Abstract:
A conditioned air unit for use in a motor vehicle providing heating or cooling to a plurality of regions having relatively independent temperature setting. The structure provides compact, flexible and convenient temperature conditioning for each region.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     A heating or air conditioning unit for a motor vehicle having a plurality of independent temperature control regions. 
     2. Description of Related Art 
     U.S. Pat. No. 4,482,009 discloses a conventional heating or air conditioning unit, including a fan and a heater, which divides the airstream downstream of the heater. Two ducts leading to the vehicle front compartment distribute conditioned air to the regions for the driver seat and passenger seat, and two ducts leading to the vehicle rear compartment distribute conditioned air to the regions for the seat behind the driver and the seat behind the passenger. Air control elements arranged at the branching points of the air ducts control the quantity of air supplied to each region; however, independent temperature control is only possible between the front and rear zones. Additional air control elements provided further downstream allow the air stream to the front zone to mix with the air stream to the rear zone; however, temperature control is still dependent on the position of the air quantity control elements for the other regions. 
     DE-A 39 40 361 discloses another conventional heating or air conditioning unit providing conditioned air to the rear zone of a motor vehicle. A first air duct conducts cold air and a second air duct conducts hot air. Air from the first and second ducts is combined in a mixing chamber so as to set the desired temperature of the air stream that goes to the rear zone. One disadvantage of this conventional arrangement is a duct conducting conditioned air to the foot region of the rear zone branches off from the hot air duct upstream of the mixing chamber, hence its temperature is dependent on the temperature setting in the front zone. Another disadvantage is the considerable amount of space required in the rear zone to control the amount of air to the rear zone. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a heating or air conditioning unit for a vehicle having a plurality of different regions in front and rear sections on both sides of a passenger compartment. A further object of the invention is to provide improved temperature setting convenience by providing a temperature setting for each region which is independent of the temperature setting in any other region, and to provide a space-saving construction. 
     A particular advantage of the invention is that the temperature can be individually set in a simple manner for at least four conditioned air regions in the motor vehicle passenger compartment. The temperature of the air stream leading to a conditioned air region is set directly in close proximity to a heater unit, thereby avoiding interaction or exchange between air streams of different conditioned air regions. Consequently, a separate temperature setting for different regions in each of four sections of the passenger compartment (e.g. driver side front seat, driver side rear seat, passenger side front seat, and passenger side rear seat) can be achieved without being influenced by the temperature setting for any other region. 
     Another advantage of the present invention is that the temperature setting for each region is established in close proximity to the heater unit. Therefore, obtaining separate temperature settings for at least four conditioned air regions does not require any more space than is required by conventional heating and air conditioning units to obtain separate temperature settings for only two conditioned air regions. 
     According to one embodiment of the present invention, the heater unit is divided into four heater core segments through which separate portions of an input air stream are conducted. Each portion of the air stream is conducted in a separate duct, which prevents mixing with other portions of the air stream. 
     According to another embodiment of the present invention, a single heater unit is vertically and horizontally separated into the four heater core segments. A central coolant tank vertically separates the heater unit into symmetrical side portions. Co-planar, parallel coolant tanks are arranged at distal ends of both side portions with respect to the central coolant tank. A horizontal partition divides each of the side portions into upper and lower segments. 
     According to yet another embodiment, the coolant carrying tubes of the heater in a lower segment include airstream turbulence inducing elements for increasing thermal transmission in the lower segment with respect to the upper segment, thereby obtaining a comparatively higher temperature setting. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated into and constitute a part of the specification, illustrate a presently preferred embodiments of the invention, and, together with the general description given above and the detailed description of the preferred embodiment given below, serve to explain the principles of the invention. 
     FIG. 1 is a schematic illustration of a conditioned air unit according to a first embodiment of the present invention. 
     FIG. 2 is a schematic illustration of a conditioned air unit according to a second embodiment of the present invention. 
     FIG. 3 is a front view of a heater unit according to the present invention. 
     FIG. 4 is a schematic illustration of a liquid flow control system according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One half of a conditioned air unit for a motor vehicle is illustrated schematically in FIG.  1 . The conditioned air unit is configured symmetrically with respect to a vertical center plane, so that temperatures for the right and left sides of the occupant compartment can be independently set. Thus, the half of the conditioned air unit illustrated in FIG. 1 is equally applicable for providing conditioned air to either of the right or left sides of the occupant compartment. 
     A conditioned air unit  100  according to the present invention is illustrated in FIG. 1. A fan  1  moves an input air stream  2  through the conditioned air unit  100 . The source of the input air stream  2  can either be fresh-air from outside the occupant compartment or air recirculated from inside the occupant compartment. A flap (not illustrated) controls the source of the input air stream  2 . The input air stream  2  passes through a refrigerant evaporator  3  for cooling the input air stream  2  to a given temperature. Downstream of the evaporator  3  is a heater unit  4 . Generally, the heater unit  4  comprises a liquid-to-air type heat exchanger, and preferably the liquid is engine coolant. However, other types of heat exchangers or heat sources are contemplated. The heater unit  4  may comprise either a single heater core or a plurality of heater core segments fitted together in a modular manner. 
     Downstream of the heater unit  4 , a plurality of ducts lead to corresponding outlet nozzles (not shown) for supplying conditioned air to separate regions in the occupant compartment of the motor vehicle. A ventilation duct  5 , a defroster duct  6 , and a foot duct  7  conduct conditioned air to a front section of one side of the vehicle. The ducts  5 ,  6 , and  7  are associated with an upper segment  8  of the heater  4 ; however, the ventilation duct  5  is adjacent a side wall of a housing  110 , and the air stream conducted by the ventilation duct  5  does not pass through the heater  4 . 
     Associated with a lower segment  9  of the heater  4  are a foot duct  10  and a ventilation duct  11  for conducting conditioned air to a rear section of the same side of the vehicle. As with the front zone ventilation duct  5 , the ventilation duct  11  is adjacent a side wall of a housing  110 , and the air stream conducted by the ventilation duct  11  also does not pass through the heater  4 . Generally, the defroster duct  6  is for conducting conditioned air to an upper region of the front section, and the ventilation ducts  5 , 11  are for conducting conditioned air to regions within their respective sections which are relatively higher in the passenger compartment than the regions receiving conditioned air conducted by the foot ducts  7 , 10 . 
     The illustrated arrangement of the ducts  5 - 7 ,  10  and  11  makes independent temperature setting simple. 
     Arranging the ventilation ducts  5 , 11  adjacent the side walls of the housing  110  permits cooled air leaving the refrigerant evaporator  3  to circumvent the heater  4  through respective bypasses  12 , 13 . 
     One or more air valves, or mixing flaps,  14 , 15  are arranged directly adjacent to the heater  4  in air distribution chamber(s). The air valves flaps  14 , 15  set the quantity of air and/or the air temperature. As illustrated, the air valve flap  14  makes it possible to set the temperature of the air streams in the ventilation duct  5  and the defroster duct  6  for the front section, and the air valve  15  makes it possible to set the temperature of the air streams in foot duct  10  and the ventilation duct  11  for the rear section. 
     The front section foot duct  10  is arranged centrally and receives an air stream which is temperature-conditioned directly by the heater unit  4 . 
     In a preferred embodiment, the temperature of the heater unit  4  is controlled with liquid valves  60 - 64  for controlling the flow of engine coolant through the heater unit  4 . opening and closing the liquid valves  60 - 64  regulates the flow of coolant through each segment of the heater unit  4 , thereby enabling different temperature settings in each segment of the heater unit  4 . As can be seen from FIGS. 1 and 4, the temperature in each of the foot duct  10  and the ventilation duct  11  can be independently set using the liquid valves  60  and  62 , and the air valve  15 . Similarly, the temperature in each of the ducts  5 ,  6  and  7  leading to the front section can be independently set using the liquid valves  60  and  62 , and the air valve  14 . 
     According to a preferred embodiment of the invention, the heater  4  comprises separate segments. As shown in FIGS. 3 and 4, the heater  4  consists of a first side portion  16  and a second side portion  17 . Coolant is supplied through the liquid valve  60  to an inlet opening  18  in a central tank  19  arranged between the two side portions  16 , 17 . The coolant flows out of the central tank  19  through horizontal tubes  20  in the upper heater core segment  8 ′ of the side portion  16  to a first end tank  21 , and through horizontal tubes  20  in the upper heater core segment  8 ′ of the side portion  17  to a second end tank  21 ′. 
     The heater side portions  16 , 17  are divided into upper segments  8 , 8 ′ and lower segments  9 , 9 ′, respectively. Partitions  28 , 29  extending outward from the central tank  19  divide the heater side portions  16 , 17  into the upper  8 , 8 ′ and lower  9 , 9 ′ heater core segments, respectively. Coolant exits the heater unit  4  through outlet openings  31 , 32 , 33 , 34  in the segments  8 , 8 ′, 9 , 9 ′, respectively. 
     According to one feature of the invention, liquid valves  61 , 63  can be used to control engine coolant flow through the upper segments  8 , 8 ′, and air flaps (not shown) can be used to control air flow through the lower segments  9 , 9 ′. This also enables the temperature settings for the front and rear sections of a side compartment to be controlled substantially independently of one another. 
     According to another feature of the invention, the tubes  20  of the lower segments  9 , 9 ′ can be designed in such a way that air streams conducted through the foot ducts  10  are heated to a higher temperature than air streams conducted through the foot ducts  7 . For example, turbulence inducing inserts in the heat-conducting tubes  20  of the lower segments  9 , 9 ′ cause eddying of the coolant which improves thermal transmission. 
     Another embodiment of the present invention is shown in FIG. 2 wherein independent temperature settings for various regions of a passenger compartment are provided exclusively with air valves (e.g., mixing flaps) controlling air flow through a heater unit  35 . An upper mixing flap  36  is located upstream of the heater  35 , and a secondary mixing flap  37  is located downstream of the heater  35  to control the quantity of air flow to the front compartment. For air flow through a lower portion of the heater  35 , a lower mixing flap  38  is located upstream of the heater  35 , and a secondary mixing flap  39  is located downstream of the heater  35  to control the quantity of air flow to the rear compartment. An input air stream  41  is cooled as it passes through a refrigerant evaporator  40 . The positions of mixing flaps  36 , 37 , 38 , 39  enable independent temperature settings for the front and rear compartments. 
     Above a partition  42  is formed an upper air distribution chamber  43  from which temperature-conditioned air is conducted into the front passenger compartment through a ventilation duct  44 , a defroster duct  45 , and a foot duct  46 . The air stream conducted by ventilation duct  44  passes through the refrigerant evaporator  40  and bypasses the heater  35 . A pivoting flap  47  is arranged in the upper air distribution chamber  43  to mix heated air in the air stream conducted through the ventilation duct  44 . 
     Below the partition  42  is formed a lower air distribution compartment  48  from which temperature-conditioned air is conducted to the rear passenger compartment. A pivoting flap  49  is arranged in the lower air distribution chamber  48  at the entrances to a foot duct  50  and a ventilation duct  51 . The pivoting flap  49  mixes cooled air from the refrigerant evaporator  40  in the air streams conducted through both the foot duct  50  and the ventilation duct  51 . 
     This embodiment of the invention also enables the temperature settings for the different regions within the front and rear zones of a side compartment to be controlled substantially independently of one another. 
     Segmenting of the heater as illustrated in FIGS. 1,  3  and  4  reduces the interior space required by the conditioned air unit while meeting the user&#39;s increased demands for convenience and flexible control. Alternatively, the same convenience and flexibility can also be ensured using an unsegmented heater, i.e., having a single heater core, with the mixing flaps as illustrated in FIG.  2 . The arrangement of the ducts and the mixing flaps in close proximity to the heater unit, as illustrated in FIG. 2, achieves the same effects as the conditioned air unit illustrated in FIG.  1 . 
     As an alternative or in addition to the horizontal tubes  20  illustrated in FIG. 3, the heater  4  can have upright, vertical tubes. Automatic temperature layering results as the temperature of the coolant decreases uniformly from a region at the vertical position of the inlet opening  18  to the vertical position of the outlet openings near the upper and lower ends of the heater  4 . Consequently, a higher temperature setting is possible for the foot duct  7  as compared to the ventilation duct  5 . Similarly, the foot duct  10 , which is nearer to the inlet opening  18 , conducts an air stream of a higher temperature than the ventilation duct  11 . 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative devices that are shown and described herein. Accordingly, various modifications may be made without departing from the spirit and scope of the general inventive concept as defined by the appended claims and their equivalents.