Abstract:
A hybrid vehicle  10  which includes an assembly  13 , a low voltage battery  14 , and a high voltage battery  12 . Particularly, the assembly  13  allows the on board low voltage battery  14  or another low voltage donor battery to recharge the high voltage battery  12  in an efficient manner while concomitantly reducing the likelihood that the high voltage battery  12  will be unnecessarily or inadvertently recharged while concomitantly ascertaining the existence of a fault within the high voltage battery  12  and preventing charge from being communicated to the high voltage battery  12  when such a fault has been detected.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a method and an assembly for selectively charging a high voltage vehicular battery by the use of a low voltage battery and to a vehicle which incorporates the method and the assembly and more particularly, to a method and an assembly which quickly and efficiently charges a relatively high voltage vehicular battery while reducing the likelihood of an inadvertent or unnecessary charging of the high voltage vehicular battery while concomitantly ascertaining the existence of a fault within the high voltage vehicular battery and preventing charge from being communicated to the high voltage vehicular battery should a fault be detected. 
     2. Background of the Invention 
     A hybrid vehicle typically includes a high voltage battery (e.g., a battery which supplies energy or potential energy of about three hundred volts) and a relatively low voltage battery (e.g., a battery which supplies energy or potential energy of about twelve volts). Particularly, the high voltage battery is typically used to operate a motor/generator assembly which selectively provides torque to the wheels of the vehicle, while the low voltage battery provides energy to the various devices and assemblies which operatively reside within the vehicle, such as a radio. 
     The high voltage battery must be recharged or receive electrical charge in the event that the high voltage battery becomes discharged or loses an amount of charge which causes the battery to fail to provide the necessary energy which is required to power the motor/generator assembly. Since there currently exists only a relatively small number of hybrid vehicles, the likelihood of quickly securing another high voltage battery or locating another hybrid vehicle whose high voltage battery may be used to jumpstart the disabled vehicle (by providing energy to the high voltage battery) is relatively small. Not only do these conventional strategies require a high voltage battery, they continue the recharging operation until the discharged or partially discharged high voltage battery is fully charged, thereby undesirably requiring a relatively large amount of time to complete the jumpstart operation. These strategies also provide electrical energy to the high voltage battery even when the energy will not charge the high voltage battery due to a fault which may exist within the high voltage battery. Moreover, these strategies also attempt to provide electrical energy to the high voltage battery even when such energy may not be needed by the high voltage battery (e.g., such as when the high voltage battery is fully charged or has an amount of charge greatly exceeding the threshold amount of charge needed to operate the motor/generator assembly). The present invention overcomes these disadvantages. 
     SUMMARY OF INVENTION 
     It is a first non-limiting advantage of the present invention to provide a method and an assembly for selectively charging a vehicular high voltage battery in a manner which overcomes some or all of the previously delineated disadvantages of prior strategies and methods. 
     It is a second non-limiting advantage of the present invention to provide a method and an assembly for selectively and quickly recharging a vehicular high voltage battery to an adequate level appropriate to allow the vehicle to start at a relatively slow speed. 
     It is a third non-limiting advantage of the present invention to provide a method and an assembly which reduces the likelihood that charge will be attempted to be communicated to a fully charged high voltage battery. 
     It is a fourth non-limiting advantage of the present invention to provide a method and an assembly for selectively and quickly recharging a vehicular battery and for quickly and efficiently detecting the presence of a fault within the battery, and for preventing charge to be communicated to the battery when such a fault is detected. 
     According to a fifth non-limiting advantage of the present invention, an assembly for selectively charging a first battery is disclosed which operatively provides a first voltage signal having a first amplitude by the use of a second battery which operatively provides a second voltage signal having a second amplitude. Particularly, the assembly includes a charger which is coupled to the first battery, which selectively receives the second voltage signal, which converts the second voltage signal to a third voltage signal having an amplitude which is equal to the first amplitude, and which communicates the third voltage signal to the first battery, and a controller which is coupled to the charger, which detects the presence of a fault within the first battery and which allows the third voltage signal to be communicated to the first battery in the absence of a fault within the first battery and for a time necessary to partially charge the first battery. 
     According to a sixth non-limiting advantage of the present invention, a vehicle is provided having a first battery providing a first voltage signal having a first amplitude and a second battery providing a second voltage signal having a second amplitude. Moreover, the vehicle includes a charger which is coupled to the first and second batteries, which receives the second voltage signal, and which converts the second voltage signal to a third signal having the first amplitude, and a controller assembly which is coupled to the charger and which selectively causes the third voltage signal to be communicated from the charger to the first battery for a certain period of time sufficient to partially charge the first battery. 
     According to a seventh non-limiting advantage of the present invention, a method is disclosed of charging a battery which is operatively disposed within a vehicle of the type having a selectively positionable ignition switch. Particularly, the method includes the steps of determining whether the battery requires a predetermined amount of electrical charge; and causing only a portion of the predetermined amount of required charge to be communicated to the battery and when the ignition switch resides in an off position. 
    
    
     These and other features and advantages of the present invention will become apparent from a reading of the following detailed description of the preferred embodiment of the invention and by reference to the following drawings. 
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a block diagram of a hybrid electric vehicle which incorporates an assembly which is made in accordance with the teachings of the preferred embodiment of the invention; and 
     FIG. 2 is a flow chart comprising the various operational steps which comprise the methodology of the preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1, there is shown a hybrid vehicle  10  which is made in accordance with the teachings of the preferred embodiment of the invention. Particularly, the hybrid vehicle  10  includes a high voltage battery  12 , such as but not limited to a battery providing a voltage signal having an amplitude of about three hundred volts, a low voltage battery  14 , such as but not limited to a battery providing a voltage signal having a amplitude of about twelve volts, a selectively movable ignition switch  15 , and an assembly  13  which is made in accordance with the teachings of the preferred embodiment of the invention. It should be appreciated that only the relevant portions of the hybrid vehicle  10  are shown in FIG.  1  and that the principles of the present invention may be applied to a wide variety of dissimilar vehicular configurations. 
     As shown, assembly  13  includes a charger assembly  16  which is adapted to receive a voltage signal having an amplitude of about twelve volts and to output a voltage signal having an amplitude of about three hundred volts, a controller  18  which is operable under stored program control, a selectively movable switch  20  which is coupled to the controller  18  by the use of bus  22 , a first selectively energizable member  24  which is coupled to the controller  18  by the use of bus  26 , a second selectively energizable member  28  which is coupled to the controller  18  by the use of bus  30 , a third selectively energizable member  33  which is coupled to the controller  18  by the use of bus  35 , and an electric current sensor  37  which is coupled to a state of charge estimator (not shown) which resides within controller  18 , by the use of bus  39 . Particularly, the charge estimator may be embodied within software, firmware, and/or hardware which is contained within the controller  18 . Moreover, the current sensor  37  detects the amount of electrical current which emanates from or is received by the high voltage battery  12  and provides this information to the controller  18  by the use of bus  39 . The charge estimator uses this electrical current information to estimate the amount of electrical charge which resides within the high voltage battery  12 . Assembly  13  further includes a power distribution box or assembly  32  which is coupled to the controller  18  by the use of bus  34 . 
     As is further shown, controller  18  is coupled to the charger assembly  16  by the use of bus  40 . The charger assembly  16  is coupled to the high voltage battery  12  by the use of the bus  50  and the charger assembly  16  is coupled to the power distribution box  32  by the bus  60 . The low voltage battery  14  is coupled to the power distribution box  32  by the bus  62  and to the controller  18  by the bus  42 , and the controller  18  is coupled to the selectively movable ignition switch  15  by the use of the bus  17 . It should be realized that the principles of the present invention may be applied to a low voltage battery which provides a amount of voltage which may be lower or greater than about twelve volts and to a high voltage battery which provides an amount of voltage which may be lower or greater than about three hundred volts. The difference between the voltage provided by the low voltage battery and the voltage provided by the high voltage battery is significant. Referring now to FIG. 2, there is shown a methodology or flowchart  100  which comprises a sequence of operational steps which comprise the methodology of the preferred embodiment of the invention. Particularly, the methodology  100  includes a first step  102  in which a low voltage donor battery or source (not shown) is connected to low voltage battery  14 . 
     Step  102  is followed by step  104  in which the switch  20  is moved and/or depressed. Such movement or depression causes the switch  20  to generate a signal on the bus  22  which is received by the controller  18 . Upon receipt of the signal, the controller  18  performs step  106 . Particularly, in step  106 , the controller  18  determines, by the use of bus  17 , whether the ignition switch  15  is in a deactivated or “off” position. If the controller  18  determines that the ignition switch  15  is in a deactivated or “off” position, controller  18  enters step  108  in which the controller  18  “sets” or enables a “charge request” flag. Alternatively, if the ignition switch is in the “on” or activated position, step  106  is followed by step  107  in which the controller  18  energizes the member or light assembly  24  by providing or sourcing electrical energy on the bus  26 . Step  107  is followed by step  110  in which the methodology  100  is ended. 
     Step  108  is followed by step  112  in which the controller  18  determines whether electrical charge is actually required by the high voltage battery  12 . In one non-limiting embodiment of the invention, this determination is made by querying the sensor  37  (e.g., if little or no current is emanating from the battery  12 , the controller  18  determines that additional charge is needed by the battery  12 ). Alternatively, the controller  18  may calculate the state of charge of the high voltage battery  12  in a known and conventional manner by use of the charge estimator (not shown) in combination with the sensor  37 . That is, each of the batteries  12 , 14  have the capacity to store a certain respective amount of electrical charge in order to be “fully charged” and these respective amounts are stored within the controller  18 . The battery  12  requires a certain amount of charge, which may be less than its respective “fully charged” amount, to operate the motor/generator assembly. If the controller  18  determines that no additional charge is needed by the battery  12  to operate the motor/generator assembly, step  112  is followed by step  114  in which the controller  18  activates or energizes the light or member  28  by sourcing or providing electrical energy or voltage on the bus  30  from the battery  14  or from another source. Step  114  is followed by step  110 . In this manner, the controller  18  substantially reduces the likelihood of or substantially prevents the inadvertent or unnecessary charging of the high voltage battery  12  by the movement of the switch  20 . 
     If the controller  18  determines that the high voltage battery  12  is in need of charge (e.g., has an amount of charge which is less than the amount of charge necessary to operate the motor/generator assembly), step  112  is followed by step  116  in which the controller  18  determines whether a fault exists within the high voltage battery  12 . This discernment may be made by reviewing the state of charge history of the high voltage battery  12  in order to determine whether the high voltage battery  12  has suddenly become discharged, thereby indicating a fault, or by the use of a conventional technique. If the controller  18  determines that a fault exists within the high voltage battery  12 , the controller  18  enters step  118  from step  116 . Particularly, in step  118 , the controller  18  activates or energizes the light  33  by sourcing or providing electrical power to the light  33 , from the battery or another source, by the use of bus  35 . Step  118  is followed by step  110 . 
     If the controller  18  determines that a fault does not exist within the high voltage battery  12 , step  116  is followed by step  120  in which the controller  18  activates the charger assembly  16  by the use of command signals which are created by the controller  18  and communicated to the charger assembly  16  by the use of bus  40 . In this manner, the charger assembly  16  uses the energy from the low voltage donor battery, converts this received voltage signal to a high voltage amplitude signal, and provides this converted voltage signal to the high voltage battery  12 . Step  122  follows step  120  and, in this step  122 , the controller  18  determines, by the use of sensor  37  or by other techniques, when the high voltage battery  12  has received a sufficient amount of charge to operate the motor/generator assembly. In the preferred embodiment of the invention, the controller  18  only allows the high voltage battery  12  to contain about one-half of its allowable or maximum amount of charge, (e.g., about one half of its full operating charge), thereby allowing the recharging operation to be quickly and efficiently accomplished. Only such a relatively low amount of charge is required since, in the preferred embodiment of the invention, the vehicle  10  is subsequently started at a relatively low engine speed. 
     If it is determined in step  122  that the high voltage battery  12  has not been sufficiently charged, step  122  is followed by step  106 . Alternatively, step  122  is followed by step  126  in which the controller  18  deactivates the charger  16  by the use of commands which are created by the controller  18  and communicated to the charger assembly  16 , by the use of bus  40 . Step  126  may, in one non-limiting embodiment, be followed by step  128  in which the controller  18  may be allowed to enter a “sleep mode” or low energy consumption state in order to conserve electrical power. Alternatively, step  126  is followed by step  110 . Step  128  is also followed by step  110 . In this “sleep mode” embodiment, the controller  18  is awakened or consumes enough electrical power from the low voltage battery  14  to fully operate, upon the depression of the movement of the switch  20  in step  104 . 
     It is to be understood that the present invention is not limited to the exact construction or method which has been discussed above, but that various changes and modifications may be made without departing from the spirit and the scope of the invention as is more fully delineated in the following claims. It should be further realized that the use of an “onboard” charger assembly  16  allows a low voltage donor battery (or even the onboard low voltage battery  14 ) to selectively charge the high voltage battery  12 , thereby allowing a “self jumpstart” operation to be quickly and efficiently accomplished and obviating the need to search for a “donor vehicle” or a “donor battery”. Moreover, it should be realized that light members  24 ,  28  and  33  may be replaced by a single light or a single multicolor light assembly.