Method and apparatus for motor vehicle heating and air-conditioning

A heating and air conditioning system for a motor vehicle includes a plenum supplied with air by each of a pair of variable speed blowers. A set of heating and air conditioning ducts extend from the plenum to the drivers side of the vehicle, and another set of heating and air conditioning ducts extend from the plenum to the passengers side of the vehicle. Accordingly, both the driver and the passenger can control the blower supplying air to the ducts on the corresponding side of the vehicle. A defrosting duct extends from the plenum to supply defrosting air to the windshield of the vehicle. One of the blowers normally supplies air to the defrosting duct, but the volume and velocity of air may be "boosted" by optional use of the other blower.

BACKGROUND AND SUMMARY OF THE INVENTION 
This invention relates to heating and air conditioning systems for motor 
vehicles, particularly vehicles having a relatively wide passenger 
compartment. 
Large motor vehicles, such as motor homes and other similar recreational 
vehicles, have been provided with a front driver's seat and a front 
passenger seat that are separated by the engine cowling. Accordingly, the 
distance between the two seats may be substantial. Prior heating and air 
conditioning systems have employed a single control arrangement for both 
seats, if not the entire vehicle. However, at any given time either the 
driver or the passenger may be too hot while the other is too cold, 
particularly if the vehicle is being driven in the early morning or late 
afternoon when the sun is shining more through the windows on one side of 
the vehicle. The only recourse typically available to the passenger and 
driver is separate control of vents from the common ducting. However, this 
has not provided the most convenient and efficient climate control since 
the ducting to both sides of the vehicle still receives a volume of blown 
air and closing the vents on one side of the vehicle affects the air flow 
at the other side. Thus, vent adjustment can require subsequent 
corresponding blower adjustment. Some prior systems have included separate 
structures and control arrangements for the rear passenger area of the 
vehicle, but again lateral differentiation in the climate control has not 
been available. Spacial constraints and weight minimization are important 
factors in vehicle design and have prohibited elaborate constructions of 
climate control systems found in static structures. 
Furthermore, such vehicles are often equipped with extremely large 
windshield areas. To effectively provide warm air for defrosting the 
entire windshield in an acceptable period of time, a significantly larger 
volume and/or velocity of air may on occasion need to be provided than 
would normally be needed for passenger climate control. That larger volume 
of air could be achieved by using a larger blower, but in doing so there 
would be spacial and cost inefficiencies. 
Accordingly, it is an object of the present invention to provide an 
improved heating and air conditioning system for use in motor vehicles. 
Other objects include the provision of: 
1. an efficient and compact ducting system for air flow in a vehicle 
climate control arrangement, 
2. a system which permits independent lateral control of heating and air 
conditioning in a vehicle, 
3. an efficient vehicle windshield defrosting and defogging system that 
requires minimal space and operating costs, and 
4. a vehicle climate control system that permits simultaneous and 
independent operation of heating and air conditioning functions. 
These and other objects of the present invention are achieved by the 
provision of a heating and air conditioning system for motor vehicles in 
which a pair of blowers are controlled to supply air independently to 
separate lateral ducts or in tandem to the windshield ducts. One blower 
provides either heated or cooled air to the driver's side of the vehicle, 
and the other blower provides heated or cooled air to the passenger side 
of the vehicle. The blowers force air through heating and air conditioning 
coils and into a plenum. Control damper doors in the plenum control 
distribution of air between the driver and passenger sides of the vehicle. 
The individually adjusted blowers enable both the driver and passenger to 
adjust the heating or cooling on their corresponding side of the vehicle. 
During a window defrost or defog cycle, a single blower motor may be used 
to force air onto the windshield area of the vehicle, but a second blower 
motor may also be used to "boost" the quantity and velocity of the air 
distributed across the windshield such that the entire windshield area is 
more quickly covered by the defrost or defog air. 
Other objects, advantages and novel features of the present invention will 
become apparent from the following detailed description, with reference to 
the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to the drawings, which illustrate a preferred embodiment of 
the present invention, the heating and air conditioning system generally 
indicated by the numeral 10 is installed on a vehicle, such as a motor 
home or similar recreational vehicle. The vehicle typically includes a 
floorboard, the forward portion of which is illustrated 12, a front 
vertical bulkhead 14, and a defrosting duct 16 and forward edge 18 of 
which adjoins the vehicle windshield (not shown). Accordingly, a 
defrosting duct 16 is preferably provided with defroster openings 20 
through which defrosting air is forced against the windshield and 
adjoining side windows (not shown) when the heating and air conditioning 
system 10 is operated in the defrosting mode. The floorboard 12 includes a 
cutaway portion 22 which accommodates the vehicle engine and engine 
cowling. 
As an alternative to the extended structure of duct 16, especially 
preferred embodiments can include a shortened defrosting duct 16A, the 
ends of which are shown in dashed lines in FIG. 1, directed to the lower 
central portions of the windshield. Defroster openings 20A are provided in 
duct 16A to permit air to be forced against the windshield. 
The heating and air conditioning system 10 includes an air distributing 
plenum 24 which is mounted on the vertical bulkhead 14. Driver's side air 
conditioning ducts 26 and a drivers side heating duct 28 extend from the 
plenum 24. Similarly, passenger side air conditioning ducts 30 extend from 
the plenum 24, as does a passenger side heating duct 32. In alternative 
embodiments, hoses of a conventional nature can be employed to serve the 
function of ducts 30. 
Plenum 24 is formed into a defrosting section 34, a driver's side 
distribution section 36, and a passenger side distribution section 38 by 
dividing walls 40, 42, and 44. A dividing wall 46 divides the section 36 
into an air conditioning section 48 communicated to air conditioning duct 
26 and a heating section 50 communicated with heating duct 28. A damper 
door 52 is movable between the solid and dashed positions to control 
communication from section 36 to either section 48 or section 50. 
Similarly, the other damper door 54 is movable from the solid position in 
FIG. 5 closing off section 36 from section 34, to the dashed position 
opening communication from section 34 into section 36, but closing off 
communication to defrost duct 16. A dividing wall 56 within section 38 of 
plenum 24 divides section 38 into a section 58 communicated with the air 
conditioning ducts 30 and a section 60 communicating with passenger side 
heating duct 32. A damper door 58 is pivotable between the solid and 
dashed positions to communicate section 38 with either air conditioning 
section 58 or heating section 60. Still another damper door 64 is movable 
between the solid line position communicating section 38 with section 34 
to the dashed position closing off communication between section 38 and 
section 34. All of the damper doors 52, 54, 62, 64 can, for example, be 
operated by conventional servo mechanisms in response to operation of 
appropriate control mechanisms (not shown) mounted on the dashboard of the 
vehicle. Since actuation of the damper doors in this matter can be 
conventional, no more detailed description will be given herein. 
A pair of centrifugal, variable speed blowers 66, 68 are, for example, 
mounted on a cover plate 70 which is secured to bulkhead 14. An outlet 73 
of the blower 66 is in communication with section 34 of plenum 24 through 
a transition duct 74, and outlet 76 of blower 68 is communicated to 
section 38 through a transition duct 78. Alternatively, the blower outlets 
73 and 76 can be connected directly to plenum 24 in embodiments where 
plate 70 is secured to bulkhead 14 at a location closer to plenum 24. 
In especially preferred embodiments, a recirculating air inlet opening 72 
is provided in cover 70 for admitting air from within the vehicle through 
cover 70. Cover 70 closes the opened end of a coil housing 74 which is 
mounted on bulkhead 14 opposite cover 70. A set of air conditioning coils 
78 and a set of heating coils 80 are located within housing 74 in a flow 
path generally indicated by the numeral 81 which extends between inlet 72 
and blowers 66, 68. A damper door 82 is pivotally mounted within flow path 
81 and is movable from the position illustrated in FIG. 3 in which air is 
communicated through both cooling coils 78 and heating coils 80 to the 
position illustrated in FIG. 4 in which damper door 82 shuts off flow 
through heating coils 80 forcing the air to bypass heating coils 80. Door 
82 in the FIG. 3 position provides heat to the passenger compartment, 
since when door 82 is in the FIG. 3 position the flow of coolant to coils 
78 will be cut off in response to the operation of the aforementioned 
control on the vehicle dashboard, in a manner which can be readily known 
to those skilled in the art. However, when door 82 is in the FIG. 4 
position, coolant is admitted to coils 78 for the purpose of cooling the 
air and providing air conditioning to the passenger compartment. Ambient 
air, that is, air from outside the vehicle is admitted to flow path 81 
through an opening 84 in floorboard 12. A damper door 86 is pivotally 
connected on cover 70 and is pivotable from the FIG. 3 position in which 
ambient air is admitted from outside the vehicle through the opening 84 
into flow path 81 to the FIG. 4 position in which opening 84 is closed and 
air is recirculated from the interior of the vehicle through opening 72. 
In embodiments where it is desired to permit either the driver or the 
passenger to have air conditioning while the other has heat, a dividing 
wall 79, such as a conventional vertical metal plate, can be mounted in 
system 10 to vertically bisect air flow path 10 and permit cooling coils 
78 on one side to operate independently from heating coils 80 on the other 
side. 
In operation, and referring to FIG. 8, plenum 24 is configured to allow 
heating of the interior of the motor vehicle. Accordingly, damper door 54 
is positioned to shut off air conditioning duct 16 and to allow blower 66 
to force air into heating duct 28, damper door 52 having been positioned 
to shut off air conditioning duct 26. Similarly, blower 68 forces heated 
air through heating duct 32 to the passenger side of the vehicle, door 64 
having been positioned to shut off air conditioning duct 30 and door 64 
having been positioned to shutoff compartment 38 from compartment 36. Door 
82 is positioned as illustrated in FIG. 3, to provide for heated air to be 
drawn through heating coils 80 by blowers 66 and 68. Accordingly, the 
driver can adjust the speed of blower 66 to provide the quantity of heated 
air through the driver's side heating ducts 28 this is comfortable to the 
driver, while the passenger can separately adjust the speed of blower 68 
to provide the quantity of air through heating ducts 32 that is 
comfortable to the passenger. It will be remembered that blower 66 and 68 
draw the heated air through the flow path 81 and through a common set of 
heating coils 80. Furthermore, damper 86 may be positioned in the FIG. 3 
position to allow outside air to be used for heating, or may be position 
in the FIG. 4 positioned to permit recirculation of heated air through the 
passenger compartment. 
When air conditioning is desired, door 82 is positioned in the FIG. 4 
position, allowing air cooled by cooling coils 78 to be made available to 
blowers 66 and 68. Referring to FIG. 9, which illustrates a configuration 
of the plenum 24 in which air conditioning is provided to the passengers, 
door 54 is positioned as shown in FIG. 8 to shut off defrost duct 16, door 
52 is positioned to shut off heating duct 28 and to open air conditioning 
ducts 26 to section 36 of plenum 24, thereby allowing cooled air to be 
communicated to the driver's side of the vehicle through air conditioning 
duct 26. Similarly, damper door 64 is positioned in the position 
illustrated in both FIG. 8 and FIG. 9 in which section 36 is shut off from 
section 38. Damper door 64, however, is positioned as illustrated in FIG. 
9, shutting off heating duct 32 and opening air conditioning duct 30 to 
blower motor 68 to provide cooled air to the passenger side of the vehicle 
through ducts 30. Again, both the driver and passenger can individually 
adjust the speed of corresponding blower 66 or 68 thereby providing the 
quantity of cooled air required by either passenger to maintain either the 
driver or the passenger in comfort. It will be noted, however, that the 
passenger and the driver can, in especially preferred embodiments, both be 
provided with heated air or both provided with air conditioned air. In an 
alternative arrangement, as, for example, where spacial constraints in the 
vehicle permit additional structure or where, for example, wall 79 is 
employed, the driver and passenger can each be provided with their choice 
of heat or air conditioning, independently of the choice made by the other 
party. 
FIG. 6 illustrates the configuration of plenum 24 when the system is 
operated in a normal defrost mode to supply defrosting air through 
apertures 20 against the windows of the vehicle. In this configuration, 
damper door 54 is moved to the position illustrated in FIG. 6, thereby 
shutting off section 34 from section 36 an opening communication from 
section 34 into the defrost duct 6. Damper door 64 is positioned to 
shutoff section 34 from section 38. Accordingly, blower 68 will be turned 
off and blower 66 will be used to force air through coils 78 and 80, 
through section 34 plenum 24 and into defrost ducts 16. There can be 
situations, however, when it is necessary or desirable to force air in 
substantial quantities at a substantial velocity through defrost duct 16 
and opening 20 to quickly defrost the windshield of the vehicle. 
Accordingly, system 10 can be operated in a "defrost boost" mode in which 
both of blower motors 66 and 68 are used to force defrost air through duct 
16. In this situation, damper doors 64 and 62 are positioned as 
illustrated in FIG. 7, to close off air conditioning ducts 30 and heating 
duct 32. Damper door 54 closes off air conditioning ducts 26 and heating 
duct 28. Accordingly, section 38 of plenum is communicated to section 34, 
thereby permitting both blower 66 and blower 68 to force air through 
section 34 and into defrost duct 16, thereby supplying defrost air to the 
windshield in substantial quantities and at substantial velocity 
sufficient to quickly defrost the windshield. 
Although the present invention has been described above in detail with 
respect to particular embodiments, the same is by way of illustration and 
example only and is not to be taken as a limitation. The spirit and scope 
of the present invention are limited only by the terms of the following 
claims.