Abstract:
A rail vehicle ( 10 ) with fuel consumers ( 20, 22, 30, 32, 34 ) and an on board fuel storage and supply system, characterised by a main fuel tank ( 24 ) adapted to be installed in a first railcar ( 12 ) of the rail vehicle ( 10 ), a buffer fuel tank ( 36 ) adapted to be installed in a second railcar ( 14 ) of the rail vehicle ( 10 ), and a fuelling device ( 38 ) for transferring fuel from the main fuel tank ( 24 ) to the buffer fuel tank ( 36 ). 
     Preferred application to internal combustion engine rail vehicles with multiple railcars equipped with multiple diesel engines.

Description:
[0001]    This claims the benefit of European Patent Application EP 13305420.5, filed Mar. 29, 2013 and hereby incorporated by reference herein. 
         [0002]    The present invention relates to a rail vehicle with fuel consumers and an on board fuel storage and supply system and to a method for storing and supplying fuel in a rail vehicle. 
       BACKGROUND 
       [0003]    A rail vehicle with on board fuel storage and supply is known from EP 1 847 413 B1. Here, a diesel engine and heater are supplied with fuel via supply lines from an onboard fuel tank. 
         [0004]    The drawback of this known solution, in particular when it is used in motor train sets with multiple railcars, is its inefficient use of available installation space. Said solution takes up most of the installation space, which is no longer available for other components of the rail vehicle, such as additional driving units. 
         [0005]    Document U.S. Pat. No. 5,566,712 provides a further example of a known rail vehicle with on board fuel storage and supply system. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an object of the present invention to provide a rail vehicle with an on board fuel storage and supply system and corresponding method that allow for better use of installation space available on the rail vehicle. 
         [0007]    The present invention provides a rail vehicle including a first railcar, a second railcar, fuel consumers and an on board fuel storage and supply system characterised in that: 
         [0008]    the first railcar has first fuel consumers and a main fuel tank providing fuel to said first fuel consumers; 
         [0009]    the second railcar has second fuel consumers and a buffer fuel tank providing fuel to said second fuel consumers; and
       the on board fuel storage and supply system has a fuelling device for transferring fuel from the main fuel tank to the buffer fuel tank.       
 
         [0011]    The object is also achieved by a method for storing and supplying fuel in a rail vehicle, characterised in that the rail vehicle includes a first railcar with first fuel consumers and a main fuel tank providing fuel to said first fuel consumers, and a second railcar with second fuel consumers and a buffer fuel tank providing fuel to said second fuel consumers, the method comprising the steps of fuelling the main fuel tank to a desired main level, operating the rail vehicle, during operation of the rail vehicle, fuelling the buffer fuel tank to a desired buffer level and maintaining the buffer fuel tank&#39;s fuel level at the desired buffer level by transferring fuel from the main fuel tank to the buffer fuel tank. 
         [0012]    By concentrating the fuel storage in a main fuel tank in the first railcar, the size of the fuel tank of the second railcar can be considerably reduced to a small buffer fuel tank. Hence, more installation space is available at the second railcar, which can be used e.g. for additional driving units. 
         [0013]    According to preferred embodiments, the inventive rail vehicle may include one, several or all of the following features, in all technically feasible combinations: 
         [0014]    the fuelling device comprises a fuel line network for conveying fuel from the main fuel tank to the buffer fuel tank, and a main fuel supply pump located in the fuel line network for installation in the second railcar and for sucking fuel from the main fuel tank to the buffer fuel tank; 
         [0015]    the fuelling device further comprises an auxiliary fuel supply pump located in the fuel line network for installation in the first railcar and for pushing fuel from the main fuel tank to the buffer fuel tank; 
         [0016]    the fuel line network further comprises a fuel supply pump bypass, preferably with a check valve, for the or each fuel supply pump; 
         [0017]    the fuelling device further comprises a controller for controlling the main fuel supply pump and the auxiliary fuel supply pump, wherein the controller is adapted to switch the fuelling device between a normal fuelling mode, wherein the main fuel supply pump supplies fuel to the buffer fuel tank while bypassing the idle auxiliary fuel supply pump via the corresponding bypass, and a fail-safe fuelling mode, wherein the auxiliary fuel supply pump supplies fuel to the buffer fuel tank while bypassing the idle main fuel supply pump via the corresponding bypass; 
         [0018]    the fuelling device further comprises a fuel flow sensor in the fuel line network upstream of the buffer fuel tank for detecting fuel flow to the buffer fuel tank, said fuel flow sensor being connected to the controller, wherein the controller is adapted to switch the fuelling device from the normal fuelling mode to the fail-safe fuelling mode if the fuel flow sensor fails to detect fuel flow to the buffer fuel tank; 
         [0019]    the fuel flow sensor comprise a fuel chamber with a fuel inlet and a fuel outlet, the inlet and the outlet being dimensioned such that fuel in the fuel chamber is maintained at a predetermined level at normal fuel flow to the buffer fuel tank, and a fuel level switch for detecting whether the fuel level in the fuel chamber is at said predetermined level and thus indicating normal or abnormal fuel flow to the buffer fuel tank to the controller; 
         [0020]    the fuelling device comprises a low fuel level switch and a high fuel level switch inside the buffer fuel tank, wherein the fuelling device is adapted to start fuelling of the buffer fuel tank when the low fuel level switch indicates a low level of fuel in the buffer fuel tank, and keep on fuelling the buffer fuel tank as long as the high fuel level switch fails to indicate a high level of fuel in the buffer fuel tank; 
         [0021]    the fuelling device has two low fuel level switches and two high fuel level switches inside the buffer fuel tank; 
         [0022]    the fuelling device comprises a one-way fuel flow member, such as a spring-loaded check valve, preventing fuel from flowing from the buffer fuel tank to the main fuel tank;
       it comprises a third railcar with a secondary fuel tank, wherein the fuelling device is adapted to transfer fuel from the main fuel tank via the secondary fuel tank to the buffer fuel tank;   the fuelling device is adapted to stop the transfer of fuel from the main fuel tank to the secondary fuel tank if the fuel level in the main fuel tank falls below a critical threshold;   a pressure relief member, such as a spring-loaded check valve, is connected in anti-parallel to the or each fuel supply pump such that the pumped fuel circulates in a closed loop between the pressure relief member and its corresponding fuel supply pump if the fuel pressure inside the fuel line network exceeds a predetermined threshold;   the first railcar has a single internal combustion engine as the first fuel consumers;   the second railcar has at least two internal combustion engines as the second fuel consumers.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention will now be described in detail with reference to the drawings, wherein: 
           [0029]      FIG. 1  shows a first embodiment of an inventive rail vehicle with two railcars; 
           [0030]      FIG. 2  illustrates the on board fuel storage and supply system of the rail vehicle of  FIG. 1 ; 
           [0031]      FIG. 3  shows the fuelling device of the system of  FIG. 2 ; 
           [0032]      FIGS. 4 and 5  are views of the fuel tanks used in the rail vehicle of  FIG. 1 ; 
           [0033]      FIG. 6  is a graph showing the fuel level vs. time in the fuel tanks when performing the inventive method; 
           [0034]      FIG. 7  shows a second embodiment of an inventive rail vehicle with three railcars; 
           [0035]      FIG. 8  illustrates the on board fuel storage and supply system of the rail vehicle of  FIG. 7 ; and 
           [0036]      FIG. 9  is a perspective view of the additional fuel tank of the rail vehicle of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
     First Embodiment 
       [0037]    With reference to  FIG. 1 , there is shown a rail vehicle  10 , namely a motor train set or diesel multiple unit (DMU) with a first railcar  12  and a second railcar  14 . Preferably, DMU  10  is a regional train intended to run on non-electrified railways. More precisely,  FIG. 1  shows the DMU manufactured by the applicant under the trade name “Coradia Lint 54/3”. 
         [0038]    The first railcar  12  is fitted with one power bogie  16  and one running bogie  18 . The power bogie  16  includes a driving unit  20  with a diesel engine known in the art as a “powerpack”. In addition to the driving unit  20 , the first railcar has a second fuel consumer, namely a heater  22 . Powerpack  20  and heater  22  are supplied with fuel from a main fuel tank  24  located next to running bogie  18  via fuel conduits  25 . 
         [0039]    Second railcar  14  is fitted with two power bogies  26  and  28 . Each power bogie  26 ,  28  includes a respective powerpack  30 ,  32 . The second railcar  14  also has a heater  34 . The fuel consumers  30 ,  32 ,  34  are supplied with fuel from a buffer fuel tank  36  located between the two power bogies  26 ,  28  via fuel conduits  37 . 
         [0040]    A fuelling device  38  connects the main fuel tank  24  to the buffer fuel tank  36 . The fuelling device  38  runs from the first railcar  12  to the second railcar  14 . 
         [0041]    The fuelling device  38 , the fuel tanks  24 ,  36  and the fuel conduits  25 ,  37  together form an on board fuel storage and supply system  40  of the DMU  10 . 
         [0042]    The on board fuel storage and supply system  40  is shown in greater detail in  FIG. 2 . The left hand side of  FIG. 2  corresponds to the second railcar  14 , and the right hand side corresponds to the first railcar  12 . Vertical dotted lines S represent the boundary of each railcar  12 ,  14 . The fuel level in each fuel tank  24 ,  36  is indicated by a horizontal line H and the fuel itself by the letter F. 
         [0043]    Each fuel consumer  20 ,  22 ,  30 ,  32  and  34  is supplied with fuel via a corresponding fuel supply device  42 . A heat exchanger  43  may be provided between two adjacent fuel supply devices  42 . Since each fuel supply device  42  is identical (apart from the simplified fuel supply devices of powerpack  32  and heater  34  that have no fuel pump), only one of them will be described. 
         [0044]    Fuel supply device  42  includes a fuel intake  44 , a fuel return line  46  and a fuel pump assembly  48 . Fuel intake  44  extends from the bottom  50  of the respective fuel tank to the respective fuel consumer. Fuel return line  46  extends from the fuel consumer to the bottom  50  of the respective fuel tank. The fuel pump assembly  48  is located in the fuel intake  44 . Each fuel pump assembly  48  comprises a fuel pump unit  52  and a check valve  54  connected in parallel. The fuel pump unit  52  includes a fuel conveying pump  56  and a spring-loaded check valve  58  connected in anti-parallel. 
         [0045]    Each fuel tank  24 ,  36  is fitted with a fuel level indicator  60 , an air vent (such as a throttle valve)  62 , and a gate valve  63 . The main fuel tank  24  also has two fuel filler necks  64 , one for each lateral side of the DMU  10 , and, in some implementations, two dry couplings  66 . The buffer fuel tank  36  lacks any fuel filler necks. 
         [0046]    The fuelling device  38  is shown in detail in  FIG. 3 . It comprises a fuel line network  68  for conveying fuel from the main fuel tank  24  to the buffer fuel tank  36 , a main fuel supply pump unit  70  located in the fuel line network  68  and installed in the second railcar  14 , an auxiliary fuel supply pump unit  72  located in the fuel line network  68  and installed in the first railcar  12 , and a controller  74  for controlling the main fuel supply pump unit  70  and the auxiliary fuel supply pump unit  72 . 
         [0047]    The main fuel supply pump unit  70  comprises a main fuel supply pump  76  and a pressure relief member  78 , such as a spring-loaded check valve, connected in anti-parallel. 
         [0048]    The auxiliary fuel supply pump unit  72  comprises an auxiliary fuel supply pump  80  and a pressure relief member  82 , such as a spring-loaded check valve, connected in anti-parallel. 
         [0049]    The fuel line network  68  includes a fuel supply pump bypass  84 ,  86  preferably with a check valve  88 ,  90  for each fuel supply pump  76 ,  80 . The bypass check valve  88 ,  90  is connected in parallel to its respective fuel supply pump unit  70 ,  72 . 
         [0050]    A one-way fuel flow member  92 , such as a spring-loaded check valve, is arranged between the main fuel supply pump unit  70  and the buffer fuel tank  36 . 
         [0051]    The fuel line network  68  extends over the two railcars  12  and  14 , with a first part P 1  of the network being installed in first railcar  12 , and a second part P 2  of the network being installed in second railcar  14 . A fuel connection assembly  94  connects the two parts P 1  and P 2 . The fuel connection assembly  94  comprises a first fuel coupling  96 , such as a dry break coupling, fitted onto the first railcar  12 , a second fuel coupling  98 , such as a dry break coupling, fitted onto the second railcar  14 , and a fuel hose  100  extending between the two fuel couplings  96 ,  98 . 
         [0052]    The fuelling device  38  also comprises a fuel flow sensor  102  between the one-way fuel flow member  92  and the buffer fuel tank  36 . This fuel flow sensor  102  comprises a fuel chamber  104  with a fuel inlet  106  and a fuel outlet  108 , and a fuel level switch  110 . 
         [0053]    Furthermore, the fuelling device  38  includes two low fuel level switches LO and LU and two high fuel level switches V 1  and V 2  inside the buffer fuel tank  36 . 
         [0054]    Controller  74  has a signal connection  112  to the main fuel supply pump  76 , the auxiliary fuel supply pump  80 , and the fuel level switches  110 , LO, LU, V 1  and V 2 . 
         [0055]      FIG. 4  is a perspective view of buffer fuel tank  36 . Buffer fuel tank  36  has a generally cuboid shape. Its preferred volume is of the order of 0.08 Cbm. The fuel chamber  104  of fuel flow sensor  102  is attached to one side wall of buffer fuel tank  36 . The three fuel intakes  44  and three fuel return lines  46  for the three fuel consumers of second railcar  14  are all arranged on the same side of buffer fuel tank  36 . 
         [0056]      FIG. 5  is a top plan view of main fuel tank  24 . Main fuel tank  24  has a generally cuboid shape. Its preferred volume is of the order of 2.7 Cbm. The fuel line network  68  as well as the fuel intakes  44  and fuel return lines  46  are all arranged on the main fuel tank&#39;s top side. The auxiliary fuel supply pump unit  72  is fixed to a side wall of main fuel tank  24 . 
         [0057]    The normal operation, also called normal fuelling mode (NM), of the inventive on board fuel storage and supply system  40  will now be described. 
         [0058]    Normal Operation 
         [0059]    The process starts when the DMU  10  is refuelled at a filling station. Depending on which side the filling station is located with respect to DMU  10 , the main fuel tank  24  is filled to a desired fuel level via one of the two fuel filler necks  64 . It is to be noted that buffer fuel tank  36  remains empty at this stage since it is supplied with fuel from the main fuel tank  24  as will be explained later on. Accordingly, refuelling of DMU  10  at a filling station is quick and simple since one only has to fill a single fuel tank. This is in contrast to prior art DMUs where the fuel tank of each railcar needs to be filled individually and thus the DMU has to move along the filling station in several steps as the different fuel tanks are filled. 
         [0060]    Once the refuelling of the DMU  10  is finished, it can then go into service. Once the DMU operates, the low fuel level switch LO indicates a low level of fuel in the buffer fuel tank  36  to controller  74 . As a consequence, controller  74  switches fuelling device  38  into a normal fuelling mode. In this mode, main fuel supply pump  76  is activated and sucks fuel out of main fuel tank  24  into buffer fuel tank  36 . The corresponding path followed by the fuel is indicated by arrows  1  in  FIG. 3 . The fuel F leaves the main fuel tank  24 , bypasses the idle auxiliary fuel supply pump  80  via the corresponding bypass  86 , crosses into the second railcar  14  via the fuel connection assembly  94 , runs through the main fuel supply pump  76  and into the buffer fuel tank  36  via the fuel flow sensor  102 . 
         [0061]    The fuelling of the buffer fuel tank  36  is carried on until the high fuel level switch V 1  or V 2  indicates a high level of fuel in the buffer fuel tank  36  to the controller  74 , whereupon the controller  74  deactivates the main fuel supply pump  76  and the fuelling device  38  goes into an idle mode. 
         [0062]    After this initial filling process, buffer fuel tank  36  is regularly refilled once the fuel inside it has been depleted. To this end, controller  74  restarts the normal fuelling mode as soon as the low fuel level switch LO detects a low fuel level inside buffer fuel tank  36 . 
         [0063]    The inventive on board fuel storage and supply system  40  has several fail-safe features, which will now be described. 
         [0064]    Fail-Safe Fuelling Mode 
         [0065]    Let us suppose that the fuelling device  38  has some kind of malfunction, which means that there is not enough fuel reaching the buffer fuel tank  36 . Such a malfunction could for example be due to cold ambient conditions, such as a temperature below −15° C. Under such conditions, the diesel fuel&#39;s viscosity increases rapidly and the main fuel supply pump may no longer be able to suck the fuel from the main fuel tank  24 . Another malfunction could be leakage of fuel from the fuel line network  68 . 
         [0066]    When such a malfunction occurs, the fuel flow sensor  102  will fail to detect sufficient fuel flow to the buffer fuel tank  36  during normal fuelling mode. More precisely, the fuel level inside the fuel chamber  104  will drop and the fuel level switch  110  will signal a lack of fuel to the controller  74 . As a consequence, the controller  74  will switch fuelling device  38  into a fail-safe fuelling mode. 
         [0067]    In the fail-safe fuelling mode, the main fuel supply pump  76  is turned off. Instead, the auxiliary fuel supply pump  80  is activated and attempts to push fuel from the main fuel tank  24  to the buffer fuel tank  36  while bypassing the idle main fuel supply pump  76  via the corresponding bypass  84 . The fuel flow path in the fail-safe fuelling mode is indicated by arrows  2  in  FIG. 3 . Thanks to its position at the beginning of the fuelling device  38 , the auxiliary fuel supply pump  80  generates high pressure inside the fuel line network  68 . In particular, auxiliary fuel supply pump  80  can push harder than the main fuel supply pump  76  can suck, since the depression generated by the latter cannot go beyond vacuum. 
         [0068]    After the fuelling device  38  has run in fail-safe fuelling mode during a predetermined amount of time, the controller then checks whether the fuel flow sensor  102  now indicates sufficient fuel flow. If it does, the controller  74  issues a warning to the rail vehicle driver indicating a fuel viscosity problem. If does not, the controller  74  issues a warning to the rail vehicle driver indicating a fuel leakage and the risk of engine outage. 
         [0069]    Excess Pressure Protection 
         [0070]    The spring-loaded check valves  82  (cf.  FIG. 3 ) act as an excess pressure protection. If the fuel pressure inside the fuel line network  68  exceeds a predetermined threshold, check valve  82  opens. Accordingly, pumped fuel circulates in a closed loop between the check valve  82  and the corresponding fuel supply pump  80 ,  76  until the fuel pressure inside the fuel line network  68  drops back below the predetermined threshold. 
         [0071]    Backflow Prevention 
         [0072]    The spring-loaded check valve  92  prevents fuel from flowing back from the buffer fuel tank  36  to the main fuel tank  24 . Furthermore, thanks to the spring, a minimum pressure is required to open check valve  92  in the downstream direction. Hence, unintentional fuel flow to the buffer fuel tank  36  is also prevented. This is particularly useful when the rail vehicle  10  stops on a slope. Without check valve  92 , the gradient would lead to uncontrolled fuel flow from one fuel tank to the other. 
         [0073]    Fuel Level Switch Redundancy 
         [0074]    Two low fuel level switches LO and LU and two high fuel level switches V 1  and V 2  are arranged inside the buffer fuel tank  36 . Thus, if one low fuel level switch and/or one high fuel level switch breaks down, the fuelling device  38  can still operate with the remaining fuel level switches. 
         [0075]    Fuel Level Switch Defect Detection 
         [0076]    The sequence of switching of the fuel level switches LO, LU, V 1 , V 2  is normally always the same. If there is a difference from the expected switching sequence an algorithm, preferably implemented in the vehicle&#39;s Train Control Monitoring System (TCMS), recognises a fuel level switch defect and gives a feedback to the driver. 
       Second Embodiment 
       [0077]    With reference to  FIG. 7 , there is shown a rail vehicle  500 , namely a motor train set or diesel multiple unit (DMU) with a first railcar  12 , a second railcar  14 , and a third railcar  502 . Preferably, DMU  500  is a regional train intended to run on non-electrified railways. More precisely,  FIG. 7  shows the DMU manufactured by the applicant under the trade name “Coradia Lint 81/4”. 
         [0078]    DMU  500  is essentially a stretched version of DMU  10 , a third railcar  502  having been inserted between the first and second railcars  12 ,  14 . In the following, only the differences with respect to DMU  10  will be described. For similar elements, reference is made to the description above in relation to DMU  10 . 
         [0079]    Third railcar  502  includes a secondary fuel tank  504  (preferred volume of around 0.9 Cbm) and two associated fuel consumers, namely a powerpack  506  and a heater  508 . Third railcar  502  has two bogies, one running bogie  510 , and one power bogie  512  powered by powerpack  506 . The secondary fuel tank  504  is illustrated in  FIG. 9 . It has a generally cuboid shape and includes an air vent  62 , two fuel filler necks  64 , a fuel level indicator  60 , as well as said fuel level switches V 1  and V 2 . 
         [0080]    Fuelling device  38  comprises a secondary fuelling device  514  for fuelling the secondary fuel tank  504 , and a buffer fuelling device  516  for fuelling buffer fuel tank  36 . The details of fuelling device  38  are shown in  FIG. 8 . It will be apparent that secondary fuelling device  514  and buffer fuelling device  516  are both identical to the fuelling device  38  of  FIG. 3  and work in the same way. During normal fuelling mode, both the buffer fuel tank  36  and the secondary fuel tank  504  are kept at a desired fuel level by taking fuel from the main fuel tank  24 . 
         [0081]    Fuel Shortage Mode 
         [0082]    In contrast to DMU  10 , DMU  500  features a fuel shortage mode SM. Fuelling device  38  switches into fuel shortage mode if the fuel level in the main fuel tank  24  falls below a critical threshold. In this mode, the transfer of fuel between the three fuel tanks  24 ,  36 ,  504  is stopped in such a way that all three fuel tanks  24 ,  36 ,  504  run dry essentially simultaneously. This increases the remaining time/distance that rail vehicle  500  can travel before the fuel runs out completely. 
         [0083]    This fuel shortage mode SM is illustrated by  FIG. 6 . The graph in  FIG. 6  plots the percentage fuel level V M , V B , V S  of main fuel tank  24 , buffer fuel tank  36 , and secondary fuel tank  504  as a function of time t1. Here, at time t0, all three fuel tanks  24 ,  36  and  504  start at a fuel level of 100%. Up to time t1, fuelling device  38  runs in normal fuelling mode NM. At time t1, fuel level V M  in main fuel tank  24  drops to a critical lower threshold V Crit . This is when secondary fuelling device  514  switches to fuel shortage mode SM. This means that no more fuel is supplied to secondary fuel tank  504 . As a result, fuel level V S  in secondary fuel tank  504  starts to drop until it reaches the critical lower threshold V Crit  at time t2. 
         [0084]    It will be noted that only main fuel tank  24  needs to be refuelled if DMU  500  reaches the filling station before the start of the fuel shortage mode. Indeed, in this case, secondary fuel tank  504  and buffer fuel tank  36  are still full. If DMU  500  reaches the filling station after the fuel shortage mode has started, both the main fuel tank  24  and the secondary fuel tank  504  need to be refuelled via the fuel filler necks  64 .