Abstract:
An air distribution door for use in a ventilation system with anti-stratification feature is provided. The door includes a tab extending from the main body of the door. The tab partially disrupts air flow going into the heat exchanger. This disruption slows high velocity airflow going across the heat exchanger and causes a more uniform thermal transfer distribution to the air from the heat exchanger, which provides preferred comfort by the user.

Description:
FIELD 
     This present invention relates to the field of automotive heating ventilating and air conditioning systems, more specifically this invention relates to the air distribution door that directs air flow to a heat exchanger. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     In automotive vehicles, it is common to have a climate control system located within an instrument panel which provides heated or cooled air to occupants through dash panel defrost air outlets, instrument panel venting air outlets and floor directed air outlets. These traditional climate control systems often include a heater core that performs heat exchange between the engine coolant, which is heated by the engine, and the cool air in the cabin/outside environment, in order to provide warm air to the passenger compartment. Some vehicles include an air conditioning system that incorporates an evaporator for absorbing heat from the warm air in the cabin and from the outside environment. The heater core and evaporator are typically provided in an HVAC housing located in the passenger compartment of the vehicle. The evaporator and heater core are generally disposed downstream of a fan for communicating cooled or warmed air into the passenger compartment. 
     Distribution or control or blend air doors within an HVAC unit are used to control the various airflows through the heat exchangers. When a “full hot” condition is required, the air doors shut off airflow from non-heated air sources. Conversely, when a “full cold” condition is required, the air doors shut off airflow from the heated air source. In “medium mode” conditions, when temperature other than “full hot” or “full cold” is required, the air doors may be positioned to allow heated and non-heated air streams, in varying degrees, to pass through the HVAC unit. 
     The air output from the HVAC unit may be supplied directly to various outlets within the vehicle cabin. It is desirable to be able to provide air through the outlets simultaneously which are all at substantially similar temperatures 
     A heater core typically does not produce uniform temperature distribution across its plane. As a result, a temperature gradient is observed along the heater core. With a typical HVAC configuration, sometimes an undesirable temperature imbalance is observed between the center and outside panel vents in the cabin of the vehicle, known in the art as stratification. Conventional methods to compensate for the temperature imbalance are to increase tank depth of the heater core, increase thickness of the heater core, or shift the position of the heater core inside the case. All of these options involve costly tooling changes and can have a negative impact in terms of airflow volume and noise. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     An air distribution door for use in a ventilation unit which aids in preventing stratification comprises that includes a main body of the door that rotates on an axis to block a predetermined amount of air distributed through the ventilation unit. The door contains a tab that extends perpendicular from the distribution door main body. The tab may be of rectangular shape and may be formed into the control door. The height of the tab may be constant and determined based on specific performance requirements of the ventilation unit. The position of the tab may be parallel to the rotation axis of the door. 
     In another form, the present disclosure provides an automotive heating, ventilating and cooling system including a blower fan, a evaporator to cool air, a heater core to increase the temperature of the air, a distribution door, which rotates on an axis, placed between the two heat exchangers to divert some of the airflow through the heater core. The distribution door has a tab protruding from the body of the door. There may be more than one distribution door with a protruding tab in the ventilation system. The protruding tab may be placed on the heater core side of the distribution door. The protruding tab may vary in height depending on the application of the automotive ventilation system. The angle of the protruding tab to the axis of the door may be predetermined based on the performance of the automotive ventilation system. The protruding tab location on the plane of the distribution door may be predetermined based on the performance of the automotive ventilation system. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a schematic representation of a vehicle having a heating, ventilating and cooling system according to the principles of the present disclosure; 
         FIG. 2  is a fragmented perspective view of an automotive vehicle showing a portion of the passenger space; 
         FIG. 3A  is a simplified view of an HVAC module; 
         FIG. 3B  is a view of the preferred embodiment HVAC module; 
         FIG. 4  is a simplified view of an HVAC module heater core; 
         FIG. 5  is a perspective view of the air distribution door in the HVAC module assembly; 
         FIG. 6  is another perspective view of the air distribution door with air disruption tab in the HVAC module assembly 
         FIG. 7 . is another perspective view of the air distribution door with air disruption tab in the HVAC module assembly; 
         FIG. 8  is another perspective view of the air distribution door with air disruption tab in the HVAC module assembly; and 
         FIG. 9  is another perspective view of the air distribution door with two air disruption tabs in the HVAC module assembly. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Referring to  FIGS. 1 &amp; 2 , an automotive vehicle  10  with an HVAC system  20  within which an HVAC module  22  according to the present teachings can be utilized is shown. Vehicle  10  includes a passenger space  12  which may have both a front passenger space  12   a  and a rear passenger space  12   b . HVAC controls  14  allow adjustment of the operation of HVAC module  22  to provide desired flows of conditioned air. 
     With reference to  FIG. 3A , a block diagram of a conventional vehicle HVAC module  22  is shown and generally identified at reference  22 . An HVAC case  24  forms a ventilation duct through which air conditioned and/or heated air is sent into the passenger compartment  12 . The HVAC case  24  contains a fan  26  which is arranged on the upstream side of an evaporator  28 . Low pressure refrigerant flowing into the evaporator  28  absorbs heat from the air inside the HVAC case  24  for evaporation. The HVAC case  24  accommodates, on the downstream side of the evaporator  28 , a hot water heater core (heat exchanger)  30 . The heater core  30  includes an inlet pipe  32  and an outlet pipe  34 . Hot water (coolant) of the vehicle engine (not shown) is directed to the heater core  30  through the inlet pipe  32  by a water pump (not shown). 
     An air bypass channel  38  is formed beside the hot water heater core  30 . An air distribution door  40  is provided to adjust the volume ratio between warm air and cool air that passes through the hot water heater core  30  and the bypass channel  38 , respectively. The air distribution door  40  adjusts the temperature of the air blown into the passenger compartment  12  by adjusting the volume ratio between the warm air and the cool air. The door rotates on an axis  42  to adjust the volume ratio. 
     Additionally, a face outlet  44 , a defroster outlet  46 , a foot outlet  48  and a rear cabin outlet  50  are formed at the downstream end of the HVAC case  24 . The face outlet  44  directs air toward the upper body portions of passengers, the defroster outlet  46  directs air toward the internal surface of a windshield, the foot outlet  48  directs air toward the feet of the front seat passengers, and the rear cabin outlet  50  directs air toward the rear seat passengers of the vehicle. The outlets  44 ,  46 ,  48 ,  50  are opened and closed by outlet mode doors (not shown). The air distribution door  40  rotates on an axis  42  and is driven by such electric driving devices such as servo motors via linkages, cables via linkages or the like (not shown). 
     In order to appreciate the advantages realized by the tab  64  extending from the air distribution door  41  of the present invention described herein, a discussion of the operation of the heater core  30  is warranted. With additional reference now to  FIG. 4 , a diagrammatic representation of the heater core  30  is shown. At the outset dashed line ‘V’ represents the vertical orientation of the heater core  30 . In this regard, line V represents a division in the downstream air from the heater core  30  between the driver side region  52  and the passenger side region  54  (for dual zone HVAC configuration) A horizontal dashed line ‘H’ represents a upper zone  56  aligned for directing air to the face outlet  44  direct at the front passenger occupants, the area of the heater core closer to the V line represents the zone of air that gets directed to the center vents  58 , the area closer to the outer edge of the heater core represents a zone that the air gets directed to the outer front vents  60 . The area closer to the bottom edge  64  of the heater core  30 , represents the zone aligned for directing air toward the foot outlet  48  and foot vent  62  in passenger cabin  12 . 
     To further appreciate the advantages realized by the current teachings, operation of an HVAC module without a tab  64  on the air distribution door is warranted. The air distribution door  40  in the current art does not have a tab  64  extending from the body of the door. However, without the tab  64  on the air distribution door the heater core may exhibit hot and cold areas which lead to inconsistent panel out temperatures at the vents  58 ,  60 , leading into the passenger space  12 . The hot and cold areas on the heater core  30  are caused by the velocity of the air moving across the heater core  30 . The areas of the heater core  30  where the air velocity is high are cooler; subsequently areas of the heater core  30  with lower air velocity flowing over it are warmer. It can be appreciated that areas of higher velocity air on the heater core  30  can change by configuration of the HVAC case  22 , downstream ducts  44 , 46 , 48 , 50 , and heater core  30  orientations. Based on the current configuration of the HVAC case  22 , stratification between front center vents  58  and outer front vents  60  was exhibited. The current configuration in a full hot mode (air distribution door  40  directing 100% of air through heater core  30 ), without the tab on the air distribution door, caused front passenger panel center vents  58  temperatures to be hotter than the outer front vents  60 . The heater core  30  experience higher velocity air flowing over the upper outer zone area  56 , causing the heater core  30  to be cooler in that area. The present teachings are to incorporate a tab on the air distribution door  40  to disrupt the high velocity air flowing over the heater core  30 , specifically in the upper zone of the heater core. 
     As illustrated in  FIG. 3B , the preferred embodiment maintains two air distribution doors  41 ; this is to allow for a dual front zone configuration by way of non-limiting example. It can be appreciated that the tab  64  can be incorporated on HVAC units that maintain single zone, dual zone, and tri zone, with a multitude arrangement of air distribution doors. Referring to  FIG. 5 , the preferred embodiment teaches of a tab  64  on the air distribution door  41  is rectangular in cross section shape and positioned distally from the midway point ‘M’ from the axis. The tab  64  may contain rib sections  66  to provide added strength or stiffness, by way of non-limiting example. The tab starts at the door outboard sealing side  68  and spans toward the inboard side  70  of the door  41 , the tab  64  spans approximately three-quarters the width of the door  41 , with a height of approximately one-third the height of the door  41 . It can be appreciated in the art that the downstream configuration can have an effect on the temperature gradient of the heater core  30 . In the preferred embodiment it was discovered that the duct length has an effect to the velocity of air and ultimately the output temperature at the vent leading to the passenger space  12 . In the current configuration the path leading to the center vents  58  is shorter than the ducting leading to outside passenger vents  60 . This was causing stratification between the center vents  58  and outer vents  60  leading into the passenger space  12 . The temperature of air coming out of the outer vents  60  was found to be colder, in the full hot position, than the center vents  58 . To counter this stratification issue the tab  64  does not span the entire width of the door  41 . The tab spans approximately three-quarters of the width of the door leaving an opening near inboard side  70  of the door that is associated with the center V line of the heater core  30 , shown in  FIG. 4 . While air passes over the door and tab, the higher velocity air is allowed to flow through the center of the upper zone  56  of the heater core  30  which is the zone associated with the center vents  58  eliminating the stratification and balancing the outlet temperature of vents  58 ,  60  leading into the passenger space  12 . The height of the tab  64  is determined on understanding the zones of the heater core  30  that lead to related vents. In the current configuration, to fully disrupt the high velocity air in the upper zone  56  of the heater core  30 , and balance the vents  58  and  60  outlet temperature, it was determined to have the tab  64  be approximately one-third the height of the door  41 , by way of non-limiting example. It can be appreciated that there are several ways in the art to determine hot and cold areas of the heater core  30 ; one potential method is to equip the heater core  30  with a grid of thermal couples (not shown) and perform various evaluations to determine the temperature differences across the heater core  30 . Another potential method is to simulate air velocity vectors using computer simulation software and determine the hot and cold areas. No matter which method is used, it is appreciated that the tab  64  will be placed to disrupt air flowing through the higher velocity areas of the heater core  30 . 
     It may be further appreciated that the tab  64  may be integrally molded with the door  41 , thus making it the same material as the door  41  such as, a synthetic polymer, by way of non-limiting example. The tab  64  may also be of different material than the door  41  and attached to the door  41  with an adhesive (not shown). The tab  64  may also be the same material as the door  41  and attached to the air distribution door  41  with an adhesive (not shown), by way of non-limiting example. 
     Referring now to  FIGS. 6-8 , the tab  64  on the air distribution door  41  can take a variety of forms, shapes, and orientation to provide the described functionality, and depending on the stratification of the particular HVAC unit, duct and panel out vent configuration. For example in  FIGS. 6A  and B; an air distribution door  78  with an air disruption tab  80  which has general “V” shape to disrupt air on the outer edges  82  of the door  78  but allow high velocity air over the middle of the door  78 . In other embodiments, referring to  FIGS. 7A  and B, an air distribution door  90  contains an air disruption tab  92  that has a linear angle triangular shape. In yet another embodiment, referring to  FIG. 8 , an air distribution door  100  contains an air disruption tab  102  that has a triangular plateau shape with a raised portion in the middle of the door  100 , by way of non-limiting example. 
     It can be appreciated that the air disruption tab  64  may be placed anywhere on the door  41  that allows for the appropriate clearances to open and close the air distribution door  41 . The tab can span across the air distribution door from a small segment of the width of the door  41 , to the full width of the door  41  depending on desired function. The height of the tab  64  may be at least a fraction of the height of the opening leading into the heater core  30 , and may be less than three quarters of the height of the opening leading into the heater core  30 . It will be appreciated that the tab may be otherwise suitably formed, shaped, relatively oriented and/or located. 
     Referring to  FIG. 9 : additionally or alternatively, the air distribution door  110  could include two or more separate tabs  112 ,  114 . For example, the vehicle  10  may include a dual or multiple zone climate control system, where a driver and one or more passengers may adjust temperature settings and/or airflow quantity settings for a localized zone within the passenger compartment of the vehicle  12 . In such an embodiment, each of the air distribution doors  110  may correspond to one of the multiple localized zones within the vehicle passenger area  12 . These differing configurations may cause the temperature gradient of the heater core  30  to be in different zones on the heater core based on the velocity of air passing over the heater core  30 . Multiple tabs  64  may be incorporated on the air distribution door  110  to disrupt air flow and allow higher velocity air to pass over the heater depending on balance needed of the vents  58 ,  60 ,  62  leading into the passenger space  12 . 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.