Ventilation – Vehicle – Railcar – bus – or trailer
Reexamination Certificate
1999-12-15
2001-05-29
Joyce, Harold (Department: 3749)
Ventilation
Vehicle
Railcar, bus, or trailer
Reexamination Certificate
active
06238282
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of heating, ventilating and air conditioning (HVAC), and more specifically to the HVAC system for the operator's cabin of a locomotive, and particularly to a method and apparatus for reducing the noise generated by the HVAC system of a locomotive.
It is known to provide an HVAC system for controlling the environmental conditions inside the operator's cabin of a railroad locomotive. A typical system, as provided by the assignee of the present invention, includes a fan and heat exchanger assembly installed below the floor of the cabin, horizontal ducts running beneath the floor between the floor joists, a vertical duct running through the control compartment forming one wall of the cabin, and a plurality of outlets connected to both the horizontal ducts and the vertical duct. Because the space for ductwork is very limited in a locomotive, the velocity of air moving through the ductwork must be maintained at a generally high level in order to satisfy the heat load specifications established for such systems. As a result, there is a considerable amount of sound energy generated by the HVAC system in a locomotive cabin. In one application, the HVAC system of a locomotive operating at maximum fan speed generates a sound level of approximately 75 dbA in the locomotive cabin.
BRIEF SUMMARY OF THE INVENTION
There is a desire on the part of some owners and operators of locomotives to reduce the background level of sound energy in the locomotive cabin. Because the HVAC system contributes significantly to the overall sound level, there is a particular need to provide a ventilation system for a locomotive that will provide the desired level of conditioning while generating a reduced sound level compared to prior art systems. There is also a particular need to produce such results with an apparatus that occupies a minimum amount of space.
Accordingly, an apparatus for ventilating a locomotive cabin is described herein having ductwork that is used for the dual function of conveying ventilating air and for some other structural purpose. By combining the function of the ductwork, one or more structural members may be eliminated, thereby providing space for increasing the size of the ducts. As the duct size is increased, the speed of the ventilating fan may be reduced without reducing the total volume of air flow, thereby reducing the level of sound generated by the apparatus.
Specifically, a low noise HVAC apparatus for a locomotive cabin is described herein as having: a fan for supplying air; a horizontal duct comprising a top portion operative to support a floor of the locomotive cabin and opposed side portions attached to the top portion and to respective opposed joists disposed under the floor, the horizontal duct in fluid communication with the fan for conveying the air; and an outlet in fluid communication with the horizontal duct for distributing the air into the locomotive cabin. By using the duct as a structural support member for the floor, one or more joists may be eliminated, thereby providing increased area under the floor for conveying ventilating air.
The apparatus is further described as including a stringer attached at opposed ends to the respective opposed joists and in contact with the horizontal duct top portion opposed the floor. The stringer provides additional support for the floor. Furthermore, the apparatus may include insulation disposed against the horizontal duct top portion opposed the floor; a cavity formed in the insulation; and the stringer at least partially disposed within the cavity. The insulation absorbs sound, thereby reducing the sound energy emitted from the apparatus. The apparatus is further described as having a vertical duct in fluid communication between the horizontal duct and the outlet, the vertical duct comprising a portion of a wall of a control compartment of the locomotive. The portion of a wall may be insulated to absorb sound and to prevent condensation from forming within the control compartment.
Similarly, a method for ventilating a locomotive cabin is described herein, the method comprising the steps of: providing a fan; replacing a joist in a floor of a locomotive cabin with a floor duct, the floor duct being operative to support the floor between adjoining opposed joists; and connecting the fan in fluid communication with the floor duct to provide air into a locomotive cabin. A further method for ventilating a locomotive cabin is described as including the steps of: providing a fan; forming a duct comprising a portion of a wall of a control compartment of a locomotive; and connecting the duct in fluid communication with the fan to provide air to the cabin of the locomotive.
REFERENCES:
patent: 3125286 (1964-03-01), Sanders
patent: 3626464 (1971-12-01), Van Der Sluys
patent: 3771293 (1973-11-01), Vest
patent: 3996762 (1976-12-01), Calme et al.
patent: 5544459 (1996-08-01), Konger
patent: 5595123 (1997-01-01), Tao et al.
Holmes Richard H.
Kindel Todd M.
General Electric Company
Holland & Knight LLP
Joyce Harold
Maire, Esq. David G.
Rowold, Esq. Carl A.
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