Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
1999-10-29
2001-04-03
Dang, Khanh (Department: 2837)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
C181S258000
Reexamination Certificate
active
06209678
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to acoustics and sound modifying means for muffling and filtering air, and more particularly to devices for muffling and filtering air exhausted from pneumatically-operated hand tools, equipment, machines, and the like.
BACKGROUND OF THE INVENTION
Pneumatic hand tools are commonly used in industrial and residential settings. Various types of pneumatic hand tools are available, including ratchets, drills, wrenches, grinders, sanders, etc. Known hand tools typically include a handle having a hollow internal chamber. The chamber includes an air intake passage and an air exhaust passage. Each passage extends between a motor and an opening in the bottom surface of the handle. The portion of the intake passage located near its respective handle opening includes components adapted to connect to a standard air coupler or the like. The coupler is in communication with a pressured air supply source. The exhaust passage opens to the atmosphere. When exhaust air is vented from the hand tool, a considerable amount of noise and particulate debris is generated, potentially causing auditory and/or respiratory damage to the operator and others located nearby.
Although ear plugs and face masks are available to workers, they are often not used for a number of reasons—most typically because they are not convenient. Numerous attempts have been made by hand tool manufacturers, therefore, to reduce the amount of noise and particles generated by the hand tool itself. These attempts include designing quieter and cleaner motors and designing hand tool components that suppress noise and trap waste prior to expulsion from the hand tool. For example, U.S. Pat. No. 5,418,339 describes a pneumatic hand tool having an exhaust port filled with a web of non-woven fibers coated with a binder resin. These types of mufflers have had some success in muffling sound, but there is often an increase in back pressure to the motor causing a decrease in the operating efficiency of the hand tool. The operating efficiency of a tool is typically measured in the operating speed of the motor in revolutions per minute (rpm) at a certain gauge pressure.
Cylindrical canister-type combination muffler and air filters are known for large machines, such as hoists and presses. For example, U.S. Pat. No. 4,134,472 describes a combination muffler and air filter having a central tubular member with a number of slots. The tubular member is surrounded by a disposable canister having inner and outer perforated rigid cylinders encasing a series of stacked annular filter members. Exhaust air passes through the inner cylinder, into the filters, and out the outer cylinder. These devices are not typically used for hand tools, however, because of they are large, heavy, and difficult to maneuver.
Thus, there exists a need for a noise muffling system that can reduce sound levels and remove entrained solid and liquid contaminates from the exhausted air before it is discharged to the atmosphere. The ideal device would effectively muffle and filter the exhaust air without creating substantial amounts of back pressure. This would allow a hand tool to be operated without jeopardizing performance of the pneumatic tool over long periods of usage. The ideal muffling system would further attach to a hand tool body and remain attached even during significant tool vibrations. In addition, it would be desirable to have a muffler that can be easily attached to existing pneumatic hand tools. The present invention is directed to fulfilling these needs and others as described below.
SUMMARY OF THE INVENTION
In accordance with aspects of the present invention, a muffler improvement for quieting exhaust expelled from a pneumatic hand tool is provided. The hand tool has a handle with an exhaust passage including a main section. The muffler includes an inner tube having distal and proximal ends and a plurality of holes. A cutoff wall is located below at least one hole in the inner tube. The cutoff wall forces exhaust air to exit the inner tube via the at least one hole located thereabove. The muffler further includes a number of dividers fixedly and spacedly positioned about the inner tube. Each divider extends outward from the inner tube exterior surface a distance less than the width of the main section. The combination of the inner tube and dividers is located within the main section. An end cap is attachable to the handle for closing off the exhaust passage. At least one of the end cap and the handle includes an exit opening. During hand tool use, exhaust air enters the inner tube proximal end, flows out the inner tube holes, moves around the number of dividers, and flows out the exit opening. The tortuous movement of the exhaust air slows it and assists in dampening any attendant noise.
REFERENCES:
patent: 3526293 (1970-09-01), Hayes et al.
patent: 3667571 (1972-06-01), Fattleay
patent: 3675732 (1972-07-01), Rosen et al.
patent: 3719251 (1973-03-01), Fedrick
patent: 3811251 (1974-05-01), Gibel
patent: 3880245 (1975-04-01), Anderson, Jr.
patent: 3880252 (1975-04-01), Mucka
patent: 3896897 (1975-07-01), Hilbush, Jr.
patent: 4082160 (1978-04-01), Schilling et al.
patent: 4134472 (1979-01-01), Trainor
patent: 4184564 (1980-01-01), Trainor
patent: 4205732 (1980-06-01), Auerbach et al.
patent: 4258798 (1981-03-01), Campbell et al.
patent: 4565259 (1986-01-01), Stoll
patent: 5097924 (1992-03-01), Reeves
patent: 5418339 (1995-05-01), Bowen et al.
patent: 5500494 (1996-03-01), Ligman
patent: 5767459 (1998-06-01), Sell
patent: 1.519.853 (1968-07-01), None
patent: 2.570.759 (1986-03-01), None
Christensen O'Connor Johnson & Kindness PLLC
Dang Khanh
LandOfFree
Pneumatic hand tool exhaust muffler does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pneumatic hand tool exhaust muffler, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pneumatic hand tool exhaust muffler will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2497030