Patent Publication Number: US-2020291712-A1

Title: Unknown

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Patent Application claims priority from Italian Patent Application No. 102019000003499 filed on Mar. 11, 2019, the entire disclosure of which is incorporated herein by reference. 
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not Applicable 
     TECHNICAL FIELD 
     The invention relates to a vehicle equipped with electrochemical energy storage systems (electric batteries), which can be subjected to thermal runway phenomena, in particular to an electric vehicle for public transportation, which is provided with said batteries housed in a suitable compartment and is provided with a security system to counter the thermal runway phenomenon. 
     KNOWN STATE OF THE ART 
     As it is known, terrestrial or marine vehicles can comprise battery packs configured to supply a sufficient amount of power needed for the drive of the vehicle and for the operation of other auxiliary comfort devices, such as the air conditioning system, and functional devices, such as screens to display information that can be useful for the passengers. 
     As it is known, the electric batteries used in these vehicles are electrochemical storage devices, which, during use, while they are being charged and as the charge depletes, tend to heat up. 
     It is possible for the inner heating of the cells to reach levels that are such as to generate a phenomenon known as “thermal runaway”, in which the temperature triggers exothermic reactions, which further increase the temperature, thus leading to possible disastrous consequences, such as explosions or fires. 
     In these cases, the battery pack needs to be quickly cooled down in order to prevent this condition from spreading to the other adjacent batteries and in order to avoid damages that are potentially lethal for the passengers of the vehicle. 
     This cooling operation, which requires large quantities of water or a mixture thereof with a fire extinguishing liquid, is normally carried out by having rescuers open the doors of the compartments housing the batteries and spray the fire extinguishing mixture. However, this operation is long and dangerous. 
     Therefore, security systems are needed, which are capable of precisely identifying the triggering of a thermal runway phenomenon in a battery pack of a vehicle and, as a consequence, allow operators to promptly and safely act so as to de-energize it through the removal of heat. 
     The object of the invention is to fulfil the needs discussed above. 
     SUMMARY OF THE INVENTION 
     The aforesaid object is reached by a vehicle provided with a security system according to the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be best understood upon perusal of the following detailed description of a preferred embodiment, which is provided by way of non-limiting example, with reference to the accompanying drawings, wherein: 
         FIG. 1  is a perspective view showing an electric bus provided with a security system according to the invention; 
         FIG. 2A  is a schematic perspective view showing a first embodiment of the security system according to the invention; 
         FIG. 2B  is a schematic side view showing a first embodiment of the security system according to the invention; 
         FIG. 3  is an electrical diagram of an example of an electric circuit to control the security system according to the embodiment of  FIGS. 2A-2B ; 
         FIG. 4A  is a schematic perspective view showing a second embodiment of the security system according to the invention; 
         FIG. 4B  is a schematic side view showing a second embodiment of the security system according to the invention; and 
         FIG. 5  is a perspective view showing an embodiment of pneumatic means to control the security system according to the embodiment of  FIGS. 4A-4B . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a vehicle  1  provided with a plurality of walls  2  defining an inner volume  3  designed for the transportation of passengers and/or goods and comprising a plurality of electric batteries  4 , namely known electrochemical storage batteries. 
     In the example described herein, reference is made to a vehicle for the public transportation of people, such as a bus; however, the invention can be applied to other types of terrestrial vehicles, such as trucks, or marine vehicles, such as boats. 
     Hence, in the case described herein, the vehicle  1  is an electric vehicle and comprises a plurality of battery pack  4  electrically connected to an electric drive system  5  carried by the vehicle  1 . As it is known, the battery packs  4  are housed in respective seats  6  obtained in a wall  2  defining the roof of the vehicle  1 . 
     In particular, with reference to  FIGS. 2A and 4A , each seat  6  comprises a lid  7  defining, relative to the roof wall  2 , a volume  8  housing, on the inside, at least one battery pack  4 , which is separated from the surrounding environment so as to avoid water and/or dust contamination, sun radiations and accidental hits. 
     The lid  7  comprises covers  9 , preferably one cover  9  for each battery pack  4 , configured to allow the volume  8  to selectively communicate with the outside. As a consequence, each cover  9  is carried by the lid  7  in a movable manner so as to assume a closed position, in which the volume  8  is separated from the outside, and an open position, in which the volume  8  communicates with the outside. 
     Each cover preferably comprises isolation means (not shown), which are configured to prevent contaminating agents, such as dust or water, from reaching the inside of the volume  8 , when each cover  9  is in the closed position. 
     In the embodiment described herein, the covers  9  are hinged relative to the lid  7  and have a shape that is such that, when they are closed, they are integrated in the lid  7 . 
     In particular, with reference to  FIGS. 2B, 4B , the covers  9  comprise an inner end, which is hinged to the lid  7  by means of a hinge  11 , which is configured to allow the inner end to rotate around an axis A, which is parallel to the longitudinal axis of the vehicle. 
     According to the invention, between each cover  9  and the lid  11  the vehicle  1  comprises security means  13 , which are configured to allow the covers  9  to be immediately opened when a threshold temperature of the battery pack  4  and/or on the inside of the volume  8  exceeds a pre-set threshold, which can be defined based on the electrochemical features of the battery. In particular, the security means  13  comprise opening means  14  for the covers  9 , which are operated based on a temperature condition of the battery pack  4  and/or on the inside of the volume  8 , which is identified by suitable thermosensitive devices  15 . This temperature is a function of the specific thermal-chemical system of the battery pack  4  and can preferably range from 120 to 180°. 
     According to a first embodiment, which is shown in  FIGS. 2A-2B , the opening means  14  comprise elastic means  16 , for example a helical spring, which are interposed between the cover  9  and one between the lid  7  and/or the roof  2  and are configured to constantly exert a force upon the cover  9  so as to enable the opening thereof, and an electric lock  17 , which is configured to keep the cover  9  closed according to a configured electronic logic. The thermosensitive devices  15  can comprise a switch, which can be switched as a function of a threshold temperature, which can be defined during the designing phase, for example 160°, in order to allow the electric lock  17  to be opened. 
       FIG. 4  shows an electric diagram for the control of the electric lock  17  according to a possible embodiment. The electric lock  17 , which is of a known type, is connected to a management module  18  for the management thereof and to a button  19 , which is configured to allow the cover  9  to be opened when it is manually operated. 
     According to the circuit example shown in the figure, when the button is pressed, the management module  18  orders the opening of the electric lock  17 . In the example described herein, the thermosensitive devices  15  comprise a thermal fuse  20 , which is arranged in parallel to the button  19  and is in a normally open configuration. If the temperature exceeds a pre-set threshold, the thermal fuse  20  switches to an open condition and the management module  18  orders the opening of the electric lock  17 . 
     The management module  18  can advantageously be the management module of the battery pack system (BMS Battery Management System) or the electronic control unit of the vehicle (ECU). 
     The embodiment described above works as follows. 
     In a standard use condition, the electric lock  17  keeps the covers  9  in a closed position or the user, by pressing the button  19 , releases the electric lock  17  and the elastic means  16  can cause the covers  9  to rotate around the hinge  11 , thus allowing them to move to the open position, in which the volume  8  communicates with the outside. 
     In an emergency condition, the thermal fuse  20 , once the pre-set temperature threshold is reached, switches, releasing the electric lock  17  so that the elastic means  16  move the covers  9  from the closed position to the open position, thus allowing an immediate cooling, thanks to the exchange of air with the outside, and, especially, allowing immediate access to rescuers with a fire extinguishing liquid suitable for the situation. 
     According to a second embodiment, which is shown in  FIGS. 4A-4B , the opening means  14  comprise pneumatic means  22 , which are interposed between the cover  9  and one between the lid  7  and/or the roof  2  and are configured to exert, when they are operated, a force upon the cover  9  so as to enable the opening thereof, and a thermal fuse module  23 , which operates the pneumatic means  22  as a function of a threshold temperature, for example 140°. 
     The pneumatic means  22  can advantageously comprise a solenoid valve  24 , which is fluidically connected to a source of pressurised fluid, for example air, of the vehicle  1  and are controlled by a management module (not shown) to open or close the cover  9  when the user needs it. Again, the management module can be the management module of the battery pack system (BMS Battery Management System) or the electronic control unit of the vehicle (ECU). 
       FIG. 5  shows the pneumatic means  22  according to a possible embodiment thereof. A cylinder-type device  25  is fluidically operated by the solenoid valve  24 , which, as mentioned above, is connected to a fluid source of the vehicle. The thermal fuse module  23  is fluidically connected to the solenoid valve  24  so as to allow the cylinder  25  to be operated and, at the same time, provide a sufficient source of fluid to supply said activation. 
     In particular, the thermal fuse module  23  can comprise a pressurised air vial, which, at a pre-set temperature, brakes, thus opening the solenoid valve  24  and providing, at the same time, a source of fluid to supply the activation of the cylinder  25 . Indeed, the vial ensures the presence of compressed air even in case of absence or fault of the pneumatic system with which some types of vehicles, for instance buses, are provided. 
     The invention further relates to a method to control the covers  9  of the compartment  6  of a vehicle of the type described above, said method basically comprising the steps of: 
     identifying a threshold temperature in the volume  8  and/or in the battery pack  4  through thermosensitive devices  15 ; 
     if said temperature is smaller than a pre-set threshold value, controlling the opening means  14  so as to prevent the covers  9  from automatically moving from the first to the second operating condition; 
     in the opposite case, controlling the opening means  14  are controlled so as to allow the covers  9  to automatically move from the first to the second operating condition. 
     Owing to the above, the advantages of a vehicle  1  provided with a security system  13  for thermal runway phenomena according to the invention are evident. 
     In particular, thanks to the security means  13 , the covers  9  can be automatically opened based on a pre-set security temperature, thus allowing users to promptly lower the temperature of the battery pack. 
     The use of electric-mechanical means  13  of the type described in the first embodiment allows the control of said temperature to be carried out in an economic fashion and to be integrated in the already existing battery/vehicle management system module. 
     The use of pneumatic security modules  13  exploits a pressurised fluid source already existing in the vehicle, without having to use electronic elements, which could be subjected to damages in case of high temperatures, thus jeopardizing the correct operation thereof. 
     Finally, the vehicle  1  provided with a security system  13  for thermal runway phenomena according to the invention can be subjected to changes and variants, which, though, do not go beyond the scope of protection set forth in the appended claims. 
     For example, the two embodiments described herein are mere examples of different equivalent electric-mechanical or pneumatic systems for controlling the opening of the covers  9 . 
     Indeed, it is clear that, through the cover control method claimed herein, the security means  13  could be of any type, provided that they can carry out the steps of the aforesaid method. 
     In particular the control circuit of the electric lock  17  or the elements present in it, such as the button  19 , could be different or absent. 
     Furthermore, the cylinder system  25  or the solenoid vale  24  or the thermal fuse module  23  could be obtained by means of equivalent devices.