Abstract:
A thermal conditioning system for the energy storage system of a hybrid vehicle. At least one auxiliary air source, other than a permanently open air source, has a selectively operable actuator door which either connects or disconnects the auxiliary air source to the energy storage system blower, the air flow being selected to optimally temperature condition the energy storage system. The auxiliary air source preferably includes the HVAC ducting.

Description:
TECHNICAL FIELD 
     The present invention relates to energy storage systems incorporating battery packs utilized in hybrid motor vehicles, and more particularly to the thermal conditioning thereof. Still more particularly, the present invention relates to thermal conditioning by selectively employing various air sources of the motor vehicle. 
     BACKGROUND OF THE INVENTION 
     Hybrid motor vehicles utilize a propulsion system which incorporates both an internal combustion engine and an electrical system which is used typically for propulsion and regenerative braking. The electrical system includes at least one electrical motor mechanically connected to one or more axles of the motor vehicle and a battery pack of cells which is an integrated component of an energy storage system (ESS) that is electrically connected to the at least one motor. When the at least one motor propels the motor vehicle, electrical energy is extracted from the ESS (the battery pack discharges). During regenerative braking the motor acts as a generator, and the electrical energy generated is delivered to the ESS (the battery pack charges). 
       FIGS. 1 and 2  schematically depict aspects of a conventional hybrid ESS and the prior art thermal conditioning arrangement therefor. 
     Within the passenger cabin  10  of the hybrid motor vehicle is disposed the ESS  12 , which may, for example, rest on the vehicle floor  14  above the fore-aft floor “tunnel”  16 . The ESS  12  is thermally conditioned by the movement of cabin air A C  via an ESS blower  18 , whereby the cabin air is circulated through the ESS, originating at least one permanently open entry vent  20  and exiting at least one permanently open exit vent  22 , both vents being permanently open in the sense of being in permanently and completely open fluidic communication with the passenger cabin. The prior art has sometimes placed the entry vent near the output of the HVAC ducting, whereby cabin air A C  and HVAC air A H  can comingle before unselectively entering the entry vent. Operation of the ESS blower  18  is controlled by a hybrid vehicle integration control module (VICM)  24 , utilizing temperature data from (among others) an inlet duct sensor  26   a , an outlet duct sensor  26   b , and an ESS temperature sensor  26   c . The VICM  24  is connected to inputs and outputs by various data lines (see for example dashed lines in  FIG. 2 ). These components are subject to an on-board diagnostics (OBD) requirement, whereby a signal is provided to the driver if a fault is detected in any of the components. 
     The passenger cabin includes a heating, ventilation and air conditioning (HVAC) module  28 , which typically includes passenger input instruments  30  and an HVAC controller  32  which operates the HVAC module in response to the passenger input. Typically, the HVAC module includes an HVAC blower  34 , an evaporator  36  for cooling the HVAC air to the cabin and a heater core  38  for heating the HVAC air to the cabin via HVAC ducting  40 . These components are not subject to an OBD requirement. 
     Utilizing the cabin environment in the prior art to provide air for thermal conditioning of the ESS is effective only when the cabin air is not too hot nor too cold. For example, after a soak in hot sun or frigid cold, the ESS will be similarly either hot or cold, and the cabin air used to thermally condition the ESS will also be likewise hot or cold. This has problematic implications for the electrical charge/discharge performance of the ESS, which is temperature dependent. As discussed hereinbelow with respect to  FIG. 3 , there is an optimal ESS performance temperature range, and the cabin air temperature extremes can easily be outside (both above and below) this range. 
     And, this problem of administering ESS thermal conditioning in the prior art is not “solved” by merely placing the entry vent someplace near the outlet of the HVAC ducting, as the commingling of cabin air with HVAC air is haphazard, unselectable and takes too much time. 
     Accordingly, what remains needed in the art is a thermal conditioning system of hybrid vehicle ESS which does more than simply utilize cabin air therefor. 
     SUMMARY OF THE INVENTION 
     The present invention is an ESS thermal conditioning system which selectively utilizes air from at least one auxiliary air source (other than the at least one permanently open entry vent of the prior art), as for example one or more passenger cabin areas, the trunk, an exterior vent, and, most preferably, the HVAC ducting. 
     Interfaced with each auxiliary air source is a selectively operable actuator door which either connects or disconnects the auxiliary air source to the ESS blower. By way of example, VICM utilizes temperature sensors associated with each of the various auxiliary air sources to open, close, or partly open each of the respective actuator doors so that the ESS is optimally temperature conditioned. In this regard, if there are more than one auxiliary air sources available, then the VICM will select the actuator door opening amount appropriate to any of them based upon, for example, the sensed temperature at the auxiliary air source in relation to the sensed temperature of the cabin air, and either or both of the ESS and/or the ESS inlet. It should be noted that the VICM does not have any control of change in temperature available at any of the air sources. 
     In the most preferred form of the ESS thermal conditioning system according to the present invention, the selective auxiliary air source is the HVAC ducting. An HVAC ESS duct is interfaced with the HVAC ducting of the HVAC module. An actuator door, or “bleed” door, is fitted to the HVAC ESS duct, and is electrically operated anywhere between a closed position to an open position responsive to the VICM. The VICM operates the bleed door based upon its programming and data from temperature sensors on either side of the bleed door, and for example, other temperature sensors. In this manner, the temperature of the ESS can be kept within the optimal performance temperature range, or brought thereinto as quickly as possible. It should be noted that the VICM does not have any control of the HVAC module. 
     In operation, if the motor vehicle has experienced a cold soak, then the driver would be expected to select a heating mode for the HVAC module. The VICM would sense the temperature rise of the HVAC air in the HVAC ducting and thereupon open the bleed door to allow the ESS blower to duct-in (bleed) a selected portion of the HVAC conditioned air from the HVAC ducting. On the other hand, if the motor vehicle has experienced a hot soak, then the driver would be expected to select a cooling mode for the HVAC module. Now, the VICM would sense the temperature decline in the HVAC air and thereupon open the bleed door to allow the ESS blower to duct-in (bleed) a selected portion of the HVAC conditioned air from the HVAC ducting. When the optimal ESS performance temperature range of the ESS (and the passenger cabin) is present, the VICM will detect there is no need for HVAC air to assist thermal conditioning of the ESS and will close the bleed door, opening the door as needed to keep the temperature of the ESS within its optimal temperature range. 
     Accordingly, it is an object of the present invention to provide an ESS thermal conditioning system which selectively utilizes air from at least one auxiliary air source, most preferably the HVAC ducting. 
     This and additional objects, features and advantages of the present invention will become clearer from the following specification of a preferred embodiment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic side view of a passenger cabin, showing an HVAC module and components associated with prior art thermal conditioning of a hybrid vehicle ESS. 
         FIG. 2  is a schematic diagram of an HVAC module and components associated with prior art thermal conditioning of a hybrid vehicle ESS. 
         FIG. 3  is a graph of available ESS power as a function of battery pack cell temperature, showing plots for charge and discharge. 
         FIG. 4  is a schematic side view of a passenger cabin, showing an HVAC module interfaced with components associated with the thermal conditioning of a hybrid vehicle ESS according to a preferred example of the present invention. 
         FIG. 5  is a schematic diagram of an HVAC module interfaced selectively with components associated with thermal conditioning of a hybrid vehicle ESS according to the present invention. 
         FIG. 6A  is a schematic plan view of an HVAC ESS duct with the bleed door in its closed position. 
         FIG. 6B  is a schematic view seen along line  6 B- 6 B of  FIG. 6A . 
         FIG. 6C  is a schematic plan view of an HVAC ESS duct with the bleed door in its open position. 
         FIG. 6D  is a schematic view seen along line  6 D- 6 D of  FIG. 6C . 
         FIG. 7  is an exemplar algorithm for carrying out the ESS thermal conditioning system according to the present invention, wherein the HVAC ducting is the selective auxiliary air source. 
         FIG. 8  is a graph of inlet air temperature versus time, including plots of selected proportions of HVAC conditioned air. 
         FIG. 9  is a graph of battery pack cell temperature versus time, including plots of selected proportions of HVAC conditioned air with respect to a selected motor vehicle operation event profile. 
         FIG. 10  is an exemplar schematic representation of a plurality of selective air sources in accordance with a second example of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the Drawings,  FIG. 3  depicts a graph  200  of power versus battery pack cell temperature of a typical hybrid vehicle ESS. Plot  202  depicts the available discharge power, and plot  204  depicts the available charge power. It is seen that there is a temperature range at which both plots  202 ,  204  plateau at a maximum, from temperature T 1  to temperature T 2 , wherein this plateau defines an optimal ESS performance temperature range  206  (any particular ESS and its battery pack will have its particular optimal ESS performance temperature range which may vary from that shown in  FIG. 3 ). For temperatures below T 1 , the power availability of the battery pack in both charge and discharge modes decreases rapidly with decreasing temperature, and for temperatures above T 2 , the power availability of the battery pack in both charge and discharge modes also decreases rapidly with increasing temperature. Therefore, it is highly desirable to keep the ESS within the optimal ESS performance temperature range (i.e., for the example of  FIG. 3 , the range  206  between T 1  and T 2 ), and indeed to keep the ESS from approaching even the limits of the range (i.e., for the example of  FIG. 3 , keeping the temperature of the ESS within about T 1 +ΔT and T 2 −ΔT, where +ΔT may be, for example, about 5 C.), if at all possible. 
     The ESS thermal conditioning system according to the present invention performs the function of keeping the ESS temperature within the optimal ESS performance temperature range, or bringing the ESS temperature into this range as quickly as possible. 
     A preferred example of the ESS temperature conditioning system  100  is shown at  FIGS. 4 through 7 . 
     As mentioned, the passenger cabin includes a heating, ventilation and air conditioning (HVAC) module  104 , which typically includes passenger input instruments  130  and an HVAC controller  132  which operates the HVAC module in response to the passenger input. Typically, the HVAC module includes an HVAC blower  134 , an evaporator  136  for cooling the HVAC air to the cabin and a heater core  138  for heating the HVAC air to the cabin via the HVAC ducting  108 . These components are not subject to an OBD requirement, being not controlled or influenced by the hybrid vehicle integration control module (VICM)  124 . 
     The ESS  102  and the HVAC module  104  are generally as described with respect to  FIGS. 1 and 2 , except now an HVAC ESS duct  106  is provided which communicates with the HVAC ducting  108  so that HVAC air A′ H  can be made selectively available to the ESS blower  110  and be mixed with the cabin air A′ C , which is always available. 
     As in  FIGS. 1 and 2 , within the passenger cabin  112  of the hybrid motor vehicle is disposed the ESS  102 , which may, for example, rest on the vehicle floor  114  above the fore-aft floor “tunnel”  116 . The ESS  102  is thermally conditioned, at least in part, by the movement of cabin air via an ESS blower  118 , whereby the cabin air is circulated through the ESS, originating at least one permanently open entry vent  120  and exiting at least one permanently open exit vent  122 , both vents being permanently open in the sense of being in permanently and completely open fluidic communication with the passenger cabin. Operation of the ESS blower  118  is controlled by the VICM  124 , utilizing temperature data from (among others) an inlet duct temperature sensor  126   a , an outlet duct temperature sensor  126   b , and an ESS temperature sensor  126   c . The VICM  124  is connected to inputs and outputs by various data lines (see for example dashed lines in  FIG. 5 ). 
     The HVAC ESS duct  106  intersects the HVAC ducting  108  of the HVAC module  104  such that the HVAC air may bleed from the HVAC ducting into the HVAC ESS duct. An actuator door, or “bleed” door,  144  is fitted to the HVAC ESS duct  106 , and is electrically operated selectively to position anywhere between a closed position to an open position responsive to the VICM  124 . The VICM  124  operates the bleed door  144  based upon its programming and data from temperature upstream and downstream temperature sensors  146   a ,  146   b  disposed on either side of the bleed door, and may for example, utilize other temperature sensors. 
     The VICM  124 , its associated data lines, the system sensors, including inlet and outlet duct temperature sensors  126   a ,  126   b , and upstream and downstream temperature sensors  146   a ,  146   b , and any actuator door position sensor (which can be incorporated into the actuator, i.e., as shown at  144   c  of  FIGS. 6A and 6C ), all constitute an electronic control system  142 . 
     These non-HVAC module components are subject to an on-board diagnostics (OBD) requirement, whereby a signal is provided to the driver if a fault is detected in any of the components. 
     By way of example as shown at  FIGS. 6A through 6D , the bleed door  144  may be a panel  144   a  having an area which matches the cross-sectional area of the HVAC ESS duct  106 , which is nonotatably mounted to an axle  144   b  which is, itself, rotatably mounted to the HVAC ESS duct. The axle  144   b  is rotated by an actuator  144   c  which is electrically connected to the VICM  124 . 
     In operation, if the motor vehicle has experienced a cold soak, for example sitting outside on a very cold night, then the driver would be expected to select a heating mode for the HVAC module  128 . The VICM  124  would sense the temperature rise of the HVAC air in the HVAC ducting via the upstream temperature sensor  146   a  and thereupon open the bleed door  144  (as for example shown at  FIGS. 6C and 6D ) to allow the ESS blower to duct-in (bleed) a selected portion of the HVAC air A′ H  from the HVAC ducting to blend or mix with the cabin air A′ C , wherein the proportion of the HVAC air to cabin air is selected by the VICM and is effected by the selected position of the bleed door (i.e., being positioned more or less open). On the other hand, if the motor vehicle has experienced a hot soak, for example sitting outside on a hot, sunny day, then the driver would be expected to select a cooling mode for the HVAC module. Now, the VICM would sense the temperature decline in the HVAC air via the upstream temperature sensor  146   a , and thereupon open the bleed door to allow the ESS blower to duct-in (bleed) a selected a portion of the HVAC conditioned air from the HVAC ducting to blend or mix with the cabin air A′ C , wherein, as mentioned above, the proportion of the HVAC air to cabin air is selected by the VICM and is effected by the selected position of the bleed door (i.e., being positioned more or less open). 
     In the mode where the bleed door  144  is open, the VICM  124  receives data from the downstream temperature sensor  146   b , and compares to the data from the upstream temperature sensor  146   a  to ascertain that the bleed door is open and air is flowing (bleeding) properly from the HVAC ducting. If it is detected that there is a fault, then an OBD fault signal is provided to the driver. 
     When the optimal ESS performance temperature range of the ESS  102  (and the passenger cabin) is present, the VICM  124  will detect there is no need for HVAC air to assist thermal conditioning of the ESS and will close the bleed door  144 . The re-opening of the bleed door is effected periodically as needed to keep the temperature of the ESS within its optimal temperature range and avoid as best as possible the extremes of the optimal temperature range. 
     Turning attention now to  FIG. 7 , an exemplar algorithm  300  for carrying out the preferred example of the ESS temperature conditioning system  100  will be described. 
     The algorithm is initiated at Block  302  and passes to Decision Block  304 , whereat inquiry is made as to whether the engine ignition is on. If the answer to the inquiry is no, then the algorithm proceeds to Block  306 , whereat the ESS blower is turned off and the bleed door is closed. The algorithm then returns to Decision Block  304 . 
     Reconsidering Decision Block  304 , if the answer to the inquiry thereat is yes, then the algorithm proceeds to decision block  308 , whereat inquiry is made as to whether the cells of the battery pack of the ESS are cold or trending toward becoming cold, that is, below a predetermined temperature or trending theretoward, as for example a temperature almost at yet above, at, or below a lowest temperature at which available charge/discharge power is optimum (see discussion of  FIG. 3 , hereinabove). If the answer to the inquiry is yes, then the algorithm proceeds to Decision Block  310 , whereat inquiry is made as to whether the HVAC air temperature is greater than or equal to the ESS inlet air temperature (i.e., the VICM compares the temperature data from the upstream temperature sensor  146   a  and the inlet duct temperature sensor  126   a ). If the answer to the inquiry is no, then the algorithm proceeds to Block  312  whereat the bleed door is closed, and the algorithm then proceeds back to Decision Block  304 . 
     However, if the answer to the inquiry at Decision Block  310  is yes, then the algorithm proceeds to Block  314 , whereat the bleed door is opened, and then proceeds to Block  316 , whereat the VICM operates the ESS blower based for example upon a predetermined look-up table stored in the VICM. The algorithm then returns to Decision Block  304 . 
     Reconsidering Decision Block  308 , if the answer to the inquiry thereat is no, then the algorithm proceeds to Decision Block  318 , whereat inquiry is made as to whether the cells of the battery pack of the ESS are hot or trending toward becoming hot, being above a predetermined temperature or trending theretoward, as for example a temperature almost at yet below, at, or above a highest temperature at which available charge/discharge power is optimum (see discussion of  FIG. 3 , hereinabove). If the answer to the inquiry is no, then the algorithm proceeds to Block  306 , whereat the ESS blower is turned off and the bleed door is closed. The algorithm then proceeds back to Decision Block  304 . 
     However, if the answer to the inquiry at Decision Block  318  is yes, then the algorithm proceeds to Decision Block  320 , whereat inquiry is made as to whether the HVAC duct air temperature is less than the ESS inlet temperature (i.e., the VICM compares the temperature data from the upstream temperature sensor  146   a  and the inlet duct temperature sensor  126   a ). If the answer to the inquiry is no, then the algorithm proceeds to Block  312 , whereat the bleed door is closed, and the algorithm then returns to Decision Block  304 . 
     However, if the answer to the inquiry at Decision Block  320  is yes, then the algorithm proceeds to Block  322 , whereat the bleed door is opened, and then proceeds to Block  316 , whereat the VICM operates the ESS blower based for example upon a predetermined look-up table stored in the VCIM. The algorithm then returns to Decision Block  304 . 
     Temperature conditioning benefits to the ESS as a result of implementation of the above described preferred form of the present invention are graphically depicted at  FIGS. 8 and 9 . 
       FIG. 8  is a graph  400  of inlet air temperature versus time, depicting four plots, all with an initial temperature of 60 C. at initial time. The first plot  402  is indicative of change in HVAC air as a function of time. The second plot  404  is indicative of the change in ESS inlet temperature as a function of time, wherein the air delivery to the ESS is proportionally 75% HVAC air and 25% cabin air. The third plot  406  is indicative of the change in ESS inlet temperature as a function of time, wherein the air delivery to the ESS is proportionally 50% HVAC air and 50% cabin air. The fourth plot  408  is indicative of the change in ESS inlet temperature as a function of time, wherein the air delivery to the ESS is 100% cabin air. It is clear that the blending of HVAC air provides a quicker reduction in temperature of the ESS inlet air over that of only cabin air. 
       FIG. 9  is a graph  500  of ESS average cell temperature versus time, showing 5 plots after a hot solar soak. The start ESS inlet temperature (the cabin temperature) is 60 C., and the ESS cell temperature is 41 C. The first plot  502  is indicative of the speed of the motor vehicle during a driving event. The second plot  504  is indicative of the change in ESS cell temperature as a function of time, wherein the air delivery to the ESS is proportionally 75% HVAC air and 25% cabin air. The third plot  506  is indicative of the change in ESS cell temperature as a function of time, wherein the air delivery to the ESS is proportionally 50% HVAC air and 50% cabin air. The fourth plot  508  is indicative of the change in ESS cell temperature as a function of time, wherein the air delivery to the ESS is 100% cabin air at a base rate of flow. The fifth plot  510  is indicative of the change in ESS cell temperature as a function of time, wherein the air delivery to the ESS is 100% cabin air at a rate 30% higher than the base rate of flow. As in  FIG. 8 , it is clear that the blending of HVAC air provides a quicker reduction in temperature of the ESS over that of conventional cabin air. 
     Table I provides exemplar operational conditions of the ESS temperature conditioning system  100 . 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE I 
               
               
                   
                   
               
               
                   
                 Condition 
                 HVAC Bleed 
                 Cabin Inlet 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 ESS Min. 
                 100% 
                 0% 
               
               
                   
                 City driving 
                 75% 
                 25% 
               
               
                   
                 Hwy. Driving 
                 50% 
                 50% 
               
               
                   
                 ESS Max. 
                 40% 
                 60% 
               
               
                   
                   
               
             
          
         
       
     
     Table II provides exemplar responses to certain fault conditions of operation by the ESS temperature conditioning system  100 . 
     
       
         
               
               
             
           
               
                 TABLE II 
               
               
                   
               
               
                 System Condition 
                 System Response 
               
               
                   
               
             
             
               
                 Bleed door stuck closed 
                 OBD indicator on 
               
               
                 Bleed door stuck midway 
                 OBD indicator on, poss. lower ESS 
               
               
                   
                 blower speed 
               
               
                 Bleed door stuck open 
                 OBD indicator on, poss. lower ESS 
               
               
                   
                 blower speed 
               
               
                 Bleed temp. sensor failure 
                 OBD indicator on, switch to ESS 
               
               
                   
                 inlet sensor 
               
               
                 Bleed duct blocked/dislodged 
                 OBD indicator on, command bleed door 
               
               
                   
                 closed 
               
               
                   
               
             
          
         
       
     
       FIG. 10  depicts a schematic diagram of a non-limiting example of possible selective air sources of the ESS temperature conditioning system  600  according to the present invention, wherein other selective air sources may be utilized other than those illustrated. 
     Air source  602  is a conventional prior art air source, as for example shown at  FIGS. 1 and 2  and discussed hereinabove. Selective air source  604  selectively draws air from a selected location of the cabin other than the conventional location of the one or more entry vents used by the conventional air source  602 , as for example at the floor or the roof of the vehicle, wherein the selectivity depends upon the open or closed position of its actuator door per the VICM. Selective air source  606  draws air from another selected location of the cabin other than the conventional location of the one or more entry vents used by the conventional air source  602 , as for example at the cargo area of a SUV, station wagon or van, wherein the selectivity depends upon the open or closed position of its actuator door per the VICM. Selective air source  608  selectively bleeds air from the HVAC, being the ESS thermal conditioning system  100  as described hereinabove. Selective air source  610  draws air from the trunk of the vehicle, wherein the selectivity depends upon the open or closed position of its actuator door per the VICM. Selective air source  612  draws air from an exterior vent, as for example at the engine compartment, wheel well or near the exhaust (safely away from exhaust gases), wherein the selectivity depends upon the open or closed position of its actuator door per the VICM. Since a plurality of auxiliary air sources are available, the VICM will select the actuator door opening amount which is most appropriate to any of them, respectively, based upon, for example, the sensed temperature at the auxiliary air source in relation to the sensed temperature of the cabin air, and either or both of the ESS and/or the ESS inlet. 
     To those skilled in the art to which this invention appertains, the above described preferred embodiment may be subject to change or modification. Such change or modification can be carried out without departing from the scope of the invention, which is intended to be limited only by the scope of the appended claims.