Abstract:
An HVAC assembly including an HVAC case disposed in a passenger compartment of a vehicle includes a first air mix door. The first air mix door is movable between open and closed positions and adapted to adjust a temperature of air blown into a front passenger compartment. A second air mix door is movable between open and closed positions and adapted to adjust a temperature of air blown into a rear passenger compartment. The HVAC assembly further includes a motor and a mechanical linkage operably coupling the motor with the first and second air mix door whereby movement of the motor corresponds to movement of both the first and second air mix doors.

Description:
FIELD OF THE INVENTION 
   The present invention relates to HVAC systems in vehicles and more particularly to an HVAC module having both front and rear air mix control using a single servo motor. 
   BACKGROUND OF THE INVENTION 
   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 air in the vehicle. The heater core and evaporator are typically provided in an HVAC module case located in the passenger compartment of the vehicle. 
   In some vehicles, the climate control system is adapted to control three zones of the cabin space. Generally, the three zones include the front driver&#39;s side, the front passenger&#39;s side and the rear occupant zone. The HVAC case typically includes ducting to accommodate air distribution to these appropriate zones as desired. Air mix doors may be provided for modifying the temperature of air passed through the ducting to the occupants of the vehicle. In one example, a front air mix door (or doors) is provided for modifying the temperature of air passed into the front cabin and a rear air mix door (or doors) is provided for modifying the temperature of air passed into the rear cabin. Typically, a pair of servo motors are provided for independently controlling the respective front and rear air mix doors. In some applications however, multiple servo motors may be cost prohibitive. 
   SUMMARY OF THE INVENTION 
   An HVAC module assembly including an HVAC case disposed in the passenger compartment of a vehicle includes a first air mix door. The first air mix door is movable between open and closed positions and adapted to adjust the temperature of air blown into the front passenger compartment. A second air mix door is movable between open and closed positions and adapted to adjust the temperature of air blown into a rear passenger compartment. The HVAC assembly further includes a motor and a mechanical linkage operably coupling the motor with the first and second air mix doors whereby movement of the motor corresponds to movement of both the first and second air mix doors. 
   According to other features, the linkage includes a rod interconnected between the first and second air mix doors. The rod is connected on a first end to a first cam communicating with the first air mix door. The rod is connected on a second end to a second cam communicating with the second air mix door. In one example, the second air mix door includes a pair of rear air mix doors such that the second cam is adapted to operably rotate both air mix doors of the pair of air mix doors. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a functional block diagram of an HVAC system of a vehicle; 
       FIG. 2  is a perspective view of the HVAC case incorporating a single servo motor and linkage shown in a first position according to the present teachings; 
       FIG. 3  is a front perspective view of the linkage of the HVAC case of  FIG. 2 ; 
       FIG. 4  is a rear perspective view of the linkage of  FIG. 3 ; 
       FIG. 5  is a perspective view of the HVAC case of  FIG. 2  shown in a second position according to the present teachings; 
       FIG. 6  is a front perspective view of the linkage of the HVAC case of  FIG. 5 ; and 
       FIG. 7  is a rear perspective view of the linkage of  FIG. 6 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   With initial reference to  FIG. 1 , a block diagram of a conventional vehicle heating ventilation and air conditioning (“HVAC”) system is shown and generally identified at reference  10 . An HVAC case  20  forms a ventilation duct through which air conditioned and/or heated air is sent into the passenger compartment. The HVAC case  20  contains a fan  22  which is arranged on the upstream side of an evaporator  26 . Low pressure refrigerant flowing into the evaporator  26  absorbs heat from the air inside the HVAC case  20  during refrigerant evaporation. An inside/outside air switch box (not shown) may be arranged on the suction side of the fan  22  (the left side in  FIG. 1 ). Alternatively, the fan  22  may be housed within the inside/outside air switch box. The air inside the passenger compartment (inside air) or the air outside the passenger compartment (outside air) switched and introduced through the inside/outside air switch box is sent into the HVAC case  20  by the fan  22 . 
   The HVAC case  20  accommodates, on the downstream side of the evaporator  26 , a hot water heater core (heat exchanger)  30 . The heater core  30  includes an inlet pipe  32  and an outlet pipe  34 . Hot water (coolant) of the vehicle engine (not shown) is directed to the heater core  30  through the inlet pipe  32  by a water pump (not shown). A water valve  36  may be incorporated to control the flow volume of engine coolant supplied to the heater core  30 . 
   A bypass channel  40  is formed beside the hot water heater core  30 . A front passenger air mix door  42  is provided to adjust the volume ratio between warm air and cool air that passes through the hot water heater core  30  and the bypass channel  40 , respectively. The front passenger air mix door  42  adjusts the temperature of the air blown into the front passenger compartment by adjusting the volume ratio between the warm air and the cool air. Similarly, a pair of rear passenger air mix doors  44  are provided to adjust the volume ratio between warm air and cool air that passes through the hot water heater core  30  and the bypass channel  40 , respectively. The pair of rear passenger air mix doors  44  adjust the temperature of air blown into the rear passenger compartment by adjusting the volume ratio between the warm and the cool air. As illustrated in  FIGS. 2-7 , the pair of rear passenger air mix doors  44  are depicted as doors  44   a  and  44   b , respectively. 
   Additionally, a face outlet  46 , a defroster outlet  48 , a foot outlet  50  and a rear cabin outlet  52  are formed at the downstream end of the HVAC case  20 . The face outlet  46  directs air toward the upper body portions of passengers, the defroster outlet  48  directs air toward the internal surface of a windshield, the foot outlet  50  directs air toward the feet of the front seat passengers and the rear cabin outlet  52  directs air toward the rear seat passengers of the vehicle. The outlets  46 - 52  are opened and closed by outlet mode doors (not shown). It is appreciated that the block diagram and related components described in relation to  FIG. 1  are merely exemplary and other configurations may be used. 
   With continued reference to  FIG. 1  and further reference to  FIGS. 2-4 , the HVAC case  20  will be described in greater detail. The HVAC case  20  according to the present teachings incorporates a single motor or servo  58  (as best illustrated in  FIGS. 4 and 7 ) for concurrently controlling the position of the front passenger air mix door  42  and the rear passenger air mix doors  44   a ,  44   b . The servo  58  is contained in a housing  60  coupled to the case  20 . A linkage  62  is provided having a rod  64  connected at opposite ends to a first cam assembly  66  and a second cam assembly  68 , respectively. 
   The first cam assembly  66  is operably coupled between the front passenger air mix door  42  and the servo  58 . The second cam assembly  68  is operably coupled between the rod  64  and the rear passenger air mix doors  44   a ,  44   b . In sum, the configuration of the linkage  62  allows rotation of the servo  58  to correspond with simultaneous rotation of the front and rear air mix doors  42 ,  44   a , and  44   b  respectively. As a result, the rear air mix doors  44   a ,  44   b  are coordinated for concurrent movement with the front air mix door  42 . As illustrated in  FIGS. 2-4 , the front and rear air mix doors  42 ,  44   a , and  44   b  are shown in a position corresponding to the maximum hot air deliverable to the front and rear passengers. 
   With reference now to  FIGS. 5-7 , the front and rear air mix doors  42 ,  44   a , and  44   b  are shown in a position corresponding to the maximum cold air deliverable to the front and rear passengers. As viewed from  FIGS. 4 and 7 , the servo  58  rotates in a counterclockwise direction from the maximum hot position ( FIG. 4 ) to the maximum cold position ( FIG. 7 ). 
   With reference now to all drawings, the linkage  62  will be described in greater detail. The first cam assembly  66  generally includes a first and second link arm  70  and  72 , respectively. The first link arm  70  includes a first end coupled to a shaft  74  formed with the front air mix door  42  ( FIG. 3 ). The shaft  74  is housed within the HVAC case  20  with freedom to rotate and defines a first axis A 1  through which the first link arm  70  rotates about. The first link arm  70  defines a groove  78  receiving a cam pin  80  extending from the second link arm  72 . The second link arm  72  is coupled at an opposite end to the servo  58  for rotation therewith about a second axis A 2  ( FIG. 7 ). The rod  64  is rotatably coupled to an intermediate portion  84  of the second link arm  72 . 
   The second cam assembly  68  generally includes a cam or rocker  86  operably coupled to the pair of rear air mix doors  44   a ,  44   b  through a pair of swing arms  88  and  90 , respectively. The rocker  86  defines a pair of grooves  92  and  94  for accepting a respective pair of pins  96  and  98  extending from first ends of the swing arms  88  and  90 , respectively. The swing arms  88  and  90  are coupled at second ends to respective shafts  100  and  102  defined along the rear air mix doors  44   a ,  44   b . The rocker  86  is fixed for rotation about a third axis A 3  ( FIG. 2 ). The rod  64  is rotatably coupled at a first end of the rocker  86 . The rear air mix doors  44   a ,  44   b  are fixed (to the HVAC case  20 ) for rotation about a fourth and fifth axis A 4  and A 5 , respectively ( FIG. 4 ). The fourth and fifth axes A 4  and A 5  correspond to the respective shafts  100  and  102  of the rear air mix doors  44   a  and  44   b.    
   Movement of the linkage  62  from the first position ( FIGS. 2-4 ) to the second position ( FIGS. 5-7 ) will now be described in greater detail. As explained above, the servo  58  is positioned in  FIGS. 2-4  at a location corresponding to the maximum heated air delivered through the outlets  46 ,  48 ,  50  and  52 . In this way, the front and rear air mix doors  42 ,  44   a  and  44   b  are positioned such that air is forced to pass through the heater core  30 . The servo  58  is positioned in  FIGS. 5-7  at a location corresponding to the maximum cool air deliverable through the outlets  46 ,  48 ,  50  and  52 . As a result, the front and rear air mix doors  42 ,  44   a  and  44   b  are positioned such that air is routed around rather than through the heater core  30 . Movement of the doors  42 ,  44   a  and  44   b  is accomplished by counterclockwise movement of the servo  58  from a position shown in  FIG. 4  to a position shown in  FIG. 7  about axis A 2 . It is appreciated that a plurality of intermediate positions may be attained between the first and second position to achieve a range of temperatures. While not specifically shown, a user input such as a temperature adjustment on a vehicle instrument panel (not shown) may initiate movement of the servo  58 . In one arrangement, a body control module (not shown) may control the servo  58  based on such a user input. Other arrangements may be used. 
   As viewed from  FIG. 3 , clockwise movement of the servo  58  causes the second link arm  72  to rotate with the servo  58 . As a result, the cam pin  80  drives the first link arm  70  by interacting within the groove  78  defined in the first link arm  70 . This movement causes the first link arm  70  to rotate about the first axis A 1  in a counterclockwise direction as viewed in  FIG. 3 . As a result, the front air mix door  42  rotates counterclockwise about the shaft  74  (axis A 1 ). Rotation of the second link arm  72  with the servo  58  causes concurrent movement of the rocker  86  through the rod  64 . In this way, clockwise movement of the servo  58  also causes the rocker  86  to rotate counterclockwise about axis A 3 . Because the rear air mix doors  44   a  and  44   b  are fixed for rotation about axes A 4  and A 5 , respectively, the pins  96  and  98  of the swing arms  88  and  90  are urged to travel in the respective grooves  92  and  94 . With specific reference now to  FIG. 7 , movement of pin  98  along groove  94  causes the swing arm  90  and the rear air mix door  44   b  to rotate counterclockwise about axis A 5 . Concurrently, movement of the pin  96  along groove  92  causes the swing arm  88  and the rear air mix door  44   a  to rotate clockwise about axis A 4 . 
   Some advantages of the HVAC dual zone temperature control with a slave linkage are that a single motor can be utilized, as opposed to multiple motors. Additionally, the rear passenger compartment passengers can receive the same temperature of air as the front passenger compartment passengers with the use of a single motor. Furthermore, because the same temperature air can be supplied to two different areas of a passenger compartment using only a single motor, there is a cost and weight savings. 
   Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. For example the linkage and respective front and rear cam assemblies are merely exemplary. It is appreciated that many other mechanical configurations may be employed for translating rotational motion of a single servo motor into rotational movement of at least two air mix doors. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.