Device and method for altering the acoustic signature of an internal combustion engine
First Claim
1. A device for altering the noise signature of a multi-cylinder internal combustion engine, said device comprising:
- power output sensing means for producing a low-load signal when the power output request to said engine falls below a predetermined limit; and
cylinder cutout means responsive to said low-load signal for pseudo-randomly disabling normal operation of the cylinders of said engine in a time-varying fashion to produce an aperiodic engine exhaust noise.
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Accused Products
Abstract
An apparatus and method for altering the acoustic signature of an internal combustion engine is disclosed. Several techniques for altering the acoustic signature of an engine are shown, including time-varying, disabling or cutout of individual cylinders of an engine in a random fashion in order to reduce the periodic characteristics of the exhaust noise of the engine. Alternate embodiments include offsetting crank pins to transform an even firing engine into an uneven firing engine, inhibiting the fueling of individual cylinders, and inhibiting the ignition signals provided to individual cylinders. A combination of the above techniques may also be implemented in order to disperse the exhaust noise energy present over a wide frequency range, making acoustic detection of the exhaust signature difficult. Cylinder cutout schemes are implemented over a single or multiple engine cycle to disperse exhaust noise pulses over time and randomize measurable spectral noise composition.
63 Citations
24 Claims
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1. A device for altering the noise signature of a multi-cylinder internal combustion engine, said device comprising:
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power output sensing means for producing a low-load signal when the power output request to said engine falls below a predetermined limit; and cylinder cutout means responsive to said low-load signal for pseudo-randomly disabling normal operation of the cylinders of said engine in a time-varying fashion to produce an aperiodic engine exhaust noise. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A device for altering the noise signature of a multi-cylinder internal combustion engine including an ignition system comprising:
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idle state sensing means for producing an idle signal when the engine is in an idle state of operation; and control means responsive to said idle signal for pseudo-randomly disabling the ignition system in a time-varying fashion to produce an aperiodic engine exhaust noise. - View Dependent Claims (12, 13)
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14. A device for altering the noise signature of an internal combustion engine including a fueling control system comprising:
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idle state sensing means for producing an idle signal when the engine is operating in an idle state of operation; and control means responsive to said idle signal for pseudo-randomly disabling the fueling control system in a time-varying fashion to produce an aperiodic engine exhaust noise. - View Dependent Claims (15)
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16. A device for altering the noise signature of an internal combustion engine including a fueling control system comprising:
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idle state sensing means for producing an idle signal when the engine is operating in an idle state of operation, wherein said idle state sensing means includes a tone wheel mounted on said engine and rotating in proportion to the speed of said engine, a magnetic sensor adapted to be mounted in magnetic relationship with said tone wheel, and speed circuit means responsive to an output signal from said magnetic sensor and producing said idle signal when the speed of said engine falls below a predetermined limit; and control means responsive to said idle signal for pseudo-randomly disabling the fueling control system in a time-varying fashion to produce an aperiodic engine exhaust noise.
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17. A method for altering the acoustic signature of an internal combustion engine having a plurality of cylinders comprising the steps of:
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detecting a low-load condition placed on the engine; and pseudo-randomly altering normal operation of at least one of said plurality of cylinders in a time-varying fashion in response to detecting said low-load condition to produce an aperiodic engine exhaust noise. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A device for altering the noise signature of a multi-cylinder internal combustion engine, said device comprising:
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power output sensing means for producing a low-load signal when the power output request to said engine falls below a predetermined limit; and fueling control means responsive to said low-load signal for pseudo-randomly altering normal operation of the cylinders of said engine in a time-varying fashion to produce an aperiodic engine exhaust noise. - View Dependent Claims (24)
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Specification