Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
2002-03-08
2004-05-18
Lockett, Kimberly (Department: 2837)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
Reexamination Certificate
active
06736237
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a cover for an engine exhaust stack of an engine, particularly to a heavy construction machinery vehicle engine, and more particularly to an exhaust cover for a machine having a turbo charged diesel powered engine. During vehicle transportation, the construction vehicle is generally carried or “piggybacked” by a separate vehicle for instance a tractor trailer. The construction vehicles' engine is turned off and the vehicles' exhaust stack, which is generally exposed to external air flow, is provided with a cover fit over the opening at the end of the exhaust stack to insure that no air flow develops within the exhaust stack during transportation of the heavy machinery.
BACKGROUND OF THE INVENTION
Heavy machinery, namely construction vehicles, for instance, loaders, diggers, bull dozers, etc., are usually delivered to a construction or work site piggybacked on either a flat bed of a tractor trailer combination or a flatbed railroad car. Modern heavy machinery construction type vehicles are driven by turbo charged diesel powered engines. Turbochargers compress the air flowing to the engine letting the engine squeeze more air into the cylinders, and thus more fuel can be added obtaining a greater explosion in each cylinder. A turbocharged engine produces more power overall than the same engine without turbocharging, which can significantly improve the power-to-weight ratio for the engine
The turbocharger uses the exhaust flow from the engine to spin a turbine, which in turn spins an air pump. The turbine in the turbocharger spins at speeds of up to 150,000 rotations per minute (rpm) and because it communicates directly with the exhaust, the temperatures in the turbine are also very high. The turbine and pump utilize bearings which of course allows them to spin, and these bearings thus must be substantially continuously supplied with lubricant during operation of the vehicle.
In order to handle speeds of up to 150,000 rpm, the turbine shaft has to be supported very carefully. Most bearings would explode at speeds like this, so most turbochargers use a fluid bearing. This type of bearing supports the shaft on a thin layer of oil that is constantly pumped around the shaft. This serves two purposes: It cools the shaft and some of the other turbocharger parts, and it allows the shaft to spin without much friction.
While being transported to and from construction sites by a separate vehicle, the heavy construction vehicle is inoperative, i.e. the engines in most cases being completely shut down. During such transportation, the machinery is subjected to air flow passing around the exhaust stack which generally extends up above the vehicle. This external air flow can create a vacuum down through the exhaust stack, and into the turbocharger, which as discussed above, is connected with the exhaust. When such a vacuum develops through the exhaust and turbocharger the turbine and pump may be caused to spin. As is apparent to those of skill in the art, without the engine operating no oil or lubricant is supplied to the turbine and pump and thus significant wear and failure of the turbocharger may result. It is therefore well known in the art of the necessity to cover the opening of the exhaust stack to eliminate any vacuum or air flow created by the transportation of the heavy machinery while the engine is shut down.
In order to overcome the above described problem it is quite common for transporting drivers and/or construction machinery operators to cover the opening of the exhaust stacks with tape, in particular heavy masking tape or duct tape for instance. While this tape can be appropriate in limited circumstances, over a period of time exposure to the elements and wind resistance forces created during transport, the tape can wear through and disintegrate and thus fail to properly protect the turbine. Furthermore, in the instance of covering the exhaust stack opening with tape, due to the high exhaust temperatures, which can reach several hundred degrees Fahrenheit, failing to remove the tape can cause the tape to burn and permanently adhere the tape remnants and adhesive to the exhaust stack where the heavy machinery is run without appropriately removing all the tape and adhesive before operation.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide protection for a turbocharger of a vehicle by covering and enclosing the open end of the exhaust stack of a muffler with an exhaust stack cover.
It is a further object of the present invention to provide an exhaust stack cover which fits elastically over the end of the exhaust stack to withstand weather and wind resistance forces and which can not easily be removed from the exhaust stack by such forces.
It is a further object of the invention to provide a reusable and replaceable cover which can withstand against substantial material degradation due to significant heat generated by the exhaust stacks when placed on an exhaust stack of a vehicle that has only been recently shut off.
It is a further object of the invention to provide a cost effective and easily manufactured cover which can be simply stored inside the cab of a vehicle and used whenever necessary and which can be cheaply replaced in case of destruction or loss.
The exhaust stack cover of the present invention is sized to substantially conform and fit snugly, or elastically over the end and opening of the exhaust stack of a vehicle engine such that during transportation of the vehicle, wherein the engine is inoperative, a vacuum or air flow is prevented within the exhaust stack and thus the communicating turbine. Elimination of this vacuum and associated air flow prevents detrimental mechanical actuation of parts. Specifically the turbine shaft is protected, which is particularly susceptible to damage due to rotation without appropriate lubrication.
The muffler cover can be formed from a substantially heat resistant material such as neoprene which can withstand a substantial direct temperature by the exhaust stack as well as provide some elasticity in order to snugly and tightly grip the outside surface of the exhaust stack. The exhaust stack cover can usually be formed from a single piece of material folded over and sewn along an edge in any shape, and leaving an opening, or can be formed from two pieces of material, also sewn along the edges leaving an opening. The cover can even be formed from a tubular formed sleeve or any other base material as is known in the art to cover a particular shape or profile of exhaust stack and opening.
REFERENCES:
patent: 4077491 (1978-03-01), Hankel
patent: 4526250 (1985-07-01), Messinger
patent: 4930597 (1990-06-01), Udell
patent: 6284201 (2001-09-01), Buck
Shaw Lisa E.
Shaw, Jr. Michael J.
Davis & Bujold PLLC
Lockett Kimberly
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