Abstract:
A device for temperature control in an aircraft cabin includes a first supply control arrangement and a first pressure control arrangement. The first supply control arrangement includes an air duct and a valve arrangement that controls a supply of heated air delivered to a first temperature area of the aircraft cabin such that a first specified temperature for the first temperature zone is achieved. When the valve arrangement fails, the first pressure control arrangement operates to control a pressure of heated air supplied into the first temperature area such that the first specified temperature for the first temperature zone is achieved.

Description:
TECHNICAL FIELD 
     The present invention relates in general to temperature control in an aircraft cabin. 
     BACKGROUND 
     Systems which extract hot exhaust air from turbines of an aircraft driving apparatus are generally employed for the control of temperatures in aircraft cabins. This hot air, referred to as driving apparatus tap air, is cooled down to a temperature desired in the aircraft cabin. In the case of aircrafts, whose cabins are divided into different temperature areas or climate zones, a portion of the hot air is cooled down to the lowest temperature of one or more temperature areas. In order to achieve higher temperatures in other temperature areas, a portion of the hot air is branched off before the cooling to the lowest temperature, is cooled to a lesser degree, thus brought to a temperature above the lowest temperature, and mixed with the air that has been cooled to the lowest temperature such that in these temperature areas the desired temperatures are achieved. With such a system, which is also known as the “Trim-Air System”, individually adjustable temperatures can be provided in the different temperature areas of an aircraft cabin. 
       FIG. 1  illustrates in simplified form such a known system  2  for temperature control in an aircraft cabin  4 . System-specific terms of components outlined below are respectively specified in brackets. 
     The aircraft cabin  4  is divided into two temperature areas  6  and  8  which comprise for example the right and left side, respectively, of the aircraft cabin  4 . Each temperature area  6 ,  8  is in turn divided into individual temperature zones. In  FIG. 4  four temperature zones  10  to  16  for the temperature area  6  and for the temperature area  8  four temperature zones  18  to  24  are exemplarily illustrated. 
     In order to indicate current temperatures prevailing in the temperature zones  10  to  24 , temperature sensors  26  to  40  (duct sensors) are used. The temperature sensors  26  to  40  are disposed in end areas (not shown) of air outlet ducts  42  to  56  (ducts), which serve for a supply of air into the temperature areas  6  and  8 . Moreover, further temperature sensors (not shown) are disposed in the aircraft cabin  4  itself in order to provide additional information about temperatures in the temperature zones  10  to  24 . 
     In each of the air outlet ducts  42  to  56  is disposed a valve  58  to  72  (trim-air valve). The valves  58  to  72  are controlled depending upon a currently prevailing temperature in a corresponding temperature zone  10  to  24 . Signals from the temperature sensors  26  to  40  are processed by a control device  74  (trim-air-system controller) in order to control the valves  58  to  72  such that in the temperature areas  6  to  8  and in the temperature zones  10  to  24 , respectively, desired temperatures are achieved and maintained, respectively. 
     The system  2  obtains heated air via two valves  76  and  78  (trim-air pressure regulating valve). Heated air supplied via the valve  76  is based on hot air from the driving apparatus on one side of the aircraft, while air supply via the valve  78  originates from the driving apparatus on the other side of the aircraft. 
     The valves  76  and  78  are pneumatically controlled valves, which are pre-adjusted such that relative to the internal pressure in the aircraft cabin  4  and to the internal pressures prevailing in the temperature areas  6  and  8  in the air ducts  80  and  82  (trim-air supply duct) a substantially constant pressure is maintained. The adjustment of the valves  76  and  78  is mechanically realized beforehand and cannot be varied during the flight. 
     In addition to the positions of the valves  76  and  78 , which positions are, variable in normal operation by means of pneumatic control, the valves  76  and  78  can be fully opened if extreme heating power is required to heat the aircraft cabin  4 . This is the case, for example, if the aircraft is to be heated rapidly before take off. 
     Heated air supplied via the valves  76  and  78  is guided via the air ducts  80  and  82  via areas  84  and  86  to the valves  58  to  72 . The areas  84  and  86  are comparable to manifold areas, which is why the areas  84  and  86  are also referred to as trim-air manifolds. Downstream from the valves  58  to  72  and upstream from the temperature sensors  26  to  40 , heated air supplied via the valves  76  and  78  is mixed with air having a temperature that corresponds with the lowest desired temperature for the temperature zones  10  to  24 . The components required for this are not shown in  FIG. 1 . 
     The air ducts  80  and  82  can be connected together via a valve  88  (trim-air shut-off valve), which is closed in normal operation. If for example the valve  76  or its air supply fails, valve  88  is opened in order to control, in addition to the temperature area  8 , the temperature of the temperature area  6  by way of heated air obtained via valve  78 . 
     Check valves  90  and  92  (trim-air check valve) are disposed in the air ducts  80  and  82  upstream from the areas  84  and  86  and downstream from the valves  76  and  78 , respectively. The valves  90  and  92  serve as blocking means in order to prevent reflux of air from the valves  76  and  78 . Should valve  88  be opened in the event of a malfunction, for example, of the valve  76 , the valve  90  prevents heated air supplied via valve  78  from reaching valve  76  and is consequently available for temperature control in the aircraft cabin  4 . 
     In view of the design of the system  2  for temperature control in two temperature areas  6 , 8  shown in  FIG. 1 , such a design is also referred to as a two-quadrant system. Should one of the valves  58  to  72  malfunction or fail completely it may no longer be possible to accomplish the temperature control in the corresponding temperature zones and potentially in the corresponding temperature area such that the temperatures desired there can be reached and maintained, respectively. 
     If, for example, valve  58  fails in a substantially fully opened state, it is possible that at least the temperature zone  10  becomes too warm. In case of a failure of the valve  58  in a substantially closed state, an undesirably intense temperature drop in the temperature zone  10  may occur. 
     In  FIG. 1 , the components of the trim-air system  2  used for the temperature area  6  represent the first quadrant, while the components serving the temperature area  8  represent the second quadrant. 
     To avoid this, in the event of a failure of one of the valves  58  to  72 , the heated air supply-serving valve  76 ,  78  of the corresponding quadrant is fully closed. Should for example the valve  58  (partly/fully) fail, the valve  76  is closed. Correspondingly, the valves  60  to  64  and thus also the temperature zones  12  to  16  are no longer supplied with heated air. A control of temperature in the temperature area  6  is then no longer possible. 
     A supply of the malfunction-free valves  60  to  64  with heated air from the valve  78  by opening the valve  88  is not achievable, because the malfunctioning valve  58  is then also supplied with heated air. It is precisely this, however, that should be avoided. 
     To avoid a too intense temperature drop or increase in the temperature area  6 , the minimum temperature of the air mixed in downstream from the valves  58  to  72  (i.e. the lowest temperature zone temperature) can be increased or lowered. In this case a compromise between temperatures in the temperature areas  6  and  8  must be arrived at to avoid on the one hand passengers in the temperature area  8  from being subjected to too high temperatures and on the other hand passengers in the temperature area  6  from being subjected to too low temperatures. 
     The object of the present invention is to provide solutions, which provide an improved temperature control in a room, and particularly to solve the problems of the state of the art named above. 
     SUMMARY 
     This object is achieved by the present invention by way of the device and the method that are defined in the following description and claims. 
     The device according to the invention for temperature control in an aircraft cabin comprises a first supply control arrangement for control of the supply of heated air from a first source into a first temperature area of the aircraft cabin depending on a first temperature specified for the first temperature area and a first pressure control arrangement for the control of a current pressure in the first supply control arrangement in the event of a malfunction of the first supply control arrangement depending on the specified first temperature. 
     In normal operation of the device according to the invention, the temperature control is carried out by controlling the supply of heated air from the first source such that in the first temperature area the specified first temperature is achieved and maintained, respectively. In the case of a malfunction of the first supply control arrangement, the temperature-dependent supply control of heated air from the first source is replaced by the control of the pressure in the first supply control arrangement by means of the first pressure control arrangement. In this case, the air pressure control is such that also in the first temperature area the specified first temperature is achieved and maintained, respectively. 
     Malfunction of the first supply control arrangement is to be understood as any operating status, in which, by means of the supply control, the temperature control in the first temperature area cannot be realized in the desired manner. This can occur not only if the supply control itself fails but also if the supply control is not suitable to achieve or maintain the specified first temperature. The latter may be the case, for example, if in the first temperature area the current actually prevailing supply-controlled temperature deviates by a maximum admissible value from the specified first temperature. 
     The first supply control arrangement is preferably further provided for the control of the supply of heated air from the first source into a second temperature area of the aircraft cabin, wherein this control is realized depending upon a specified second temperature for the second temperature area. In this manner, at least in normal operation, a separate temperature control can take place for different temperature areas of the aircraft cabin based on air used for both temperature areas, namely heated air from the first source. Since the supply-controlled temperature adjustment of the first and second temperature areas can be realized in general independently of one another, the first and second temperatures can differ although heated air from the first source is used for both temperature areas. 
     In the case of a malfunction of the first supply control arrangement, is indented to achieve, depending on the specified second temperature, by means of the first pressure control arrangement the temperature control by control of a current pressure in the first supply control arrangement depending on the specified second temperature. This pressure-controlled temperature control in the aircraft cabin is particularly beneficial in the event that the first supply control arrangement comprises different components for a supply of heated air from the first source into the first temperature area and the second temperature area. Should the malfunction of the first supply control arrangement relate to the second temperature area, the second temperature area can be temperature-controlled comparably with respect to normal operation depending on the specified second temperature by means of the pressure control. As described in greater detail below, there is no requirement that the supply-controlled temperature control of the first temperature area be replaced by a pressure control. 
     The device according to the invention can also comprise a second supply control arrangement for the control of a supply of heated air from a second source into a third temperature area of the aircraft cabin depending on a third temperature specified for the third temperature area and a second pressure control arrangement in order to control, depending on the specified third temperature, a current pressure in the second supply control arrangement in the event of a malfunction of the second supply control arrangement. 
     The above descriptions with respect to the supply-controlled temperature control in normal operation and the pressure-controlled temperature control in the event of a failure apply here accordingly. 
     The use of the second supply control arrangement and the second pressure control arrangement enables the design of a two-quadrant system with respect to the aircraft cabin, wherein the aircraft cabin is supplied at least in normal operation via two supply control arrangements and/or two pressure control means. 
     Preferably, the second supply control arrangement serves for the control of a supply of heated air from the second source into a fourth temperature area of the aircraft cabin depending on a specified fourth temperature for the fourth temperature area, wherein, in the event of a malfunction of the second supply control arrangement, the second pressure control means arrangement serves to control a current pressure in the second supply control arrangement depending on the specified fourth temperature. The above descriptions also apply accordingly in this case. 
     The embodiment of the device according to the invention for temperature control in four temperature areas of the aircraft cabin permits a design of a four-quadrant-system in order to control, at least in normal operation, four different areas of the aircraft cabin separately with respect to desired temperatures. 
     In the case of a malfunction of one of the supply control arrangements for one of the four temperature areas, the affected temperature area can be maintained at the corresponding temperature by pressure control. The not-affected temperature areas can continue to be temperature-controlled via a supply control of heated air as described in more detail below. 
     It is furthermore intended that the device according to the invention can comprise further supply control arrangements comprising the features and functions cited above and further pressure control arrangements associated to said further supply control arrangements also comprising the features and functions cited above in order to supply more than four room temperature areas. 
     Irrespective of the number of supply control arrangements and pressure control arrangements and/or the number of temperature areas, it can be prevented by means of the device according to the invention that, in the event of an error affecting a temperature area, the temperature control of this area must be terminated. Rather, even the temperatures of the affected temperature area(s) in the event of a malfunction can continue to be controlled, namely by pressure control. 
     In the case of the following further preferred embodiments, reference is generally made to one supply control arrangement, one temperature area, one pressure control arrangement etc. Depending on the number of provided supply control arrangements, temperature areas, pressure control arrangements etc., the following descriptions apply to the first supply control arrangement and/or the second supply control arrangement, the first temperature area and/or the second temperature area and/or the third temperature area and/or the fourth temperature area, the first pressure control arrangement and/or the second pressure control arrangement etc. 
     The supply control arrangement preferably comprises an air intake, which is coupled with the pressure control arrangement provided for the supply control arrangement, an air outlet, which is coupled with the temperature area(s) serviced by the supply control arrangement, and an air duct, in order to supply the respective air between the air intake and the air outlet. 
     When at least one of the temperature areas is divided into temperature zones, for which a separate temperature control shall be possible, the air outlet of the supply control arrangement that is appropriate for this temperature area comprise air outlet ducts in order to supply the different temperature zones with heated air. 
     Preferably, the control of the supply of air to a temperature area is accomplished by means of a valve arrangement included in the supply control arrangement provided for this temperature area. In this case the valve arrangement can be disposed at the corresponding air outlet in order to supply temperature-dependently controlled heated air to the corresponding temperature area. 
     In the event that air outlet ducts are used for the supply of different temperature zones, the valve arrangement for each air outlet duct can incorporate a valve. In order to a detect a malfunction of a supply control arrangement, the device according to the invention may comprise at least one operating status detecting arrangement associated to a supply control arrangement. Information about the operating status of the supply control arrangement(s) can also be provided by devices or arrangements separate with respect to the device according to the invention, which separate devices or arrangements are connected in accordance with the respective supply control arrangement and/or the device according to the invention. 
     Preferably, the at least one operating status detecting arrangement serves for the purpose of detecting of a current operating status of the corresponding valve arrangement and/or, where present, corresponding valves. 
     The device according to the invention can comprise at least one pressure detecting arrangement associated to a pressure control arrangement in order to detect the current air pressure in the corresponding supply control arrangement. The use of a pressure detecting arrangement permits the use of a pressure controlled valve as pressure control arrangement associated thereto, which pressure controlled valve, for example, in normal operation can be differently controlled from preliminary settings. A pressure detecting arrangement further supplies the corresponding pressure control arrangement in the event of a malfunction of the allocated supply control arrangement with information about currently prevailing pressures in this supply control arrangement without the use of separate pressure detecting systems. 
     In the case of the use of the first supply control arrangement and the second supply control arrangement, is contemplated to use a connecting arrangement in order to enable a selective connection of the supply control arrangements. 
     When the device according to the invention is provided, for example, for the supply of the first temperature area and of the second temperature area, it is possible to establish a connection between the first supply control arrangement and the second supply control arrangement by means of the connecting arrangement. Should one of the pressure control arrangements malfunction in normal operation, the other pressure control arrangement supplies both supply control arrangements. Using of the device according to the invention for more than two temperature areas permits that the connecting arrangement ensures the continued temperature controlled heating and/or cooling of the temperature areas not affected by the malfunction, by connecting the first supply control arrangement and the second supply control arrangement with each other such that the unaffected temperature areas are serviced by a pressure control arrangement. The temperature area affected by the malfunction can then be pressure-controlled maintained at the respective temperature by the other pressure control arrangement. 
     The device according to the invention preferably comprises at least one shut-off arrangement associated to a supply control arrangement in order to prevent airflow upstream in the direction from the respective temperature area to the corresponding pressure control arrangement. This embodiment is particularly beneficial in the event that the connecting arrangement is provided in order to prevent airflow from the pressure control arrangement, which serves for a supply of unaffected temperature areas, to the other pressure control arrangement and particularly pressure changes resulting from this event, which pressure changes hinder or prevent a pressure-controlled temperature control in the affected temperature area. In normal operation, the at least one shut-off arrangement can prevent damages to the corresponding pressure control arrangement, for example, in the case of a pressure drop in the aircraft cabin. 
     The above explanations with respect to the device according to the invention apply correspondingly to the method according to the invention for controlling temperature in an aircraft cabin. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following refers to preferred embodiments with reference to the figures included: 
         FIG. 1  is a schematic illustration of a known system for temperature control in an aircraft cabin, 
         FIG. 2  shows a device according to the invention provided for one temperature area for temperature control in an aircraft cabin (single-quadrant system), 
         FIG. 3  shows a device according to the invention provided for two temperature areas comprising a pressure control arrangement for temperature control in an aircraft cabin, 
         FIG. 4  shows a device according to the invention provided for two temperature areas comprising two pressure control arrangements for temperature control in an aircraft cabin (two-quadrant system), and 
         FIG. 5  shows a device according to the invention provided for four temperature areas for temperature control in an aircraft cabin (four-quadrant system). 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an embodiment of a system  102  for temperature control in an aircraft cabin  104 , particularly in a temperature area  106  of the aircraft cabin  104 . 
     The temperature area  106  is divided into individual adjacently disposed temperature zones  110  to  124 . Temperature sensors  126  to  140  serve to detect the current prevailing temperatures in the temperature zones  110  to  124 . The temperature sensors  126  to  140  are disposed in outlet areas of air outlet ducts  142  to  156  via which the heated air is supplied to the temperature zones  110  to  124 . 
     In order to control the supply of heated air in the temperature zones  110  to  124 , valves  158  to  172  are respectively disposed in the air outlet ducts  142  to  156 . Based on signals/data of the temperature sensors  126  to  140 , a controller  174  controls the valves  158  to  172  such that a specified temperature for the temperature area  106  is achieved. 
     Heated air originating from one or a plurality of turbines of the aircraft drive (i.e., a first source  300  of heated air) is supplied via a pressure-controlled valve  176 . The valve  176  is pressure-controlled and serves as a pressure control arrangement for air pressure in an air duct  180 , which is connected with the valve  176  by an air intake  181  and comprises an area  184 , which is connected with the air outlets  142  to  156 , in order to supply heated air supplied via valve  176  via the valves  158  to  172  to the temperature zones  110  to  124 . 
     Downstream from the valve  176 , a pressure sensor  177  is disposed in the air duct  180  for detecting the current prevailing pressure in the said air duct. Downstream from the pressure sensor  177  is disposed a shut-off arrangement  190  embodied as a check valve. The check valve  190  permits airflow in the direction from the valve  176  to the valves  158  to  172 ; the check valve  190  prevents airflow in the opposite direction. 
     The controller  174 , which receives information from the pressure sensor  177  about the current prevailing air pressure, also controls the valve  176 . 
     In normal operation the valve  176  is actuated by the controller  174  depending on pressures present in the air duct  180  such that in the air duct  180  a constant pressure relative to a current prevailing pressure in the aircraft cabin  104  is maintained. As opposed to the prior art system described at the outset, in normal operation the pressure controlled valve  176  is permitted to vary such that the desired pressure in the air duct  180  is controlled relative to the internal pressure in the aircraft cabin  104 . 
     In normal operation, the temperature of the temperature area  106  is controlled by detecting, by means of the temperature sensors  126  to  140 , information about the prevailing temperatures in the temperature zones  110  to  124  and by closing or opening the valves  158  to  172  (to a sufficient degree) by the controller  174  to an extent to achieve the desired temperature for the temperature area  106 . In addition to the illustrated temperature sensors  126  to  140 , further temperature sensors can be used in temperature area  106 , for example, associated to the temperature zones  110  to  124  (not shown) in order to obtain additional information about current prevailing temperatures in the temperature area  106  and/or the temperature zones  110  to  124 . 
     In the event of a malfunction of one or a plurality of the valves  158  to  172 , it can be possible that, at least for the affected temperature zone(s), it is no longer possible to achieve and/or maintain the desired temperature via a valve-controlled air supply regulation. It is intended that the pressure-controlled temperature control of the temperature area  106  described below is not brought about in the case of every valve error. Should one of the valves  158  to  172  malfunction but an acceptable supply-controlled temperature control of the temperature area  106  is nevertheless possible within specified limits, the system  102  can be operated as in normal operation (i.e. no valve malfunction) if also with a certain loss of comfort in temperature area  106 . In the case of a valve error, which permits no supply-controlled temperature control in temperature area  106 , the system  102  is operated such that the supply control of the temperature in temperature area  106  is replaced by a pressure control. 
     Should, for example, valve  158  fail in a fully or nearly fully open state and remain blocked in this state, the associated temperature zone  110  will be subjected to too high heating power due to a too high supply of heated air. A supply-controlled temperature control in the temperature zone  110  is then no longer possible. In the event that the malfunction of the valve  158  is detected by an operating status detecting arrangement  310 , the supply-controlled temperature control of the temperature area  106  is deactivated and replaced by a pressure-control temperature control. 
     In order to prevent too high temperatures arising in the temperature zone  110  due to the (too widely) opened valve  158 , the valve  176  is controlled such that the prevailing pressure in the air duct  180  is lowered to a value that reduces the air quantity supplied via valve  158  to the temperature zone  110  such that the desired temperature is achieved there. In this case, by means of the temperature sensors  126 , it is checked as to whether the desired temperature for the temperature zone  110  is being achieved. Unless it is affected by the malfunction, the valve  176  is controlled such that a further pressure drop in the air duct  180  and thus a further reduction of the air supplied via the valve  158  is brought about. Once the desired temperature for the temperature zone  110  is achieved, the pressure in the air duct  180  is maintained and/or controlled by means of a corresponding controller of the valve  176  such that is the desired temperature for the temperature zone  110  can be maintained. 
     In order to maintain the corresponding temperatures in the unaffected temperature zones  112  to  124 , the non-malfunctioning valves  160  to  172  are controlled such that the amount of heated air reaching temperature zones  112  to  124  via these valves is sufficient to achieve and/or to maintain the corresponding temperature zone temperatures. In the case of the malfunction assumed here, the pressure in the air duct  108  is lowered. Correspondingly, the valves  160  to  172  are opened further in order to compensate for the lowered supply pressure and to supply the temperature zones  112  to  124  with corresponding heating power. 
     Should, for example, the valve  158  fail in a nearly closed state, the heating power provided by the quantity of air flowing through this valve is no longer sufficient to maintain the desired temperature for the temperature zone  110 . In this case, the supply-controlled temperature control of the temperature area  106  is terminated and is replaced by a pressure-controlled temperature control. In this case, the valve  176  is operated such that a pressure increase in the air duct  180  is brought about such that, despite the state of the valve  158 , sufficient air passes through it in order to control the temperature in the zone  110  in the desired manner. In order to prevent too high temperatures in the temperature zones  112  to  124  supplied by non-malfunctioning valves  160  to  172 , these valves are closed far enough to compensate for the increased supply pressure so that the desired temperatures can be achieved in these zones. 
     Should it be determined in the event of such a malfunction on the basis of information detected by the temperature sensor  126  that a pressure increase in the air duct  180  does not lead to the desired temperature increase for the temperature zone  110 , is it is intended to cease further pressure increase via the valve  176 . This thereby avoids pressures in the air duct  180  that do not provide in the desired manner for a temperature control in the temperature zone  110  and which could lead to damages. 
     Should the valve  158  fail in a fully closed state, the supply-controlled temperature control of the temperature area  106  can be maintained or removed by pressure-controlled temperature control. Since in the event of such a malfunction there can be no further air supply through the valve  158  in the temperature area  106 , a separate temperature control for the temperature area  110  is not possible. In order to achieve and/or maintain the respectively desired temperatures in the unaffected temperature zones  112  to  124 , the valves  160  to  172  can be controlled as in normal operation. Due to the closed valve  158  a pressure increase is brought about in the air duct  180 . Correspondingly, too high temperatures in the unaffected temperature zones  112  to  124  are avoided by controlling the valves  160  to  172  such that less heated air passes through these valves. Alternatively, it is intended to also replace the supply control by a pressure control, wherein in this case the valve  176  is controlled for the purpose of compensating for the pressure increase caused due to the failure of the valve  158 . 
     The embodiment shown in  FIG. 3  differs from the embodiment shown in  FIG. 2  in that the aircraft cabin comprise  104 , along with the temperature area  10 , a temperature area  108 , which is divided into temperature zones  194  to  208 . For the purpose of supplying the temperature zones  194  to  208 , air outlet ducts  212  to  226  are provided, wherein are respectively disposed valves  228  to  242 . In the air escape ducts  212  to  226  are respectively disposed, not shown here sensors, which are comparable with the sensors  158  to  172 . The air outlet ducts  212  to  226  are connected to an air duct  182 . The air duct  182  comprises a check valve  192  and an air intake  183  via which the air from the valve  176  is supplied. To detect the pressure in the air duct  182 , a pressure sensor  177  is disposed downstream from the valve  176 . The above explanations taking into account  FIG. 2  correspondingly apply here for all features and functions of the embodiment in accordance with  FIG. 3 . This applies particularly for the normal operation, wherein temperature control of the temperature areas  106  and  108  is supply-controlled, and in the event of malfunction, wherein the temperature control for temperature area affected by the malfunction is pressure controlled. 
     Technical Field 
     In the case of the embodiment illustrated in  FIG. 4 , the system  102  serves for temperature control in an aircraft cabin  104  with two temperature areas  106  and  108 . This system  102  can be described as a two-quadrant system since the temperature areas  106  and  108  can be operated as areas with separate temperature control. The temperature area  106  comprises temperature zones  110  to  116 , which are supplied with heated air via air outlet ducts  126  to  132 , valves  142  to  148 , an air duct  180 , a check valve  109 , an air outlet  181  and a valve  176  serving as a pressure control arrangement, the valve  176  communicating with the first source  300  of heated air. The temperature area  108  comprises temperature zones  118  to  124 , which are supplied via air outlet ducts  134  to  140  and valves  150  to  156  and an air duct  182  and a check valve  192  and an air outlet  183  and further valve  178 , which serves as a further pressure control arrangement and is communicating with a second source  301  of hot air. For the purpose of pressure detecting, in the air duct  180  and  182  pressure sensors  177  and  179  are provided, which are associated to the pressure control arrangement  176  and/or  178 . Information about temperatures in the temperature areas  106  and  108  is obtained by means of temperature sensors  126  to  132  and/or  134  to  140 . 
     The air ducts  180  and  182  are connectable via a valve  188 . In normal operation, the valve  188  is closed. Therefore, the components of the system  102  that are used for the temperature area  106  are operated independently of the components of the system  102  that are responsible for the temperature area  108 . Also in the event that one of the valves  158  to  164  and/or  166  to  172  malfunctions, the valve  188  remains closed; thus also in the event of a valve malfunction, the system  102  can be operated respectively separately for the temperature area  106  and the temperature area  108 . The above explanations with reference to  FIG. 2  therefore also apply accordingly for the normal and malfunction cases described there both for the components of the system  102  for the temperature area  106  and for the components of the system  102  for the temperature area  108 . 
     In the case of a malfunction of the valve  176  or  178 , the corresponding temperature area  106  and/or  108  can no longer be supplied. In such a case, the valve  188  is opened in order to conned the air ducts  180  and  182  to one another. Should, for example, the valve  176  fail and if the valve  188  is open, both the temperature area  106  and the temperature area  108  are supplied via valve  178 . The check valve  190  prevents air supplied via valve  178  from reaching damaging or causing a loss of pressure at the valve  176 . By the closure of the air duct  180  by means of the check valve  190  is brought about an arrangement, which is comparable with the embodiment from  FIG. 2 , namely a system with a pressure generating arrangement  178  for temperature control in the whole aircraft cabin  104 . Correspondingly also in those cases wherein the valve  188  is open and the temperature areas  106  and  108  are supplied via one of the valves  176 , 178 , in the event of malfunctioning supply-controlled temperature control this is replaced as described above with a pressure-controlled temperature control. 
     The embodiment illustrated in  FIG. 5  of a system  102  serves to supply four temperature areas  106 , 108 , 107  and  109 . The system  102  from  FIG. 5  can be described as a four-quadrant system since the temperature areas  106  to  109  can be operated as areas with separate temperature control. 
     The temperature area  106  comprises temperature zones  110  to  116 , which are supplied with heated air via air outlet ducts  126  to  132 , valves  142  to  148 , an air duct  180 , a check valve  109 , an air outlet  181  and a valve  176 , which serves as a pressure control arrangement. The temperature area  108  comprises temperature zones  118  to  124 , which are supplied with heated air via air outlet ducts  134  to  140 , valves  150  to  156 , an air duct  182 , a check valve  192 , an air outlet  183  and a valve  178 , which serves as a pressure control arrangement. 
     The temperature area  107  comprises temperature zones  194  to  200 , which are supplied with heated air via air outlet ducts  212  to  218 , valves  228  to  234 , an air duct  244 , a check valve  246 , an air outlet  245  and also via the valve  176 . The temperature area  109  comprises temperature zones  202  to  208  that are supplied with heated air via air outlet ducts  220  to  226 , valves  236  to  242 , an air duct  248 , a check valve  250 , an air outlet  249  and also via the valve  178 . 
     For the detecting of pressure, pressure sensors  177  and  179  are provided in the air ducts  180 ,  244  and  182 ,  248 , which pressure sensors  177  and  179  are the pressure control arrangement  176  and/or  178 . Information about temperatures in the temperature areas  106  and  108  is obtained by means of temperature sensors  126  to  132  and/or  134  to  140 ; accordingly temperature sensors provided for the temperature areas  107  and  109  are not shown. 
     The air ducts  108  and  182  are connectable via a valve  188 . In normal operation the valve  188  is closed. The air ducts  244  and  248  are also connected via a valve  252 , which is also closed in normal operation. In normal operation, the in temperature areas  106  to  109  are supply-controlled temperature-controlled by means of the corresponding components of the system  102 . In the case of a malfunction of the valve  176  or  178 , the corresponding temperature areas  106 , 107  and/or  108 , 109  can no longer be supplied. In such a case, the valves  188  and  252  are opened in order to connect the air ducts  180  and  182  and the air ducts  244  and  248  to one another. Should, for example, the valve  176  fail and should the valves  188  and  252  be open, the supply of all temperature areas  106  to  109  is brought about via valve  178 . The check valves  190  and  246  prevent air supplied via the valve  178  from reaching the valve  176 . By the closure of the air ducts  180  and  244  by means of the check valve  190  and/or  246  is brought about an arrangement, which is comparable with the embodiment from  FIG. 3 , namely a system having a pressure generating arrangement  178  for controlling temperature in the whole aircraft cabin  104 . Should a malfunction of the supply-controlled temperature control arise during such an operation, this is replaced by a pressure-controlling temperature control provided by a valve used for the supply of the temperature areas  106  to  109 . 
     Should a malfunction of the supply-controlled temperature control of the temperature areas  106  to  109  arise in normal operation (valves  188  and  252  are closed, the supply-controlled temperature control is replaced for the temperature area affected by the malfunction by a pressure-controlled temperature control. 
     Should, for example, the valve  158  malfunction, the temperature control of temperature area  106 , as described above in detail with reference to  FIG. 1 , is realized by pressure-control. Should the valves  188  and  252  remain closed, as described with reference to  FIG. 3 , the temperature area  107  is also supplied with heated air by means of pressure control. 
     In order to continue supply-controlled supply of the temperature area  107  not immediately affected by the malfunction of the valve  158 , valve  252  is opened. This permits the temperature area  107  to be supplied with heated air via the valve  178 . In the case of this procedure, it is to be taken into account that the prevailing pressure in the air ducts  182 ,  244  and  248  is to be higher than the pressure in the air duct  180  in order to keep the valve  246  closed. The closed valve  246  separates those areas of the system  102  that are operated for a pressure-controlled temperature control from those areas that serve for a supply-controlled temperature control. 
     Should a pressure reduction be necessary in the event of the here supposed malfunction of the valve  158 , the system  102  with respect to the temperature areas  107 , 108  and  109  can be operated in a substantially unchanged supply-controlled manner because the valve  178 , as in normal operation wherein valves  188  and  252  are closed, provides for a relatively constant pressure in the air ducts  182 ,  244  and  248 . 
     Should the malfunction of the valve  158  necessitate a pressure increase in the air duct  180 , the pressure in the air ducts  182 ,  244  and  248  is to be reduced until it is lower than the pressure in the air duct  180 . For this purpose, the valve  178  is accordingly controlled wherein the supply control of the valves  150  to  156 ,  228  to  234  and  236  to  242  is adjusted to the reduced pressure. 
     Should it be determined in the event of a pressure-controlled temperature control that a pressure increase in the corresponding air duct does not lead to a desired temperature increase for the affected temperature zone, is intended to cease further pressure increase via the valve employed for this purpose. Thus, pressures are avoided in the corresponding air duct, which do not provide in the desired manner for a temperature control in the affected temperature zone and which could lead to damages.