Abstract:
A rail vehicle includes a graywater line which is in communication with the surroundings of the rail vehicle directly or by way of a collecting container. The graywater line is equipped with a pressure protection valve, which protects a graywater line section upstream of the pressure protection valve from pressure surges occurring in the surroundings of the rail vehicle. The pressure protection valve is constructed as a pinch valve which is controlled by a control device in order to protect the graywater line section from pressure surges.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a rail vehicle having a graywater line, which is connected to an area surrounding the rail vehicle directly or via a collection container, wherein the graywater line is equipped with a pressure protection valve, which protects a segment of the graywater line upstream of the pressure protection valve from pressure surges occurring in the area surrounding the rail vehicle. 
     Particularly in high-speed trains, a pressure tight passenger compartment plays a significant role: while the train is in motion, differences between an ambient pressure and a car interior pressure can occur, especially when traveling through tunnels or when encountering other trains, and these produce pressure fluctuations in the passenger compartment that should be avoided for reasons of comfort. Any lack of leaktightness in the car through which pressure surges can propagate in the vehicle should therefore be avoided. 
     For reasons of design, however, it is not possible to avoid all openings in a rail vehicle, for which reason special pressure protection solutions have to be installed at the locations concerned. 
     One of these openings is the graywater line leading to the collecting container for the sanitary equipment. The graywater line connects the outlet from a hand-wash basin of the sanitary equipment to the collecting container of the rail vehicle, for example. In high-speed trains, for example, the collecting container is arranged outside the passenger compartment, in the underfloor region. It has an overflow line, and there is therefore a continuous open connection to the surrounding area. 
     Embodiments of rail vehicles in which the graywater line from the hand-wash basin does not lead to a collecting container but directly to the outside in order to take the graywater directly onto the track are also known. In this case too, there is a connection between the area surrounding the rail vehicle and, via the graywater line, the interior thereof. 
     It is therefore possible for an excess pressure surge to propagate through the wastewater container or directly through the graywater line as far as the hand-wash basin and hence into the interior of the rail vehicle or for a vacuum at this location to suck air out of the rail vehicle. The graywater line must therefore be provided with a pressure protection solution which, however, does not prevent the graywater from draining away. 
     In order therefore to allow pressure protection for the interior of the rail vehicle and to allow graywater to drain away, the graywater line is fitted with a valve. DE 10 2008 007 748 A1, for example, discloses a duckbill valve, which consists of a specially molded rubber element installed in the graywater line. The design is such that the rubber element ends with flat mutual contact. If this element is subjected to a load by water from its upstream side, the weight of the water pushes the element apart, allowing the water to drain away. An excess pressure surge occurring upstream does not allow this valve to open. On the contrary, an excess pressure merely presses the element more tightly together, thus preventing pressure from being transmitted in the direction of the interior of the rail vehicle in an effective manner. 
     This embodiment of a valve operates passively and, by virtue of its design, does not close the opening permanently or absolutely. 
     BRIEF SUMMARY OF THE INVENTION 
     On this basis, it is the underlying object of the invention to develop the rail vehicle mentioned at the outset in such a way that better security against pressure surges in the area surrounding it is made possible. 
     This object is achieved by virtue of the fact that the pressure protection valve is designed as a pinch valve, which is controlled by a control device in order to protect the segment of the graywater line from pressure surges. 
     In this way, the valve which serves to protect the upstream segment of the graywater line is actively controlled, thereby improving protection from external pressure surges in an effective manner. 
     According to a preferred embodiment, it is envisaged that the control device opens or closes the pinch valve in accordance with actuation of a water consumer connected to the graywater line, said actuation being detected by means of a sensor. For example, actuation of a water tap on a hand-wash basin can be detected with the aid of a sensor. When this sensor outputs a signal which represents actuation of the water tap, this signal is transmitted to the control device for the pinch valve, with the result that the pinch valve, which can otherwise be permanently closed, is opened. 
     The control device can control the pinch valve in accordance with a signal coming from the train control system of the rail vehicle, for example. Such a signal indicates whether a pressure surge is to be expected from the area surrounding the rail vehicle or whether a general operating situation of the rail vehicle is such that there is a high probability of pressure surges. For example, the signal coming from the train control system can be a speed signal and can be evaluated by the control device for the pinch valve in such a way that exceeding of a threshold value for the speed signal prevents opening of the pinch valve. This is based on the fact that high speeds entail an increased probability of pressure surges, and therefore the pinch valve should advantageously be closed at these speeds. 
     To indicate a pressure surge, it is also possible to exploit the fact that, in some embodiments of rail vehicles, a pressure surge signal which controls pressure protection flaps of an air-conditioning system and closes said flaps when required is generated. This pressure surge control signal can be used to close the pinch valve by means of the control device if a pressure surge occurs. 
     The control device can open or close the pinch valve in accordance with a pressure surge detected by means of a pressure sensor. For this purpose, the graywater line or the collecting container for graywater can be fitted with the pressure sensor for detecting a pressure surge, wherein the pressure sensor is arranged downstream of the pinch valve or, in other words, on an outward-directed side of the pinch valve. 
     A signal generated by the sensor, which indicates the presence of a pressure surge, is passed to the control device for the pinch valve, which thereupon closes the pinch valve. This can also apply, for example, when a sensor on a water tap indicates the actuation thereof, as explained above. The resulting procedure here is such that the avoidance of penetration of a pressure surge into the interior of the vehicle always takes precedence over rapid drainage of graywater. 
     The control device for the pinch valve can control a further pinch valve, which is connected in series with the pinch valve, wherein the control device controls the two pinch valves in such a way that at least one of the pinch valves is always closed. This ensures that the graywater line is always closed by at least one of the two pinch valves provided, and therefore reverse surges cannot act on the interior of the rail vehicle. To drain graywater, the pinch valves can be alternately opened and closed. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       Illustrative embodiments of the invention are explained in greater detail below with reference to the drawings. In the figures, functionally identical components are denoted by the same reference signs. In the drawings: 
         FIG. 1  shows a schematic view of a sanitary arrangement in a rail vehicle in a first embodiment, 
         FIG. 2  shows a schematic view of a sanitary arrangement in a rail vehicle in a second embodiment, 
         FIG. 3  shows a schematic view of a sanitary arrangement in a rail vehicle in a third embodiment, 
         FIG. 4  shows a schematic view of a sanitary arrangement in a rail vehicle in a fourth embodiment, and 
         FIG. 5  shows a schematic view of a sanitary arrangement in a rail vehicle in a fifth embodiment. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     In the embodiment according to  FIG. 1 , a water tap  1  is illustrated, which can be opened by means of an actuation sensor  2  and is supplied with fresh water via a water feed line  3 . Graywater is collected in a wash basin  4 , which can be regarded as a water consumer together with the water tap  1 , and leaves said wash basin via a graywater line  5 . A pneumatically controllable pinch valve  6  is provided at the downstream end of said line. A control device  8  for the pinch valve controls the opening and closing movements of said valve via a control line  7 . 
     When the pinch valve  6  is opened, graywater initially flows as far as a car body wall  9 , namely via an outlet line  10 , which extends from the pinch valve  6  to the car body wall  9 . The graywater is finally carried away via an outlet line  11  outside the rail vehicle, which is connected to the outlet line  10 . 
     The pinch valve  6  is controlled in such a way by means of the control device  8  that it is fundamentally held closed, preventing pressure surges which occur in the area surrounding the rail vehicle from propagating into the interior of the rail vehicle. However, the control device  8  is connected to the actuation sensor  2  for the water tap  1  via a control line  12 . When the actuation sensor  2  indicates actuation of the water tap  1 , the control device  8  opens the pinch valve for a period of time which allows the graywater to drain away completely. 
     In the embodiment illustrated in  FIG. 2 , the version of  FIG. 1  is supplemented inasmuch as the control device  8  for the pinch valve  6  is additionally connected to a signal source  13 , which indicates via a control line  14  a pressure surge to be expected. The signal source  13  can be a train control system of the rail vehicle, for example. In the train control system, it is possible, for example, to generate a control signal which represents a speed of the rail vehicle. Since it can be assumed that an increased speed also entails an increased probability of the occurrence of pressure surges, the speed signal coming from the train control system via control line  14  can be evaluated in such a way that speeds above a speed threshold value entail closure of the pinch valve  6 . Here, the signal coming via control line  14  from the signal source  13 , which indicates a pressure surge to be expected, has priority over the signal which passes from the actuation sensor  2  for the water tap  1  via control line  12  to the control device  8  for the pinch valve  6 . In other words, the pinch valve  6  remains closed even if actuation of the water tap  1  is indicated but an imminent pressure surge is simultaneously indicated by the signal source  13 . 
       FIG. 3  then shows an embodiment in which the control device  8  is connected to a separate pressure sensor  16  for indicating a pressure surge via a signal line  15 . The pressure sensor  16  is situated downstream of the pinch valve  6 , in particular on the other side of the car body wall  9 , on an external side of the rail vehicle. As soon as the pressure sensor  16  detects a pressure surge, this surge is indicated to the control device  8 , which thereupon closes the pinch valve  6 . The pinch valve  6  can remain open as long as the pressure sensor  16  is not indicating the occurrence of a pressure surge. 
     The embodiment according to  FIG. 4  differs from that according to  FIG. 3  in that the pressure sensor  16  is provided on a collecting container  17  for graywater. To this extent, the embodiment according to  FIG. 3  relates to the application in which the pressure sensor  16  is arranged in the outlet line  11  for the purpose of detecting a pressure surge, wherein the outlet line  11  opens directly onto a track. In the embodiment according to  FIG. 4 , the graywater which is discharged via the outlet line  11  is collected in the collecting container  17 , which is emptied at a later time. 
     Although no signal connection between the actuation sensor for the water tap  1  and the control device  8  is shown in the embodiments according to  FIGS. 3 and 4 , additional indication of the actuation state of the water tap  1  for the control device  8  would also be possible in the embodiments according to  FIGS. 3 and 4 . 
     Another embodiment, in which two pinch valves  61 ,  62  are arranged in series downstream of the wash basin  4  and are each in signal communication with the control device  8 , is illustrated by means of  FIG. 5 . As in the embodiments according to  FIGS. 1 and 2 , the control device  8  is connected to the actuation sensor  2  for the water tap  1  via control line  12 . The control device  8  controls the pinch valves  61 ,  62  in such a way that one of the two pinch valves  61 ,  62  is closed in each case. If, for example, the hand-wash basin  4  is used, pinch valve  62 , which is closer to the hand-wash basin  4  than pinch valve  61 , is first of all opened by means of the control device  8 , with the result that the graywater collects ahead of the closed pinch valve  61 . Pinch valve  62  is then closed and pinch valve  61  is opened, allowing the graywater to leave the rail vehicle via the outgoing line  11 . Since one of the two pinch valves  61 ,  62  is always closed, penetration of a pressure surge into the interior of the rail vehicle is prevented in an effective manner.