Abstract:
A fresh air and recirculation air switching case using a rotary door, since an introduced air flows along an inner surface of a circumferential wall of the rotary door, a convex grid is formed on an inner surface of the circumferential wall of the rotary door. In this system, the air flow directed toward a suction inlet is prevented from becoming turbulent behind the rotary door and the air flow noise can be suppressed.

Description:
FIELD 
       [0001]    This present invention relates to the field of automotive heating ventilating and air conditioning systems, more specifically this invention relates to the fresh air/recirculation air switching rotary door. 
       BACKGROUND 
       [0002]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0003]    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. 
         [0004]    A fresh air/recirculation air switching case is also used in a vehicle climate control system for switching and introducing an outside air and an inside air into the fan then through the desired heat exchangers and ultimately to the passenger cabin of the vehicle. To control the amount of fresh outside air or recirculation air, a rotary door having an arc-shaped circumferential wall is disposed inside the case. The rotary door opens and closes an inside air introduction inlet and an outside air introduction inlet. In the fresh air/recirculation air switching case employing a rotary door creates a packaging advantage because the door installation space can be reduced as compared with an ordinary flat plate door. 
         [0005]    However, according to the present inventors&#39; experiments and evaluations, the inside fresh air/recirculation air switching case using a rotary door may create a problem that air flow noise increases and become objectionable to passengers in the vehicle. This noise is created by the introduced air flowing from one end to the other end of the circumferential wall of the rotary door along the inner surface thereof. As a result, the flow of the air creates a turbulent pocket underneath the circumferential wall of the rotary door which causes unwanted noise to enter in the passenger cabin of the vehicle. 
         [0006]    U.S. Pat. No. 5,836,813 provided several ways to address this particular issue. This patent disclosed using a guide attached to the inside of the circumferential wall; this guide will direct the air flow and prevent turbulence. Additionally, this patent disclosed using a reflection plate, for irregularly reflecting the noise, this plate protrudes from the inner surface of the circumferential wall of the rotary door. However, neither embodiment fully eliminates the potential for turbulent flow from occurring under the circumferential wall. 
         [0007]    U.S. Pat. No. 7,575,511 provides including a convex surface under the circumferential wall, however this patent discloses one solid surface. It is understood in the art that having an integrally molded rotary door with 2 curved opposite surfaces is extremely difficult to manufacture and control quality of the component itself. Additionally, adding the convex surface as a second piece to the rotary door complicates manufacturing and may reduce production efficiency. 
         [0008]    It would be desirable to automotive HVAC system which provides an easily manufactured fresh air/recirculation air switching door that eliminates potential for turbulent air flow to occur under the circumferential wall and lead to unwanted noise in the vehicle cabin. 
       SUMMARY 
       [0009]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0010]    The present invention is directed to a vehicle HVAC fresh air/recirculation air inlet case and rotary door that meet these needs. The vehicle HVAC comprises an inlet air flow casing having a first suction inlet and a second suction inlet. The first inlet for introducing recirculated air from a passenger compartment, the second inlet for introducing fresh air from outside the vehicle. Attached to the inlet casing is a scroll casing. The scroll casing is where a blower fan located. The scroll casing and blower fan are downstream of the air flow from inlet case and fresh air and recirculation air inlets. Within the inlet case is a rotary door, the rotary door can be rotated about its center axis to open and close the fresh air inlet and the recirculation inlet. The rotary door has an arc-shaped circumferential wall that spans the length of the door. Additionally, the rotary door has a convex arc-shaped grid portion protruding from an inner surface of the circumferential wall, the cross-section of the circumferential wall and convex grid create an oval shape. 
     
    
     
       DRAWINGS 
         [0011]    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. 
           [0012]      FIG. 1  is a schematic representation of a vehicle having a heating, ventilating and cooling system according to the principles of the present disclosure; 
           [0013]      FIG. 2  is a fragmented perspective view of an automotive vehicle showing a portion of the passenger space; 
           [0014]      FIG. 3  is a simplified view of an HVAC module; 
           [0015]      FIG. 4  is a simplified view of an inlet and scroll casing with the prior art door; 
           [0016]      FIG. 5  is a perspective view of the prior art rotary door; 
           [0017]      FIG. 6  is a perspective view of the preferred embodiment rotary door; 
           [0018]      FIG. 7  is a simplified view of an inlet and scroll casing with the preferred embodiment of the rotary door; and 
           [0019]      FIG. 8  is a simplified view of an inlet and scroll casing with the preferred embodiment of the rotary door; 
       
    
    
       [0020]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0021]    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. 
         [0022]    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. 
         [0023]    With reference to  FIG. 3 , a general layout of a conventional vehicle HVAC module  22  is shown and generally identified at reference  22 . An HVAC module consists of different cases or housings. A fresh air/recirculation air switching case  24 , also known as an inlet casing, which is connected to the scroll case  26 , also referred to in the art as the blower case, which is attached to the mode case  28 . All the casings may be made by a synthetic resin or plastic polymer material by way of non-limiting example. The scroll case  26  contains a fan  30  which is arranged on the upstream side of the mode case  28 . Upstream of the scroll case  26  and fan  30  is the fresh air/recirculation air switching case  24 . The fresh air/recirculation air switching case  24  contains two inlets. One inlet for introducing outside air to the passenger compartment  12 , is known as the fresh air inlet  32 . The other inlet for introducing inside air within the passenger compartment  12  is known as the recirculation inlet  34 . Within the fresh air/recirculation air switching case  24 , a fresh air/recirculation air switching rotary door  36  is rotatably disposed.  FIG. 3  illustrates the rotary door  36  positioned to let outside air through the fresh air inlet  32 . Also, an air filter  38  may be disposed within the fresh air/recirculation air switching case  24  downstream from the rotary door  36  to filter air prior to entering the scroll case  26  and fan  30 . The air filter  38  may be constructed in such a manner that a filtering material made of corrugated paper, porous urethane foam or the like is supported with a resin frame member. Here, the entire configuration of the air filter  38  is a flat plate illustrated in  FIG. 3 . The air filter  38  removes the dust in the air, and if necessary, a deodorizing function may be performed, by adding an adsorbent for adsorbing malodorous components such as active carbon to the filtering material. It is understood in the art that the air filter  38  may be placed anywhere between the rotary door and blower fan  30 . It is also understood in the art that the air switching case  24  and scroll case  26  may be a single case based upon specific application packaging. 
         [0024]    Disposed below the fresh air/recirculation air switching case  24  is the scroll case  26 . Within the scroll case  26 , is an air blowing fan  30  consisting of a centrifugal multi-blade fan which is disposed at a central position of the scroll configuration. By the rotation of this fan  30 , the air having been taken in from fresh air/recirculation air switching case  24  flows outwardly in a radial direction of the fan  30  as indicated by an arrow A. The air blowing fan  30  is connected to and rotated by a rotary shaft  60  (shown in  FIG. 4 ) of a driving motor  40 . 
         [0025]    Connected to an air outlet side of the scroll case  26 , is the mode case  28 . Disposed within the mode case  28  is an evaporator  42  of the refrigeration cycle, the refrigeration cycle is driven by a compressor (not shown) as the driving source. The blown air is cooled and dehumidified by the evaporator  42 . Downstream air side of the evaporator  42 , the mode case  28  is equipped with a heater core  44  which heats the blown air by using the engine cooling water (hot water) as the heat source. An air mix door  46 , also known as a mode door, is located adjacent to the heater core  44  and adjusts the ratio of air amounts between the air passing through and heated by the heater core  44  and the cool air bypassing the heater core  44 , thus serving as temperature adjusting means for adjusting the temperature of the blown-out air to the passenger cabin  12 . 
         [0026]    Downstream of the heater core  44 , the mode case  28  contains a mixing chamber  48  for mixing the warm air and the cool air, and the air mixed in the mixing chamber  48  and having a desired temperature is blown out into the passenger compartment  12  through a defroster air outlet  50 , face air outlet  52  and foot air outlet  54 . These air outlets are opened or closed by outlet mode doors  56 ,  58 , and  60  respectively. 
         [0027]      FIG. 4  displays a larger view in more detail of the fresh air/recirculation air switching case  24  and the scroll casing  26  portion of  FIG. 2 . However, this figure is slightly modified from  FIG. 3 . That is, in this example, the air filter  30  is disposed at a position that is lower than the position of the rotary door shaft  36   c.  Here and as illustrated in  FIG. 5 , more detail of the prior art rotary door  36  is displayed. The rotary door  36  comprises an arc-shaped circumferential wall  36   a  is so formed as to connect outer-peripheral ends of two fan shaped side plates  36   b.  The rotary shaft  36   c  is provided at the position of an angular corner portion of each fan shaped side plate  36   b  (the center position of the curvature radius of the circumferential wall  36   a ). The rotary door  36  is rotatably supported in the case  24  with the rotary shaft  36   c  as its center. The rotary door  36  may be manufactured easily, for example, it may be molded plastic or polymer by way of non-limiting example. 
         [0028]    The limitations with the prior art is with the layout of case  24  combined with the arc-shaped circumferential wall  36   a  of the rotary door  36 . As air flow B passes through the case, in  FIG. 4 , turbulence C can be created underneath the rotary door. This turbulence C causes unwanted noise to travel to the passenger cabin  12 . Prior art solutions as discussed in the background section are insufficient to completely eliminate the noise. 
         [0029]      FIG. 6  and  FIG. 7  illustrate the preferred embodiment of the current invention.  FIG. 6  illustrates the rotary door  50 . The rotary door  50  comprises an arc-shaped circumferential wall  50   a  is so formed as to connect outer-peripheral ends of two fan shaped side plates  50   b.  A rotary shaft  50   c  is provided axially outwardly at the position of an angular corner portion of each fan shaped side plate  50   b  (the center position of the curvature radius of the circumferential wall  50   a ). It is also known in the art that the shafts could be bearing holes to accept shafts that are built into the casing, or the rotary door  50  could contain one shaft  50   c  and one bearing aperture  50   h  to accept a shaft (not shown) from the inlet casing  24 . Extending inward from the circumferential wall  50   a  is a grid  50   d  in a convex arc shape; the circumferential wall  50   a  and convex grid  50   d  provide a general cross section of the door to be an oval shape. The grid  50   d  has lateral stringers  50   e  that are different heights that span from one side plate  50   b  to the opposite side plate  50   b.  The grid also contains medial stingers  50   f  in a convex curved shape that are perpendicular to the lateral stringers  50   e  and extend toward the center axis  50   g  of the rotary door  50 . The stringers  50   f  and  50   e  combine to create the overall grid  50   d.  This grid  50   d  can be integrally molded with the rotary door  50  or may be a separate structure bonded to the rotary door  50 , by way of non-limiting example. 
         [0030]      FIG. 7 . Illustrates rotary door  50  integrated into the fresh air/recirculation air switching case  24  and the scroll case  26 , in fresh air mode which only allows outside air from the inlet  32 . The rotary door  50  is rotatably supported in the case  24  with the rotary shaft  50   c  as its center. The rotary door convex grid  50   d  takes up the volume of space underneath the circumferential wall  50   a.  As previously noted, the prior art door  36 , provides a pocket underneath the circumferential wall  36   a,  this pocket allows for the undirected air flow that turns into turbulent air C and creates objectionable noise. The grid  50   d  does not act as an air guide to direct the air flow and remove turbulence, similar to prior art noted in the background section; rather it assumes the volume underneath the circumferential wall and prevents airflow from assuming that space and becoming turbulent behind the rotary door  50 , and this is illustrated by airflow D. Another advantage of preferred embodiment is that by eliminating the turbulent air flow C behind rotary door  50 , the airflow distribution across the blower fan  30  is improved. This improvement also lowers noise concerns in vehicle cabin  12 , it also increases the efficiency of the blower fan  30  and motor  40 . 
         [0031]    It is understood in the art that the size and radius of the door can be customized to fit a particular use and package. The radius of the circumferential wall  50   a  can range from 50 millimeters to 150 by non-limiting example. The preferred embodiment is an integrally formed single piece rotary door  50  and convex grid  50   d.  Because the rotary door  50  is a single piece the height of the medial stringers  50   f,  measured from the circumferential wall  50   a,  is critical for manufacturing, the current height H represents the furthest distance from the medial stringer  50   f  away from the circumferential wall  50   a.  The preferred embodiment range is 10-50 millimeters; this height range was chosen for its noise reduction capability but also for manufacturing, any larger of an H dimension may create tooling breakage issues in a high volume molding machine (not shown). The width W of the openings of the grid shown in  FIG. 6 , is determined by manufacturing tooling capability. The preferred embodiment can range from 10-50 millimeters, which allows for efficient manufacturing of the integrally molded rotary door  50  and grid  50   d.  As known in the art, having a larger opening allows for a larger and stronger molding slide tool (not shown) which prevents unwanted tool breakage and manufacturing efficiency issues. However, as recognized in the art, if the convex grid  50   d  may a separate piece that is later bonded to the rotary door  50 , the height could be smaller to address specific noise, manufacturing and packaging needs. Additionally, the height of the medial stringer  50   f  could be less than the preferred embodiment using any method recognized in the art and based on testing to provide the best outcome for noise and manufacturing. 
         [0032]      FIG. 8  illustrates the rotary door  50  in full recirculation mode. The outside inlet  32  is completely closed, and inside inlet  34  is completely open. It is understood in the art that the rotary door  50  can be rotatably moved within the casing  24  by electric servo, motor and a linkage, cables or the like by way of non-limiting example. Additionally it is understood in the art that the rotary door  50  can be placed in any position ranging from completely closing fresh inlet  32  to completely closing recirculation inlet  34 , or anywhere in-between. It is also understood in the art that a rotary door can be placed anywhere in the HVAC system. A rotary door can be used as a fresh recirculation door in the inlet case, a mode door or a temperature door in the mode case. The preferred embodiment can be implemented in any rotary door application to prevent turbulent air flow. 
         [0033]    From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.