Abstract:
A battery operated vehicle includes a battery for powering an electric motor. A fan is installed in the vehicle and is directed toward the battery. When a battery charger starts charging the battery, a controller automatically activates the fan to cool the battery during the charging session. Switching circuitry in the vehicle automatically connects the battery to the fan and disconnects the battery from other vehicle electrical equipment during the charging session. Operating parameters in the vehicle are monitored to more effectively predict remaining battery charge.

Description:
BACKGROUND  
         [0001]    Electrically powered vehicles use one or more batteries that must be periodically recharged. Electrically powered industrial vehicles may need to be operated around the clock. In these around the clock industrial applications, discharged batteries have to be physically replaced one or more times a day with fully charged batteries. Industrial vehicle batteries, such as the batteries used to power lift trucks, are quite large. Having to periodically replace discharged batteries with fully charged batteries is time consuming and requires additional equipment and personnel to move the batteries in and out of the lift trucks. For example, a special crane apparatus is typically required to lift the discharged battery out of the lift truck and then place another fully charged battery back into the lift truck. Having to purchase several backup batteries also increases operating expense.  
           [0002]    In some applications, the discharged batteries are left in the vehicle. A battery charger is then attached to the battery and the battery recharged while the vehicle is not in use. This recharging time can keep the vehicle out of commission for substantial periods of time.  
           [0003]    The present invention addresses this and other problems associated with the prior art.  
         SUMMARY OF THE INVENTION  
         [0004]    A battery operated vehicle includes a battery for powering an electric motor. A fan is installed in the vehicle and is directed toward the battery. When a battery charger starts charging the battery, a controller automatically activates the fan to cool the battery during the charging session. Switching circuitry in the vehicle automatically connects the battery to the fan and disconnects the battery from other vehicle electrical equipment during the charging session. Operating parameters in the vehicle are monitored to more effectively predict remaining battery charge.  
           [0005]    The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention which proceeds with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a diagram of a battery operated lift truck that includes an improved battery charging system.  
         [0007]    [0007]FIG. 2 is an electrical diagram for the battery charging system.  
         [0008]    [0008]FIG. 3 is an electrical diagram showing how the battery charging system can be used for downloading vehicle operating data.  
         [0009]    [0009]FIG. 4 is a flow diagram showing how monitored vehicle operation parameters can be used to predict how long a battery can operate a vehicle. 
     
    
     DETAILED DESCRIPTION  
       [0010]    [0010]FIG. 1 shows an electrically powered lift truck  12 . The lift truck  12  is conventional and includes a forklift  19  that moves up and down in a vertical direction. A cab  13  of the lift truck  12  is occupied by an operator (not shown) and includes a steering wheel  15  for steering the truck  12 . A battery  14  is located somewhere in the lift truck  12  and powers an electric motor  9  and other electrically powered vehicle equipment.  
         [0011]    In one embodiment, the battery  14  is located underneath the seat  17  in the cab  13 . However, the battery may be located anywhere within the lift truck  12 . The battery charging system described below is shown used with the lift truck battery  14 . However, it should be understood that this is just one preferred embodiment. The battery charging system described below can be used with different types of batteries in different types of vehicles.  
         [0012]    A battery charger  18  is used to recharge the battery  14 . An electrical cable  24  is plugged into a socket  25  on the vehicle  12 . The charger  18  is connected to an external power source (not shown) with electrical cable  27 . The charger  18  converts Alternating Current (AC) power received from electrical cable  27  into a Direct Current (DC) or AC current that is used for recharging battery  14 .  
         [0013]    One problem with this charging arrangement is that the vehicle  12  can not be operated while the battery  14  is being charged and a relatively long period of time may be required to charge battery  14 . Any reduction in this charge time would increase the available operating time-for vehicle  12 . Battery charge time is limited by the amount of heat generated during the battery charging process. If the battery is charged too quickly, the battery can overheat and possibly be damaged.  
         [0014]    An improved battery charging system in FIG. 1 reduces the required charging time by activating a fan  16  during and possibly after the charging session. The fan  16  is permanently installed in the lift truck  12  and is activated during the battery charging session. The fan  16 , removes some of the heat that is typically generated by battery  14  during the charging process. This allows the battery  14  to be charged faster since the reduced temperature allows more energy can be applied to the battery  14  by the charger  18 . This reduced charging time allows the battery  14  to be recharged during work breaks preventing the battery  14  from having to be replaced during work shifts.  
         [0015]    [0015]FIG. 2 shows in more detail how the battery charging system operates. Whenever the battery  14  needs to be recharged, the cable  24  from charger  18  is plugged into the socket  25  located in vehicle  12 . The cable  24  may include a positive power line  26  and a negative power line  28 . The charger  18  may also include a control line  30  that provides electrical communication with a controller  22  located either on the battery  14  or in some other location in the vehicle  12 .  
         [0016]    The controller  22  detects a signal on control line  30  that indicates the charger  18  is connected or beginning to charge the battery  14 . Upon detecting the signal on control line  30 , the controller  22  activates an electrical interlock switch  20 . Upon detecting the beginning of a battery charging session, the controller  22  causes the electrical interlock switch  20  to maintain or connect battery  14  to fan  16  via connection  41 B and disconnect the battery  14  from other electrical equipment in vehicle  12 . For example, interlock  20  may disconnect the battery  14  from the vehicle electric motor  9  (FIG. 1).  
         [0017]    In another embodiment, when the beginning of the battery charging session is detected, the controller  22  directs the interlock switch  20  to connect power directly from the battery charger  18  to the fan  16  via power lines  41 A. If the fan  16  is powered directly from the battery charger  18 , a power converter  49  might be used to convert the output from the battery charger  18  into a voltage and current rated for operating the fan  16 .  
         [0018]    A filter  23  may be coupled into line  21  to filter out electrical surges that may be generated by the battery charger  18  while charging battery  14 . The controller  22  may be powered by a separate backup battery (not shown) or may receive power from battery  14 .  
         [0019]    As soon as the charger  18  starts charging battery  14 , the controller  22  enables interlock switch  20  to supply power from battery  14  or directly from the battery charger  18  to the fan  16 . The fan  16  begins to blow air, removing heat from the battery  14  during the charging process. This allows the charger  18  to charge battery  14  faster using more energy than what would normally be possible.  
         [0020]    In another embodiment, a sensor or switch  44 B is connected to socket  25  and detects the start of the battery charging session when an electrical plug  42  on cable  42  is mechanically or electrically engaged with socket  25 . In a different embodiment, a sensor  44 A senses the beginning of the battery charging session when power from battery charger  18  energizes power lines  41 A. Upon receiving a signal from sensor  44 A,  44 B, or directly from control line  30 , the controller  22  activates interlock  20  connecting power from battery  14 , or connecting power directly from battery charger  18 , to the fan  16  while disconnecting the battery  14  from the other vehicle equipment.  
         [0021]    The controller  20  senses the completion of the charging process either through control line  30 , sensor  44 A, or sensor  44 B either when the plug  42  is disconnected from socket  25  or when the battery charger  18  stops supplying charge to battery  14 . The controller  22  then automatically directs the interlock  20  to reconnect the vehicle electrical equipment to the battery  14 . The controller  22  may then direct the interlock switch  20  to correct or maintain power from battery  14  to the fan  16  via lines  41 B for some period of time after the completion of the charging session to remove any remaining residual heat from the battery  14 .  
         [0022]    [0022]FIG. 3 shows another aspect of the charging system. A battery monitor  32  may exist on some batteries  14  and is used by the battery charger  18  while charging battery  14 . The battery monitor  32  can control battery charging by battery charger  18  according to measured battery temperature and other battery parameters. Battery monitor  32  and battery chargers that vary charging characteristics according to monitored battery parameters are well known and therefore are not described in further detail.  
         [0023]    The battery monitor  32  can alternatively activate the fan  16  during a battery charging session. Because the fan  16  is blowing during the battery charging session, the battery monitor  32  will monitor a lower battery temperature. This allows the battery monitor  32  to direct the battery charger  18  to charge the battery  14  at a higher energy level. As a result, the battery  14  will be charged more quickly.  
         [0024]    Either the battery monitor  32 , or the controller  22  as described above in FIG. 2, can detect when the battery charging session begins. Battery charging is detected internally by the battery monitor  32  or by the controller  22  either by monitoring power or a control signal in the power cable  24  or by a mechanical switch in connector assembly  25  and  42 . The monitor  32  or controller  22  accordingly activates a control signal  42  that causes interlock switch  20  to connect power line  43  from battery  14  or directly from the battery charger  18  to fan  16 . The fan  16  is activated during the charging process and possibly for a predetermined period after the charging process.  
         [0025]    Another aspect of the invention includes using the battery monitor  32  to also receive and download vehicle operating parameters from the controller  22 . For example, the controller  22  monitors different vehicle operating components  46 , such as the operating time for electric motor  9  (FIG. 1). Other information in vehicle operating components  46  may include password identifiers (IDs) for drivers operating the vehicle  12  and fault information.  
         [0026]    For example, in some vehicles a vehicle operator has to enter a password into the controller  22  in order to start the vehicle. The controller  22  can store the entered IDs in memory  47 . The controller  22  can also track fault information such as a hydraulic fluid failure or a failure of the electric motor  9 . For instance, a hydraulic fluid failure could be detected by using a sensor in hydraulic fluid lines that measures the hydraulic fluid pressure. If the hydraulic fluid pressure falls below a predetermined pressure, a failure condition is recorded by controller  22  in memory  47 .  
         [0027]    An electric motor failure could be detected using a meter that measures the impedance across the electric motor. If the impedance is outside a normal value, a failure could be recorded by controller  22  in memory  47 . Alternatively, sensors could notify the controller  22  of a failure when the electric motor  9  does not activate after receiving power from battery  14 . Other means for detecting vehicle failures are known and are not described in further detail.  
         [0028]    It may be desirable to download this failure and other vehicle and battery information from either battery monitor  32  or controller  22  to a computer  38 . The computer  38  can be a laptop, Personal Computer (PC) or any other type of computing device.  
         [0029]    In one embodiment, the vehicle information is downloaded from the controller  22  through the battery monitor  32  over the control line  30  in cable  24 . Other battery information can also be generated and downloaded directly from the battery monitor  32 . The vehicle data and battery data is then downloaded from the battery charger  18  to the computer  38  over an external data line  40 , such as a Universal Serial Bus (USB).  
         [0030]    Alternatively, the external data line  40  is coupled directly from the controller  22  to the computer  38 . The computer  38  can be connected to the battery charger  18  or connected to controller  22  directly or via a network, wireless connection, or some other method. Any of the connections between controller  22 , battery, monitor  32 , and computer  38  can be through a CAN bus or other type of vehicle communication link. A Local Area Network (LAN) can also be used to couple the battery charger  18  to the computer  38 .  
         [0031]    Predicting Remaining Battery Charge  
         [0032]    It is important to accurately determine the charge remaining in a battery. In industrial applications, such as in lift truck operations, knowing the amount of remaining life left in a vehicle battery may help determine when the lift truck operator can take a break or needs to change batteries. For example, depending on the amount of remaining battery charge, the lift truck operator may be able to conduct a partial recharge during a lunch break that would be enough to keep the lift truck operational for the remainder of the shift. The battery in the lift truck could then be fully charged at the end of the shift. Alternatively, if the same lift truck is used in multiple shifts, the battery could be replaced during the shift change instead of during a shift.  
         [0033]    Thus, being able to accurately predict how long the battery can operate a vehicle helps manage when vehicle batteries are recharged or replaced. In addition, it is often detrimental to unnecessarily recharge batteries. For example, battery life can be reduced when the battery is constantly recharged before the remaining charge in the battery is depleted. Accurately identifying how long a battery can operate a vehicle would reduce the number of unnecessary recharges.  
         [0034]    Referring to FIGS. 3 and 4, the controller  22  is used to adjust battery charge measurements to more accurately estimate remaining battery charge. A battery charge indicator  36  in the vehicle  12  is coupled to the battery monitor  32 . The battery monitor  32  sends battery charge status information to the battery charge indicator  36  that then displays the charge status on a display  48 . Alternatively, the battery status and charge information is read from the battery monitor  32  by the controller  22  and then forwarded to the battery charge indicator  36 . The monitor  32  or controller  22  predicts long the battery can operate the vehicle and outputs the predicted remaining time to indicator  36 . The remaining vehicle operation time is then displayed on display  48  for viewing by the vehicle operator.  
         [0035]    Referring to FIG. 4, in block  60  the controller  22  or battery monitor  32  monitors certain operational information associated with the vehicle components  46 . For example, the controller  22  can keep track of any combination of the following: the number of vehicle sessions, the duration and time of each vehicle session, average ambient temperature for each vehicle session, battery discharge rate during each vehicle session, and time periods of vehicle non-use between each vehicle session. A vehicle session in one instance refers to electric motor operation. For example, the periods when the electric motor is energized by the battery and moving or idling the vehicle. Vehicle sessions are easily determined by monitoring current or voltage from the battery  14  to the electric motor  9 .  
         [0036]    The battery monitor  32  or the controller  22  periodically monitors the amount of battery charge in block  62 . Charge is determined by measuring battery voltage or current. A prediction of remaining time the battery can operate the vehicle is calculated in block  64  based on both the measured remaining battery charge and on the monitored vehicle operating parameters. The battery may have charge characteristics that change over time or change depending on types of vehicle operation. Therefore the monitored vehicle operating parameters are used to help better estimate how long the battery can continue to operate the vehicle.  
         [0037]    For example, the controller  22  may monitor the vehicle for a previous month of operation. It may be determined that at a current battery charge level and for a current operational routine of the vehicle that the battery can continue to operate the vehicle for approximately four more hours.  
         [0038]    Specifically, the controller may detect that the battery has approximately half of its remaining charge. Further, the controller may also over the last month monitor the vehicle as operating generally at constant one hour sessions with ten minute shut-off periods between each one hour session. With this previously monitored and stored profile of vehicle operation, the controller  22  may determine that at half charge, and with the vehicle operating at one hour periods with ten minute breaks between each period, that the battery will have enough charge to operate the vehicle for four more hours.  
         [0039]    The four hour remaining time period is displayed on the display  48  (FIG. 3) and then reduced proportionally with additional operation of the vehicle. If the vehicle is completely or partially recharged, the controller adjusts the available operation time shown in display  48  according to the battery measurement after the charge session. If the vehicle skips one of the one hour breaks, the controller  22  also readjusts the predicted operation time.  
         [0040]    The remaining vehicle operation time can be further adjusted according to other monitored vehicle parameters. For example, the controller may determine that at colder ambient temperatures, the amount of time the battery  14  can continue to operate the vehicle  12  may be reduced by ten percent. The controller measures the temperature and adjusts the predicted remaining vehicle operation time according to the measured temperature. In another example, the controller may determine that after a long period of non-use, such as more than two hours, that the operation time for a measured battery charge value may increase by thirty minutes. The controller accordingly increases the predicted remaining vehicle operation time by thirty minutes.  
         [0041]    The controller in block  68  can also display certain charge information associated with particular vehicle sessions. For example, in many industrial applications the battery powered vehicle is operated more or less in the same daily routine. For example, the vehicle operates in a shift that includes three one hour sessions in the morning and three one hour sessions in the afternoon, separated by a one hour break at lunch. Depending on the current monitored charge, and the other monitored parameters described above, the controller can determine if the battery has enough charge to operate the vehicle for the next one hour session, or for all the remaining sessions for the remainder of the shift.  
         [0042]    This information would be displayed to the vehicle operator in block  68 . If the battery would not likely have enough charge to complete a shift, this information would be communicated to the vehicle operator on display  48 . This could then prompt the vehicle operator to charge the vehicle during the lunch break. If the predicted operation time indicates the battery cannot operate the vehicle for even the next one hour shift, then the operator can replace the battery during the next break. Thus, the vehicle operator has a better idea of how long the vehicle can be operated before recharging or replacing the battery.  
         [0043]    The system described above can use dedicated processor systems, micro controllers, programmable logic devices, or microprocessors that perform some or all of the operations. Some of the operations described above may be implemented in software and other operations may be implemented in hardware.  
         [0044]    For the sake of convenience, the operations are described as various interconnected functional blocks or distinct software modules. This is not necessary, however, and there may be cases where these functional blocks or modules are equivalently aggregated into a single logic device, program or operation with unclear boundaries. In any event, the functional blocks and software modules or features of the flexible interface can be implemented by themselves, or in combination with other operations in either hardware or software.  
         [0045]    Having described and illustrated the principles of the invention in a preferred embodiment thereof, it should be apparent that the invention may be modified in arrangement and detail without departing from such principles. We claim all modifications and variation coming within the spirit and scope of the following claims.