Ventilation – Vehicle – Having inlet airway
Reexamination Certificate
2000-01-21
2001-08-14
Joyce, Harold (Department: 3749)
Ventilation
Vehicle
Having inlet airway
C165S042000
Reexamination Certificate
active
06273811
ABSTRACT:
TECHNICAL FIELD
This invention relates to air conditioning systems in general, and specifically to dual film belt temperature control system with improved temperature and air flow control.
BACKGROUND OF THE INVENTION
Vehicle air conditioning systems (broadly defined to include both heating and cooling the air) are often referred to by the shorthand acronym of “HVAC” system. The heart of such a system is a box shaped housing containing an evaporator and heater, which are spaced apart, with inner faces that face one another and outer faces that face away from one another. Fan forced air flow is selectively directed through the two heat exchangers, cold and hot, to attain a final, mixed air stream of a desired temperature and flow rate. In essentially all commercially available systems, the evaporator is located upstream of the heater, and is the physically larger of the two heat exchangers, so that all of the forced air stream passes through it initially. However, the evaporator can be deliberately turned off, so the fact that all air passes through it all the time does not jeopardize the ability to control final temperature. The heater, however, typically operates all the time, so that the system must be able to route or block air selectively through the heater, in order to achieve a desired final, mixed temperature. Older mechanisms for blocking or unblocking the air flow through the heater used a swinging flapper door located in the space between the evaporator and heater, which would admit more or less air through the heater depending on its angular position. The final temperature, mixed air stream would finishes downstream of the beater. Such systems obviously require enough space between the evaporator and heater for the door to swing, limiting how compact the entire system can be made. In addition, swinging door systems tend to lack linearity. That is, they tend to be all on, or all off, but are far less adept at attaining. mid range settings.
More recent designs, attempting to attain both improved packaging and better linearity, have incorporated a rolling film belt to selectively block or unblock air flow through the heater. An example may be seen in U.S. Pat. No. 5,653,630. The design disclosed there uses a single belt (temperature belt) wrapping around the entire inner face of the heater, and which also extends up beyond the heater inner face and partially over, but only partially over, the inner face of the evaporator. The portion of the inner face of
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the larger evaporator not covered by the single film temperature belt is selectively blocked or unblocked by a swinging door of conventional design. Air that has passed the evaporator is let through, or by passed around, the heater by a combined action of the moving belt and the swinging door, to mix together downstream of the heater. An entirely separate belt (mode belt) moves independently to admit the mixed, final temperature air into the passenger compartment.
The single belt temperature control disclosed, and any single belt design, suffers from an inevitable shortcoming, however. A single belt, as it moves, inherently shifts solid areas to locations where open areas of the belt previously were, and vice versa. Open and blocked areas are not independently achievable, in other words, which means that not every desired combination of final temperature and air flow rate can achieved. A temperature change created by allowing more or less air through the heater core inevitably affects total final air flow rate, as well. The extra by pass door in the design disclosed in U.S. Pat. No. 5,653,630 noted above which needs its own actuator and swinging room which negates much of the advantage of using a film belt in the first instance.
SUMMARY OF THE INVENTION
A vehicle air conditioning system in accordance with the present invention is characterized by the features specified in claim
1
.
In the embodiment disclosed, a box shaped system housing contains a conventionally sized evaporator and heater, the evaporator being the larger of the two and located upstream of the heater. The evaporator and heater are preferably arranged in a V shape, with opposed inner faces diverging upwardly from opposed lower edges toward conventional vehicle interior air outlets, creating an air mixing space between the two heat exchangers and below the air outlets. An air flow diversion passage extends from the lower edge of the heater's inner face down and around to its outer face, so that forced air can be routed in a reverse flow through the heater and into the mixing space. Air flow into the diversion passage is assisted by a dividing wall that extends up from the heater lower edge and partially into the mixing space, blocking a portion of the inner faces of the evaporator and heater from one another.
The dividing wall cooperates with a pair of separate film belts to provide improved handling, sealing and mixing of the flow through the two heat exchangers. A first rolling film belt is located between the inner face of the evaporator and the upstream side of the dividing wall. The first film belt extends from a lower roller across the remainder of the inner face of the evaporator to an upper roller. A second rolling film belt is located between the inner face of the heater and the downstream side of the dividing wall. The second belt, oriented roughly in a V shape relative to the first, extends from a lower roller across the remainder of the inner face of the heater to an upper roller. Each belt contains a solid area as well as one or more elongated windows, which, in the embodiment disclosed, may be staggered relative to one another.
The two separate belts, with independently movable solid and open areas, provide the capability for better control of total air flow rate and final temperature mix than would a single belt wrapped around a single lower roller in a similar V shape. For example, each belt can be set to present the same basic degree of open area to the heat exchanger face that it covers, one fifth open each, one third open each, three quarters open each, etc, and thereby achieve the same basic mixed temperature, but with different total air flow rates. A single belt, wrapped around a common central idler roller into a similar V shape, would require basically an inverse relationship of open and blocked areas, (one fifth-four fifths, one third-two thirds, etc). This is because a single window would be shared across the two heat exchanger faces as the single belt moved. In the invention, mixing of the two air streams is also assisted by the staggered relationship of the two belts′ windows, which would also not be possible with a single belt. A single belt wrapping around a central, shared roller would also require a wiping belt seal to prevent air which had passed through the evaporator from leaking directly around the shared roller and in front of the heater, without passing through the heater. But a wiping seal, if forcefil enough to really be effective, would resist free belt movement. Such leakage in the invention is prevented by the fact that the lower heater belt is sheltered on the downstream side of the dividing wall, without the necessity for a belt to pass through an interface between the cold and hot side. The system also has the capability of completely closing off both heat exchanger faces, thereby eliminating the need for a separate external valve door to block off ram air flow through the ventilation system at high vehicle speeds.
REFERENCES:
patent: 5653630 (1997-08-01), Higashihara
patent: 5881558 (1999-03-01), Kawahara et al.
patent: 6045444 (2000-04-01), Zima et al.
patent: 5-141763 (1993-06-01), None
Delphi Technologies Inc.
Griffin Patrick M.
Joyce Harold
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