Abstract:
A heating, ventilation and air conditioning system for a vehicle is constructed from two modules, one for the engine compartment and a second for the passenger compartment. The engine compartment module has a base formed for positioning on at least two locations on a dash panel, a outside air inlet, a secondary air inlet for communication with the passenger compartment, an air outlet and defining a air transport conduit connecting the outside air inlet or the secondary air inlet with the air outlet. Downstream from the engine compartment is a passenger compartment module having a slide slot for a heater core, an inlet for communication with the air outlet from the engine compartment module, an air manifold, a panel exhaust from the air manifold, a defrost exhaust from the air manifold, a compartment door providing access to the slide in friction slot, and an air channel from the inlet to the air manifold. The heater core is positioned in the slide in slot.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is related to provisional application No. 60/271,084 filed Feb. 23, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to motor vehicle cabin climate control and more particularly to interoperative, easily maintained cabin and engine compartment modules, which are used to implement cabin heating and cooling in an efficient and reliable manner. 
     2. Description of the Problem 
     Combined systems for heating, ventilation and air conditioning (HVAC) have become an industry norm for automobiles and trucks. Among the features common to most if not all such systems are, a heater core, a blower to force air through the heater core, an evaporator for cooling air, distribution duct work, and a plurality of flow directing doors controlling the source of intake air, the route of the air through the system and the distribution points of the air into the cabin. The construction, arrangement, packaging and control of these elements has a number of ramifications for unit efficiency, cost and ease of manufacture and maintenance, space requirements for installation and passenger comfort. 
     Passenger cabin heating and windshield defrosting is provided by forcing air through interstices in a heater core, which, in vehicles with liquid cooled engines, use circulating engine coolant as a source of heat. Contemporary HVAC systems often provide no cutoff valve for interrupting coolant circulation through the core, Instead, internal air flow control doors cut off the core from air circulation when heat is not desired. Coolant cutoff valves have proven relatively unreliable in many applications, and eliminating them has produced maintenance savings. Heater cores themselves are an occasional maintenance problem, being prone to corrosion and leakage with long term use, The positioning and manner of installation of heater cores has made them difficult to replace. 
     Combined heating, ventilation and cooling systems have been adopted to reduce the costs of duct work, since only one set of distribution channels is required. Such an arrangement, combined with the absence of a heater core cutoff valve, contributes to greater complexity in the arrangements for air flow control. Rapid cooling of the vehicle passenger compartment when a vehicle is first turned on is often achieved by recirculating cabin air rather than drawing in outside air. Some defogging regimens call for both cooling the air, to remove moisture, and heating the air to clear interior surfaces of the vehicle greenhouse. Flow control doors must be positionable to draw air from either outside or inside the passenger compartment, to direct air through either or both the heater core and the evaporator and then to mix the air before it is directed against the glass. Finally, vent doors must provide for distribution of air to the desired locations. Kinematic positioning movements control the position of various vent and flow control doors and to deliver adequate air flow to the desired zone. 
     Individual products of the motor vehicle industry are frequently sold world wide. What were once considered North American trucks have found markets in South America, Australia and South Africa, among other places. Australia and South Africa use right hand drive vehicles and an HVAC system intended for a vehicle to be sold in both left hand and right hand drive countries can cost less in tooling if the components fit either type of vehicle. 
     SUMMARY OF THE INVENTION 
     According to the invention there is provided a heating, ventilation and air conditioning system for a vehicle. The system includes an engine compartment module having a base formed for positioning on at least two locations on a dash panel, an outside air inlet, a secondary air inlet for communication with the passenger compartment, an air outlet and defining an air transport conduit connecting the outside air inlet or the secondary air inlet with the air outlet. Downstream from the engine compartment, on the opposite major surface of the dash panel, is a passenger compartment module having a slide in slot for a heater core, an inlet for communication with the air outlet from the engine compartment module, an air manifold, a panel exhaust from the air manifold, a defrost exhaust from the air manifold, a compartment door providing access to the slide in friction slot, and an air channel from the inlet to the air manifold. A heater core is positioned in the slide in slot. A temperature blend door is positioned in the air channel on a pivoting mount allowing movement of the temperature blend door to various positions controlling the proportion of air flow through the air channel diverted through the heater core. A pulse count actuator is coupled to the temperature blend door for positioning the temperature blend door. A vent door is mounted on a pivoting mount and positionable in the air manifold for diverting air flow through the panel exhaust. A defrost door is mounted on a second pivoting mount and positionable in the air manifold for diverting air flow through the defrost exhaust. A kinematic movement including a pulse count actuator provides for positioning the vent and defrost doors. A blower is situated along the air channel of the passenger compartment module upstream from the slide in friction slot. An evaporator is mounted in the engine compartment module. 
     Additional effects, features and advantages will be apparent in the written description that follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a truck on which the heating, ventilation and air conditioning system of the invention is installed; 
     FIG. 2 is a side elevation of the heating, ventilation and air conditioning system installation in accordance with a preferred embodiment of the invention; 
     FIG. 3 is a perspective view of an evaporator or engine compartment module of the preferred embodiment; 
     FIG. 4 is a schematic view of the heating, ventilation and air conditioning system of the preferred embodiment; 
     FIG. 5 is a perspective view of the heating or passenger compartment module of the preferred embodiment; 
     FIGS. 6A-B illustrate in perspective and elevation a kinematic movement for controlling the mode of the panel and defrost ventilation control doors in the preferred embodiment; 
     FIG. 7 is a perspective view of a blower and scroll assembly for a heater module; 
     FIG. 8 is a perspective view of an evaporator; and 
     FIG. 9 is a control schematic for the heating, ventilation and air conditioning system. 
     FIG. 10 illustrates a control arrangement for an HVAC system including driver controls. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures and particularly to FIG. 1, a truck  10  is shown on which the heating, ventilation and air conditioning system of the invention is advantageously installed. Truck  10  comprises a cab  11  which rests on a frame  12 . An engine compartment  14  is separated from a passenger compartment  15  by a dash panel  16 . Dash panel  16  includes a pair of mating positions  18  toward each side of the truck  10 , one being visible on the driver&#39;s side  42  of truck  10 . A second position is hidden from view behind an engine compartment module  22 . Mating positions  18  include openings  20  through the dash panel  16  through which a steering column  46  may pass or which may be used as an channel to direct air through. 
     An evaporator or engine compartment module  22  is mounted over the mating position  18  not required for steering column  46 , i.e. on the side opposite to the drivers side  42  of the vehicle, Engine compartment module  22  includes an air intake  24  and is positioned on the dash wall  16  adjacent to, but extending from the opposite major face of dash panel  16 . 
     Referring now to FIG. 2, a heating, ventilation and air conditioning (HVAC) system  17  for a motor vehicle is shown. HVAC system  17  comprises two major modules, an engine compartment module  22 , which includes an evaporator for air cooling, and a passenger compartment module  26  which has a heater core for heating air, Both modules are supported on dash panel  16 , one on each of the opposed major surfaces of the dash panel. Modules  22  and  26  communicate with each other by way of openings through the dash panel  16 . Extending from the bottom of engine compartment module  22  are two drains, a precipitation drain  34  and a condensate drain  36 . 
     Passenger compartment module  26  includes a coolant drain  60  (See FIG.  4 ), providing an escape for coolant loss from a leaking heater core. A panel vent  30  and a defrost vent  28  are located adjacent one another along the top of passenger compartment module  26 . A conduit  38  distributes air to the floor from a manifold internal to module  26 . Panel  41  is attached to module  26  by conventional fasteners and is removable to provide ready access to the interior of module  26  for repairs, particularly replacement of a heater core or a blower, The heater core is located under a end fitting region  45  in panel  40  which helps locate the heater core firmly within module  26 . 
     Referring now to FIG. 3, engine compartment module  22  is illustrated in greater detail. Engine compartment  22  is constructed from two half sections  50  and  52 , which are attached to one another along a series of projecting flanges  54  by conventional fasteners. Similar flanges  56  extend from a back edge of the module allowing attachment of the module to the dash panel. A recirculation control door  58  is located inside of module  22  visible through outside air inlet  24 . A pulse actuator  48 , hung from the outside of the module, controls the position of recirculation control door  58 , which can be rotated to close inlet  24 . 
     Referring now to FIG. 4, the major internal elements of HVAC system  17  are shown in a schematic view, which also illustrates by a series of arrows the flow of air through the system. Outside air enters HVAC system  17  by an outside air inlet  24 , provided recirculation control door  58  is positioned away from the inlet. Recirculation control door  58  is mounted on a rotatable axle  62 , allowing the door to be moved between positions fully closing inlet  24 , door  58  moved upwardly against stop  25 , and a position with door  58  fully retracted from inlet  24  allowing outside air to enter the system freely. When door  58  is in the closed position air is recirculated from the passenger cabin manifold  84  and channels  63  and  250 . 
     Through inlet  24  air enters a channel  64  from which there are two drains, a precipitation drain located ahead of filter  66  and evaporator  70 , and a condensation drain  36 , which is downstream in the air path from the evaporator. Filter  66  and evaporator  70  are mounted in frames  68  and  72 , respectively. From evaporator  70  air is drawn further down channel  64  to a blower  76 , which includes a D.C. motor and a centrifugal fan, the details of which are conventional. Blower  76  pushes air out along a heater module  26  air channel  74 , which passes next to a heater core plenum  80 . Air may be directed through or by plenum  80  by the position of a temperature blend control door  78 , which is pivotally  79  mounted along channel  74  and which may be moved between positions A and B at which positions it closes channel  74  and access to plenum  80 , respectively. 
     With temperature blend door  78  positioned at position A, and air flow thereby diverted through plenum  80 , the flowing air encounters and passes through heater core  82  before returning to channel  74  on the downstream side of door  78 . Heater core  82  typically will not have a shut off valve, and accordingly, coolant from an engine will, if the vehicle is on, be flowing through the core. Normally the air will draw heat from heater core  82 , which is functions as a heat exchanger. When module  26  is opened or partially disassembled, heater core  82  may be slid into and out of a slot  81 , allowing ready replacement of the core if required. Door  78  extends from sides of pivot mount  79 , and when positioned as indicated by the letter B, it closes off plenum  80  on both sides, preventing air from contacting heater core  82 . 
     Downstream from plenum  80  is located an air distribution manifold  84 . Air may be discharged from manifold  84  through a panel vent  30 , a defrost vent  28 , or to floor vents by channel  300 . The direction of air is set by two ventilation control doors, a panel vent door  86  located upstream from defrost vent door  88 . Doors  86  and  88  are mounted on rotatable axes  87  and  89 , respectively. Doors  86  and  88  may be positioned to direct air into channel  300  for distribution to the floor conduits. 
     Referring now to FIG. 5, an alternative, perspective view in partial section of heater module  26  is shown. Heater core  82  connects to an engine coolant system by coolant circulation pipes  90 , which extend through an opening in the dash panel  16 . Recirculation air can escape manifold  84  back to the engine compartment module  22  by a vent  96 . Heater core  82  rests in a slot  81  formed in part from the top of a blower/scroll subassembly  92 . 
     All air flow control doors, including recirculation control door  58 , temperature blend control door  78 , panel vent door  86  and defrost vent door  88 , are positioned using pulse actuators, such as the pulse actuator  100  illustrated in FIG. 6A. A kinematic movement controlling the mode of each of the flow or ventilation doors is provided. A kinematic movement for vent door  30  and the defrost door  28  is illustrated as it is the most complex of the three systems provided. In the case of the temperature blend door and recirculation door, that portion of the system  98  depicted in FIGS. 6A-B used to position the vent door  86  suffices to effect position control. Accordingly, the kinematic movements controlling the recirculation door and temperature blend door are not described in detail. In all of the kinematic movements, a pinion gear directly or indirectly engages a cam follower, which is in turn attached to the axle on which a flow or ventilation door is mounted. FIGS. 6A-B are specifically directed to the kinematic arrangement  98  for the panel vent and defrost vent control doors  86  and  88 , but are representative of the remaining, simpler kinematic mechanisms for the other doors. In FIG. 6B the pulse actuator  100  has been removed to more clearly illustrate gearing system. 
     Pulse actuator  100  turns a pinion gear  102  which includes, around its circumference, smooth regions  101  and toothed regions  103 , which engage toothed regions of a following gear  104 . Gear  102  has mounted thereto a grooved cam  190  with a cam groove  192  is formed. A cam follower  108  is coupled to the cam  190  by a pin  194  which extends into the groove  192 . Cam follower  108  is attached to axle  87 , so that as gear  102  rotates, and pin  194  tracks the moving groove  192 , axle  87  rotates back and forth, resulting in the repositioning of vent door  86 . Substantially identical arrangements provide for the positioning of the temperature blend control door  78  and the recirculation door  58 . 
     Kinematic movement  98  is extended to provided coordinated control of the defrost door  88  with the panel vent door  86 , thus requiring only one pulse actuator for the control of both doors. Control of the defrost door  88  depends from a gear  104 , which engages pinion gear  102  along a portion of its circumference  105 . A cam  180  with cam groove  182  depend from gear  104 . A cam follower  106  includes a pin fitted into groove  182  so to move axle  89 , which is attached to the cam follower  180 . Axle  89  moves back and forth moving the defrost door  88  between closed and open positions following movement of the cam follower  106 . By appropriate arrangement of the geared regions, and shape of the grooves  192  and  182 , the movements of door  88  and door  86  are coordinated with one another so that the doors are appropriately positioned for ventilation of the cabin, directing air onto the windshield  32  or to the floor. Only one motor is required for coordinating the positioning of both doors. At engine start up the system is initialized to the last mode selected. 
     FIG. 7 illustrates blower/scroll subassembly  92 . A pulse actuator  111  may be positioned as indicated on the side of the assembly for connection to the pivot axle for temperature blend control door  78 . 
     FIG. 8 better illustrates an evaporator  70 , which has a plate fin evaporator coil with block style fittings  110  and  112 . 
     FIG. 9 illustrates the coolant circulation in heater core  82 . Coolant enters a manifold  138  from whence it is distributed among a plurality of tubes  140 . Coolant circulates outwardly in the tubes and returns by return conduits which, are under the outward flow section, to a return manifold under manifold  138 ; 
     FIG. 10 illustrates a control arrangement for HVAC system  17 , including driver controls  116 . These controls may or may not include a cabin thermostat. Controller  114  output signals include a variable low voltage D.C. control signal to a linear power module  118 , operating as a variable resistor, which in turn controls blower  76 . Further control signals include outputs to pulse count actuator  100  for the vent and defrost control doors, to pulse count actuator  111  for the temperature blend control door and to pulse count actuator  48  for the recirculation control door. Depending upon the inputs provided by the driver and vehicle conditions, controller  114  determines the appropriate positions for each of the pulse actuators and the blower speed. 
     The invention provides a space efficient, widely applicable truck HVAC system, which is easily maintained and efficient. While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.