Abstract:
Danger of electrocution and fire from high voltage systems in electric and hybrid electric vehicles is mitigated by isolating high voltage electric power sources, of vehicles involved in accidents, in a sealed enclosure. 
     It involves the use of voltage disconnect devices to rapidly, manually or automatically disconnect and isolate the vehicle energy storage devices from the electrical system of the vehicle with ease and safety. The electrical power source may be a battery, a battery pack, a capacitor or other device which may be used to store electrical energy onboard a vehicle.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from provisional application Ser. No. 61/283,652 filed on Dec. 4, 2009, the entire contents of which is hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field of Invention 
         [0003]    This invention pertains to electric vehicles (EVs) and hybrid electric vehicles (HEVs) and more particularly to the improved safety of electrical systems used in such vehicles. 
         [0004]    2. Description of Prior Art 
         [0005]    During the past decade, there has been renewed interest in EVs and HEVs. These vehicles offer significant improvement in fuel economy and emissions. The electrical systems of such vehicles typically operate at voltages of 40 volts DC or more which is significantly higher than the conventional 12 volt automotive systems. Such vehicles utilize high voltage battery packs to store significantly greater amounts of electrical energy onboard the vehicle than is the case in conventional vehicles today. These battery packs are usually comprised of multiple sub-groupings of cells or batteries of lower capacity that are connected in series or in parallel to achieve the desired voltage and amperage capacity at the output terminals of the battery pack. Unfortunately, the high voltages that are used in such vehicles pose significant hazards, including danger of electrocution or increased risk of fire. Certain occurrences, such as an accident where various components in an EV or HEV may be damaged, crushed or dislodged or where the vehicle becomes partially or wholly immersed in water, exacerbate these dangers for vehicle occupants, rescue personnel or others who may need to come into contact with such vehicles. 
         [0006]    Also, it typically takes an extended amount of time to recharge the battery pack of an EV. This limits its effective driving range because of the maximum amount of energy that can be typically stored onboard such a vehicle at any given time. One solution that has been considered is the establishment of swap stations at convenient locations where partially or fully discharged battery packs can be swapped with pre-charged units. One of the key drawbacks of this approach is that during the swapping process, the exposed terminals of a charged battery pack can pose added risk of electrocution or other injury to personnel performing the swap. 
       SUMMARY OF INVENTION 
       [0007]    One object of the present invention is to provide a method and apparatus for improving the safety of high voltage vehicular electrical systems especially during and after accidents and in case of immersion in water. Although the present invention is especially suited to EVs and HEVs, it may be utilized with electrical systems where the voltage is high enough to be hazardous. 
         [0008]    These and other objects, advantages and features of the present invention are achieved, according to one embodiment, by placing an electrical disconnect mechanism (EDM) between the electric storage device (ESD) and at least a portion of the electrical system of a vehicle such that when the EDM is activated, that portion of the electrical system is disconnected from the ESD. It is preferable that at least one EDM be located such that when it is activated, the entire electrical system of the vehicle is disconnected from the ESD. The ESD may be comprised of, for example, a battery, a battery pack, a capacitor, flywheel or other device which may be used to store electrical energy onboard a vehicle. The EDM may be, for example, an automatic circuit breaker, an electrical relay or a manual switch. 
         [0009]    It is preferable that an EDM is activated automatically in the event of, for example, an accident or immersion in water. An EDM may be activated by sensors such as accelerometers, inclinometers, water detectors, pressure sensors, and temperature sensors. The EDM may also be activated by sensors that detect airbag deployment. 
         [0010]    A manual disconnect switch may also be used to trigger an EDM. Manual switches may be located at various locations in the vehicle such as the passenger compartment or in close proximity to the ESD. Remote manual switches may also be used to activate an EDM remotely. For this purpose, a special button may be incorporated with the remote door opener which activates a switch located in the vehicle. 
         [0011]    In accordance with the invention, an ESD may be partially encased in a protective enclosure that may include one or more EDMs. It is preferred that the ESD be completely enclosed although only certain terminals of the ESD may be encased. The enclosed electrical storage unit (EESU) would preferably have at least one positive and one negative external terminal. Each such terminal would be connected to the corresponding terminal of an ESD within the enclosure. The external terminals of an EESU would be used to connect to the electrical system of the vehicle. Intervening EDMs within the EESU may be used to disconnect one or more of its external terminals from the ESD terminals. It is preferable that the EESU be made waterproof. It is further preferred that the enclosure of the EESU be made of insulating material. If the enclosure is manufactured of conductive material, it is preferred that at least its internal surface be coated with an insulating material. It is further preferred that the enclosure materials or the coating materials be resistant to caustic substances such as battery acid. 
         [0012]    Sensors may be used to detect the presence of water at various locations in the vehicle. These sensors may trigger one or more EDMs within the EESU so that the external terminals are deactivated and the risk of electrocution is minimized. 
         [0013]    It is a further object of the present invention to provide a method and apparatus for easily and safely removing a high voltage EESU from a vehicle and replacing it with a fully charged unit without exposing personnel performing the task to risk of injury. 
         [0014]    In accordance with the invention, an EESU may be designed to be easily and safely removed from the vehicle and swapped with another unit. The EESU may include, on its exterior, one or more proximity or other switches that are automatically tripped when the EESU is removed. These switches would trigger one or more EDMs in the EESU. As a result, the external terminals of the EESU may then be automatically disabled during the removal process. The terminals may be reactivated when an EESU is reinstalled in the vehicle. 
         [0015]    Automatic activation of EDMs may occur, for example, as a result of unexpected events such as an accidental crash or immersion in water. Automatic activation of the EDM may also occur when certain hazardous operations are performed such as the withdrawal of a fully or partially charged removable EESU from the vehicle. 
         [0016]    One or more EDMs may also be activated manually under various conditions. Mechanics, emergency personnel or others who need to work on the vehicle may activate EDMs prior to starting work on the vehicle. An EDM may be activated from the passenger compartment, other location in the vehicle, or from a remote position. 
         [0017]    The EDMs may be completely mechanical, electrical, or may comprise a combination of electrical and mechanical components. An EDM may be activated manually by electrical or mechanical switches that are in close proximity or remote from it. The switches may be connected to an EDM electrically or mechanically by, for example, various linkages or gears. An EDM may be triggered by means of sensors connected directly to it or through an intervening controller. Sensors may also communicate with an EDM or controller by such methods as acoustic, radio or other electromagnetic transmission. 
         [0018]    It is a further object of the present invention to use an auxiliary circuit breaker switch that triggers the EDM as a result of current in an auxiliary branch of the circuit. Such a circuit breaker switch may interrupt a main circuit branch because high current is present in the auxiliary circuit branch. 
         [0019]    It is a further object of the present invention to use an EDM to disconnect an ESD as an antitheft measure. The switch would be used to trip at least one EDM so that the ESD is disconnected from at least a portion of the electrical system of the vehicle. The switch could then be used to reconnect the ESD. A code protected switch may be used for this purpose. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  illustrates an EESU configured according to an embodiment of the invention which comprises an enclosure, which comprises an ESD, and an EDM which communicates with several sensors. 
           [0021]      FIG. 2  is a schematic drawing of an ESD that may be employed in the embodiment in  FIG. 1 . 
           [0022]      FIG. 3  illustrates an EESU configured according to another embodiment of the invention which comprises an enclosure which encases a terminal of an ESD and an EDM. 
           [0023]      FIG. 4  illustrates an EESU configured according to another embodiment of the invention which comprises an enclosure which encases one terminal of an ESD and an EDM. A remote water sensor is connected directly to the EDM which is an auxiliary circuit breaker. 
           [0024]      FIG. 5  illustrates another ESD, comprising a battery pack, for use in an EESU configured according to an embodiment of the invention. The batteries in the battery pack are connected in parallel. 
           [0025]      FIG. 6  illustrates another ESD, comprising a battery pack, for use in an EESU configured according to an embodiment of the invention. It includes switches or relays that may be used to connect the individual subunits of the ESD in a series configuration or to electrically separate individual subunits. The subunits may be, for example, batteries or individual cells. 
           [0026]      FIG. 7  illustrates an EESU configured according to another embodiment of the invention wherein a removable enclosure comprises an ESD, an EDM and a switch which is mounted on its exterior surface. Cover of enclosure is not shown. 
           [0027]      FIG. 8  illustrates an EESU configured according to another embodiment of the invention which comprises intake and exhaust cooling ports. Cover of enclosure is not shown. 
           [0028]      FIG. 9   a  illustrates an un-tripped auxiliary circuit breaker configured to operate as an EDM according to another embodiment of the invention.  FIG. 9   b  illustrates the EDM in  FIG. 9   a  in a tripped state. 
           [0029]      FIG. 10  illustrates an EESU configured according to another embodiment of the invention comprising the EDM in  FIG. 9   a.    
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Descriptions of figures and embodiments that follow are intended to be illustrative and exemplary and are not intended to limit the invention. 
         [0031]      FIG. 1  is a schematic of an EESU  1  which comprises an ESD  2  with positive  3  and negative  4  terminals. The EESU has external terminals  10  and  12  which may be used to deliver electrical power to various vehicle systems and to return energy to the ESD for storage. In  FIG. 1 , the ESD  2  is comprised of one or more batteries that are connected to produce the desired voltage and current capacity across the terminals  3  and  4 .  FIG. 2  shows such a battery pack comprised of three subunits  5 ,  6 , and  7  which are connected in series. The subunits in the ESD may be, for example, batteries or individual cells. Also shown are the positive  3  and negative  4  terminals of the ESD. The ESD in  FIG. 1  is surrounded by a protective enclosure  8 . This enclosure is preferably waterproof and insulating. 
         [0032]    In the  FIG. 1  embodiment, the negative terminal  4  is connected by lead  9  to the EESU negative terminal  10  which may be grounded by lead  11 . Positive terminal  3  is connected to external positive terminal  12  with an intervening EDM  13 . When the EDM is triggered, the link between terminal  3  and terminal  12  is broken and the battery pack is effectively isolated within the enclosure  8  and the EESU is disabled and the ESD isolated. 
         [0033]    The EDM may be triggered automatically by sensors such as  14 ,  15 , and  16 . A controller  17  may be used to monitor the output from sensors and to control the operation of one or more EDMS. The communication between the controller  17  and the sensors occurs through leads  19  and the transmission link  20  which may utilize, for example, acoustic or electromagnetic signals. The EDM may also be grounded by means of leads  9 ,  11  and  24 . Sensors for triggering an EDM may be located within the ESU enclosure (not shown), attached to the enclosure (sensor  15 ) or remote from the enclosure, such as sensors  14  and  16 . Sensors  14  and  16  may be, for example, accelerometers or water sensors that detect the presence of water. Sensor  15  may be, for example, a pressure transducer. To avoid excessive pressure build-up in the enclosure, relief valve  21  may be used to equalize pressure with the surroundings. The EDM may also be triggered by a manual switch  22  which may communicate with the EDM directly or through controller  17 . 
         [0034]    In the embodiment in  FIG. 1 , the internal terminal  3  may be automatically disconnected from external terminal  12  when certain conditions occur, such as a crash or immersion of the vehicle in water. Manual switches may also be used for the same purpose by people such as the vehicle operator, a mechanic or emergency personnel. 
         [0035]    It may also be necessary to seal penetrations through the walls of the enclosure with seals  23  to keep the enclosure waterproof. The enclosure may be kept permanently waterproof or be made waterproof when the presence of water is detected at certain locations in an EV or HEV. With a waterproof enclosure, an EDM may be used to deactivate one or more external terminals of the EESU and mitigate the possibility of electrocution, injury or fire. 
         [0036]    Alternatively, one or more EDMs may be used in an EESU to disconnect both positive and negative terminals of the battery pack. As another alternative, in situations where the positive terminal  12  is grounded, the EDM may be used to disconnect only the negative terminal. Alternatively, the controller  17  may be located within the enclosure  8  or combined with an EDM in a single unit. 
         [0037]      FIG. 3 , which illustrates another embodiment of the invention, shows an EESU where a protective enclosure  30  is used to enclose one terminal  31  of the ESD  2 . Before the EDM is activated, terminals  31  and  33  are electrically connected. When the EDM is activated or tripped, it causes terminals  31  and  33  to become separated such that EESU terminal  33  is electrically isolated from the ESD terminal  31 . The EDM may be connected to external sensors by means of lead  34  and ground by means of leads  35  and  36 . The enclosure is preferably sealed so that water cannot reach terminal  31  inside the enclosure in the event that the enclosure is submerged. Seals  23  and  37  may be necessary at various locations in order to maintain a waterproof enclosure  30 . It is further preferred that the enclosure  30  is made of an insulating material 
         [0038]    Alternatively, the protective enclosure  30  can be used to encase and isolate a positive and a negative terminal of the ESD without enclosing the entire ESD. 
         [0039]    Referring to  FIG. 4 , the schematic illustrates an embodiment of an EESU according to the invention comprising an EDM  40  in an enclosure  41  that encases an ESD terminal  49 . In this embodiment, the external water sensor  42  comprises two conductive plates  43 ,  43   a,  preferably metallic. The sensor housing is perforated with holes  45  which could permit water to enter the sensor and cover the plates  43  and  43   a.  While switch  46  is in the closed position (shown by the dashed line), and the sensor  42  is submerged, current will flow through lead  47 , coil  48 , lead  48   a,  and plates  43 ,  43   a  to ground. The current flowing through coil  48  will establish a magnetic field that will move plunger  50  axially within core  50   a  and open switch  46 . Internal terminal  49  of battery pack  52  (shown segmented) will therefore be electrically disconnected from the EESU terminal  53 . The water detectors may be placed in various convenient locations in the vehicle. Multiple sensors could be used. Alternatively, in sensor  42 , plate  43   a  may be connected to the negative terminal of the ESD. Switch  46  may also be spring loaded so that once opened, it will remain open till it is reset manually. EDM  40  in  FIG. 4  is an auxiliary circuit breaker that interrupts electrical flow through one branch of the EDM circuit, comprising leads  46   a  and  47   a  and switch  46 , using the voltage in that branch to establish a current in an auxiliary branch, comprising leads  47 ,  48   a  and coil  48  and sensor  42 . 
         [0040]      FIG. 5  shows an ESD  54 , comprising three batteries or cells  55  connected in parallel. In this embodiment, the configuration of the ESD may be modified by using one or more intermediate EDMs  56  to disconnect and isolate individual batteries or cells in the EDM. 
         [0041]      FIG. 6  illustrates an EDM  57  comprised of three batteries  55   a,    55   b  and  55   c  connected in series with intermediate EDMs  59   a  and  59   b  that can be used to disconnect individual sub-components of the battery pack. Terminals  68  and  69  are the terminals of the EDM  57 . 
         [0042]    In the ESD in  FIG. 6 , batteries  55   a,    55   b  and  55   c  may be connected in series by using EDM  59   a  to connect lead  65   a  to lead  65   b  and lead  64   a  to lead  63   a,  while EDM  59   b  is used to connect lead  65   b  to lead  65   c  and lead  62   a  to lead  61   a.    
         [0043]    Alternatively, EDM  59   b  may be used to disconnect lead  62   a  from lead  61   a  and lead  65   b  from  65   c  while connecting  61   a  to  65   c.  In this case, the voltage at terminals  68  and  69  will be equivalent to the voltage of battery  55   c.    
         [0044]      FIG. 7  illustrates a removable EESU  69  with enclosure  70  (enclosure cover not shown). The ESD is a battery pack which comprises three batteries  71   a,    71   b  and  71   c,  an EDM  72  between the positive terminal of the battery pack  73  and the positive terminal of the EESU  74 . The EDM is triggered by a mechanical switch  75 . When the switch is released, the EDM disconnects terminal  73  from terminal  74  disabling the EESU and isolating the ESD. When the EESU is placed in the vehicle, terminals  74  and  76  engage corresponding positive and negative terminals in the vehicle electrical system (not shown). A properly located protrusion (not shown) in the vehicle is used to engage and depress switch  75  when the EESU is placed in its receptacle in the vehicle. When the switch  75  is depressed, terminals  73  and  74  are reconnected and the EESU is reactivated. 
         [0045]      FIG. 8  shows an embodiment of the invention comprising an EESU  80 . The EESU comprises a battery pack  81  with a positive terminal  82  and a negative terminal  83  in a sealable enclosure  84  which has a watertight cover (not shown). The terminals of the battery pack are connected to positive cable  85  and negative cable  86 . External supply cables  87  and  88  are used to supply electrical energy to the vehicle system from the battery pack or to obtain electrical energy from the vehicle system and supply it to the battery pack for storage. An intervening combination EDM and controller  89  is configured to disconnect cables  85  and  86  from external supply cables  87  and  88  respectively. The EDM is activated by means of a sensor  89   a  which is connected to the combination EDM controller unit by cable  89   b.  The enclosure also comprises intake ports  90  and exhaust ports  91  for circulating cooling air into and out of the enclosure. Intake port cover  92  is used to close intake ports  90 . An exhaust port cover (not shown) is used to seal exhaust ports  91 . Circulation of air through the ports  90  and  91  may be used to remove heat generated during the charging and discharging of the battery pack  81 . 
         [0046]    Intake port cover  92  is moved into position by actuator  93 . Actuator  93  which may be, for example, a linear motor or a screw mechanism, is activated by command from the controller in response to input from sensor  89   a.  Actuator for exhaust port cover is not shown. When the intake and exhaust ports are covered, the enclosure becomes waterproof. 
         [0047]      FIG. 9   a  is a schematic of a two pole un-tripped auxiliary circuit breaker  100  connected to a water sensor  101 . Sensor is comprised of plates  101   a  and  101   b  with an intervening gap  101   c.  When the gap is filled with air, the sensor acts as an open switch. When untripped, the circuit breaker transfers voltage supplied to its input terminals  102  and  103  to its output terminals  104  and  105  respectively. 
         [0048]    Water sensor is connected to sensor terminals  106  and  107 . Switch  108  connects terminals  102  and  103  and switch  109  connects terminals  103  and  105 . In the embodiment in  FIG. 9   a , switches  108  and  109  are ganged together and loaded by spring  110  to open automatically when plunger  111  is withdrawn so it no longer engages triangular stop  112  attached to switch  108 . 
         [0049]      FIG. 9   b  illustrates the auxiliary circuit breaker shown in  FIG. 9   a , where the sensor  101  has been submerged and gap  101   c  is filled with water which allows current to flow through the sensor. Current flowing through the sensor will also flow through the coil  113  which will establish a magnetic field that causes plunger  111  to be withdrawn and allows switches  108  and  109  to open.  FIG. 9   b  illustrates that when the auxiliary circuit breaker is tripped, input terminals  102  and  103  are disconnected from output terminals  104  and  105  respectively. Stops  114  and  115  limit the motion of the switches  108  and  109  and plunger  111  respectively. 
         [0050]      FIG. 10  illustrates an embodiment of the invention comprising an EESU  120  comprising enclosure  121  that encases ESD terminals  122  and  123  and auxiliary circuit breaker  124 . The enclosure and ESD are preferably waterproof. When the auxiliary circuit breaker is tripped, the EESU terminals are deactivated and the ESD terminals  122  and  123  are isolated. 
         [0051]    The invention has been described in terms of its functional principles and several illustrative embodiments. Many variants of these embodiments will be obvious to those of skill in the art based on these descriptions. Therefore, it should be understood that the ensuing claims are intended to cover all changes and modifications of the illustrative embodiments that fall within the literal scope of the claims and all equivalents thereof.