Abstract:
A vehicle air-conditioning system has an evaporator for receiving air discharged into a casing of the system and changing the air to a cold air flow that can flow rearward, and a heater for selectively receiving at least a portion of the cold air flow and heating such portion to a warm air flow. The system includes partition means for directing the warm air flow to permit mixing of the warm air flow and the remaining cold air flow that bypasses the heater. The partition means includes a top end portion and guide means for downwardly directing the cold, warm, or the mixed cold and warm air which has flowed beyond the top end portion for blowing-out such air out of the system. The top end portion defines a surface having a streamlined or curved configuration along which the cold, warm, or mixed cold and warm air can flow.

Description:
REFERENCE TO RELATED APPLICATION 
   This is a continuation of International Patent Application No. PCT/JP02/07448, filed Jul. 23, 2002. 

   FIELD OF THE INVENTION 
   The present invention relates to an air-conditioning system for a vehicle, and more particularly, to such a vehicle air-conditioning system of the type which includes an evaporator and a heater arranged serially in a lengthwise direction of the vehicle. 
   BACKGROUND ART 
   In recent years, a vehicle air-conditioning system has been used which incorporates a cooler unit which includes an evaporator, and a heater unit, which includes a heater, as a unitary arrangement wherein the cooler and heater units are arranged serially lengthwise in the vehicle so as to provide an improved space availability in the foot area of the passenger within the vehicle, more particularly, to increase a foot-receiving space, and also to reduce the manufacturing cost. An example of such a vehicle air-conditioning system is disclosed by Japanese Laid Open Patent Application No. 250345/1998. 
     FIG. 3  illustrates a sectional view of the vehicle air-conditioning system as illustrated and described in the aforementioned application. The air-conditioning system  50  comprises an evaporator  52  for receiving therein an air flow that is discharged through a front portion of the vehicle into a casing of the system by a blower, and for changing the received air flow to a cooled or cold air through a heat exchanging process that can then flow rearward of the evaporator  52  and a heater  54  that is located rearward or downstream of the evaporator  52 . The heater  52  receives at least a portion of the cold air flow and heats the portion of the cold air flow to a warm air that can then flow rearward from the heater  56 . The air-conditioning system also comprises a partition plate  56  that is disposed rearward or downstream of the heater  54 . The partition plate  56  is adapted to direct the warm air flow through the heater  54  upwardly in a manner so as to permit mixing of the warm air flow and the cold air flow being discharged from the evaporator  54  and bypassing the heater  54  thereabove. The air-conditioning system further comprises a guide wall  60  located adjacent to the partition member  56  for downwardly directing the cold air, the warm air or the mixture of cold and warm air which has passed over a top end  58  that is defined by the partition plate  56  for blowing-out such air. The top end  58  of the partition plate  56  may be in the form of a thin plate which is turned or bent forwardly. The air-conditioning system  50  also has three outlets, i.e., a defrost outlet  62 , vent outlet  64  and floor outlet  66  as well as five dampers, i.e., a cold air damper  68 , a warm air damper  70 , a defrost damper  72 , a vent damper  74  and floor damper  76 . 
   When it is desired to operate the air-conditioning system in a so-called “bi-level” mode wherein conditioned air is discharged through the vent outlet  64  and warm air is discharged through the floor outlet  66 , the defrost damper  72  is closed, the cold air, warm air and vent dampers  68 ,  70 ,  72  are half opened, and the floor damper  76  is opened. The degree to which the cold air and warm air dampers  68 ,  70  are opened can control a ratio of the cold and warm air to be mixed together to thereby adjust the temperature of the mixed air to be discharged. A portion of the cold air passing through the evaporator  52  can flow through the opened cold air damper  68  and then bypass the heater  54  thereabove while the remaining portion of the cold air can flow through the opened warm air damper  70  into the heater  54  where the remaining portion of the cold air is heated and becomes a warm air flow. The warm air flow being discharged rearward from the heater  54  is directed upward while impinging upon the partition plate  56  and is then redirected forwardly by the forwardly bent top end  58  of the partition plate  56 . As a result, most of the forward warm air flow can meet the rearward cold air flow bypassing the heater  54  thereabove, thereby resulting in the warm air and cold air flows being mixed so as to provide a conditioned air flow which is then discharged through the vent outlet  64 . On the other hand, the remaining portion of the warm air is turned through 180 degrees downwardly in the region of the top end  58  of the partition plate  56  by the vent damper  74  and the guide wall  60  and is then discharged through the floor outlet  66 . 
   The air-conditioning system of the above-mentioned type may, however, produce considerable noise during operation of the system that can impair the operator&#39;s comfort in operating the vehicle. The inventors of the present invention have found that the warm air flow through the heater  54  may be separated from the top end portion  58  of the partition plate  56  as the warm air moves upward along the partition plate  56  and flows beyond the top end portion  58 , thereby resulting in the creation of an eddy in the region of the top end portion  58  of the partition plate  56  that may lead to the considerable noise that is produced during operation of the system. Moreover, such a separation of the air flow can lead to creation of pressure loss in the air flow and a reduction in the air flow rate. 
   It is therefore an object of the present invention to provide a vehicle air-conditioning system which is arranged to reduce the noise that results from the separation of flow that is encountered in the conventional air-conditioning system. 
   Another object of the present invention to provide a vehicle air-conditioning system which is arranged so as to avoid the reduction of the air flow rate to attain a more efficient operation of the vehicle air-conditioning system. 
   SUMMARY OF THE INVENTION 
   To this end, the present invention provides an air-conditioning system for a vehicle. The air-conditioning system of the present invention includes an evaporator for receiving air that is discharged into a casing of the system by a blower and changing the discharged air to a cold air flow, where the cold air flow is allowed to be directed rearward. The air-conditioning system also includes a heater that is located downstream of the evaporator for selectively receiving at least a portion of the cold air flow and heating such portion of the cold air flow to a warm air flow. Further, the air-conditioning system includes partition means disposed downstream of the heater for directing the warm air flow upwardly in such a manner as to permit mixing of the warm air flow through the heater and the remaining cold air flow that bypasses the heater. The partition means includes a top end portion and guide means for downwardly directing the cold air, where the partition means is provided for blowing-out the warm air or the mixture of the cold and warm air which has flowed beyond the top end portion of the partition means out of the air-conditioning system. The top end portion of the partition means defines a surface having a streamlined or curved configuration along which the cold air, the warm air or the mixture of the cold and warm air can flow. 
   In the vehicle air-conditioning system as constructed above, the air that is discharged into the casing of the system by the blower is changed into a cold air by the evaporator. A portion of the cold air can then flow beyond the heater thereabove, whereas the remaining portion of the cold air is heated into warm air by the heater and then flows backward away from the evaporator. It is possible to selectively direct the cold air flow, the warm air flow, or the mixed flow of cold and warm air according to several modes of operation of the present invention. The warm air flowing through the heater is diverted upwardly by the partition means and meets the cold air bypassing the heater thereabove so as to permit mixing of the warm air and cold air to create a conditioned air. The cold air, the warm air or the conditioned air can flow beyond the top end portion of the partition means thereabove and then be redirected downward of the partition means by the guide means for blowing-out. In this case, the cold air flow is directed to impinge angularly upon the top end potion of the partition means. The warm air flows beyond the top end portion of the partition means in such a manner so as to be turned through 180 degrees therearound. Any portion of the cold air, warm air and conditioned air can flow along the streamlined or curved surface of the partition means so that such portion does not separate from the top end portion of the partition means, thereby avoiding the creation of an eddy. As a result, the reduction of noise in the vehicle air-conditioning system can be attained. Also, it is to be understood that no separation of flow can reduce or substantially eliminate the pressure loss in the flow which would otherwise take place, which can contribute to suppression of the reduction of the air flow rate, which in turn can lead to a more efficient operation of the vehicle air-conditioning system. 
   In the vehicle air conditioning system according to the present invention, the top end portion of the partition means preferably can have a radius of curvature ranging between about 5 and 25 mm. 
   Also, in the vehicle air-conditioning system according to the present invention, the streamlined or curved configuration of the top end portion surface preferably comprises substantially an airfoil configuration. 
   Also, in the vehicle air-conditioning system according to the present invention, the top end portion of the partition means preferably is bent forwardly toward a vent outlet of the air-conditioning system. 
   With the arrangement of the present invention, the warm air flow is directed upwardly by the partition means and then forwardly by the forwardly bent top end portion of the partition means. Thus, it is possible to make a greater angle at which the warm air flow can meet the cold air flow bypassing the heater thereabove, thereby attaining a more efficient and effective mixing of the warm air and cold air flows. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross sectional view of an embodiment of a vehicle air-conditioning system according to the present invention. 
       FIG. 2  is a graph illustrating a relationship between the radius of curvature of a guide plate and a pressure loss coefficient. 
       FIG. 3  is a cross sectional view of a conventional vehicle air-conditioning system. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A vehicle air-conditioning system or unit according to an embodiment of the present invention will be described with reference to the drawings. 
     FIG. 1  is a cross-sectional view of a vehicle air-conditioning system  1  that is an embodiment of the present invention. As shown in  FIG. 1 , the vehicle air-conditioning system  1  comprises a case  2  in which an evaporator  4 , a heater  6 , a partition plate  8 , and a guide wall  11  are mounted therein. The evaporator  4  is provided for cooling air from the front thereof and directing the cooled or cold air in the backward direction. The heater  6  is disposed rearward or downstream of the evaporator  4  and is provided for heating the air from the front thereof and directing the heated or warm air in the backward direction. The partition plate  8  is disposed rearward of the heater  6  and the guide wall  11  for downward directing the cold air, warm air or the mixture of cold and warm air which has flowed backward beyond the top end portion  10  of the partition plate  8 . The vehicle air-conditioning system  1  also comprises three outlets (i.e., a defrost outlet  12 , a vent outlet  14  and a floor outlet  16 ) and three dampers (i.e., an air mixing damper  18 , a vent damper  20  and a floor damper  22 ), all of which will be described later. 
   A void space or plenum  24  is formed within the case  2  in the front of the evaporator  4 . This void space  24  is adapted to receive fresh air from the outside and/or air fed by a blower (not shown). 
   The heater  6  is adapted to take in and heat cold air from the evaporator  4  at the front thereof and to direct the heated or warm air in the backward direction. The ratio of the cold air to be taken in is determined by the position of the air mixing damper  18  that is disposed between the evaporator  4  and the heater  6 , the position of which will be described later. 
   The partition plate  8  has a front face  26  that is opposed to the back of the heater  6 , a top end portion  10  and a rear face  28 . 
   The front face  26  of the partition plate  8  is adapted to direct the warm air from the heater  6  in the upward direction such that the warm air from the heater  6  can be mixed with the cold air that bypasses the heater  6  thereabove. The top end portion  10  of the partition plate  8  has a thickness which is sufficient to provide a surface  30  smoothly connecting between the front and rear faces  26 ,  28 . This surface  30  is of a streamlined or curved configuration along which the air can smoothly flow. In this embodiment, this surface  30  is configured to a shape similar to an airfoil. It is preferable that the top end portion  10  of the partition plate  8  has a radius of curvature R ranging between about 5 and 25 mm. Moreover, the top end portion  10  is further bent forwardly toward the vent outlet  14  that is positioned thereabove. 
   The guide wall  11  is spaced apart from the top end portion  10  of the partition plate  8  and is disposed to extend downward along the top end portion  10  substantially parallel to the rear face  28  of the partition plate  8 . As shown in  FIG. 1 , a duct  32  is defined so as to communicate with the floor outlet  16  between the rear face  28  of the partition plate  8  and the guide wall  11 . The duct  32  also communicates with another duct  33  which is formed to extend upward below the heater  6  in the front of the evaporator  4  and the void space  24 . This duct  33  communicates with the defrost outlet  12 . 
   The air mixing damper  18  is disposed between the evaporator  4  and heater  6  and is moveable between an upper position  34  as shown by the solid line and a lower position  36  as shown by the two-dot-chain line. It is to be noted that the air mixing damper  18  may be positioned at any intermediate position  38  between the upper and lower positions  34 ,  36 . When the air mixing damper  18  is in its upper position  34 , all of the cold air from the evaporator  4  is conducted into the heater  6 , thereby discharging only the warm air that is heated by the heater  6  from the vehicle air-conditioning system  1 . on the other hand, when the air mixing damper  18  is in its lower position  36 , all of the cold air from the evaporator  4  flows above the heater  6 , thereby discharging only the cold air from the vehicle air-conditioning system  1 . When the air mixing damper  18  is in its intermediate position  38 , the cold air bypassed above the heater  6  is mixed with the warm air from the heater  6 , thereby discharging the mixture of the cold and warm air from the vehicle air-conditioning system  1 . By changing the intermediate position  38  taken by the air mixing damper  18 , the ratio of the cold and warm air to be mixed together can be changed so as to adjust the temperature in the mixed air. 
   The vent damper  20  is disposed adjacent to the vent outlet  14  and is moveable between an upper position  40  as shown by the solid line and a lower position  42  as shown by the two-dot-chain line. It is to be also noted that the vent damper  20  may be positioned at any intermediate position  44  between the upper and lower positions  40 ,  42 . When the vent damper  20  is in its upper position  40 , all the cold air, the warm air or the mixture of the cold and warm air will flow into the duct  32 . On the other hand, when the vent damper  20  is in its lower position  42 , all the cold air, the warm air or the mixture of the cold and warm air will be discharged through the vent outlet  14 . When the vent damper  20  is in its intermediate position, the cold air, the warm air or the mixture of the cold and warm air will flow into both the duct  32  and the vent outlet  14 . 
   The floor damper  22  is disposed adjacent to the floor outlet  16  and is moveable between an upper position  46  as shown by the solid line and a lower position  48  as shown by the two-dot-chain line. When the floor damper  22  is in its upper position  46 , all the air that passes through the duct  32  will be discharged through the floor outlet  16 . On the other hand, when the floor damper  22  is in its lower position  48 , all the air that passes through the duct  32  will be discharged from the defrost outlet  12  through the duct  33 . The operation of the vehicle air-conditioning system  1  according to this embodiment of the present invention will now be described in connection with three modes. 
   The discharge of the warm air through the floor outlet  16  in the first warm-air mode will now be described. The air mixing damper  18  is positioned in its upper position  34  while the vent damper  20  is positioned in its upper position  40 . Thus, the vent outlet  14  is closed. All of the cold air flowing backward from the evaporator  4  through the air mixing damper  18  is conducted into the heater  6  wherein the cold air is heated so as to form warm air. The warm air moves in the upward direction until it impinges upon the partition plate  8  whereat it is further directed in the upward direction toward the vent direction  14 . The warm air flow is then conducted into the duct  32  by means of the vent damper  20 , guide wall  11  and so on. When the warm air flows beyond the top end portion  10  of the partition plate  8  and before it turns through about 180 degrees over the top end portion  10 , the warm air flows upward along the front face  26  of the partition plate  8  and then flows along the front and rear faces  26 ,  28  of the top end portion  10  of the partition plate  8 . Since the top end portion surface  30  of the partition plate  8  is of a stream-line or curved configuration along which the warm air can smoothly flow along the surface  30 , the warm air will not separate from the surface  30  of the top end portion  10  when the warm air flows beyond the top end portion  10  of the partition plate  8 . The warm air is then discharged through the floor outlet  16 . 
   Next, the discharge of the cold air through the defrost outlet  12  in the second cold-air mode will be described. The air mixing damper  18  is placed in its lower position  36 , the vent damper  20  is positioned in its upper position  40 , and the floor damper  22  is located in its lower position  48 . AU the cold air from the evaporator  4  flows beyond and above the heater  6  in the presence of the air mixing damper  18 . The cold air then flows beyond the top end portion  10  of the partition plate  8  and is conducted into the duct  32  through the vent damper  20 , guide wall  11  and so on. When the cold air flows beyond the top end portion  10  of the partition plate  8 , the cold air moves angularly or obliquely into impingement with the top end portion  10  of the partition plate  8 . However, the cold air will not separate from the top end portion  10  of the partition plate  8  since the surface  30  of the top end portion  10  is of a streamlined or curved configuration along which the cold air smoothly flows. Subsequently, the cold air is discharged from the defrost outlet  12  through the ducts  32 ,  33 . 
   Finally, the third temperature-regulating mode in which the  20  conditioned air is discharged from the vent outlet  14  and the warm air is discharged from the floor outlet  16  will be described. The air mixing damper  18  is positioned in an intermediate position  38  while the vent damper  20  is positioned in an intermediate position  44 . A portion of the cold air flowing backward from the evaporator  4  through the air mixing damper  18  flows beyond and above the heater  6  while the remaining portion of the cold air is conducted into the heater  6  at which the cold air is heated, whereby the heated or warm air then flows backward of the heater  6 . The warm air moves in the upward direction until it impinges upon the partition plate  8  whereupon the warm air is directed in the upward direction. Since the top end portion  10  of the partition plate  8  is bent forwardly, the warm air is further directed in the forward direction. As a result, the warm air impinges upon the cold air that bypasses the heater  6  substantially at a right angle. Thus, the cold and warm air are effectively mixed together so as to form a temperature-regulated air. Since the vent damper  20  is in its intermediate position  44 , about half of the temperature-regulated air is discharged from the vent outlet  14 . The remaining portion of the temperature-regulated air is directed beyond the top end portion  10  of the partition plate  8  in the backward and downward direction by being guided by the vent damper  20  and the guide wall  11 . Since the surface  30  of the top partition plate end  10  is of a streamlined or curved configuration along which the cold air smoothly flows and since the temperature-regulated air flows beyond the top partition plate end  10 , the flow of the temperature-regulated air will not separate from the top end portion  10  of the partition plate  8  similar to the first warm-air mode and second cold-air mode. Subsequently, the flow of the temperature-regulated air is discharged from floor outlet  16 . 
   In any of the three modes described above, the flow of the warm air, the cold air or the temperature-regulated air will not separate from the top end portion  10  of the partition plate  8  due to the streamlined or curved configuration of the top end portion  10 . Thus, the creation of an eddy at the top end portion  10  of the partition plate  8  can be suppressed so as to reduce noise. Moreover, the pressure loss in the air flow can be reduced by preventing the separation of the air flow. Thus, the reduction of the air flow rate can be suppressed so as to operate the vehicle air-conditioning system  1  more effectively. In particular, this is advantageous in the warm-air mode in which the air flow is turned about 180 degrees. 
     FIG. 2  is a graph illustrating the relationship between the radius of curvature R and the pressure loss coefficient ζ at the top end portion  10  of the partition plate  8  in a vehicle air-conditioning system  1  according to an embodiment of the present invention. The radius of curvature R is made dimensionless with the distance Gap between the partition plate  8  and the guide wall  11  in the vehicle air-conditioning system  1  (see FIG.  1 ). In this embodiment, the distance Gap is about 40 mm. The pressure loss coefficient ζ is a value that is made dimensionless in relation to the loss between points A and B in FIG.  1 . When the dimensionless radius of curvature R/Gap is at zero, that is, when the top end portion  58  of a partition plate  56  is not of a streamlined or curved configuration as in a vehicle air-conditioning system  50  according to the conventional system (see FIG.  3 ), the pressure loss coefficient ζ is 4, as shown in FIG.  2 . On the other hand, when the dimensionless radius of curvature R/Gap is between about 0.12 and 0.63, that is, the radius of curvature R is between about 5 and 25 mm, the pressure loss coefficient ζ is 3 or less. Therefore, the vehicle air-conditioning system can make the pressure loss coefficient ζ lower than the conventional vehicle air-conditioning system  50  and thereby cause the vehicle air-conditioning system  1  to operate more effectively. 
   Although the vehicle air-conditioning system according to an embodiment of the present invention has been described, it is to be noted that the scope of the invention is defined only by the appending claims.