Ventilation – Vehicle – Having inlet airway
Reexamination Certificate
2000-08-25
2002-04-09
Joyce, Harold (Department: 3749)
Ventilation
Vehicle
Having inlet airway
C454S261000, C454S269000
Reexamination Certificate
active
06368207
ABSTRACT:
TECHNICAL FIELD
This invention relates to automotive heating, air conditioning and ventilation systems in general, and specifically to such a system in which the housing or module incorporates an improved means for mixing heated and cooled air.
BACKGROUND OF THE INVENTION
Automotive heating, ventilating and air conditioning systems, HVAC systems in short, typically contain features and components shown in FIG.
1
. Referring first to
FIG. 1
, a typical HVAC housing, indicated generally at
10
, is a large, hollow box, generally a multi piece unit built up out of two or more molded plastic sub sections. A non illustrated blower and scroll housing draw in air and force it through the housing
10
, first through an evaporator
12
, through which the entire air flow initially passes, and then toward a heater core
14
. While the evaporator
12
always has air flow through it, it may or may not be active and cold, depending on whether the compressor is active. However, it is always cold relative to the heater core
14
, which always has hot engine coolant circulating through it.
Air flow through the evaporator
12
and heater core
14
is controlled by a series of internal walls, ducts and doors. In general, the air stream is bifurcated or split between a heated and a cold stream, and then the two streams are reintroduced downstream to, at least ideally, remix to a mid temperature, which depends on the proportion of the split. Specifically, an upper interior wall
16
downstream of evaporator
12
has an internal opening
18
, and cold air that has passed through evaporator
12
passes straight through opening
18
, unless it is blocked totally by a flapper type temperature door
20
. A lower interior wall
22
has an air inlet opening
24
which, unless in is blocked by the said temperature door
20
, passes some of the air that has passed through evaporator
12
through heater core
14
. The degree of the split in streams between the two heat exchangers is dependent on the relative position of the temperature door
20
, which can swing back and forth to apportion the air flow through both openings
18
and
24
. The separate air flow (if any) diverted through opening
24
and through the hot heater core
14
is routed by another internal wall, which effectively creates an internal hot air duct
26
that ends at opening
18
. The internal hot air duct ends just below a central mix area, indicated generally by the dotted area labeled “M”. There, the bifurcated hot air flow is routed transversely across the outside of the internal opening
18
, generally normal to the cold air flow passing through opening
18
. Any separate identity of the hot air flow is quickly erased, however, as it engages the cold air flow that has exited opening
18
and the two flows mix, at least ideally, to achieve a final net temperature. From the final mix air, some flow is routed to one of several possible ducts, which are connected to outlet openings in the housing
10
. Specifically, an uppermost duct
28
(generally called the window defroster duct), a mid level duct
30
, and a lower heater duct
32
, all receive an air flow as determined by some dedicated opening and closing means, generally referred to as mode control. In the embodiment disclosed, the mode control is a film belt or belts
34
. Separate flapper type doors could also be used.
A continuing problem has been the actual attainment of a good mix of cold and hot air within the mixing space M. the two air streams have a tendency to stratify without mixing. Cold air coming out of evaporator
12
will shoot straight up and out of the defroster duct
28
, for example, without the desired level of mixing with hot air that has passed through heater core
14
. Known means of promoting mixing have not proved entirely satisfactory, because of cost, complexity or an undesirable extra pressure drops in the air stream. One known means includes additional, dedicated ducts within the housing
10
, referred to as bleed ducts, which direct a portion of the hot air coming off of heater core
14
around and deliver it directly to or below the defroster duct
28
. Another means is a separate and additional valve door that is slaved to the mode control door, and which extends out into the mix area to promote turbulence and mixing.
SUMMARY OF THE INVENTION
The subject invention provides a simpler and more cost effective means of promoting hot-cold air mix, which does not entail any extra closed ducts or valve doors, and which has a minimal impact on pressure drop in the system.
In the embodiment disclosed, a series of specially designed, parallel channels extend transversely across the internal air opening, extending past the mix area and rising from the end of the internal hot air duct toward the defroster duct above. The channels are basically half cylindrical troughs or pipes, with rounded undersides facing the evaporator air stream and concave inner surfaces facing toward the mix area. The cold air stream is forced between the gaps between the curved undersides of the troughs, where it is accelerated and constricted to a degree, but its pressure is not significantly reduced, given the smooth, curved surfaces past which it flows. Hot air from the internal duct is routed into the inside of the troughs, at the trough lower ends, and flows upwardly, essentially normal to the cold air flow. The cold air flow rushing around and past the sides of the troughs creates a turbulent wake or vortex that pulls hot air out of the troughs and mixes thoroughly with it. Improved mixing is achieved with a very simple, inexpensive, non moving additional structure, which requires no extra room. Any increase in air flow restriction is minimal.
REFERENCES:
patent: 1395938 (1921-11-01), Barducci
patent: 2339629 (1944-01-01), Fischer, Jr.
patent: 5653630 (1997-08-01), Higashihara
patent: 5927380 (1999-07-01), Scoccia
patent: 5934361 (1999-08-01), Parisi et al.
patent: 5988263 (1999-11-01), Schwarz
patent: 6106386 (2000-08-01), Schwarz
patent: 59-84616 (1984-05-01), None
Farag Ashraf A.
McLaughlin John W.
Miller H. Charles
Delphi Technologies Inc.
Griffin Patrick M.
Joyce Harold
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