Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
2003-06-16
2004-04-06
Lockett, Kimberly (Department: 2837)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
C181S211000
Reexamination Certificate
active
06715583
ABSTRACT:
FIELD OF THE INVENTION
The instant invention relates to a device that reduces harmful emissions from the exhaust of internal combustion engines and enhances engine power while functioning as a muffler to greatly decrease the noise associated with such engines.
BACKGROUND OF THE INVENTION
Since the invention of the internal combustion engine there has been the need to muffle the noise generated by such engines and to decrease the harmful emissions that they inevitably produce. Many devices have been developed to solve these problems, but most of the devices address one problem or the other. Those claiming to solve both problems often fall short or require considerable space making their use in motor vehicles impractical.
Many mufflers rely on changing the flow direction of the exhaust gases which results in a change in the fluid dynamics with a concomitant reduction in noise. Gramm, in U.S. Pat. No. 823,115 discloses a muffler that consists of two sections, the first being the larger. The exhaust gases enter the first section then pass into the second section from which the gases are discharged. Both sections are made up of a series of concentric cylinders having perforations in their walls. The perforations are located at different levels in adjacent cylinders. The gases move in altering directions as they pass from one cylinder to another in the first section then through similar paths of changing flow directions in the second section. The gases can expand freely in the larger first section, and then the volume is decreased in the second section before the gases are discharged. The gases are permitted to move freely through the system with no formation of back pressure. Construction materials include cast iron and sheet metal making for a clumsy and heavy unit. A lightweight muffler is described by Flugger in U.S. Pat. No. 4,220,219. The gases enter through an inlet tube having a wide exit end with a cup barrier that causes the flowing gases to change direction and thereafter pass through a narrow outlet from which the gases again strike a wall and reverse direction. Finally the gases exit through a perforated outlet pipe. See also U.S. Pat. Nos. 5,952,625 and 6,199,658 both to Huff. None of these patents effect pollutants that leave the systems as part of the exhaust gases.
A muffler also relying on repeated changes in direction of the gas flow and utilizing a closed system of pipes with circulating water within the main chamber to remove heat from the exhaust gases is taught by Khosropour et al. in U.S. Pat. No. 4,450,932. The added circulating water cooling system would not be practical for use in motor vehicles.
Kasper designed a muffler to reduce back pressure and increase engine efficiency that is taught in U.S. Pat. No. 4,222,456. A housing contains a large tube with a widening conical exit end. The tube is surrounded by material that conducts heat from the tube to the housing and also deadens sound. Within the large tube is another inner tube with a converging midsection and narrow exit port through which the gases pass before entering the diverging exit end of the large tube. Vanes are situated around the narrow exit port of the inner tube. Some of the gases bypass the inner tube and flow in a straight pattern while the gases passing through the inner tube and vanes are caused to move in a vortex around the first stream and reduce back pressure. Basically the gases travel in a straight line through this system. The insulation accounts for most of the noise suppression.
Childs describes an apparatus used to remove smoke and extract heat from the exhaust gases from a diesel engine. The exhaust gases pass into an insulated pipe that has a Venturi section and fresh air source. The gas and air mixture then moves over a heating element after which the flow path changes directions several times before the discharge at the top of the system. This device is designed to be mounted vertically and is not practical for use in automobiles and other motor vehicles. (U.S. Pat. No. 5,245,933) A device used to burn automobile exhaust gases utilizes a cylindrical outer shell and an inner shell with insulation between them. The gases enter a ceramic spiral cone to concentrate the exhaust flow which then passes through a series of slotted ceramic discs and finally into a cooling pipe. The discs become very hot and the increased surface area of the several discs assist in burning any pollutants. A second embodiment has an air intake and spark plug to insure more complete combustion of the exhaust gases. (Gordon in U.S. Pat. No. 4,183,896) The burning of gases near the exit port may present a problem if used with motor vehicles, and this device would have to be used in addition to a muffler.
Devices have been developed that muffle engine noise and also oxidize the exhaust gases. One of those is described by Barkelew in U.S. Pat. No. 2,831,548 which comprises several concentric tubes, some made of conducting material and others holding insulation. There is an air intake to insure better combustion of exhaust gases and a heating element near the exit port. A flame can also be used for combustion of the gases. The change in direction of flow through the various tubes provides the muffling effect. Miller et al. in U.S. Pat. No. 2,938,593 discloses a muffler that is oval in cross section with an inlet pipe and outlet pipe. The interior has a main section separated by four baffles into three chambers and there are two side sections, each separated into two chambers. The gases pass from one chamber to the other by means of stub pipes and finally enter an outlet chamber. The different paths taken create different dynamics causing the sound to be muffled and eliminating back pressure. A second embodiment includes a n electric current to ionize the gases and decrease pollutant content. Gerlach, in U.S. Pat. No. 2,986,000 teaches a muffler and burner that is square in cross section and is divided into three chambers. The main central chamber is surrounded by a wire coil and has a Meeker burner screen at the top. There are two perforated side tubes and two narrow air intake tubes that discharge air into the central chamber. All gases mix in an upper chamber where combustion can take place before the gases enter the discharge pipe. Changing the flow directions changes the dynamics to muffle the sound and combustion removes pollutants from the discharge. Initiation of combustion in the muffler, especially near the exit port, would expel very hot gases into the atmosphere which would be detrimental to the environment.
Another device designed to be used to silence and purify exhaust gases from a n internal combustion engine is taught by Frederiksen et al. in U.S. Pat. No. 6,312,650. This device consists of an airtight casing with an exhaust inlet pipe and an exhaust outlet pipe and has at least two acoustic compartments within. The first compartment contains one or more “monolithic bodies” with multiple channels or porosities. One type of monolith is made from corrugated foil that is wound u p cylindrically while the other type is made of a ceramic material with many vertical and horizontal channels. The internal surfaces of the monolith may be covered by catalytic layers to promote purification of gases. Specific solid catalytic particles or a spray of active solutions may be introduced to break down the gases. The second compartment is packed with absorbent material such as glass wool. The fluid dynamics undergoes several changes to diminish sound. This system is suited to diesel engines. Since thin layers of catalytic material are applied, they would have to be reapplied periodically to maintain proper emission control
None of the prior art devices cause combustion of the exhaust gases without the necessity of a means to ignite the gases and an entry for the introduction of air to the combustion chamber. None of the prior art devices rely on frictional effects and molecular collisions to generate the heat needed to break down pollutants.
None of the prior art devices are capable of both muffling the s
Kotin Sandra M.
Lockett Kimberly
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