Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
2001-08-31
2003-02-18
Dang, Khanh (Department: 2837)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
C181S227000, C181S252000
Reexamination Certificate
active
06520285
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an adjustable muffler for an engine exhaust system, and more particularly relates to a system and apparatus to tune the volume and type of sounds that are generated by the muffler.
BACKGROUND OF THE INVENTION
There are several measures of an engine's performance. There are power performance measures such as horsepower and torque. However, power performance measures are not readily discernible by the general public without specialized equipment such as a dynamometer. One measure of an engine's performance that is discernible by the general public is the sound or roar of an engine. The general public generally associates the volume level of an engine with the power level of an engine. Additionally, automobile, motorcycle, and engine enthusiasts recognize as favorable the type of sound emitted by a “hot rod”, “muscle car”, or “race car” type engine.
For the automobile, motorcycle, or engine enthusiast, it is important to optimize all measures of an engine's performance. Therefore, it is important to optimize the sound emitted from an engine's exhaust system. Optimization of an engine's sound includes both increasing the volume level and causing the sound quality to emulate that of a hot rod, muscle car, or race car. However, there are laws that prescribe acceptable noise levels for all types of engines operated in public areas. The noise levels that are deemed acceptable under the law are often below the volume levels that are considered optimum by automobile, motorcycle, or engine enthusiasts. A muffler system is typically attached to the ventilation discharge pipe of an engine to, in part, reduce engine noise levels to within acceptable standards. Generally, muffler systems alter and absorb the sound waves emanating from the ventilation discharge pipe to reduce the engine noise. However, the muffler systems that are widely available often fail to emit a desirable sound quality that emulates a hot rod, muscle car, or race car.
Muffler systems that provide a sound quality that emulates a hot rod, muscle car, or race car have been implemented in the past. One such system, called a “glasspack,” includes a muffler body having a perforated inner tube with sound dampening media (i.e., a fiberglass or steel wool blanket) packed in between. Glasspacks and similar muffler systems are known by the automobile, motorcycle, or engine enthusiast to provide a desirable sound quality. However, current glasspack muffler systems and similar muffler systems are designed to generically muffle engine volume level to meet noise level laws and are not customizable for particular engines. Accordingly, current glasspack muffler systems often fail to meet an engine enthusiasts sound requirements, both volume and quality, for a particular engine because they are not customizable for the particular engine.
Adjustable muffler systems that allow the user to modify the sound waves emanating from the engine have also been implemented in the past. While these systems can provide engine sounds that are adjustable to optimum volume levels, these systems involve complicated designs that often negatively impact the engine's power performance or require additional maintenance.
Automobile, motorcycle, or engine enthusiasts often operate their respective vehicles at auto shows, races, or other events that are not on public roadways and therefore not subject to noise level laws or regulations. However, because they often have to utilize public roadways to transport their vehicles to such events, they must utilize muffler systems that keep the engine sound volume levels within the limits prescribed by law. There is a need for an adjustable engine muffler system that allows the automobile, motorcycle, and engine enthusiasts to customize engine sounds to optimum volume levels and to optimum sound quality levels. Furthermore, there is a need for an engine muffler that allows one to adjust or tune the sound volume level emitted and sound quality without negatively impacting the engine's power performance.
SUMMARY OF THE INVENTION
The present invention pertains to an adjustable muffler system for attachment to an engine exhaust system. More specifically, the present invention provides a novel and non-obvious adjustable muffler system that allows the user to customize engine sounds to optimum volume and quality levels, without negatively impacting the engine's power performance.
In the present invention, a simple, efficient apparatus and method of adjusting or tuning the volume level of the sounds emitted from an engine muffler without impacting the engine's power performance has been developed.
Generally, in the present invention, a blocking tube is used for removably inserting into the muffler housing and provides the user with a simple means for adjusting or tuning the amount of muffler capacity utilized, thereby allowing the user to adjust or tune the volume level and quality of the engine sounds emitted.
In the example of glasspack mufflers, sound dampening media absorbs the engine's exhaust pulses that pass through perforations in an inner tube. In the present inventive apparatus, a blocking tube operates to partially or fully block the perforations in the inner tube and provide a straight pipe flow path along the blocked section. Accordingly, the volume level and quality of the sounds emitted can be adjusted or tuned by varying the number of perforations blocked. This is accomplished in one embodiment by varying the length of the blocking tube. A very short blocking tube covers less perforations than a long blocking tube and therefore produces a sound with a lower volume level. A blocking tube that covers all of the perforations produces a straight pipe sound with the highest volume level.
In one embodiment of the present invention, the muffler system includes a housing having an exhaust receiving portion configured for attachment to a motorcycle exhaust pipe, an exhaust exiting portion opposite the exhaust receiving portion, a perforated tube interior to the muffler housing and extending from the exhaust receiving portion to the exhaust exiting portion, and sound dampening media packed between the muffler housing and the perforated tube. Also included is a non-perforated blocking tube movably positioned interior to the perforated tube. The blocking tube includes a free portion and a latched portion. The latched portion of the blocking tube is removably affixed to the exhaust exiting portion of the muffler housing and the free portion of the blocking tube is opposite the latched portion. Finally, the latched portion includes a means for removably securing the blocking tube with the muffler housing.
The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings.
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Dang Khanh
Dorsey & Whitney LLP
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