI to C6.
[0019] The supply mechanism 103 is a mechanism to deliver the gas, discharged from the plurality of compressors 102, to a common supply destination. Though the supply destination may be any place, the supply destination in the embodiment is a production line 115 in the factory. The supply mechanism 103 according to the embodiment includes a receiver tank 108 and compressed-air pipes 111. The receiver tank 108 accumulates compressed air from the compressors 102 and supplies the compressed and accumulated air to the production line 115. The compressed-air pipes 111 connect the compressors 102 and the receiver tank 108.
[0020] The detection mechanism 104 is a mechanism to detect an indoor temperature distribution. In the embodiment, the detection mechanism 104 is a mechanism to detect an indoor humidity distribution, as well. The detection mechanism 104 according to the embodiment includes temperature and humidity sensors 113 and a pressure sensor 114. The temperature and humidity sensors 113 are mounted on the respective compressors 102 so as to monitor temperatures and humidity in vicinities of the respective compressors 102. The pressure sensor 114 measures a pressure in the receiver tank 108. The temperature and humidity sensors 113 may monitor a whole space in which the plurality of compressors 102 are installed, all over. The temperature and humidity sensors 113 may measure temperatures and humidity of intake air for the compressors 102. Temperature sensors may be used in place of the temperature and humidity sensors 113. Correlated humidity may be estimated from temperatures measured by the temperature sensors. Infrared cameras capable of monitoring a temperature distribution may be used in place of the temperature and

humidity sensors 113.
[0021] In the embodiment, the control system 100 further includes the air conditioner 109. The air conditioner 109 is equipment having a cooling function of cooling inside of a room. The air conditioner 109 is a type of air-cooling mechanism. A water-cooling mechanism may be used in place of the air-cooling mechanism. [0022] In the embodiment, the control system 100 further includes valves 110 and signal lines 112. The valves 110 connect the respective compressors 102 and the compressed-air pipes 111. The valves 110 may operate in conjunction with the respective compressors 102 or may operate by being controlled by the control device
•
101. The signal lines 112 connect the control device 101 to the compressors 102 and to the air conditioner 109. Furthermore, the signal lines 112 connect the control device 101 to the temperature and humidity sensors 113 corresponding to the compressors 102 and to the pressure sensor 114 corresponding to the receiver tank 108. [0023] As illustrated in Fig. 2, data is transmitted from the pressure sensor 114 and the six temperature and humidity sensors 113 denoted by SI to S6 via the signal lines 112 to the control device 101. In addition, data and control signals are transmitted and received via the signal lines 112 between the control device 101 and the six compressors 102 denoted by CI to C6 and the air conditioner 109. Communication between the pressure sensor 114 and the temperature and humidity sensors 113 and the control device 101 may be carried out through a wireless system, instead of a wired system. Communication between the control device 101 and the compressors 102 and the air conditioner 109 also may be carried out through a wireless system, instead of the wired system.
[0024] With reference to Fig. 3, a configuration of the control device 101 according to the embodiment will be described.

[0025] The control device 101 is a computer. The control device 101 includes a
processor 301 and other hardware such as a memory 302, a control interface 303, a
sensor interface 304, an input interface 305, a display interface 306, and an auxiliary
storage device 320. The processor 301 is connected to the other hardware through
signal lines so as to control the other hardware.
[0026] The control device 101 includes an identification unit 311 and a control unit
312 as functional components. Functions of the identification unit 311 and the control
unit 312 are implemented by software.
[0027] The processor 301 is an IC to execute various processes. The term "IC" is an
abbreviation for Integrated Circuit. The processor 301 is a CPU, for instance. The
term "CPU" is an abbreviation for Central Processing Unit.
[0028] The memory 302 is a flash memory or a RAM, for instance. The term
"RAM" is an abbreviation for Random Access Memory.
[0029] The control interface 303 is an interface for connection with the compressors
102 and the air conditioner 109 through the signal lines 112. The control interface 303
includes a receiver to receive data and a transmitter to transmit data. The control
interface 303 is a communication chip or an NIC, for instance. The term "NIC" is an
abbreviation for Network Interface Card.
[0030] The sensor interface 304 is an interface for connection with the pressure sensor
114 and the temperature and humidity sensors 113 through the signal lines 112. The
sensor interface 304 includes a receiver to receive data and a transmitter to transmit data.
The sensor interface 304 is a communication chip or an NIC, for instance.
[0031] The input interface 305 is an interface for connection with an input device not
illustrated. The input device is a mouse, a keyboard, or a touch panel, for instance.
[0032] The display interface 306 is an interface for connection with a display not

illustrated. The display is an LCD, for instance. The term "LCD" is an abbreviation
for Liquid Crystal Display.
[0033] The auxiliary storage device 320 is a flash memory or an HDD, for instance.
The term "HDD" is an abbreviation for Hard Disk Drive.
[0034] In the memory 302, a program 321 that implements the functions of the
identification unit 311 and the control unit 312 is stored. The program 321 is read into
the processor 301 and is executed by the processor 301. An OS is also stored in the
memory 302. The term "OS" is an abbreviation for Operating System. The processor
301 executes the program 321 while executing the OS. A portion or all of the program
321 may be integrated into the OS.
[0035] In the embodiment, the program 321 and the OS are stored in the auxiliary
storage device 320. The program 321 and the OS that are stored in the auxiliary
storage device 320 are loaded into the memory 302 and are executed by the processor
301.
[0036] The control device 101 may include a plurality of processors that substitute for
the processor 301. Execution of the program 321 may be divided among the plurality
of processors. Each of the processors is an IC that executes various processes as with
the processor 301.
[0037] Information, data, signal values, and variable values that indicate results of
processes in the identification unit 311 and the control unit 312 are stored in the
memory 302, the auxiliary storage device 320, or a register or a cache memory in the
processor 301. In particular, data and setting values that are required for control over
the compressors 102 and the air conditioner 109 are stored as a file 322 in the auxiliary
storage device 320.
[0038] The program 321 may be stored in a portable storage medium such as a

magnetic disc and an optical disc. [0039] *** Description of operation ***
With reference to Fig. 4, operation of the control system 100 according to the embodiment will be described. In particular, operation of the control device 101 corresponds to a control method according to the embodiment. [0040] In step S401, a setting pressure range, a setting humidity value, and a setting temperature value are inputted into the control device 101. The setting pressure range is a setting range of a value that is required of the receiver tank 108 by the production line 115. Though the setting pressure range is set by upper and lower thresholds in the embodiment, the setting pressure range may be set by only either of the upper and lower thresholds. The setting pressure range may be one setting value. The setting humidity value is a threshold that is set by a manager. When humidity in a region exceeds the setting humidity value, operation of compressors 102 located in the region is stopped, as will be described later. The setting temperature value is a threshold that is set by the manager, as well. The setting temperature value is a value such as 30°C, for instance. When a temperature in a region exceeds the setting temperature value, the operation intensity of a compressor 102 located in the region is lowered, as will be described later. When a temperature in a region falls below the setting temperature value, by contrast, the operation intensity of a compressor 102 located in the region is heightened.
[0041] In step S402, the control unit 312 of the control device 101 starts operation of the plurality of compressors 102. In step S414, simultaneously, the control unit 312 of the control device 101 starts operation of the air conditioner 109. In step S415, the air conditioner 109 continues the operation pursuant to the setting humidity value and the setting temperature value that have been inputted in step S401.

[0042] In step S403, the control unit 312 of the control device 101 compares a measured pressure value from the pressure sensor 114 with the lower threshold of the setting pressure range inputted in step S401. When the measured pressure value from the pressure sensor 114 is lower than the threshold, the control unit 312 of the control device 101 heightens the operation intensity of at least one compressor 102 in step S404. Then a process of step S403 is executed again.
[0043] In step S405, the control unit 312 of the control device 101 compares the measured pressure value from the pressure sensor 114 with the upper threshold of the setting pressure range inputted in step S401. When the measured pressure value from the pressure sensor 114 is higher than the threshold, the control unit 312 of the control device 101 lowers the operation intensity of at least one compressor 102 in step S406. Then a process of step S405 is executed again.
[0044] In step S407, the identification unit 311 of the control device 101 extracts a high-temperature spot based on comparison between measured temperature values from the temperature and humidity sensors 113 and the setting temperature value inputted in step S401. That is, the identification unit 311 of the control device 101 identifies an indoor region with high temperature as the high-temperature spot, based on the temperature distribution detected by the detection mechanism 104. In an example illustrated in Fig. 5, an operational environment of CI has a high temperature. In this case, the control unit 312 of the control device 101 exercises control for lowering the operation intensity of CI in step S408. That is, the control unit 312 of the control device 101 exercises the control for the lowering the operation intensity of the compressor 102 installed in the high-temperature spot identified by the identification unit 311. [0045] In step S409, the identification unit 311 of the control device 101 extracts a

low-temperature spot based on the comparison between the measured temperature values from the temperature and humidity sensors 113 and the setting temperature value inputted in step S401. That is, the identification unit 311 of the control device 101 identifies an indoor region with low temperature as the low-temperature spot, based on the temperature distribution detected by the detection mechanism 104. In step S410, the control unit 312 of the control device 101 exercises control for heightening the operation intensity of the compressor 102 installed in the low-temperature spot identified by the identification unit 311.
[0046] In step S411, the identification unit 311 of the control device 101 extracts a high-humidity spot based on comparison between measured humidity values from the temperature and humidity sensors 113 and the setting humidity value inputted in step S401. That is, the identification unit 311 of the control device 101 identifies an indoor region with high humidity as the high-humidity spot, based on the humidity distribution detected by the detection mechanism 104. In the example illustrated in Fig. 5, an operational environment of C6 has the high humidity. In this case, in step S412, the control unit 312 of the control device 101 stops the operation of C6 and separates C6 from a compressed-air supply system by closing the valve 110 that connects C6 and the compressed-air pipes 111. That is, the control unit 312 of the control device 101 exercises control for stopping the operation of the compressor 102 installed in the high-humidity spot identified by the identification unit 311. When the measured humidity value in an operational environment of a compressor 102 that has been stopped does not exceed the setting humidity value, by contrast, the control unit 312 of the control device 101 starts the operation of the compressor 102 and opens the valve 110 that connects the compressor 102 and the compressed-air pipes 111, in step S413. [0047] After processes of step S412 and step S413, processes of step S403 and later

are executed again. In step S404, the operation intensity of at least one compressor 102 except the compressors 102 whose operation intensity has been lowered by a process of previous step S408 and except the compressors 102 whose operation has been stopped by the process of previous step S412 is heightened. In step S406, the operation intensity of at least one compressor 102 except the compressors 102 whose operation intensity has been heightened by a process of previous step S410 and except the compressors 102 whose operation has been stopped by the process of previous step S412 is lowered.
[0048] In step S403 to step S410, as described above, the control unit 312 of the control device 101 exercises control over the plurality of compressors 102 for lowering the operation intensity of the compressors 102 installed in the high-temperature spots and heightening the operation intensity of the compressors 102 installed in the low-temperature spots while maintaining a pressure of the gas delivered from the supply mechanism 103 in the setting range. A degree of adjustment in the operation intensity of each of the compressors 102 is optimized with use of an arbitrary method. For instance, optimization based on machine learning is carried out. [0049] In step S403 to step S413, as described above, the control unit 312 of the control device 101 exercises the control over the plurality of compressors 102 for stopping the operation of the compressors 102 installed in the high-humidity spots while maintaining the pressure of the gas delivered from the supply mechanism 103 in the setting range. In the control, control for heightening the operation intensity of other compressors 102 as appropriate such that the pressure of the gas delivered from the supply mechanism 103 may not fall below the setting range is included. [0050] *** Description of effects of embodiment ***
As operation control over the compressors 102 in the embodiment, the control

is exercised in which the operation intensity of the compressor 102 installed in the high-temperature spot is lowered and the operation intensity of the compressors 102 installed in the low-temperature spot is heightened while maintaining the pressure of the gas delivered from the supply mechanism 103 in the setting range. Thus the temperature in the high-temperature region produced in the space where the plurality of compressors 102 are installed may be lowered while a supplied amount of compressed air that satisfies a demand is maintained.
[0051] In the embodiment, the plurality of temperature and humidity sensors 113 and the plurality of compressors 102 are installed in an environment in which the temperatures and the humidity are managed. The control device 101 individually controls the operation intensity of the compressors 102 based on the values from the various sensors and thereby eliminates a nonuniform distribution of the temperatures. Consequently, an environment with a satisfactory compressing operation efficiency may be maintained. Thus various effects such as energy saving, extension of service lives, and reduction in costs for maintenance may be obtained. [0052] In the embodiment, the air conditioner 109 having cooling capacity is introduced into the place where the plurality of compressors 102 are installed, such as a compressor room or a space in a factory. An air-cooling effect for the compressors 102 and a surrounding environment thereof is brought about by cold air. Input of energy is required for the operation of the air conditioner 109. With introduction of the air conditioner 109, however, the energy saving, prevention of deterioration, and decrease in frequency of maintenance for the compressors 102 may be expected particularly under hot and humid climate conditions.
[0053] Even in the environment in which the air conditioner 109 is installed, the temperatures in the vicinities of the individual compressors 102 or the temperatures of

the individual compressors 102 themselves are not made the same, due to various factors such as installation sites, capacities, operational status, or distances to other heat sources of the individual compressors 102. Specifically, the compressors 102 placed in environments with high temperature may not receive a benefit of cooling because of the nonuniform distribution of the temperatures even if the temperature in the vicinity of the air conditioner 109 has been sufficiently lowered by cooling operation. On condition that the vicinity of the air conditioner 109 has a higher temperature than other places have for such a reason as proximity to a compressor 102 which generates a particularly large quantity of heat, on the contrary, the air conditioner 109 may consume more energy than necessary, for the cooling. Consequently, a sufficient energy-saving effect may not be obtained. In order to cope with such problems, the compressors 102 whose operation loads are variable are introduced in the embodiment. Based on monitoring of spatial temperatures in the vicinities of the compressors 102 or the temperatures of the compressors 102 themselves, the operation intensity of the compressors 102 located in environments having comparatively high temperatures is lowered and the operation intensity of the compressors 102 located in environments having comparatively low temperatures is heightened. Thus it is made possible to lower the temperatures in the high-temperature spots and to heighten the temperatures in the low-temperature spots. As a result, a nonuniform distribution of the spatial temperatures may be eliminated.
[0054] Cooling air that is supplied from the air conditioner 109 is air with low humidity. Therefore, problems with both temperature and humidity may be addressed. In an environment to which steam is supplied and a position to which humid outside air is supplied, however, humidity of air sucked by the compressors 102 is problematic. On condition that the air sucked by the compressors 102 contains much moisture, a

large amount of moisture in the air is condensed in compression processes so as to be accumulated in the compressors 102. Therefore, resultant decrease in compression efficiency may make it difficult to maintain the operation intensity or may cause increase in energy consumption. In order to cope with such a problem, in the embodiment, the humidity is monitored with use of the temperature and humidity sensors 113, so that humid places may be identified. The compressors 102 in the identified places are stopped. Thus the problem with the humidity may be avoided. The stoppage of the compressors 102 in accordance with the humidity influences the temperature distribution in the space. The effects of the embodiment, however, are maintained by the optimization of the operation control over the other compressors 102. [0055] According to the embodiment, an environment that is suitable for the operation of the compressors 102 may be attained by the control over the operation intensity of the compressors 102 and the stoppage of the compressors 102 in accordance with the humidity that have not been considered so far. That is, in the embodiment, the pressure in the receiver tank 108 and the temperatures and the humidity of the compressors 102 or the vicinities of the compressors 102 are inputted as parameters, to be used by the control system 100 to manage the indoor environment, into the control device 101, so that optimal individual operation control over the compressors 102 is exercised. Therefore, the energy-saving effect that has been unattainable in conventional methods may be obtained. [0056] *** Other configurations ***
Though the functions of the identification unit 311 and the control unit 312 are implemented by the software in the embodiment, the functions of the identification unit 311 and the control unit 312 may be implemented by a combination of software and hardware in a modification. That is, a portion of the functions of the identification unit

311 and the control unit 312 may be implemented by dedicated electronic circuits and the remainder may be implemented by software.
[0057] The dedicated electronic circuits are single circuits, composite circuits, programmed processors, parallelly programmed processors, logic ICs, GAs, FPGAs, or ASICs, for instance. The term "GA" is an abbreviation for Gate Array. The term "FPGA" is an abbreviation for Field-Programmable Gate Array. The term "ASIC" is an abbreviation for Application Specific Integrated Circuit.
[0058] The processor 301, the memory 302, and the dedicated electronic circuits are collectively referred to as "processing circuitry". That is, the functions of the identification unit 311 and the control unit 312 are implemented by the processing circuitry, irrespective of whether the functions of the identification unit 311 and the control unit 312 are implemented by software or are implemented by a combination of software and hardware.
[0059] The "device" of the control device 101 may be read as "method" and the "unit" of the identification unit 311 and the control unit 312 maybe read as "step". Alternatively, the "device" of the control device 101 maybe read as "program", "program product", or "computer-readable medium having a program recorded therein" and the "unit" of the identification unit 311 and the control unit 312 may be read as "procedure" or "process". [0060] Embodiment 2.
As for the present embodiment, differences from Embodiment 1 will be principally described with use of Figs. 6 to 8.
[0061] In Embodiment 1, the setting temperature for the air conditioner 109 is set by the manager. In the present embodiment, power consumption by each of the compressors 102 and power consumption by the air conditioner 109 are measured. A

setting temperature for the air conditioner 109 that minimizes a total of the power consumption by the compressors 102 and the power consumption by the air conditioner 109 is automatically set. [0062] *** Description of configuration ***
A configuration of the control system 100 according to the present embodiment is substantially the same as the configuration of Embodiment 1 illustrated in Fig. 1.
[0063] In the present embodiment, the detection mechanism 104 is a mechanism to detect the power consumption by the plurality of the compressors 102 and the air conditioner 109, as well. Though not illustrated, the detection mechanism 104 according to the embodiment includes wattmeters in addition to the temperature and humidity sensors 113 and the pressure sensor 114. The wattmeters are each incorporated in the individual compressors 102 and the air conditioner 109 and monitor the power consumption by the individual compressors 102 and the air conditioner 109. Data on the power consumption is transmitted from the six compressors 102 denoted by CI to C6 and the air conditioner 109 through the signal lines 112 to the control device 101. Wattmeters to measure the power consumption through CTs from electric wires or a switchboard to supply power to the compressors 102 and the air conditioner 109 may be used in place of the wattmeters incorporated in the compressors 102 and the air conditioner 109. The term "CT" is an abbreviation for Current Transformer. [0064] With reference to Fig. 6, a configuration of the control device 101 according to the embodiment will be described.
[0065] The control device 101 includes an analysis unit 313 other than the identification unit 311 and the control unit 312 as functional components. Functions of the identification unit 311, the control unit 312, and the analysis unit 313 are

implemented by software.
[0066] *** Description of operation ***
With reference to Fig. 7, operation of the control system 100 according to the embodiment will be described. In particular, operation of the control device 101 corresponds to a control method according to the embodiment.
[0067] As for processes of step S802 to step S813, which are the same as processes of step S402 to step S413 in Fig. 4, description is omitted.
[0068] In step S801, a setting temperature range, as well as the setting pressure range, the setting humidity value, and the setting temperature value, is inputted into the control device 101. The setting temperature range is a range in which the setting temperature for the air conditioner 109 may be altered and is set by the manager. Though the setting temperature range is set by upper and lower thresholds in the embodiment, the setting temperature range may be set by only either of the upper and lower thresholds. [0069] In step S814, simultaneously with step S802, the control unit 312 of the control device 101 starts operation of the air conditioner 109. In step S815, the analysis unit 313 of the control device 101 receives the data on the power consumption from the individual compressors 102 and the air conditioner 109 through the signal lines 112. The analysis unit 313 of the control device 101 uses the received data to determine the setting temperature for the air conditioner 109 that minimizes the total power consumption by the compressors 102 and the air conditioner 109. [0070] In Fig. 8, a relationship among the power consumption by the plurality of the compressors 102, the power consumption by the air conditioner 109, and the setting temperature for the air conditioner 109 is illustrated. A vertical axis represents the power consumption. A horizontal axis represents the setting temperature for the air conditioner 109. The temperature gradually decreases from left to right along the

horizontal axis. On a graph of Fig. 8, the power consumption by the compressors 102 and the power consumption by the air conditioner 109 are plotted. Though one curve is illustrated as the power consumption by the compressors 102 for simplification of description, a number of curves corresponding to a number of the compressors 102 installed exist actually. With decrease in the setting temperature for the air conditioner 109, the power consumption by the air conditioner 109 increases monotonically and linearly or curvilinearly. By contrast, the power consumption by the compressors 102 monotonically decreases for such reasons as described above. In Fig. 8, sum of the power consumption Wa by the air conditioner 109 and the power consumption Wc by the compressors 102 has a minimum value Wt when the setting temperature for the air conditioner 109 is X°C. It is thus found that an optimal value of the setting temperature for the air conditioner 109 at this time point is X°C. An amount of compressed air that is supplied to the production line 115 changes depending on production activities. Hygrothermal environments of the installation sites of the compressors 102 are changed by external factors and uniforming of the temperature distribution that is similar to that in Embodiment 1. Therefore, X°C is nothing but an optimal solution at a time point. The analysis unit 313 of the control device 101 appropriately finds the optimal solution changing moment by moment in such a manner. That is, the analysis unit 313 of the control device 101 makes an analysis of a reduction in the power consumption by the plurality of compressors that is attained by lowering of the setting temperature for the air conditioner 109 and a reduction in the power consumption by the air conditioner that is attained by heightening of the setting temperature for the air conditioner, based on the power consumption by the plurality of compressors 102 detected by the detection mechanism 104, the power consumption by the air conditioner 109 detected by the detection mechanism 104, and the setting

temperature for the air conditioner 109.
[0071] In step S816, the control unit 312 of the control device 101 alters the setting
temperature for the air conditioner 109 within the setting temperature range inputted in
step S401, in accordance with the optimum value found in step S815. That is, the
control unit 312 of the control device 101 adjusts the setting temperature for the air
conditioner 109 in accordance with a result of the analysis by the analysis unit 313. In
step S817, the air conditioner 109 carries out operation pursuant to the setting humidity
value and the setting temperature range that have been inputted in step S801 and to the
setting temperature that has been altered in step S816. Then a process of step S815 is
executed again.
[0072] *** Description of effects of embodiment ***
In the embodiment, automated temperature setting for the air conditioner 109 pursuant to operating conditions of the compressors 102 and temperature conditions that change moment by moment is attained, so that the total power consumption by the air conditioner 109 and the compressors 102 maybe minimized. [0073] In the embodiment, the power consumption by each of the compressors 102 and the power consumption by the air conditioner 109 are inputted as the parameters, to be used by the control system 100 to manage the indoor environment, into the control device 101 and the operation control over the air conditioner 109 is thereby exercised. Therefore, the energy-saving effect that has been unattainable in the conventional methods may be obtained. [0074] *** Other configurations ***
Though the functions of the identification unit 311, the control unit 312, and the analysis unit 313 are implemented by the software in the embodiment as with Embodiment 1, the functions of the identification unit 311, the control unit 312, and the

analysis unit 313 may be implemented by a combination of software and hardware as with the modification of Embodiment 1. Reference Signs List
[0075] 100: control system; 101: control device; 102: compressor; 103: supply mechanism; 104: detection mechanism; 108: receiver tank; 109: air conditioner; 110: valve; 111: compressed-air pipe; 112: signal line; 113: temperature and humidity sensor; 114: pressure sensor; 115: production line; 301: processor; 302: memory; 303: control interface; 304: sensor interface; 305: input interface; 306: display interface; 311: identification unit; 312: control unit; 313: analysis unit; 320: auxiliary storage device; 321: program; 322: file

We Claim:
[Claim 1] A control system comprising:
a plurality of compressors installed in a room and to compress and discharge gas;
a supply mechanism to deliver the gas, discharged from the plurality of compressors, to a common supply destination;
a detection mechanism to detect a temperature distribution in the room; and
a control device to respectively identify a region with high temperature and a
region with low temperature in the room as a high-temperature spot and a
low-temperature spot, based on the temperature distribution detected by the detection
mechanism, and to exercise control over the plurality of compressors, the control
including lowering operation intensity of a compressor installed in the high-temperature
spot and heightening operation intensity of a compressor installed in the
low-temperature spot while maintaining a pressure of the gas delivered from the supply
mechanism in a setting range.
[Claim 2] The control system according to claim 1, wherein
the detection mechanism detects a humidity distribution in the room, and
the control device identifies a region with humidity higher than a threshold in
the room as a high-humidity spot, based on the humidity distribution detected by the
detection mechanism, and exercise control over the plurality of compressors, the control
including stopping operation of a compressor installed in the high-humidity spot while
maintaining the pressure of the gas delivered from the supply mechanism in the setting
range.
[Claim 3] The control system according to claim 1 or 2, further comprising:
an air conditioner to cool inside of the room, wherein

the detection mechanism detects power consumption by the plurality of compressors and the air conditioner, and
the control device makes an analysis of a reduction in the power consumption by the plurality of compressors that is attained by lowering of a setting temperature for the air conditioner and a reduction in the power consumption by the air conditioner that is attained by heightening of the setting temperature for the air conditioner, based on the power consumption detected by the detection mechanism and the setting temperature for the air conditioner, and adjusts the setting temperature for the air conditioner in accordance with a result of the analysis.
[Claim 4] A control device to control a plurality of compressors to compress
and discharge gas, the control device comprising:
an identification unit, based on a temperature distribution in a room where the plurality of compressors are installed, to respectively identify a region with high temperature and a region with low temperature in the room as a high-temperature spot and a low-temperature spot; and
a control unit to exercise control over the plurality of compressors, the control
including lowering operation intensity of a compressor installed in the high-temperature
spot identified by the identification unit and heightening operation intensity of a
compressor installed in the low-temperature spot identified by the identification unit
while maintaining a pressure of the gas, delivered from a supply mechanism to deliver
the gas discharged from the plurality of compressors to a common supply destination, in
a setting range.
[Claim 5] The control device according to claim 4, further comprising:
an analysis unit, based on power consumption by the plurality of compressors, power consumption by an air conditioner to cool inside of the room, and a setting

temperature for the air conditioner, to make an analysis of a reduction in the power consumption by the plurality of compressors that is attained by lowering of the setting temperature for the air conditioner and a reduction in the power consumption by the air conditioner that is attained by heightening of the setting temperature for the air conditioner, wherein
the control unit adjusts the setting temperature for the air conditioner in accordance with a result of the analysis by the analysis unit.