Abstract:
The invention relates to a device for tempering and ventilating of motor vehicles with an air inlet opening and an air outlet region, wherein air flows are distributed into different vehicle regions. The device is provided with a basic casing, through which a partition extends to divide the flow path of the air from the air inlet opening to the air outlet region into two flow paths. In one flow path, a waste heat exchanger is arranged to heat the air.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a device and a process for tempering air for use in ventilating a passenger compartment of a motor vehicle, such as a heating, ventilation, and air conditioning system. 
       BACKGROUND OF THE INVENTION 
       [0002]    A heating, ventilation, and air conditioning (HVAC) system for a motor vehicle tempers air for use in a passenger compartment thereof, that is to heat or cool it as required and to ventilate it. For that, the tempered air flows are directed into different regions of the vehicle. External air is fed to the device by a fan and brought to the different areas of the passenger compartment. On its way, the inflowing air is passed over various air treatment devices. The air is cooled on the outside of an evaporator inside the casing of the heating, ventilating, and air conditioning system, and air is heated at an engine waste heat exchanger and, if necessary, at an additional heater. Air outlets lead, for example, into a footwell, an instrument panel, a central and outer regions of the passenger compartment, and to the lower inside of the windscreen through outlets designated as defroster outlets. Ventilation can be realized by circulation of the air of the passenger compartment instead of using the outside air. 
         [0003]    Many heating, ventilating, and air conditioning systems have the disadvantage that the hot air and the cold air flow parallel to each other in the mixing region provided. Further, in compact heating, ventilation and air conditioning systems for vehicles, the mixing space for mixing of hot and cold air is very small. Therefore sufficient mixing of the cold air and hot air flows is difficult, which results in unfavourable temperature layering, and undesirable temperature differences between the individual outlets. Accordingly, the hot air, for example, is directed into a flow path which leads to the outlet for the instrument panel and/or footwell regions and the cold air, only just mixed with hot air, arrives at the defroster outlet. That results in that in certain operational modes where the instrument panel region is heated too much, the windscreen is not sufficiently heated and defrosted, and temperature layering occurs in the passenger compartment of the vehicle which is unpleasant for a driver or a passenger. 
         [0004]    In order to improve mixing, usually additional guiding elements are provided. Guide vanes can, for example, be provided in flow channels in the heating, ventilating, and air conditioning system or on a temperature door. Elevations or reflecting plates can also be provided on the temperature door. These solutions are disadvantageous in that such guiding elements reduce the air flow, increase noise emission, and increase an overall weight of the heating, ventilating, and air conditioning system. 
         [0005]    In commonly owned DE 101 47 114 A1, hereby incorporated herein by reference in its entirety, a device for tempering and ventilating of vehicle compartments is presented which makes possible better mixing of cold and warm air. The device has an air inlet region and an air outlet region, starting from which air flows are distributed into different vehicle regions by a distribution apparatus. The device is provided with a casing configured hollow, through which a partition extends in longitudinal axial direction, which in this embodiment is established as hollow channel for a cross member. The hollow channel divides the air flow path from the air inlet to the air outlet into two flow paths. In one of these flow paths between the hollow channel and the casing wall an engine waste heat exchanger and, if necessary, an additional heater are provided so that the air flowing along this flow path is heated. Downstream of both flow paths there is a temperature door which controls the flow from the cold air flow path and the warm air flow path to the air outlet. The temperature door is designed angled or curved such that at the end stop positions one of both air flow paths is closed and at an intermediate position the air of an air path is, at least partially, laterally or frontally directed into the other air path. 
         [0006]    In another embodiment of this device, an essentially U-shaped hot air bypass envelops the casing in the region of the air outlet before the subsequent distribution casing. The hot air bypass with its two U-legs draws hot air over openings from hot air-containing regions of the casing through openings in the casing and thus directs the hot air into a region to be applied with hot air, such as the windscreen, or the defroster outlet. There the hot air is fed through at least one opening at the U-base leg and at least one identical opening in the outer casing. The advantage of this embodiment with hot air bypass is that the bypass is arranged outside the casing so that it does not influence the air flows inside the casing, particularly does not have a negative effect on them by noise emission. Simple in design and manufacture, the hot air bypass allows to take hot air at specific locations and to specifically add hot air into a certain region. 
         [0007]    In DE 102 61 036 A1, a heating, ventilating, and air conditioning system casing with an evaporating apparatus and a heating apparatus is disclosed that has a mixing chamber from which air flows to the rear footwell and rear ventilation. This casing is provided with an air control that controls the air flowing through the evaporating apparatus and the heating apparatus into the mixing chamber by means of a mixing door. In addition, the device is provided with a separate layering channel through which cool air can be passed into the rear ventilation region. This device assumes relevant, especially in the summer months. One disadvantage is that for specific temperature control and layering only additional cooling of certain regions is provided. The special requirements of the temperature layering in winter as, for example, the possibility of specific heating of certain regions of the passenger compartment, seem insufficiently considered. 
         [0008]    It would be desirable to provide a device for tempering and ventilation of vehicle passenger compartments that makes possible improved mixing of hot and cold air and appropriate temperature stratification with low noise emission. 
       SUMMARY OF THE INVENTION 
       [0009]    Consistent and consonant with the present invention, a device for tempering and ventilation of vehicle passenger compartments that makes possible improved mixing of hot and cold air and appropriate temperature stratification with low noise emission, has surprisingly been discovered. 
         [0010]    According to an embodiment of the invention, improved mixing of cold and hot air and appropriate temperature stratification are reached by that a separate hot air channel running outside the casing around said casing as well as a separate cold air channel inside the unit are provided. The combination according to the invention of a separate hot air channel and a separate cold air channel makes it possible that the hot air flow and the cold air flow run crosswise without penetrating each other. The separate hot air channel draws a portion of the hot air from the air outlet region above the engine waste heat exchanger, directs this hot air in bypass manner around the casing and finally redirects it to an air flow, for example, the air flow for defrosting of the windscreen. The separate cold air channel draws a portion of the cold air from the air outlet region above the evaporator and passes it directly to a region more to be cooled of the vehicle, for example, to the instrument panel outlets, and admixes it below these outlets to the air flow there. 
         [0011]    In another embodiment of the invention, the magnitude of the channels is adjustable in order to control the amount of air flowing to the appropriate outlets. 
         [0012]    In another embodiment of the invention, the device with the above mentioned combination of a separate hot air channel and a separate cold air channel is supplemented by a temperature door according to DE 101 47 114 A1. This temperature door is arranged downstream of the partition and configured angled or curved in direction of the partition such that at the end stop positions either the hot air flow path, which passes the heat exchanger, or the cold air flow path, which passes above the evaporator, is closed. At an intermediate position the air of an air path is at least partially led into the other air path in each case. In the end, this results in effective mixing and, in combination with the two separate channels, appropriate temperature stratification. 
         [0013]    Upstream of the partition, a bent air guide plate can be provided which divides the hot air flow path into an upper and a lower path, thus ensuring that the heat exchanger is homogeneously approached. 
         [0014]    Additionally, up to three walls of the additional separate channels are part of the heating, ventilation and air conditioning unit casing and hence made of the same material, whereby an additional covering completes the channels each. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0015]    Further details, features and advantages of the invention will become apparent from the following description of examples of embodiment with reference to the accompanying drawings. In the drawings it is shown by: 
           [0016]      FIG. 1 : the device according to the invention in a sectional side view; 
           [0017]      FIG. 2 : the device of  FIG. 1  with marked flow lines of the hot air flow path and the cold air flow path; 
           [0018]      FIG. 3 : the device of  FIG. 1  in a highly schematized sectional view in the region of the hot air bypass viewed in direction of the cover wall of the bypass; and 
           [0019]      FIG. 4 : the device of  FIG. 1  in a perspective partial lateral top view of the separate hot air channel with the flow course of the hot air in the hot air channel. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. 
         [0021]    A device  1  according to the invention is provided with a basic casing  2 , which is shaped irregular in its outer borders. This basic casing  2  is configured to  FIG. 1  as a hollow body, whereby approximately in the centre of the hollow body basic casing  2  a partition  3  is provided extending along the entire basic casing  2 . The partition  3  is configured in the lower region  3   a  as hollow channel with a drop-shaped cross-section so that the partition  3  is rounded in its lower region  3   a . In addition, the partition  3  is bent in direction of flow in its lower region  3   a.    
         [0022]    Between the concave side of the curvature in the lower region  3   a  of the partition  3  and an outer wall  4  of the casing  2 , a heat exchanger  5  such as an engine waste heat exchanger (and, if desired, an additional heater not shown in  FIG. 1 ) is arranged axially extending over the whole length of the casing  2  and ending with the partition  3  and outer wall  4 . Favorable results have been obtained where the heat exchanger  5  is arranged approximately parallel to the upper one-wall part  3   b  of the partition  3 . Below the partition  3  there is an air guide plate  3   c  bent in flow direction which divides the flow path to the heat exchanger  5  into an upper path  16   a  between the air guide plate  3   c  and the lower drop-shaped end  3   a  of the partition  3  and a lower path  16   b  between the air guide plate  3   c  and the outer wall  4 , which is intended to ensure homogeneous approach to the heat exchanger  5 . 
         [0023]    Opposite to the heat exchanger  5 , i.e. opposite relative to the partition  3 , the casing  2  is provided with an air inlet opening  6 . The air inlet opening  6  is configured essentially rectangular in top view, whereby the air inlet opening  6  extends box-like from the casing  2  outwards. 
         [0024]    In the box-like air inlet opening  6 , which is delimited by the box wall  7 , an evaporator  8  is arranged in direction of the casing  2  and an upstream filter  9  in direction of the air inlet opening  6 . Above the one-wall end  3   b  of the partition  3  an air outlet region  10  axially extending over the whole length of the casing  2  is provided. The air outlet region  10  is also configured essentially rectangular extending longitudinally. 
         [0025]    Above the one-wall end  3   b  of the partition  3  and between the partition  3  and the air outlet region  10  a temperature door  15  is provided. The partition  3  passing through the casing  2  divides the casing  2  from an air inlet  6  to an air outlet region  10  into a first or hot air flow path  16  provided with the heat exchanger  5  and a second or cold air flow path  17 . The temperature door  15  serves to block the hot air flow path  16  or the cold air flow path  17  or to partially open or block both flow paths  16 ,  17 . 
         [0026]    The casing  2  and the partition  3  are configured such that the air inflowing according to the air inlet range  6 , or the entering air flow, respectively, divides itself and can flow around the partition  3  and parallel re-unites above the partition  3 , whereby the casing  2  in direction of the air outlet region  10  above the partition  3  re-tapers, or the flow paths re-narrow. 
         [0027]    In the narrowing region above the partition  3  the temperature door  15  is positioned. The temperature door  15  axially extends corresponding with the longitudinal extension of the partition  3  through the whole casing  2 , whereby the temperature door  15  includes a shaft  18 , on which the temperature door  15  is pivotable. The shaft  18  passes through the axially front-end casing walls of the casing  2  so that the end regions of the shaft  18  of the temperature door  15  protrude from the casing and hence the temperature door  15  can be actuated from outside. The temperature door  15  is designed such that on both sides of the shaft  18  there are door wings  19  of the temperature door  15 . The temperature door wings  19  are configured angled, curved or bent to each other such that they include a smaller angle to the partition  3  compared with the angle in direction of the air outlet region  10 . Different shapes of the temperature door  15  are conceivable. The temperature door  15  can be configured curved or convex with a C-shape as well as roof-like with flat wings extending outwards, whereby the shaft  18  runs in the region of the ridge. The wing span of the door  15  between the outer longitudinal edges  20  of the door wings  19  is chosen such that at the end stop positions of the door a longitudinal edge  20  of a door wing  19  bears on a casing wall of the casing  2  and the opposite longitudinal edge  20  of the opposite door wing  19  at the end  3   b  bears at or on the partition  3 , respectively. At the end stop positions, hence, the hot air flow path  16  or the cold air flow path  17  are totally blocked so that either only cold air comes into the region of the air outlet region  10  or only hot air comes into the region of the air outlet region  10 . 
         [0028]    In one embodiment, the temperature door  15  is curved or angled roof-like such that the flow paths, particularly the cold air flow paths  17 , are influenced when the temperature door  15  is not at the end stop positions. If the temperature door  15  is opened by an end stop blocking the cold air, a portion of the air flow according to the hot air flow path  16  comes through the heat exchanger  5 , i.e. this air flow passes the inner partition  3  in the region  3   a , whereas particularly a smaller portion of the cold air according to the cold air flow path  17  in the region above the one-wall end  3   b  is positively guided around the inner partition  3 . So the cold air and the warm air are forced to mix by collision and then guided above the door  15  in direction of the air outlet region  10 . 
         [0029]    Above the air outlet region  10  a distribution apparatus  30  is provided. This distribution apparatus  30  distributes the air flows over outlets  32 ,  34 ,  36  in a channel system. The distribution apparatus  30  is configured essentially box-shaped. Inside the box-shaped structure, in clockwise direction, a defroster outlet  32  blockable with a door  31 , an instrument panel outlet  34  adjacently arranged in the box-shaped outlet blockable with a door  33  and a footwell outlet  36  arranged at the underside of the box blockable with a door  35  are established. 
         [0030]    According to the invention, to enrich the air passing through the defroster outlet  32  a separate hot air channel bypass  40  is arranged. The separate hot air channel  40  is positioned in the zone of the air outlet region  10 . In the zone of the air outlet region  10  the casing  2  has an approximately rectangular cross-section, whereby in a region approximately above the heat exchanger  5 , adjacent to a wall of the casing  2  in direction of the hot air flow path  16 , axially at the face-side casing openings  41  are provided in the entering region of the separate hot air channel  40  in the casing wall. It is understood that the channel  40  can be sized or tuned to control the amount of air permitted to flow therethrough. This can be accomplished through hydraulic diameter sizing, orifices (not shown), or tuning valves or dampers (not shown), for example. Above the casing openings  41  guide elements  42  are arranged at the wall of the casing  2 . The guide elements  42  pass at least a partial flow of the rising hot air through the casing openings  41 . The separate hot air channel  40  is, in its cross-section, configured U-shaped, whereby the separate hot air channel  40  is a U-shaped hollow body. This U-shaped hollow separate hot air channel  40  has, to  FIG. 3 , a U-base leg  43  and U-legs  44  branching off from the U-base leg  43 . The distance between the U-legs  44 , or the width of the base leg  43  are dimensioned such that the U-base leg  43  has a length approximately equal to the length of a broad side casing wall, and the length of the U-legs  44  which are arranged approximately rectangular, is approximately equal to the breadth of a narrow face-end casing wall. Adjacent to the outer free edges  45  in the region of the casing openings  41  the separate hot air channel  40  has casing openings  46  flush with the casing openings  41 . In an upper cover wall  47  of the base leg  43  the U-base leg  43  has a hot air outlet opening  48  directed upwards corresponding to the flow direction. Above the cover wall  47  a wall of the distribution apparatus  30  adjacent to the cover wall  47  is provided accordingly with identical openings  49 . So hot air that flows through the openings  41  and  46  into the U-base leg  43  can flow into the region  32  and mix with the air present. 
         [0031]      FIG. 2  shows the flow course  53  in the hot air flow path  16  over the heat exchanger  5  up to the casing opening  41  in the inflow region of the hot air channel  40 .  FIG. 4  shows the further flow course  53  through the hot air channel up to the distribution casing  30 , whereby the flow course  53  of the hot air is represented in form of flow vectors. 
         [0032]    The device  1  according to the invention is provided in addition to the separate hot air channel  40 , with a separate cold air bypass channel  50  with an inlet opening  51  and an outlet  52  which runs inside the casing  2 . It is understood that the channel  50  can be sized or tuned to control the amount of air permitted to flow therethrough. This can be accomplished through hydraulic diameter sizing, orifices (not shown), or tuning valves or dampers (not shown), for example. The flow course  54  in the cold air flow path  17  over the evaporator  8  to the inlet opening  51  of the separate cold air channel is shown in  FIG. 2  also by means of flow lines. The inlet opening  51  of the  50  is positioned adjacent to the evaporator  8  at the level of the air outlet region  10  and hence can directly take a portion of the air cooled at the outside of the evaporator  8  and direct it to the instrument panel outlet  34 . 
         [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.