JPH09236341A - Method of adjusting temperature and humidity in aircraft ground air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain arbitrary temperature conditioning air keeping humidity required as the conditioning air with a simplified method without use of a refrigerant such as a chlorofluorocarbon. SOLUTION: Atmospheric air is compressed into pressure feeding air, which is further raised in its pressure into pressure raised air. This is cooled to separate oversaturated water, and thereafter the raised air is rendered to adiabatic expansion with an expansion turbine 8 to produce low temperature air. The oversaturated water in the low temperature air is removed into low temperature saturated air and the air before introduction into the expansion turbine 8 is branched to and mixed in the low temperature saturated air to obtain mixture air which is then raised in temperature. By adjusting the amount of the mixture air temperature and relative humidity of conditioning air obtained after the mixing are adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground air conditioner for aircraft, and more particularly to a method of adjusting temperature and humidity of conditioned air.

[0002]

2. Description of the Related Art Aircraft ground air conditioners supply conditioned or cooled conditioned air to various electronic devices and passenger compartments of an aircraft for cooling and heating.
Those disclosed in Japanese Patent No. 2835 and Japanese Patent Laid-Open No. 7-208773 are known. These devices consist of a drive source, drive train, and drive train on a trailer towed by a tow vehicle.
The system is equipped with a refrigerant system, a ventilation system and a control system. The blower system consists of a pressure feeder that introduces atmospheric air and feeds it under pressure, a precooler that removes the heat of compression, an evaporator that cools a refrigerant such as CFCs as a cold source when the temperature of the air that is introduced into the atmosphere is high, and an atmospheric introduction. It is composed of a heating heater and the like which raises the temperature when the temperature of air is low.

A method for adjusting the temperature of conditioned air in such an apparatus is a chilled water continuously obtained by cooling the air in the blast system with a refrigerant in an evaporator or a cooling air amount to a precooler fan according to the atmospheric temperature to be introduced. This is done by adjusting the amount of sprayed air to the precooler, the refrigerant system load, and the heater load.

[0004]

However, the use of CFCs, which are generally used as a refrigerant, has been regulated from the viewpoint of global environmental pollution and global warming, and alternatives thereto have been demanded. Even if a substitute could be obtained, the above-mentioned configuration would complicate the device, and would not only cause problems such as large size, weight increase, traction, operability, drivability, maintainability, etc. Operating costs will increase.

Further, the above-mentioned method for adjusting the temperature of conditioned air is a method in which only temperature adjustment is performed, and the content of water content is not taken into consideration. That is, during the cooling operation, the air in the blower system is cooled by the evaporator to generate cold water, and the conditioned air has a saturated humidity (relative humidity 100) at that temperature.
%) Of the air, and there is a problem such as dew condensation at the place of use.

Therefore, the present invention provides unsaturated conditioned air at an arbitrary temperature while maintaining the humidity (relative humidity of 95% or less) required for conditioned air by a simple method without using a refrigerant such as CFC. It is an object of the present invention to provide a temperature control / humidity control method for an aircraft ground air conditioner capable of achieving the above.

[0007]

In order to achieve the above object, the temperature control in the aircraft ground air conditioner of the present invention,
The humidity control method is to compress atmospheric air into compressed air, further pressurize the compressed air into pressurized air, cool it to separate supersaturated moisture, and adiabatically expand the pressurized air with an expansion turbine. Generating low-temperature air, removing supersaturated moisture in the low-temperature air to obtain low-temperature saturated air, branching the air before introduction of the expansion turbine to the low-temperature saturated air, mixing as mixed air, and raising the temperature, It is characterized in that unsaturated conditioned air is obtained by adjusting the temperature and relative humidity of the conditioned air obtained after mixing by adjusting the amount of the mixed air. Further, the amount of the mixed air is adjusted by detecting the temperature of the conditioned air obtained after the mixing, and receiving the detection signal to control the mixed air control valve so that the temperature becomes a predetermined conditioned air temperature. Is characterized by. Further, the pumping pressure of the compressed air, the boosting pressure of the boosted air, the flow rate, and the temperature of the conditioned air, which are determined from the atmospheric condition and the specification condition of the conditioned air, are set in the controller, and the pressure, temperature, and flow rate are detected. The detection signal from each detector is taken into the controller, the calculation based on the set value is performed, and the adjusting mechanism at each control end that controls the pressure, the flow rate, and the flow rate of the mixed air is adjusted to adjust the system. The feature is that the entire control is performed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the drawings. The aircraft ground air conditioner shown in FIG. 1 includes an air filter 1 for removing dust when introducing a required amount of air from the atmosphere, and a pressure feed for pumping the air introduced through the air filter 1 to a required pressure. Machine 2, a primary cooler 3 for removing compression heat from the compressed air generated by the pump 2, a primary water separator 4 for removing water generated by the primary cooler 3, and a primary water separator 4 A booster 5 for further boosting the pressure-fed air, a secondary cooler 6 for removing boosted heat from the boosted air generated by the booster 5, and a secondary water separator for removing water generated by the secondary cooler 6. And the expansion turbine 8 that drives the booster 5 by its rotational force while adiabatically expanding the booster air derived from the secondary water separator 7 to generate low-temperature air, and the low-temperature air generated by the expansion turbine 8. Supersaturated water vapor, water, frost, contained in And a low temperature air filter 9 for removing air and the like, and a part of the compressed air drawn out from the pump 2 is mixed with the low temperature saturated air drawn out from the low temperature air filter 9 to adjust the temperature and humidity required as conditioned air. Temperature and humidity controller 10, flexible hose 11 for sending conditioned air from the air conditioner to the aircraft, and pipes 12, 13, 13 ', 14, 15, 1 connecting these devices
5 ′, 16, 17, 17 ′ and a mixed air control valve 20 constituting the temperature / humidity control device 10, branching from the outlet pipe 12 of the pump 2 and the outlet pipe 17 of the low temperature air filter 9.
It is composed of mixed air pipes 21 and 21 'connected to.

Next, a first embodiment for obtaining unsaturated conditioned air having a temperature of 18 ° C. at a temperature of 34 ° C. and a relative humidity of 80% will be described with reference to FIG.

The temperature 34 at which dust is removed by the air filter 1
℃, relative humidity 80% (water content about 0.0275kg / kg
(Dry air)), the amount of atmospheric air of 1700 Nm ³ / h is
Introduced into the pumping machine 2, the pressure is raised to 1 kg / cm ² G, about 115 ° C., the temperature is raised to the pipe 12, and as compressed air, most of it is introduced into the primary cooler 3 and exchanges heat with air or cooling water. It is cooled to 38 ° C. At this time, the pressure-fed air discharged from the pipe 13 has a relative humidity of 100 due to being cooled.
%, The water is supersaturated, and the water of the supersaturated portion is used as drain water, and the primary water separator 4 has a well-known drain trap function such as baffle plate type, demister type, and cyclone type.
It is separated from the compressed air and discharged to the outside of the system.

Water is removed by the primary water separator 4 and 1 kg
/ Cm ² G, pumped air in a saturated state at 38 ° C. is pipe 1
3 ', then introduced into the booster 5 and 1.8 kg /
cm ² G, the pressure is raised to about 85 ° C., the temperature is raised, and the air is discharged as pressurized air. After passing through the pipe 14, the secondary cooler 6 exchanges heat with air or cooling water and is cooled to 38 ° C. again and is discharged from the pipe 15. . Then, also here, it becomes supersaturated air, and the water of supersaturated amount is separated from the air as the drain water by the secondary water separator 7 having the drain trap function and is discharged out of the system.

The pressurized air that has been pressurized and cooled as described above and has its supersaturated water content removed is introduced into the expansion turbine 8 through the pipe 15 'and adiabatically expanded to lower the temperature and pressure to a pressure of 0.3 kg / cm ² G , It becomes low-temperature air with a temperature of 13 ° C and is led out through the pipe 16 to separate the drain trap function similar to the primary water separator 4 and the secondary water separator 7 and the one in which water is frost or ice-like solid. It is introduced into the low temperature air filter 9 which also has a solid separation function that can be removed. The low-temperature air introduced here is also supersaturated low-temperature air, and the water content of supersaturation is discharged as drain water from the low-temperature air filter 9 to the outside of the system in this case by the drain trap function. Therefore, the low temperature air discharged from the pipe 17 has a pressure of 0.3.
Saturated air (relative humidity 100% = water content 0.0072 kg / kg (dry air)) in a state of kg / cm ² G and temperature of 13 ° C.

The low temperature air filter 9 may be a laminate of wire mesh, synthetic fiber, glass fiber, filler and the like. Further, it is possible to adopt a structure in which a heater is incorporated to melt solids, or a switchable type.

On the other hand, the pressure of the pump 2 is 1.0 kg / cm.
² G, the temperature is increased to 115 ° C., the temperature is increased to 115 ° C., and a part of the compressed air containing the same amount of water as the introduced atmospheric air (water content of about 0.0275 kg / kg (dry air)) is part of the outlet pipe of the pump 2. 1
It is branched from 2, and mixed with the low temperature air which passes through the mixed air pipes 21 and 21 'and the mixed air control valve 20 and leads out the outlet pipe 17 of the low temperature air filter 9.

The temperature / humidity adjusting device 10 comprises a temperature detector 1
8, a temperature controller 19, and a mixed air control valve 20. The temperature detector 18 is installed in the pipe 17 'after mixing the low temperature air and the mixed air, and detects the temperature of the conditioned air obtained after the mixing. The temperature controller 19 sets the required temperature of the conditioned air as a set value, receives the temperature signal 18 'of the conditioned air detected by the temperature detector 18, and mixes the temperature of the conditioned air to the set temperature of the conditioned air. An operation signal 19 'is sent to the air control valve 20. The mixed air control valve 20 operates the operation signal 1 from the temperature controller 19.
In response to 9 ', the valve opening is adjusted to adjust the amount of mixed air.

In the case of this embodiment, the temperature of the conditioned air is 18 ° C.
Therefore, the temperature controller 19 is set to 18 ° C. as a set value. With this setting, the mixed air control valve 20
Is the temperature signal 1 detected by the conditioned air temperature detector 18.
The opening is adjusted by the operation signal 19 'from the temperature controller 19 which receives 8', and the conditioned air temperature after mixing is 1 of the set temperature.
The amount of mixed air is adjusted so that it becomes 8 ° C.

By the above-mentioned adjustment, 1617 Nm ³ / h of the pressurized air of 1700 Nm ³ / h is introduced into the expansion turbine 8 via the booster 5 and cooled to be discharged as supersaturated low temperature air. Water is removed outside the system by the air filter 9 to become low temperature saturated air (water content 0.0072 kg / kg (dry air)) at a temperature of 13 ° C.
Is derived.

On the other hand, the remaining 83 Nm ³ / h, temperature 115
Saturated pressurized air at a temperature of ℃ (water content 0.0275 kg / kg (dry air)) is mixed with the low temperature saturated air which is discharged from the low temperature air filter 9 as mixed air through the mixed air control valve 20 to raise the temperature. As a result, the temperature was 18 ° C and the relative humidity was about 82% (water content 0.0082 kg / kg (dry air))
It is possible to obtain unsaturated conditioned air whose temperature and humidity have been controlled.

As described above, according to the present embodiment, the boosted air is adiabatically expanded by the expansion turbine to generate low temperature air having a temperature lower than the required temperature as the conditioned air, the supersaturated water is removed, and then the low temperature saturated air is discharged. By mixing the low temperature saturated air with the air before introducing the expansion turbine and raising the temperature, unsaturated conditioned air at an arbitrary temperature required as ground conditioned air for aircraft can be easily generated.

In this embodiment, the temperature drop is smaller than the pressure drop at the inlet and outlet of the expansion turbine because the amount of water in the air introduced into the expansion turbine is relatively large and the cold energy generated by the adiabatic expansion is contained. This is because the water is consumed for cooling.

Next, a second embodiment of the present invention in which the boosted air in the inlet pipe 15 'of the expansion turbine 8 is used as the mixed air will be described with reference to FIG.

The atmospheric temperature, the relative humidity, the air amount, the pump, the booster, the discharge pressure and temperature of the expansion turbine, and the conditioned air temperature are the same as those in the first embodiment, and those having the same functions as those in FIG. The same symbols are attached and detailed description thereof is omitted.

In FIG. 2, 170 introduced from the atmosphere
The air of 0 Nm ³ / h passes through the pump 2, the primary cooler 3, the primary water separator 4, the booster 5, and the secondary cooler 6 to reach the secondary water separator 7, where the supersaturated water content is increased. After being removed, the saturated pressurized air having a pressure of 1.8 kg / cm ² G and a temperature of 38 ° C. is led to the pipe 15 ′. Similar to the first embodiment, the mixed air control valve 20 receives the temperature signal 18 'detected by the temperature detector 18 provided in the conditioned air outlet pipe 17', and receives the operation signal 19 'from the temperature controller 19. The opening degree is adjusted by, and the mixed air amount is adjusted so that the conditioned air temperature after mixing reaches the set temperature of 18 ° C.

By the above adjustment, 1360 Nm ³ / h of the pressurized air of 1700 Nm ³ / h is introduced into the expansion turbine 8 and cooled to reach the low temperature air filter 9, where supersaturated water is removed, It becomes low temperature saturated air (water content 0.0072 kg / kg (dry air)) at a temperature of 13 ° C. and is led to the pipe 17. On the other hand, the remaining 340 Nm ³ / h,
Saturated pressurized air at a temperature of 38 ° C (water content 0.0152 kg /
kg (dry air) is the inlet pipe 1 of the expansion turbine 8.
The temperature is 18 ° C. by branching from 5 ′, passing through the mixed air pipes 21 and 21 ′ and the mixed air control valve 20, mixed with the low temperature saturated air from the low temperature air filter 9 as mixed air and raising the temperature. , Relative humidity about 88% (water content 0.008
It is possible to obtain unsaturated conditioned air whose temperature and humidity are adjusted to 8 kg / kg (dry air).

Next, a third embodiment will be described with reference to FIG.

This embodiment has the same structure as the apparatus of FIG. 1 described in the first embodiment, and the atmospheric air has a temperature of 10 ° C. and a relative humidity of 50%, and finally, unsaturated conditioned air having a temperature of 18 ° C. This is an example of the case of obtaining Further, it is a case where the device is provided with an automatic control system so that conditioned air having a required temperature and humidity can be automatically supplied by setting a predetermined condition. In addition, conditions other than the above, that is, the amount of air,
The discharge pressure of the pump, the discharge pressure of the expansion turbine, and the conditioned air temperature are set to the same conditions as in the first embodiment, and those having the same functions as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

As the control system, a controller 25 including a computer in addition to the apparatus of the first embodiment, an atmospheric temperature detector 26, a humidity detector 27, pressure feeding, pressure boosting air pressure detectors 28, 29, pressure feeding, pressure boosting air are supplied. Pressure control valves 30 and 31 are provided.

To the controller 25, preset values such as the outlet pressure of the pressure transmitter 2 and the booster 5 which are determined by the atmospheric conditions, the conditioned air specifications, etc. are input in advance, and the detectors 18, 2 are supplied.
The signals detected from 6, 27, 28 and 29 are input to the controller 25, the calculation based on the set value is performed, and the opening degree of the control valves 20, 30, 31 at each control end is adjusted to control the entire system. Take control.

The operation of the control system when the above device is operated is performed as follows, for example. Atmospheric temperature detector 26,
The signal detected by the humidity detector 27 is input to the controller 25, and the discharge amount of the pump 2 is determined based on the set value of the required air amount.
The discharge pressure and the discharge pressure of the booster 5 are calculated and set. A signal of the set value is sent from the controller 25 to the pressure control valves 30 and 3
1, the valve opening is adjusted. In addition, the temperature detector 1
The temperature signal 18 'detected in 8 is input to the controller 25,
Similar to the above, calculation is performed in combination with other signals, an appropriate opening of the mixed air control valve 20 is calculated, and a signal is sent to the control valve 20.
Adjust the opening of.

In FIG. 3, the temperature at which dust is removed by the air filter 1 is 10 ° C., the relative humidity is 50%, and the water content is about 0.0
038 kg / kg dry air)), amount 1700 Nm ³ / h
Atmospheric air is introduced into the pump 2 and 1.0 kg / cm ²
G, the pressure is raised to about 95 ° C., the temperature is raised, and it is led out to the pipe 12 to be compressed air, most of which is introduced into the primary cooler 3
Cool to 2 ° C. At this time, the relative humidity of the pressure-fed air discharged from the pipe 13 is about 87%, and drain water is not generated.

The compressed air in the above-mentioned state, which has been discharged from the primary water separator 4, is then introduced into the booster 5 to obtain 1.4 kg / c.
m ² G, the pressure is increased to about 37 ° C., and the temperature of the air is increased, and the air is cooled to 12 ° C. again by the secondary cooler 6 and discharged from the pipe 15. Then, here, the relative humidity exceeds 100% to become supersaturated air, and a trace amount of water of supersaturation is separated as drain water from the boosted air by the secondary water separator 7 and is discharged to the outside of the system.

Further, this boosted air is introduced into the expansion turbine 8 through the pipe 15 'and adiabatic expansion is performed to lower and lower the temperature, leading to low temperature air having a pressure of 0.3 kg / cm ² G and a temperature of -9 ° C. Through 16 to the low temperature air filter 9. This low-temperature air becomes supersaturated air with relative humidity exceeding 100%, and the water of supersaturation is deposited as frost and ice, and is thus captured by the low-temperature air filter 9 by the solid separation function and removed from the low-temperature air to the outside of the system. To be done. Therefore, the low-temperature air drawn out from the low-temperature air filter 9 to the pipe 17 is saturated low-temperature air having a pressure of 0.3 kg / cm ² G and a temperature of -9 ° C (relative humidity 100% = water content 0.00147 kg / kg (dry air )).

On the other hand, with the pressure feeder 2, the pressure is 1.0 kg / cm.
² G, the temperature is raised to 95 ° C., the temperature is raised to 95 ° C., and a part of the compressed air containing the same amount of water as the introduced atmospheric air (water content of about 0.0038 kg / kg (dry air)) is part of the outlet pipe of the pump 2. 1
It is branched from 2 and mixed with the low temperature saturated air which passes through the mixed air pipes 21 and 21 'and the mixed air control valve 20 and leads out the outlet pipe 17 of the low temperature air filter 9.

In the case of this embodiment, the temperature of the conditioned air is 18 ° C.
Therefore, the temperature of the conditioned air of the controller 25 is set to 18 ° C. as a set value. When set in this manner, the opening degree of the mixed air control valve 20 is adjusted by an operation signal from the controller 25 which receives the temperature signal 18 'from the conditioned air temperature detector 18, and the conditioned air temperature after mixing is adjusted. Is the set temperature of 18 ℃
Adjust the amount of mixed air so that With this adjustment,
Among the pressured air of 1700 Nm ³ / h, 1259 Nm ³ /
h is introduced into the expansion turbine 8 via the booster 5 and cooled to reach the low temperature air filter 9, where water of supersaturated portion is captured and removed as frost and ice, and low temperature saturated air of temperature −9 ° C. ( Water content 0.00147 kg / kg (dry air))
Then, the low temperature air filter 9 is led to the pipe 17.

On the other hand, the remaining 441N branched to the pipe 21
m ³ / h, temperature 95 ° C compressed air (water content 0.0038
kg / kg (dry air) is mixed with the low temperature saturated air which is led out from the low temperature air filter 9 as the mixed air through the mixed air control valve 20, and the temperature is raised to 1 ° C.
8 ° C, relative humidity about 21% (water content 0.00208 kg /
It is possible to obtain unsaturated conditioned air whose temperature and humidity have been adjusted to kg (dry air).

The discharge amounts and discharge pressures of the pump 2 and the booster 5 can be adjusted by using the guide vanes attached to them. Alternatively, a bypass or a circulation path may be provided for adjustment. Furthermore, the present control system can be applied and operated in exactly the same manner as the device shown in FIG. Further, in the case of this embodiment, the amount of water in the introduced air is relatively small compared to the first and second embodiments, so the temperature difference between the inlet and the outlet of the expansion turbine 8 is large.

As can be understood from each of the embodiments described above, the temperature of the low temperature saturated air generated through the expansion turbine 8 is increased by about 5 ° C. by mixing the air before introduction into the expansion turbine under any condition. If heated, unsaturated conditioned air (relative humidity 95% or less) can be obtained. The mixed air may be taken out from any position in the air system after the pump is introduced and before it is introduced into the expansion turbine. The outlet pipes 13 and 13 ′ of the primary cooler 3 and the secondary cooler 6 may be used. It may be from the inlet and outlet pipes 14 and 15.

The numerical values shown in the above embodiments are merely examples to which the present invention is applied and are not limited to these.

As described above, the air heated to a high temperature by compression and pressure is cooled to about room temperature to separate supersaturated water to generate saturated air, and the saturated air is adiabatically expanded to generate low temperature air. At the same time, the supersaturated water in the low-temperature air is removed to obtain low-temperature saturated air, and the low-temperature saturated air is mixed with a part of the compressed and pressurized high-temperature air or a part of the saturated air at room temperature by adjusting the amount thereof. By doing so, unsaturated conditioned air having a predetermined temperature and relative humidity can be easily obtained.

Further, by adjusting the amount of the high temperature air or the saturated air mixed with the low temperature saturated air according to the temperature of the unsaturated conditioned air, the unsaturated conditioned air having a predetermined temperature and relative humidity can be surely obtained. Obtainable.

[0041]

According to the present invention, in order to obtain the temperature and humidity required for conditioned air, low temperature air lower than the temperature required for conditioned air is generated in the expansion turbine, and supersaturated moisture is removed by the low temperature air filter. Derives as saturated low-temperature air, and mixes the low-temperature saturated air with air having a high temperature before introducing the expansion turbine, and detects the temperature of the conditioned air obtained after mixing to detect the temperature and the temperature required as conditioned air. Since the amount of mixed air is adjusted by the mixed air control valve whose opening is adjusted by the operation signal from the temperature controller set to
It is possible to easily obtain unsaturated conditioned air at an arbitrary temperature while maintaining the humidity (relative humidity of 95% or less) required as conditioned air.

Further, since no refrigerant such as CFC is used during the cooling operation, the environment is not polluted, and a heater for heating is not required, so that power is reduced and cooling is performed.
Operability is improved because there is no need to perform a switching operation for each heating operation.

Further, the aircraft ground air conditioner according to the method of the present invention has a simple structure, can be reduced in weight and size, can be easily towed, and can be reduced in equipment cost, operation cost and maintenance cost. .

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment to which the present invention is applied.

FIG. 2 is a system diagram showing a second embodiment to which the present invention is applied.

FIG. 3 is a system diagram showing a third embodiment to which the present invention is applied.

[Explanation of symbols]

2 ... Pressurizer, 5 ... Booster, 8 ... Expansion turbine, 9 ... Low temperature air filter, 10 ... Temperature / humidity control device, 18 ... Temperature detector, 19 ... Temperature controller, 20 ... Mixed air control valve

Claims (3)

[Claims] 1. Atmospheric air is compressed into compressed air, and the compressed air is further boosted into pressurized air, which is cooled to separate supersaturated water, and then the pressurized air is adiabatically expanded by an expansion turbine. Generating low-temperature air, removing supersaturated moisture in the low-temperature air to obtain low-temperature saturated air, branching the air before introduction of the expansion turbine to the low-temperature saturated air, mixing as mixed air, and raising the temperature, By adjusting the temperature and relative humidity of the conditioned air obtained after mixing by adjusting the amount of the mixed air, unsaturated conditioned air is obtained, and temperature control and humidity control in an aircraft ground air conditioner are characterized. Method. 2. The adjustment of the amount of the mixed air is performed by detecting the temperature of the conditioned air obtained after the mixing, and receiving the detection signal to control the mixed air control valve so as to reach a predetermined conditioned air temperature. The temperature control and humidity control method in an aircraft ground air conditioner according to claim 1, wherein 3. The pressure, the pressure, the flow rate, and the temperature of the conditioned air, which are determined by the atmospheric conditions and the specification conditions of the conditioned air, are set in a controller, and the pressure, temperature, and flow rate are set. The detection signal from each of the detectors for detecting the above is taken into the controller, the calculation based on the set value is performed, and the adjusting mechanism at each control end that controls the pressure, the flow rate, and the flow rate of the mixed air is adjusted. The temperature control / humidity control method in the aircraft ground air conditioner according to claim 1, characterized in that the entire system is controlled thereby.