Abstract:
A pair of rotary valves for opening and closing two outlets of an HVAC system. A shaft has oppositely threaded and axially spaced sections each engaging one of the valves for moving the valves axially. Each valve includes a guide plate defining an upper surface curved along the periphery of one of the outlets to define a guide for limiting rotational moving of each valve in response to rotation of the shaft. Each guide plate defines a lower surface that is a contoured shape and parallel to the axis for directing air flow through each outlet.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a climate control system also commonly referred to as an HVAC system (heating, ventilation, and air conditioning) for a vehicle and more specifically to a valve assembly for controlling airflow through an outlet of the climate control system. 
         [0003]    2. Description of the Prior Art 
         [0004]    Conventional heating, ventilation and air conditioning (HVAC) systems for vehicles generally include a housing, an evaporator, a heater core having a housing, an evaporator assembly coupled to the housing, an evaporator, a heater core, an air inlet, a fan and various doors or mode valves for controlling the volume and direction of air flow and generating outlet air of a desired volume and temperature. Together these components receive, temper and direct the flow of forced air through several outlets or vents in the vehicle. The outlets through which the forced air ultimately exits are determined by the various doors which move between open and closed positions and cause air flow to be forced in one direction or another or a combination of both. Air may be directed to various areas of the car depending on the state of the mode valves. For example, air may be forced through outlets directed at the windshield in a defrost or defog mode, or through outlets directed at mid-height level in an air-conditioning mode, or to lower outlets directed to the floor in a heat mode, or various combinations thereof. Generally, designs have been utilized in which the housing has a plurality of outlets each having a periphery. More recently, the housing is defined by two oppositely facing outlets. A motor or mechanism is attached to a shaft that is rotatably supported by the housing outside the peripheries of the outlets. A rotary plate valve is disposed about the shaft and is movable to cover or block air from exiting the outlets in a closed position and uncover or unblock the outlets to permit air to exit the housing in an open position. The plate valve&#39;s periphery is connected to the shaft and the plate valve is covered with material which complies with the interior of the housing in order to form an air seal. This material generally is made from a compressible cellular foam or molded thermoset rubber that forms a wiper. As the shaft rotates, the plate valve rotates with the shaft so that the foam or rubber attached to the plate valve seals the outlets. 
         [0005]    These rotary plate valves require the plate and its seal to be in sliding contact with the housing when alternating between the open and closed positions. Such a sliding valve requires relatively high contact pressure in order to compress the foam or deform the rubber wiper in order to achieve a desired seal. 
         [0006]    Furthermore, these rotary plate valves rely on a torque limited motor to rotate the shaft end either directly or remotely via a cam, link and lever in order to move the valve plate to the open and closed positions. When the contact pressure is too high for the motor to overcome, the plate valve can become immobilized in an undesired position and may result in failure of the motor. HVAC systems having these rotary plate valves do not have a means to direct the cold air from the evaporator core and hot air from the heater towards the outlet in order to achieve a desired outlet temperature while in an open position. Additionally, these rotary plate valves do not have a means to meter a portion of these airstreams while in an intermittent position between open and closed. These intermittent positions are desired in order to achieve the proper air balance between the various outlets such as the lower outlets directed to the floor in a heat mode. 
         [0007]    Examples of rotary valves in HVAC systems are included in U.S. Pat. No. 4,683,913 to Hoffman et al. and U.S. Pat. No. 5,009,392 to Ostrand. 
         [0008]    Hoffman et al. teach a rotary valve for sealing outlets defined by a curved surface. The air valve has a radius of curvature measured from an axis which is offset from that of the radius of curvature for the surface defining the outlets being sealed. This valve&#39;s plate and sealing surface which cover or uncover an outlet are parallel with the axis of the shaft and as such is only able to seal an outlet that is located parallel with the axis of the shaft. The contact pressure is therefore high when the valve is in a closed position and diminishes to zero after the valve is rotated to an open position. 
         [0009]    Although the prior art provides valves which move between open and closed positions, there remains a need for a valve that does not produce high frictional loads while simultaneously aiding in directing air flow through the outlet of the housing. Furthermore, there also remains a need for a valve that can direct the cold air from the evaporator core and hot air from the heater towards the outlet in order to achieve a desired outlet temperature and can meter a portion of these airstreams while in an intermittent position between open and closed. Additionally, there remains a need for a rotary valve whose plate and sealing surface is perpendicular to the shaft. 
       SUMMARY OF THE INVENTION AND ADVANTAGES 
       [0010]    The invention provides such an assembly for controlling air flow in an HVAC system wherein the rotatable shaft has a threaded section. The interior surface of the plate valve is threaded and is in threaded engagement with the threaded section of the shaft for moving the plate valve axially away from the outlet in response to rotation of the shaft in a first direction and moving the first plate valve axially toward the outlet in response to rotation of the shaft in a second direction opposite to the first direction while the plate valve is kept from rotating due to its relative engagement with the outlet. 
         [0011]    The invention provides a valve which uses linear valve motion in order to seal an outlet with a uniform seal about the periphery. Moreover, the linear motion eliminates the friction related to sliding described in the prior art and thereby reduces the risk of failure or fatigue. Additionally, the invention structurally baffles a hot or cold airstream towards the outlet to facilitate air mixing in order to achieve the desired outlet temperature. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0013]      FIG. 1  is a cross-sectional view of an embodiment of an HVAC system; 
           [0014]      FIG. 2  is a perspective cross-sectional view of another embodiment of the invention illustrating a pair of plate valves; 
           [0015]      FIG. 3  is a fragmentary view of the embodiment of  FIG. 2  illustrating the shaft, valves and guide; 
           [0016]      FIG. 4  is a fragmentary view of the embodiment of  FIG. 3  illustrating the valve in a closed position; 
           [0017]      FIG. 5  is a fragmentary view of the embodiment of  FIG. 3  illustrating the valve in an open position; 
           [0018]      FIG. 6  is fragmentary cross-sectional view of the embodiment shown in  FIG. 3 ; and 
           [0019]      FIG. 7  is an alternative embodiment of the embodiment of an HVAC system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    A plurality of different embodiments of the invention are shown in the Figures of the application. Similar features are shown in the various embodiments of the invention. Similar features are structured similarly, operate similarly, and/or have the same function unless otherwise indicated by the drawings or this specification. Furthermore, particular features of one embodiment can replace corresponding features in another embodiment unless otherwise indicated by the drawings or this specification. 
         [0021]    A climate control or HVAC system  20  can be disposed in a vehicle to control conditions associated with air inside a passenger compartment of a vehicle. The exemplary climate control system  20  includes a blower  22  for blowing air through the housing  24  and a plurality of heat exchangers  26  for heating and cooling the air in the housing  24 , as shown in  FIGS. 1 and 7 . 
         [0022]    Referring to  FIGS. 3-6 , the housing  24  defines a first outlet  28  having a first outer periphery  30  and a second outlet  32  having a second outer periphery  34 . The outlets  28 ,  32  oppositely face one another. The first outer periphery  30  may have a fan-like shape extending radially, but is not limited to this geometry, and defines a first contoured surface  36 . The second outer periphery  34  may similarly have a fan-like shaped, but is not limited to this geometry, and defines a second contoured surface  38  equal in size and shape to the first contoured surface  36 . 
         [0023]    A shaft  40  is rotatably supported by the housing  24  outside the peripheries  30 ,  34  of the outlets  28 ,  32  and extends along an axis A. The shaft  40  extends between and perpendicular to the peripheries  30 ,  34  of the outlets  28 ,  32 . 
         [0024]    The assembly  20  includes a first plate valve  42  for covering the first outer periphery  30  of the first outlet  28  in a closed position and axially movable to an open position.  FIGS. 4 and 5  illustrate the first plate valve  42  in the open and closed positions respectively. The first plate valve  42  includes a first bushing  44  defining a first interior surface  46  surrounding the shaft  40 . The first valve  42  also includes a first plate extending radially from the first bushing  44  in a fan-like shape for sealing the first periphery  30  of the first outlet  28 . A first reinforcing web  48  interconnects the first bushing  44  and the first plate for reinforcing the first plate on the first bushing  44 . 
         [0025]    A second plate valve  50  is included for covering the second outer periphery  34  of the second outlet  32  in a closed position and movable to an open position. The second valve  50  includes a second bushing  52  defining a second interior surface  54  surrounding the shaft  40 . The second valve  50  also includes a second plate extending radially from the second bushing  52  in a fan-like shape for sealing the second periphery  34  of the second outlet  32 . A second reinforcing web  56  interconnects the second bushing  52  and the second plate for reinforcing the second plate on the second bushing  52 . 
         [0026]    The assembly  20  is distinguished by the shaft  40  having oppositely threaded first and second sections  58 ,  60  disposed at opposite ends of the shaft  40  as best shown in  FIG. 3 . The interior surfaces  46 ,  54  of the bushings  44 ,  52  are oppositely threaded, and the first interior surface  46  of the first bushing  44  is in threaded engagement with the first section  58  of the shaft  40 , as illustrated in  FIG. 3 . Likewise, the second interior surface  54  of the second bushing  52  is in threaded engagement with the second section  60  of the shaft  40 . The threaded engagements move the plate valves  42 ,  50  axially toward one another in response to rotation of the shaft  40  in a first direction and move the plate valves  42 ,  50  axially away from one another in response to rotation of the shaft  40  in a second direction opposite to the first direction. 
         [0027]    The assembly  20  includes a guide  62 , generally indicated, for limiting rotation of the valves  42 ,  50  relative to the axis A in response to rotation of the shaft  40 . The first valve  42  may include a first guide plate  64  and the second valve  50  may include a second guide plate  66  to define the guide  62 . 
         [0028]    As best shown in  FIG. 6 , the first guide plate  64  defines a first upper surface  68  and the second guide plate  66  defines a second upper surface  70 . The first upper surface  68  of the first guide plate  64  extends parallel to and through the first contoured surface  36  of the first outlet  28  for limiting rotation of the first valve  42  relative to the axis A in response to rotation of the shaft  40 . The first guide plate  64  defines a first lower surface  72  which has a contoured shape extending parallel to the axis A for directing radial air flow axially through the first outlet  28  in the open position. Similarly, the second upper surface  70  of the second guide plate  66  extends parallel to and through the second contoured surface  38  of the second outlet  32  for restricting rotation of the second valve  50  about the axis A in response to rotation of the shaft  40 . The second guide plate  66  defines a second lower surface  74  which has a contoured shape extending parallel to the axis A for directing radial air flow axially through the second outlet  32  in the open position. The upper surfaces  68 ,  70  of the guide plates  64 ,  66  profile the contoured surfaces of the outlet and the lower surfaces  72 ,  74  are flat, however the surfaces of the guide plates  64 ,  66  are not limited to this geometry. 
         [0029]      FIG. 7  illustrates an alternative embodiment of the HVAC system  20  having a plurality of rotary valves  80  and detailing an arrangement where the plate valves  42 ,  50  would be able to catch the air flow and redirect the path of the air flow into the outlets  28 ,  32 . 
         [0030]    While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing form the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.