Patent Publication Number: US-2009229788-A1

Title: Vehicle Air Conditioner

Description:
TECHNICAL FIELD 
     The present invention relates to an air-mixing type vehicle air conditioner including an air-mixing damper interposed between an evaporator and a heater core. 
     BACKGROUND ART 
     A large proportion of vehicle air conditioners employs an air mixing method for temperature control. An air-mixing type vehicle air conditioner includes a heater core disposed downstream of an evaporator provided in an air channel of a casing and a bypass channel for bypassing the heater core. The air-mixing type air conditioner regulates temperature by using an air-mixing damper to regulate the flow rate of an air flow to be reheated by the heater core in the air flow cooled at the evaporator and by mixing the air flow that is reheated at the heater core and the air flow that bypasses the heater core at a downstream air-mixing area. 
     In many cases, the air-mixing damper is supported between the evaporator and the heater core such that a rotary shaft thereof is rotatable near one end of the heater core and such that the degrees of opening of an air inlet channel to the heater core and an inlet channel to the bypass channel can be regulated. A gate-type planar damper is used as such an air-mixing damper. 
     To reduce the size of the air-mixing type vehicle air conditioner and reduce the operational force of the air-mixing damper, the radius of the rotation of the air-mixing damper is minimized and a sealing portion that completely closes the air inlet channel to the heater core and the bypass channel when the tip portion of the air-mixing damper contacts the sealing portion is integrated with the casing and protrudes into the air channel. 
     As described above, if the sealing portion protrudes from the casing into the air channel, the channel sidewall constituting the air inlet channel of the heater core is formed of the casing sidewall that extends from the sealing portion to the other end of the heater core (for example, refer to Patent Documents 1 and 2). 
     In Patent Document 1, the sidewall of the air inlet channel to the heater core is formed of a sidewall that extends substantially vertically downward from the sealing portion and that is curved to protrude outward from the channel. In Patent Document 2, the sidewall of the air inlet channel to the heater core is formed of a straight vertical sidewall that extends substantially vertically downward from the sealing portion. 
     Patent Document 1: Japanese Unexamined Patent Application, Publication No. HEI-11-301243 ( FIGS. 1 and 2 ) 
     Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2000-219027 ( FIGS. 1 to 3 ) 
     DISCLOSURE OF INVENTION 
     However, according to Patent Document 1, the air flow stagnates at the curved portion protruding outward from the channel, and according to Patent Document 2, the air flow is separated at the straight vertical sidewall. The stagnation and separation causes the heating ability to decrease due to a decrease in the air volume. In particular, in the area below the heater core, the air volume and the air velocity are reduced, causing the air-velocity distribution of the heater core to be degraded. As a result, the heat-exchange efficiency is reduced, causing a problem of reduced heating ability. Moreover, vortexes generated by the stagnation and separation cause noise to increase. In particular, in recent vehicles, the air conditioner noise is one noticeable noise source in the vehicle interior since the engine noise and driving noise have been reduced, and thus, there is an urgent need to reduce such noise. 
     The present invention has been conceived in light of the problems described above. Accordingly, it is an object of the present invention to provide a vehicle air conditioner that is capable of improving the heat-exchange efficiency of the heater core by improving the air inlet channel of the heater core and suppressing stagnation and separation of an air flow so as to increase the heating ability and that is capable of reducing noise. 
     To achieve the above-described objects, a vehicle air conditioner according to the present invention employs the following solutions. 
     More specifically, the vehicle air conditioner according to the present invention includes a vehicle air conditioner including an evaporator disposed in an air channel in a casing; a heater core disposed downstream of the evaporator in a heating-side air channel; a bypass channel disposed downstream of the evaporator and bypassing the heater core; and an air-mixing damper interposed between the evaporator and the heater core for regulating the flow rate of air to be flown through the heating-side air channel and air to be flown through the bypass channel, wherein a heater-core inlet channel sidewall of the casing from a sealing portion of the casing to an edge of the heater core is an inclined surface, the sealing portion being contacted by a tip portion of the air-mixing damper when the inlet of the heating-side air channel is completely closed, and wherein the inclined surface is formed as a curved surface protruding toward the inlet channel of the heater core. 
     According to the present invention, the inlet-channel sidewall of the heater core is an inclined surface and this inclined surface is formed as a curved surface protruding toward the inlet channel of the heater core. Therefore, in the air flow guided to the heater core through the evaporator, the air flow along the inclined surface of the inlet channel of the heater core is attached to the curved surface of the inclined surface by means of the Coanda effect and is guided to the edge of the heater core without stagnation or separation, and heat exchange is carried out at the heater core. Therefore, an air flow can be guided substantially evenly on the entire surface of the heater core, and the velocity distribution of the air flow passing through the heater core can be made even. Therefore, the heat-exchange efficiency of the heater core can be improved, and the heating ability can be increased. Moreover, since stagnation and separation of the air flow at the inlet channel of the heater core can be suppressed, noise caused by vortexes due to stagnation or separation can be reduced, and the noise of the air conditioner can be reduced. 
     Furthermore, the vehicle air conditioner according to the present invention may be the above-described vehicle air conditioner, wherein the evaporator and the heater core are disposed parallel to each other, and the curved inclined surface is inclined from the sealing portion to the edge of the heater core with respect to a direction orthogonal to the evaporator. 
     According to the present invention, the evaporator and the heater core are disposed parallel to each other, and the curved inclined surface is inclined from the sealing portion to the edge of the heater core with respect to a direction orthogonal to the evaporator. Therefore, the inclined surface from the sealing portion to the edge of the heater core can be a relatively gradually inclined surface. In this way, the air flow from the sealing portion to the heater core along the inclined surface can be attached to the curved inclined surface by means of the Coanda effect and can be smoothly guided to the edge of the heater core. Accordingly, stagnation and separation of the air flow at the inlet channel of the heater core and pressure loss can be suppressed, and noise caused by such problems can be reduced. Moreover, since an air flow can be guided substantially evenly over the entire surface of the heater core and the velocity distribution of the air flow passing through the heater core can be made even, the heat-exchange efficiency of the heater core can be improved, and the heating ability can be increased. 
     Furthermore, the vehicle air conditioner according to the present invention may be one of the above-described vehicle air conditioners, wherein the evaporator and the heater core may be disposed substantially vertically and parallel to each other. 
     According to the present invention, since the evaporator and the heater core are disposed substantially vertically and parallel to each other, the air flow that horizontally passes through the evaporator flows diagonally downward toward the heater core and then flows downstream through the heater core horizontally. In this air flow, the air that flows from the sealing portion to the heater core along the inclined surface is attached to the relatively gradually inclined curved surface, is smoothly guided to the edge of the heater core, and flows through the heater core substantially horizontally. In this way, the entire air flow smoothly flows to reduce pressure loss due to the resistance of the channel, performance can be improved, and noise can be reduced. 
     According to the present invention, the air flow along the inclined surface of the inlet channel to the heater core is guided to the edge of the heater core while being attached to the curved inclined surface by means of the Coanda effect, the air flows into the heater core without stagnation or separation. Therefore, the air flow can be guided over the entire surface of the heater core in a substantially even manner, and the velocity distribution of the air flow passing through the heater core can be made even. Therefore, the heat-exchange efficiency of the heater core can be improved, and the heating ability can be increased. Furthermore, since stagnation and separation of an air flow at the inlet channel of the heater core can be suppressed, noise caused by vortexes due to stagnation or separation can be reduced, and noise of the air conditioner can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view of the structure of a vehicle air conditioner according to a first embodiment of the present invention. 
         FIG. 2  is an analysis diagram of the state of an air flow in a heater core section of the vehicle air conditioner according to the first embodiment of the present invention. 
     
    
    
     EXPLANATION OF REFERENCE SIGNS 
     
         
           1 : vehicle air conditioner 
           2 : casing 
           2 A: heater-core inlet-channel sidewall 
           3 : air channel 
           4 : evaporator 
           5 : heater core 
           6 : air-mixing damper 
           6 B: planar damper portion 
           6 C: tip portion 
           11 : sealing portion 
           13 : heating-side air channel 
           14 : bypass channel. 
           30 : inclined surface 
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     An embodiment of the present invention will be described below with reference to the drawings. 
     An embodiment of the present invention will be described below with reference to  FIGS. 1 and 2 . 
       FIG. 1  is a cross-sectional view of the structure of a vehicle air conditioner according to an embodiment of the present invention. A vehicle air conditioner  1  includes a resin casing  2  that is connected to a blower unit which is not shown in the drawings. An air channel  3  that guides an air flow from the blower unit is provided inside the casing  2 . The casing  2  is provided as a plurality of separate pieces. Air conditioner components, such as an evaporator  4 , a heater core  5 , an air-mixing damper  6 , and a plurality of blowing-mode switching dampers  7 ,  8 , and  9 , are provided inside the casing  2  and are assembled as a single unit to form an HVAC unit  10 . 
     At the downstream side of the evaporator  4 , the air channel  3  is throttled by upper and lower sealing portions  11  and  12  contacted by the air-mixing damper  6 . Then, the air channel  3  is separated into two channels: a heating-side air channel  13  in which the heater core  5  is disposed and a bypass channel  14  that bypasses the heater core  5 . The heating-side air channel  13  extends upward from the downstream side of the heater core  5 , passes above the heater core  5 , and merges with the bypass channel  14  in an air-mixing area  15 . The air channel  3  connects to a face outlet  16  and a defrost outlet  17  at the downstream side of the air-mixing area  15 , to a foot outlet  19  via a foot channel  18 , and to a rear-seat outlet, not shown in the drawing, via a rear-seat duct  20 . 
     The evaporator  4  constitutes a known refrigeration cycle, together with a compressor, a condenser, an expansion valve, and so on, which are not shown in the drawings. The evaporator  4  exchanges heat between a refrigerant circulated in the refrigeration circuit and air sent from a blower unit, which is not shown in the drawings, so as to cool the air by vaporizing the refrigerant. The evaporator  4  is formed of a laminated tube-fin heat exchanger having a rectangular external shape with a predetermined thickness. The evaporator  4  is vertically disposed in the HVAC unit  10  in the area at the most upstream side of the air channel  3  such that the evaporator  4  intersects the air channel  3 . 
     Warm water from a vehicle engine, not shown in the drawings, is circulated through a cooling water circuit and then through the heater core  5 . The heater core  5  is disposed in the heating-side air channel  13  and exchanges heat between the warm water and the air cooled at the evaporator  4  to heat the air. The heater core  5  is formed of a laminated tube-fin type heat exchanger having a rectangular external shape with a predetermined thickness. The heater core  5  is disposed vertically and substantially parallel to the evaporator  4  such that the heater core  5  intersects the heating-side air channel  13 . 
     The air-mixing damper  6  is interposed between the evaporator  4  and the heater core  5 , and a rotary shaft  6 A is disposed near the upper edge of the heater core  5  such that the air-mixing damper  6  is installed in the casing  2  in such a manner as to be capable of rotation. The air-mixing damper  6  is a butterfly-shaped damper. A planar damper portion  6 B is movable and adjusted to an arbitrary position between a maximum cooling position (max cool position) C where the tip portion  6 C contacts the sealing portion  11  to completely close the inlet of the heating-side air channel  13  and a maximum heating position (max hot position) H where the tip portion  6 C contacts the sealing portion  12  to completely close the inlet of the bypass channel  14 . A planar damper portion  6 D is rotated together with the planar damper portion  6 B to adjust the degree of opening of the outlet of the heating-side air channel  13 . The planar damper portion  6 D closes the outlet of the heating-side air channel  13  when the air-mixing damper  6  is at the maximum cooling position C. 
     Among the blowing-mode switching dampers  7 ,  8 , and  9 , the face damper  7  is attached to a face outlet  16  in such a manner as to be capable of rotation; the defrost damper  8  is attached to the defrost outlet  17  in such a manner as to be capable of rotation; and the foot damper  9  is attached to the foot channel  18  in such a manner as to be capable of rotation. The blowing-mode switching dampers  7 ,  8 , and  9  can open and close the outlets by moving in conjunction with each other and can be switched between modes such as a face mode in which the face damper  7  is opened, a defrost mode in which the defrost damper  8  is opened, a foot mode in which the foot damper  9  is opened, a defrost foot mode in which both the defrost damper  8  and the foot damper  9  are opened, and a bi-level mode in which both the face damper  7  and the foot damper  9  are opened. The rear-seat duct  20  adjoins the face outlet  16 , and an inlet is connected longitudinally (front to rear direction of the vehicle) so as to guide cooled or heated conditioned air to the rear seats. 
     In the vehicle air conditioner  1  having the above-described structure, the evaporator  4  and the heater core  5  are disposed in the air channel  3  and the heating-side air channel  13  such that they are substantially orthogonal to the air flow direction, disposed substantially vertically, and disposed parallel to each other. The air-mixing damper  6  for regulating the flow rate of air flowing through the heating-side air channel  13  and the bypass channel  14  is interposed between the evaporator  4  and the heater core  5 . The sealing portion  11  where the tip portion  6 C of the planar damper portion  6 B contacts when the air-mixing damper  6  is at the maximum cooling position C is formed as an integral member of the casing  2 . 
     A heater-core inlet channel sidewall  2 A of the casing  2  that forms the heating-side air channel  13  from the above-described sealing portion  11  to the installation position of the heater core  5  is an inclined surface  30  that is inclined downward toward the lower edge of the heater core  5 . The entire inclined surface  30  is formed on a protruding curved surface on the inlet-channel side of the heater core  5 . 
     The above-described embodiment has the following advantages. 
     The air flow from the blower unit, not shown in the drawings, to the air channel  3  of the HVAC unit  10  is cooled by exchanging heat with the refrigerant while passing through the evaporator  4 . Then, the air is flown through the heating-side air channel  13  and the bypass channel  14  according to the flow rate regulated by the air-mixing damper  6 . The air flow through the heating-side air channel  13  is heated at the heater core  5  by exchanging heat with the heated water. Then, the air is mixed with the cooled air from the bypass channel  14  at the air-mixing area  15  to be set to a predetermined temperature. Then, the air is blown into the vehicle interior through the outlets  16 ,  17 , and  19  and the rear-seat outlet, not shown in the drawings, in accordance with the blowing mode set by switching the blowing-mode switching dampers  7 ,  8 , and  9 . 
     During this time, the air flow guided by the air-mixing damper  6  from the air channel  3  to the heater core  5  via the heating-side air channel  13  is throttled by the sealing portions  11  and  12  and, then, as shown in  FIG. 2 , is guided diagonally downward to the heater core  5 . Here, the air flowing along the inclined surface  30  of the heater-core inlet channel sidewall  2 A is attached to the curved surface of the inclined surface  30  by means of the Coanda effect and is guided to the lower edge of the heater core  5  without stagnation or separation. 
       FIG. 2  illustrates a state of maximum heating (max hot) in which the air-mixing damper  6  completely closes the bypass channel  14 . When the air-mixing damper  6  is positioned somewhere between the maximum heating position (max hot position) H and the maximum cooling position (max cool position) C, similar to the above-described case, the air flow toward the heater core  5  is smoothly guided to the lower edge of the heater core  5  by being attached to the curved surface of the inclined surface  30  by means of the Coanda effect, and the air flows into the heater core  5 . 
     As described above, the evaporator  4  and the heater core  5  are disposed parallel to each other, and the curved inclined surface  30  is an inclined surface that is relatively gradually inclined from the sealing portion  12  to the lower edge of the heater core  5  with respect to a direction orthogonal to the evaporator  4 . Therefore, the air flow along the inclined surface  30  from the sealing portion  11  to the heater core  5  can be smoothly guided to the lower edge of the heater core  5  by being attached to the air flow to the curved surface of the inclined surface  30  by the Coanda effect. 
     Therefore, the air flow can be guided substantially evenly over the entire surface of the heater core  5 , and the velocity distribution of the air flow that passes through the heater core  5  can be made substantially even. Thus, the heat-exchange efficiency of the heater core  5  can be improved, and the heating ability can be improved. Furthermore, stagnation or separation of the air flow in the heater-core inlet channel and pressure loss can be suppressed, and noise can be reduced by reducing noise caused by such problems. 
     Since the evaporator  4  and the heater core  5  are disposed substantially vertically and parallel to each other, as shown in  FIG. 2 , the air flow guided substantially horizontally through the evaporator  4  is guided downward through the heating-side air channel  13  toward the heater core  5 , passes through the heater core  5  in a substantially horizontal direction, and is guided downstream. In this air flow, the air that flows from the sealing portion  11  to the heater core  5  along the inclined surface  30  is smoothly guided to the lower edge of the heater core  5  by being attached to the curved surface of the relatively gradually inclined surface  30 , and then guided substantially horizontally to the heater core  5 . In this way, the entire air flow can be smoothly guided, the pressure loss due to the resistance of the channel can be reduced, performance can be improved, and noise can be reduced. 
     The present invention is not limited to the above-described embodiment, and modifications are possible within the scope of the invention. 
     For example, the evaporator  4  and the heater core  5  do not necessarily have to be disposed parallel to the vertical direction and may be disposed at an angle or horizontally. The air-mixing damper  6  does not have to be butterfly-shaped; it may include only the planar damper portion  6 B.