Method and apparatus for attenuating sound in a vehicle exhaust system
An exhaust system for the discharge of exhaust gases from a vehicle engine includes a resonator. The resonator comprises a resonator body having at least one, and preferably more than one, elongated composite strip. Each composite strip has a center foil which is corrugated to provide alternate ridges and grooves and is sandwiched between two perforated foils to provide a multiplicity of parallel fluid passages between the corrugated foil and the perforated foils. The composite strips are tightly wound about a central axis parallel to the fluid passages. A housing encloses the resonator body and has an inlet at one end of the fluid passages and an outlet at an opposite end of the fluid passages. The exhaust gases flow through the passages causing a break up and tuning of the sound waves in the system.
1 . An exhaust system for the discharge of exhaust gases from a vehicle engine, comprising:
a resonator for breaking up and tuning sound waves from the exhaust gases,
said resonator comprising a resonator body including at least one elongated composite strip having a center foil which is corrugated to provide alternate ridges and grooves and is sandwiched between two perforated foils to provide a multiplicity of parallel fluid passages between the corrugated foil and the perforated foils,
said composite strip being wound about a central axis parallel to said fluid passages,
a housing enclosing said resonator body and having an inlet at one end of the fluid passages and an outlet at an opposite end of the fluid passages, and
an exhaust line having a tube for transmitting the exhaust gases from the engine to the inlet of the housing for the movement of the exhaust gases through the fluid passages and out through the outlet.
2 . The exhaust system of claim 1 , wherein each of the perforated foils has a plurality of holes, each of said holes has a diameter of about 8 millimeters, and the spacing between each of the holes and the nearest adjacent holes is about 2 millimeters.
3 . The exhaust system of claim 1 , wherein said composite strip is folded and doubled back on itself about a transverse fold line.
4 . The exhaust system of claim 1 , wherein said resonator body includes second and third elongated composite strips of substantially the same construction as the at least one composite strip, each of said composite strips being folded and doubled back on itself about a transverse fold line at a midpoint in its length, said composite strips overlying one another in a parallel relationship and together being tightly and spirally wound about an axis extending parallel to said passages to provide a tightly wrapped resonator body.
5 . The exhaust system of claim 5 , wherein each of the perforated foils has plurality of holes, each of said holes has a diameter of about 8 millimeters, and the spacing between each of the holes and the nearest adjacent holes is about 2 millimeters.
6 . The exhaust system of claim 5 , wherein each of said foils has a thickness on the order of about 0.065 millimeters.
7 . An exhaust system for the discharge of exhaust gases from a vehicle engine, comprising:
a catalytic converter,
an exhaust line having a first tube section transmitting the exhaust gases from the engine to the catalytic converter,
a resonator for breaking up and tuning sound waves in the exhaust gases,
the exhaust line having a second tube section transmitting the exhaust gases from the catalytic converter to the resonator,
a muffler,
the exhaust line having a third tube section transmitting the exhaust gases from the resonator to the muffler, and
the exhaust line having a fourth tube section transmitting the exhaust gases away from the muffler,
the resonator comprising a resonator body including at least one elongated composite strip having a center foil which is corrugated to provide alternate ridges and grooves and is sandwiched between two perforated foils to provide a multiplicity of parallel fluid passages between the corrugated foil and the perforated foils,
said composite strip being tightly wound about a central axis parallel to said fluid passages,
and a housing enclosing said resonator body and having an inlet at one end of the fluid passages to admit the exhaust gases transmitted to the resonator by the second tube section for movement of the exhaust gases through the fluid passages and having an outlet at an opposite end of the fluid passages to discharge the exhaust gases into the third tube section.
8 . The exhaust system of claim 7 , wherein each of the perforated foils has a plurality of holes, each of said holes has a diameter of about 8 millimeters, and the spacing between each of the holes and the nearest holes is about 2 millimeters.
9 . The exhaust system of claim 8 , wherein said composite strip is folded and doubled back on itself about a transverse fold line.
10 . The exhaust system of claim 7 , wherein said resonator body includes second and third elongated composite strips of substantially the same construction as the at least one composite strip, each of said composite strips being folded and doubled back on itself about a transverse fold line at the midpoint in its length, said composite strips overlying one another in a parallel relationship and together being tightly and spirally wound about said central axis.
11 . The exhaust system of claim 10 , wherein each of the perforated foils has a plurality of holes, each of said holes has a diameter of about 8 millimeters, and the spacing between each of the holes and the nearest adjacent holes is about 2 millimeters
12 . The exhaust system of claim 11 , wherein each of said foils has a thickness on the order of about 0.065 millimeters.
13 . A method of breaking up and tuning sound waves in exhaust gases discharged from a vehicle engine comprising:
providing a resonator comprising a resonator body including at least one elongated composite strip having a center foil which is corrugated to provide alternate ridges and grooves and is sandwiched between two perforated foils to provide a multiplicity of parallel fluid passages between the corrugated foil and the perforated foils,
said composite strip being wound about a central axis parallel to said fluid passages,
and passing the exhaust gases through the fluid passages of the composite strip.
14 . The exhaust system of claim 13 , wherein each of the perforated foils has a plurality of holes, each of said holes has a diameter of about 8 millimeters and the spacing between each of the holes and the nearest adjacent holes is about 2 millimeters.
15 . The exhaust system of claim 13 , wherein said composite strip is folded and doubled back on itself about a transverse fold line.
16 . The method of claim 13 , wherein said resonator body includes second and third elongated composite strips of substantially the same construction as the at least one composite strip, each of said composite strips being folded and doubled back on itself about a transverse fold line at the midpoint in its length, said composite strips overlying one another in a parallel relationship and together being tightly and spirally wound so that the entire resonator body is tightly wrapped about said central axis.
17 . The method of claim 16 , further including enclosing the resonator body in a housing, and admitting the exhaust gases into one end of the fluid passages through an inlet in the housing and discharging the exhaust gases from the opposite end of the fluid passages through an outlet in the housing.
18 . The method of claim 17 , wherein each of the perforated foils has a plurality of holes, each of said holes has a diameter of about 8 millimeters, and the spacing between each of the holes and every hole next adjacent thereto is on the order of about 2 millimeters.
19 . The method of claim 18 , wherein each of said foils has a thickness on the order of about 0.065 millimeters.