Abstract:
An evaporator core drying system in which air that is blown by a blower is concentrated into a narrow cross-sectional air stream of high speed purge air which passes progressively across the area of the evaporator core, per an appropriate blow algorithm, so as to effectively and efficiently dry the evaporator core. Preferably, the configurable barrier is composed of at least one roller door located between the blower and the evaporator core.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to heating, ventilation and air conditioning (HVAC) systems, and particularly HVAC systems of motor vehicles. More particularly, the present invention relates to an evaporator core drying system implemented at the termination of operation of the air conditioning component of an HVAC system. 
       BACKGROUND OF THE INVENTION 
       [0002]    The passenger compartment of motor vehicles provides a space which is environmentally adjustable to suit the predilections of the passengers via a heating, ventilation and air conditioning system, hereinafter simply referred to as an HVAC system. In this regard,  FIGS. 1 and 2  are schematic depictions of aspects of a conventional HVAC system  10  of a motor vehicle. 
         [0003]    As shown at  FIG. 1 , the HVAC system  10  includes an HVAC module  10   a  which, in turn, includes a heater core  12  and an evaporator core  14 , both of which serving to provide conditioned air to the passenger compartment  16  of the motor vehicle. The heater core  12  conditions the air by heating it as it passes therethrough to the passenger compartment  16  via heated coolant passing therein, wherein the coolant is heated by the internal combustion engine  18 , cooled by a radiator  20 , and temperature regulated by a thermostat  22 . The evaporator core  14  conditions the air by cooling it as it passes therethrough to the passenger compartment  16  via cooled refrigerant passing therein, wherein the refrigerant is compressed by a compressor  24 , the heat of compression is rejected to the atmosphere by a radiator  26 , and then cooled thereafter by an expansion process. In either case, the temperature of the air entering the passenger compartment is user selectable. 
         [0004]    Referring next to  FIG. 2 , the HVAC module  10   a  is depicted, the module being defined by an enclosing sidewall  28 . Air input is provided thereto, either via a first air-in path  30  which provides air outside the motor vehicle, or a second air-in path  32  which provides air recirculated with respect to the passenger compartment, selection of which of the first and second air-in paths being determined by an air-in door  34 . A blower  36  causes air to be drawn in from the first and second air-in paths, and blown air  38  is passed downstream therefrom to the evaporator core  14 . A temperature door  40  is positioned to cause the blown air to pass entirely or partly through the heater core  12  or to entirely by-pass it in the event the air conditioning is on maximum. A series of downstream vent doors then direct how the conditioned air passes into the passenger compartment, for example via a floor vent door  42  of a floor vent  42   a , and a panel/windshield vent door  44  of a panel vent  44   a  and a windshield (defroster) vent  44   b.    
         [0005]    During a typical air conditioning operation of an HVAC system, the evaporator core  14  cools the air which is blown over the evaporator tubes. As the air passes through the evaporator core, it becomes cooler and drier due to loss of moisture content. Usually, the moisture captured from air accumulates on the evaporator core surface and flows down and out via a drain tube  46 . However, not all of the accumulated liquid leaves the evaporator core, depending upon the amount of moisture and the environmental conditions, most notably in high temperature and high humidity environments. Water retention at the evaporator core can be problematic, as the accumulated moisture could result in passengers sensing humidity from air entering through the vents, smelling odor due to bacteria and microbial growth, and, from a mechanical point of view, there is potential for rusting of the evaporator core. Accordingly, it is very desirable to ensure this accumulated water at the evaporator core is vacated therefrom whenever the motor vehicle is turned off. 
         [0006]    Current HVAC system practices operate the blower intermittently for a short period of time after engine shut-down to remove as much moisture as possible (according to a “blow algorithm” that is well known in the HVAC system art). The blow algorithm directs the blower to blow air across the whole evaporator core surface area at the same time, which means that the air stream speed of the blow air is low and, as a result, could possibly not remove all of the moisture out of the evaporator core before blower shut-down. In addition, the moisture removal rate is limited by the vehicle&#39;s battery voltage and is potentially ineffective in humid environments. Accordingly, it is sometimes necessary to use UV light at the evaporator core to get rid of the bacterial growth, the source of which light having attendant packaging, cost and service issues. 
         [0007]    Accordingly, what remains needed in the art is an efficient and effective way to ensure removal of moisture from the evaporator cores of HVAC systems. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is an evaporator core drying system in which air that is blown by the blower is concentrated into a narrow cross-sectional air stream of high speed purge air which passes progressively across the area of the evaporator core, per an appropriately designed blow algorithm, so as to effectively and efficiently dry the evaporator core. 
         [0009]    The evaporator core drying system according to the present invention utilizes a configurable barrier disposed closely adjacent and upstream the evaporator core (downstream of the blower). The configurable barrier is dynamically configurable from a fully open configuration in which the evaporator core is fully exposed to the air blown by the blower, to a slotted configuration in which only a narrow cross-sectional slot exposes the evaporator core to the air blown by the blower, wherein the slot is progressively movable across the area of the evaporator core (as for example progressively from one side to the other; ie., either vertically, horizontally, or diagonally). 
         [0010]    In operation of the evaporator core drying system, during utilization of the HVAC system of the motor vehicle, the configurable barrier is in its fully open configuration. However, when the blow algorithm implements, the configurable barrier reconfigures into its slotted configuration, wherein the slot is located at one side of the area of the evaporator core and then moves progressively thereacross to the opposite side. The operation of the blower creates a region of high air pressure between the configurable barrier and the blower, and a region of low air pressure exists downstream of the configurable barrier, wherein these two regions of differing air pressure mutually communicate via the slot. As a consequence of the air pressure drop across the slot, a rapidly moving stream of high speed purge air passes therethrough, the passage of which drying the evaporator core in a progressive manner as the slot progresses across the evaporator core. 
         [0011]    According to the preferred embodiment of the evaporator core drying system, the configurable barrier is composed of a roller door system composed of either a selectively actuatable double roller door or a selectively actuatable single roller door. 
         [0012]    Accordingly, it is an object of the present invention to provide an evaporator core drying system in which an air stream of high speed purge air passes progressively across the area of the evaporator core so as to effectively and efficiently dry the evaporator core. 
         [0013]    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 
         [0014]      FIG. 1  is a schematic diagram of a motor vehicle HVAC system environment of operation according to the prior art. 
           [0015]      FIG. 2  is a schematic diagram of a motor vehicle HVAC system module according to the prior art. 
           [0016]      FIG. 3A  is a schematic diagram of a motor vehicle HVAC system module, including an evaporator core drying system according to the present invention, wherein the configurable barrier of the evaporator core drying system is at its fully open configuration. 
           [0017]      FIG. 3B  is a schematic diagram of a motor vehicle HVAC system module, including an evaporator core drying system according to the present invention, wherein now the configurable barrier of the evaporator core drying system is at its slotted configuration. 
           [0018]      FIG. 4A  is a perspective view of a first preferred type of configurable barrier of the evaporator core drying system according to the present invention, seen at line  4 A- 4 A of  FIG. 3B , having a pair of separately actuatable roller doors, wherein the roller doors are each in the form of a rollable panel composed of a flexible panel. 
           [0019]      FIG. 4B  is a perspective view of the first preferred type of configurable barrier of the evaporator core drying system according to the present invention having a pair of separately actuatable roller doors, wherein now the roller doors are each in the form of a rollable panel composed of a multiplicity of adjacently hinged segments. 
           [0020]      FIGS. 5A through 5F  are schematic depictions of progressive actuations of the roller doors of  FIGS. 4A and 4B  in the course of operation of the of the evaporator core drying system according to the present invention. 
           [0021]      FIG. 6A  is a block diagram of steps of a blow algorithm according to the present invention. 
           [0022]      FIG. 6B  is a components diagram for implementing the blow algorithm of  FIG. 6A . 
           [0023]      FIG. 7  is a perspective view of a second preferred type of configurable barrier of the evaporator core drying system according to the present invention having a single actuatable roller door. 
           [0024]      FIG. 7A  is a plan view of a planar member of the folding door of  FIG. 7 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]    Referring now to the Drawing,  FIGS. 3A through 7A  depict various views of details of implementation of the evaporator core drying system according to the present invention. 
         [0026]    Referring firstly to  FIGS. 3A and 3B , an HVAC module  100  is depicted which includes the evaporator core drying system  102  according to the present invention. 
         [0027]    By way merely of exemplification which follows the description with respect to  FIG. 2 , the HVAC module  100  is defined by a space enclosing sidewall  104 , to which an air input is provided either via a first air-in path  106  which provides air outside the motor vehicle or via a second air-in path  108  which provides air recirculated with respect to the passenger compartment, selection of which of the first and second air-in paths being determined by an air-in door  110 . A blower  112  causes air to be drawn in from the first and second air-in paths, and passed as blown air  134  downstream therefrom to an evaporator core  114 . A temperature door  116  is positioned to cause the air to pass partly through a heater core  118  or to entirely by-pass it in the event the air conditioning is on maximum. A series of downstream vent doors then direct how the conditioned air passes into the passenger compartment, for example via a floor vent door  120  of a floor vent  120   a , and a panel/windshield vent door  122  of a panel vent  122   a  and a windshield (defroster) vent  122   b . Water which accumulates at the evaporator core during operation of the air conditioning drains via a drain tube  124 . 
         [0028]    The evaporator core drier system  102  includes a configurable barrier  130 , which is configurable between a fully open configuration shown at  FIG. 3A  and a slotted configuration shown at  FIG. 3B . 
         [0029]      FIG. 3A  depicts motor vehicle HVAC system operation during running of the engine in which the HVAC system is generally utilized for conditioning the air entering into the passenger compartment via heating, cooling and ventilation, as desired. In this mode, the HVAC compartment  100  operates in a mode which is unobstructed by the configurable barrier  130  (ie., analogous to a conventional mode of operation), in that the configurable barrier is in its fully open configuration, whereby an opening  132  is formed thereof that has an area generally as large as the area of the evaporator core  130 , and thereby allows free passage thereto of the blower air  134 . 
         [0030]      FIG. 3B  depicts motor vehicle HVAC system operation during execution of a blow algorithm (see description below with respect to  FIGS. 6A and 6B ). It will be seen that the configurable barrier  130  is now reconfigured from the fully open configuration of  FIG. 3A  into its slotted configuration in which the opening  132  has been reduced to a slot  136 . During execution of the blow algorithm, the evaporator core  114  is dried during operation of the blower via a progressively moving air stream  134 ′ of high speed purge air formed of the blower air  134  by the slot  136 . 
         [0031]    Operationally with respect to drying of the evaporator core  114 , the air stream  134 ′ is provided by a difference between a high air pressure region HP and a low air pressure region LP, each on a respective side of the configurable barrier  130 , wherein the two differing air pressure regions mutually communicate via the slot  136 . According to the blow algorithm, the configurable barrier  130  is thereupon continually reconfigured so that the slot (which retains a constant width) moves progressively across the area of the evaporator core  114 , drying progressive portions of the evaporator core as they are progressively exposed to the air stream  134 ′ until the entire evaporator core has been dried. 
         [0032]    It should be noted that while the slot  136  as depicted in  FIG. 3B  is movable progressively in the vertical plane, it is to be understood the slot may be oriented otherwise and move in a direction otherwise (i.e., horizontally or at some arbitrary angle between horizontal and vertical) progressively across the area of the evaporator core from one side of the sidewall  104  to the opposite other side thereof Thereafter, the configurable barrier  130  is reconfigured to again assume its fully open configuration of  FIG. 3A  (i.e., the slot  136  again becomes the opening  132 ). 
         [0033]    Referring now to  FIGS. 4A and 4B , a first (most) preferred type of configurable barrier  102 ′,  102 ″ is depicted, composed of a pair of separately actuatable roller doors. 
         [0034]    As shown at  FIG. 4A , each roller door  140   a ,  140   b  is composed of a rollable panel  142   a ,  142   b  in the form of a flexible panel, as for example a flexible plastic sheet, each of which being rolled  144   a ,  144   b  upon a respective spool (not visible). Each spool is connected with a respective electric motor  146   a ,  146   b , as for example a stepper motor, which rolls and unrolls its respective rollable panel  142   a ,  142   b , wherein the rollable panels are guided by guide channels  148   a ,  148   b  at each side. Each rollable panel  142   a ,  142   b  has a respective leading edge  150   a ,  150   b , wherein the relative position of the leading edges with respect to each other defines the fully open configuration of the configurable barrier  102 ′ thereby providing the opening (per  FIG. 3A ), and the slotted configuration thereof providing the shown slot  136 ′ (per  FIG. 3B ). 
         [0035]    Turning attention now to  FIG. 4B , the modification to the configurable barrier  102 ″ is that the pair of roller doors  140   a ′,  140   b ′ is now composed of rollable panels  142   a ′,  142   b ′ in the form of a foldable panel composed of a multiplicity of segments that are adjacently hinged to each other in a manner well known in the roller door art, wherein like numbers of  FIG. 4B  with primes represent like functioning parts with respect to the parts of  FIG. 4A . 
         [0036]    Operation of the evaporator core drying system of  FIGS. 3A and 3B  will now be detailed with additional reference to  FIGS. 5A through 6B . 
         [0037]    A blow algorithm  200  of  FIG. 6A  commences running, typically when the engine is turned off. At execution Block  210  the blower is turned on providing an air stream  134 , wherein the configurable barrier  130  is initially in the fully open configuration providing an opening  132  (in the sense of  FIG. 4A , the roller doors  140   a ,  140   b  are both rolled up, wherein the leading edges  150   a ,  150   b  are mutually separated sufficiently to thereby provide the opening). This is the ordinary configuration during engine operation. 
         [0038]    Next, at execution Block  212 , one of the roller doors (the upper one) unrolls to provide the slot  136  of the slotted configuration of the configurable barrier at one side of the evaporator core  114 , as depicted at  FIG. 5B . At execution Block  214 , the roller doors roll/unroll in unison so that the slot retains the same width and progressively moves across the area of the evaporator core  114 , as depicted between  FIGS. 5B through 5E , whereduring the fast moving air stream  134 ′ through the slot  136  progressively dries the evaporator core. The width of the slot and the rate at which the slot moves is predetermined, in conjunction with the specifications of the blower and the evaporator core, to provide the maximum moisture removal rate yet balancing the vehicle battery state of charge (since the blower is operated by the voltage from the battery) and the overall time allowed for by the blow algorithm logic. 
         [0039]    At execution Block  216 , the roller doors reconfigure into the fully open position by one of the roller doors rolling down (the lower roller door), as shown between  FIGS. 5F and 5A . 
         [0040]    Finally, at execution Block  218  the blower is shut-off. 
         [0041]      FIG. 6B  is a components schematic  300  for implementing the blow algorithm of  FIG. 6A . An electronic control module (ECM) or other computer device at Block  312  is programmed with the blow algorithm  200 , and may or may not receive an input from one or more input sensor(s) at Block  310  (in the preferred embodiment, there is no Block  310 ). The ECM sends commands to the blower at Block  314  and the roller door(s) electric motor(s) at Block  316  to implement the blow algorithm as described above. The rate of movement of the slot progressively across the evaporator core is predetermined according to the blow algorithm, or can be dynamically adjusted at the ECM according to detected moisture, temperature, humidity, etc, from Block  310 . 
         [0042]    It is to be understood that the configurable barrier may be implemented in any suitable manner. For example, as shown at  FIG. 7 , depicted is an alternative configurable barrier  102 ′″ composed of a single roller door  160 . A single electric motor  146  rolls the door, and a spring  162  biases the return rolling (two electric motors could be used, alternatively). The roller door is constructed of a rollable panel  142 , being for example either in the form of a flexible panel or a foldable panel composed of a multiplicity of hinged segments, and is guided by guide channels  148   a ″,  148   b ″. The rollable panel  142  has a pre-formed slot  136 ′″ and a pre-formed opening  132 ′″, as shown at  FIG. 7A . Accordingly, depending upon the extent of the rolling of the rollable panel per rolls  144   a ″,  144   b ″ on the respective spools, the open configuration or the slotted configuration is provided, and in the case of the slotted configuration, the slot is progressively movable so as to provide the configurations analogous to the depictions of  FIGS. 5A through 5F . 
         [0043]    It is to be understood, therefore, that the present invention provides hardware and control methodology to: a) optimize the moisture removal rate after engine shuts down; b) eliminate potential for window fogging after the driver starts the engine the next time, since the evaporator core will have minimum (or no) moisture; c) provide a cost effective implementation of a rapid heating technology such as heat pump or hot gas cycles using the evaporator core as the heating device (conventional evaporator cores cannot be used in this manner due to moisture accumulation and the issue with window fogging); and finally, d) obviates need for UV lights. 
         [0044]    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.