Abstract:
A vehicle ventilation system includes an inlet duct incorporating a poppet valve. The system also includes an evaporator core, a heater core, an air discharge duct and a blower. The blower moves air from the inlet duct through at least one of the evaporator core and the heater core to be discharged through the air discharge duct.

Description:
TECHNICAL FIELD 
       [0001]    This document relates generally to the motor vehicle equipment field and, more particularly, to a vehicle ventilation system that incorporates an inlet duct including a poppet valve to provide a significant number of benefits and advantages over current state-of-the-art swinging door and flap valve systems. 
       BACKGROUND 
       [0002]    State-of-the-art vehicle ventilation systems typically utilize some sort of doors/flaps to change from fresh air (outside air) to recirculating interior air. Such a state-of-the-art system is disclosed in  FIG. 1  which illustrates an inlet duct housing H including a fresh air inlet F in the top wall, a recirculating air inlet R in one sidewall, and a blower inlet O in the bottom wall. The door or flap D may be pivoted about the pivot P between a first, full line position, closing the fresh air inlet F and a second phantom line position closing the recirculating air inlet R. As should be appreciated, such a swinging or pivoting door D only allows for two simple inlets from two different directions (i.e. fresh air inlet F in the top wall and recirculating air inlet R in the sidewall). 
         [0003]    This document relates to a new and improved vehicle ventilation system incorporating an inlet duct having a poppet valve. In contrast to the swinging motion of the door D utilized in the prior art inlet duct illustrated in  FIG. 1 , a poppet valve uses linear motion thereby allowing recirculating air to be brought in from multiple directions and not just one single sidewall inlet R. Advantageously, a vehicle ventilation system incorporating an inlet duct with a poppet valve provides a number of benefits including, but not limited to improved blower efficiency, improved packaging, improved sealing, lower blower motor power consumption, lower pressure drop across the inlet duct as well as lower tooling costs. 
       SUMMARY 
       [0004]    In accordance with the purposes and benefits described herein, a vehicle ventilation system is provided. That vehicle ventilation system comprises an inlet duct including a poppet valve, an evaporator core, a heater core, an air discharge duct and a blower. The blower moves air from the inlet duct through at least one of the evaporator core and the heater core to the air discharge duct. 
         [0005]    More specifically, the inlet duct includes a housing having a fresh air inlet and a recirculating air inlet. The poppet valve is displaceable between a first position opening only the fresh air inlet, a second position opening only the recirculating air inlet and a third position opening both the fresh air inlet and the recirculating air inlet. 
         [0006]    In one possible embodiment, the housing includes a first end wall, a second end wall and a cylindrical sidewall. The fresh air inlet is provided in the first end wall and the recirculating air inlet is provided in the cylindrical sidewall. In addition, a blower inlet is provided in the second end wall opposite the fresh air inlet. 
         [0007]    Still further, the system includes an inlet manifold in the housing and a partition that divides that inlet manifold into a first chamber and a second chamber. The fresh air inlet opens into the first chamber and the recirculating air inlet opens into the second chamber. Further the blower inlet also opens into the second chamber. The partition includes an air flow aperture and the poppet valve seats on the partition and extends through the air flow aperture when in the first position. 
         [0008]    The poppet valve includes a fresh air inlet sealing face, a fresh air passageway and a recirculating air inlet sealing face. The fresh air passageway extends concentrically around the fresh air inlet sealing face and the recirculating air inlet sealing face extends concentrically around the fresh air passageway. 
         [0009]    The system further includes an actuator displacing the poppet valve between the first position, the second position and the third position. The actuator may assume a number of different forms including, but not limited to, a vacuum motor, an electric motor, a pneumatic drive or the like. In one possible embodiment, the actuator includes a cam that engages and moves the poppet valve. Further, the poppet valve includes guide pins that ride in guide channels provided in the housing. 
         [0010]    In accordance with an additional aspect, a motor vehicle is provided including the vehicle ventilation system just described. 
         [0011]    In yet another aspect, a method is provided for controlling the flow of fresh air and recirculating air through the vehicle ventilation system. That method may be broadly described as comprising the step of equipping an air inlet duct having a fresh air inlet, a recirculating air inlet and a blower inlet with a poppet valve. Still further, the method may include displacing the poppet valve between a first position opening only the fresh air inlet, a second position opening only the recirculating air inlet and a third position opening both the fresh air inlet and the recirculating air inlet. In addition the method may also include the step of drawing air from the inlet duct through the blower inlet by means of a blower. 
         [0012]    In the following description, there are shown and described several preferred embodiments of the vehicle ventilation system. As it should be realized, the vehicle ventilation system is capable of other, different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the vehicle ventilation system as set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0013]    The accompanying drawing figures incorporated herein and forming a part of the specification, illustrate several aspects of the vehicle ventilation system and together with the description serve to explain certain principles thereof. In the drawing figures: 
           [0014]      FIG. 1  is a schematic illustration of a prior art vehicle ventilation system inlet duct incorporating a swinging or pivoting door/flap for controlling the flow of fresh air and recirculating air through the ventilation system. 
           [0015]      FIG. 2  is a schematic block diagram of the new and improved vehicle ventilation system that is the subject matter of this document. 
           [0016]      FIG. 3  is a perspective view of the poppet valve that is provided in the air inlet duct. 
           [0017]      FIG. 4  is a top plan view of the poppet valve shown in  FIG. 3 . 
           [0018]      FIG. 5  is a schematic elevational view illustrating the poppet valve in a first position opening only the fresh air inlet to the blower inlet. 
           [0019]      FIG. 6  is a schematic elevational view illustrating the poppet valve in a second position opening only the recirculating air inlet to the blower inlet. 
           [0020]      FIG. 7  is yet another schematic elevational view illustrating the poppet valve in an intermediate position opening both the fresh air inlet and the recirculating air inlet to the blower inlet. 
           [0021]      FIGS. 8 a  and 8 b    are schematic illustrations of one possible actuator for displacing the poppet valve between the first, second and third positions. 
           [0022]      FIG. 9  is a schematic illustration of one possible embodiment wherein the poppet valve includes guide pins received in cooperating guide channels provided in the housing. 
       
    
    
       [0023]    Reference will now be made in detail to the present preferred embodiments of the vehicle ventilation system, examples of which are illustrated in the accompanying drawing figures. 
       DETAILED DESCRIPTION 
       [0024]    Reference is now made to  FIG. 2  which schematically illustrates the vehicle ventilation system  10 . For purposes of this description the middle, horizontal line of blocks represents the airflow circuit  12  and the arrows between the blocks in that horizontal line represent airflow conduits. 
         [0025]    As illustrated, the airflow circuit  12  includes an intake or manifold duct  14 . The intake duct  14  includes a poppet valve  15 . As described in greater detail below, the poppet valve  15  is positioned to selectively direct (a) only fresh air, (b) only recirculated air from the interior of the vehicle or (c) a mixture of both (a) and (b) into the intake duct  14 . A blower  16  draws air from the intake duct  14  and then forces that air through the evaporator core  18 . There the air is cooled and dehumidified through heat exchange with a refrigerant fluid of the vehicle air-conditioning system. That refrigerant fluid flows between a compressor  19 , a condenser  20  and the evaporator core  18  through the lines  22 ,  23 ,  24 . More specifically, cool refrigerant is delivered from the condenser  20  to the evaporator core  18  through the line  23 . That cool refrigerant absorbs heat from the air forced through the evaporator core  18  by the blower  16  and then is returned to the compressor  19  through the line  24 . After compression, the refrigerant is routed through the line  22  to the condenser  20  where it is again cooled before being recycled back to the evaporator core  18 . 
         [0026]    After being cooled and dehumidified, the air is forced by the blower  16  through the heater core  26  located in the airflow circuit  12  downstream from the evaporator core  18 . As should be appreciated, the heater core  26  is connected by lines  28  and  30  to the engine and radiator system  33 . In winter, hot engine coolant is pumped through the line  28  from the engine to the heater core  26  where it heats the air being forced through the heater core by means of heat exchange before being returned to the engine/radiator system through the line  30 . 
         [0027]    After being dehumidified in the evaporator core  18  and warmed in the heater core  26 , the air in the airflow circuit  12  is forced by the blower  16  through the airflow restrictor  32  to one or more of a number of discharge ducts  34  provided in the vehicle so as to clear fog from the windscreen and/or heat the vehicle cabin. In summer, the air flow either bypasses the heater core  26  or no hot engine coolant is circulated through the heater core from the engine/radiator system  33 . 
         [0028]    Reference is now made to  FIGS. 3 and 4  which are detailed illustrations of the poppet valve  15 . As illustrated, the poppet valve  15  includes a fresh air inlet sealing face  40 , a fresh air passageway  42  and a recirculating air inlet sealing face  44 . More specifically, the fresh air inlet sealing face  40  is connected to a lower lip  46  of the recirculating air sealing face  44  by means of a series of spaced posts  48 . The fresh air passageway  42  is designed all the way around the poppet valve  15  between the posts  48 . Thus, it should be appreciated that the fresh air passageway  42  extends concentrically around the fresh air inlet sealing face  40  while the recirculating air inlet sealing face  44  extends concentrically around the fresh air passageway  42 . 
         [0029]    Reference is now made to  FIGS. 5-7  illustrating the poppet valve  15  in the inlet duct  14  in respective first, second and third operating positions. 
         [0030]    More specifically the inlet duct  14  includes a housing  50  having a first end wall or top wall  52 , a second end wall or bottom wall  54  and a cylindrical sidewall  56  extending between the first and second end walls. A partition  58  divides the inlet manifold  60  within the housing  50  into a first or upper chamber  62  and a second or lower chamber  64 . The petition  58  includes a central air flow aperture  66  that provides communication between the two chambers  62 ,  64  and through which the poppet valve  15  is moved between operating positions. 
         [0031]    A fresh air inlet  68  is provided in the first end wall  52 . The recirculating air inlet  70  is provided in the cylindrical sidewall  56 . That recirculating air inlet  70  may extend substantially 360° around the cylindrical sidewall  56  between wall segments  71 . A blower inlet  72  is provided in the second end wall or bottom wall  54 . Thus, it should be appreciated that the blower inlet  72  is opposite the fresh air inlet  68 . Further, the fresh air inlet  68  opens into the first or upper chamber  62  while both the recirculating air inlet  70  and blower inlet  72  open into the second or lower chamber  64 . 
         [0032]    Reference is now made to  FIG. 5  which illustrates the poppet valve  15  in a first operating position wherein the upper, outwardly projecting lip  74  of the recirculating air sealing face  44  seats against the upper face of the partition  58  and the lower, inwardly projecting lip  46  seats against the bottom wall  54  of the inlet duct  14  completely around the blower inlet  72 . This effectively seals off airflow from the recirculating air inlet  70  to the blower inlet  72 . As should be appreciated, when the poppet valve  15  is in this position, the fresh air inlet sealing face  40  is positioned away from the fresh air inlet  68  and fresh air is free to flow through the inlet  68  into the first or upper chamber  62  and then through the fresh air passageway  42  in the poppet valve  15 , downwardly through the central flow aperture  76  provided concentrically within the lower lip  46  of the poppet valve  15  and then through the blower inlet  72  to the blower  16 . Note particularly action arrows A in  FIG. 5 . When the poppet valve  15  is in the first position, it should be appreciated that only fresh air is directed through the inlet duct  14  to the blower  16 . Any flow of recirculating air is cut off by the poppet valve  15 . 
         [0033]    Reference is now made  FIG. 6  illustrating the poppet valve  15  in the second position. In this position, the poppet valve  15  has been displaced into the first or upper chamber  62  so that the fresh air inlet sealing face  40  completely engages and seals against the first end wall or top wall  52  completely closing the fresh air inlet  68 . Since the poppet valve  15  is in the first or upper chamber  62 , the recirculating air sealing face  44  of the poppet valve  15  has been moved away from the recirculating air inlet  70  which comprises a series of openings that extend as much as 360° around the cylindrical sidewall  56  of the inlet housing  50 . Accordingly, recirculating air flow passes freely through the recirculating air inlet  70  into the second or lower chamber  64  and then through the blower inlet  72  to the blower  16 . While the prior art ventilation system equipped with a swinging door D as illustrated in  FIG. 1  limits the recirculating air inlet R to only one side of the inlet duct housing H, the poppet valve  15  of the present vehicle ventilation system  10  allows the recirculating air inlet  70  to extend substantially 360° completely around the housing  50  thereby providing an opening with a greater surface area for enhanced airflow that also simultaneously places a lower power load on the blower motor. 
         [0034]    Reference is now made to  FIG. 7  illustrating the poppet valve  15  in a third or intermediate position allowing a mixture of fresh air and recirculating air to flow through the inlet duct  14  to the blower  16 . Note action arrows C. 
         [0035]    Reference is now made to  FIGS. 8 a , 8 b    and  9  illustrating one possible actuator  80  that may be utilized to displace the poppet valve  15  between the various operating positions illustrated in  FIGS. 5-7 . As illustrated, the actuator  80  may comprise a vacuum motor, an electric motor, a pneumatic drive motor or the like. The actuator  80  is connected to two cams  82  by means of the drive shaft  84 . Each cam  82  may have a profile as illustrated in  FIG. 8 b   . The poppet valve  15  rides the cams  82  (note the fresh air sealing face  40  riding on the cams  82  in  FIG. 8 a   ). The poppet valve  15  is guided in the inlet duct housing  50  as it is displaced between the various operating positions by means of the projecting guide pins  86  which ride in guide channels  88  provided in the sidewall  56 . 
         [0036]    In summary, the vehicle ventilation system  10  provides a number of benefits and advantages including, but not necessarily limited to (a) provision of a more uniform flow of air into the blower  16 , (b) provision of a larger recirculating air inlet  70  in the inlet duct  14 , (c) packaging benefits associated with an inlet duct of lower overall height, (d) improved sealing capability, (e) lower HVAC system noise and vibration, (f) lower blower motor power consumption, (g) improved blower efficiency, (h) lower pressure drop across the inlet duct and (i) lower tooling costs. Advantageously, the poppet valve  15  incorporated into the vehicle ventilation system  10  is also associated with a beneficial method of controlling the flow of fresh air and recirculating air through a vehicle ventilation system  10 . That method may be broadly described as comprising the step of equipping an air inlet duct  14 , having a fresh air inlet  68 , a recirculating air inlet  70  and a blower inlet  72 , with a poppet valve  15 . Further, the method includes displacing the poppet valve  15  between a first position opening only the fresh air inlet  68 , a second position opening only the recirculating air inlet  70  and a third position opening both the fresh air inlet and the recirculating air inlet. Still further, the method may be described as including the additional step of drawing air from the inlet duct  14  through the blower inlet  72  by means of the blower  16 . 
         [0037]    The foregoing has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Obvious modifications and variations are possible in light of the above teachings. For example, as illustrated in  FIG. 4 , the lower face opposite the fresh air sealing face  40  may include optional vanes  90  to preswirl the air flow through the poppet valve  15  before it enters the blower  16 . This should reduce turbulence and increase operating efficiency. All such modifications and variations are within the scope of the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.