Ventilation – Vehicle – Freight
Reexamination Certificate
1999-08-31
2001-10-02
Lu, Jiping (Department: 3749)
Ventilation
Vehicle
Freight
C454S091000, C165S041000, C165S042000, C062S239000
Reexamination Certificate
active
06296561
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to an air return bulkhead used in temperature controlled trailers to maintain the desired flow of temperature controlled air through the trailer conditioned space; and more particularly the invention relates to a bulkhead that is easily installed in the trailer and prevents short cycling of the temperature controlled air in the conditioned space.
Temperature control units for use in trailers are mounted on a trailer which defines a conditioned space, and the air in the conditioned space is maintained at a predetermined desired temperature by the temperature control unit which is typically mounted on the front trailer wall or panel. The temperature control unit evaporator extends through the front trailer wall and into the conditioned space. A load of palletized cargo is loaded into the conditioned space and the evaporator serves to cool and force the conditioned air into the conditioned space and around the palletized load in the manner generally indicated by arrows
150
in FIG.
1
. The conditioned air is forced rearwardly out the evaporator, around the back of the load and below the load and back to the front of the trailer.
An air return bulkhead is located at the front of the trailer and is typically attached to the interior of the front trailer wall and behind the temperature control unit. Prior art bulkheads have inlet openings which permit the air to pass behind the bulkhead and directly into the evaporator. The return air passes through the evaporator and the majority of the discharged volume of conditioned air returns to the conditioned space. However a portion of the conditioned air does not flow to the back of the trailer but rather “short cycles”. Rather than flowing rearwardly and around the load, the short cycling air remains at the front of the load and simply returns to the evaporator through the bulkhead inlet openings. The short cycling conditioned air can negatively affect the temperature of the conditioned air.
It is well known to one skilled in the relevant art that short cycling is not desirable when frozen loads are in the conditioned space. However, a small volume of short cycled air is desirable for fresh loads such as lettuce. Therefore, it would be desirable to provide a means for easily selectably changing between permitting and preventing short cycling in bulkheads.
The foregoing illustrates limitations known to exist in present air return bulkheads. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
SUMMARY OF THE INVENTION
In one aspect of the present invention, this is accomplished by providing an air return bulkhead comprising a base; a return air duct extending outward from the base, the base and air duct defining a bulkhead return air chamber, the duct comprising a first wall, a second wall, a third wall, a fourth wall, and a fifth wall joining the other walls; at least one return air inlet notch formed in the air duct fourth and fifth walls; and means for producing turbulent return air flow through the return air chamber, said means located downstream from the at least one inlet notch. The bulkhead further includes air dam positioning means on the first and second walls. Individual air dam members are slid in the positioning means to be removably mounted along the bulkhead.
Molded pallet stops are formed in the fifth wall and fourth wall. Additionally removable pallet stops may overlay the molded pallet stops so that if the pallet stops are damaged during cargo loading only the pallet stop would need to be replaced.
A seam is provided along the fifth, first and second walls and permits the bulkhead to be cut to permit access to the evaporator unit without removing the bulkhead and also to permit the bulkhead to be shipped in two pieces with the temperature control unit.
The means for producing turbulent air flow through the chamber is comprised of a first aligned array of support columns directed toward the center of the bulkhead in the direction of return air flow through the chamber and a second aligned array of support columns directed away from the center of the bulkhead in the direction of return air flow through the chamber.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.
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Thermo King Parts Bulletin 1244, dated Dec. 19, 1997.
Gast Randal
George Gregg
Hotch Pat
Kiefer Kevin W.
Sirotek, Jr. Robert L.
Lu Jiping
Michael & Best & Friedrich LLP
Thermo King Corporation
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