US5063598A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Active noise control system with two stage conditioning
Assignee: Ford Motor Co
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Filing: 1990-04-25
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Granted: 1991-11-05
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Expires: 2010-04-25
Abstract
Abstract An active muffler for motor vehicle exhaust conduits comprises a pulse tracking sensor generating a signal input to an electronic control for actuating an acoustic transducer imposing cancellation pulses upon the sound pressure pulse train travelling through the conduit. The system includes a preconditioning circuit for reducing the crest factor of the waveform pulse train travelling through the exhaust conduit by introducing negative pressure pulses into the exhaust conduit. Preferably, a digitally controlled one bit injector includes a fluid outlet in communication with the exhaust conduit and an inlet in communication with a vacuum source such as the intake manifold of the motor vehicle engine. Accordingly, the amplifier and the transducer of the acoustic actuator can be substantially downsized for employment in mass produced motor vehicles.
Inventors
- 👤 Earl R. Geddes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:13
CPC Classifications
F; F01; F01N; F01N1/00; F01N1/06; F01N1/065; G; G10; G10K; G10K11/00; G10K11/16; G10K11/175; G10K11/178; G10K11/1785; G10K11/17853; G10K11/17854; G10K11/1787; G10K11/17879; G10K11/17881; G10K11/17883; G10K2210/00; G10K2210/10; G10K2210/128; G10K2210/1282; G10K2210/12822; G10K2210/30; G10K2210/301; G10K2210/3039; G10K2210/321; G10K2210/3212; G10K2210/32121; G10K2210/50; G10K2210/509
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
81 words
An active noise attenuation muffler for a motor vehicle engine exhaust conduit comprising: a tracking source for generating a tracking signal representative of an input pulse train; a transducer coupled to said conduit; electronic control means for driving said transducer in response to said tracking signal and producing an output pulse train having a phase opposite to said input pulse train at a predetermined point along said conduit; and means for pneumatically reducing the crest factor of said input pulse train.
Claim 2
Dependent Claim
81 words
An active noise attenuation muffler for a motor vehicle engine exhaust conduit comprising: a tracking source for generating a tracking signal representative of an input pulse train; a transducer coupled to said conduit; electronic control means for driving said transducer in response to said tracking signal and producing an output pulse train having a phase opposite to said input pulse train at a predetermined point along said conduit; and means for pneumatically reducing the crest factor of said input pulse train.
Claim 3
Dependent Claim
79 words
The invention as defined in claim 1 wherein said means for pneumatically reducing the crest factor of said input pulse train comprises a valve having an inlet and an outlet; a vacuum source coupled to said inlet, said outlet being coupled in communication with the engine exhaust conduit, and a control for opening said valve during each pulse of the input pulse train to introduce a negative pressure pulse that reduces the crest factor of the input pulse train.
Claim 4
Dependent Claim
39 words
The invention as defined in claim 2 wherein said control comprises: a tracking source for generating a tracking signal responsive to engine operation; and a pulse width modulator for generating a control signal in response to said tracking signal.
Claim 5
Dependent Claim
14 words
The invention as defined in claim 3 wherein said tracking source comprises a microphone.
Claim 6
Dependent Claim
16 words
The invention as defined in claim 3 wherein said tracking source comprises an engine driven accessory.
Claim 7
Dependent Claim
21 words
The invention as defined in claim 3 wherein said tracking source comprises an electronic control unit of the motor vehicle engine.
Claim 8
Dependent Claim
20 words
The invention as defined in claim 2 wherein said control comprises a pulse width modulator responsive to said tracking signal.
Claim 9
Independent Claim
66 words
A method for muffling engine exhaust conduits comprising: tracking engine speed to generate a tracking signal representative of sound pressure waveforms introduced to the exhaust conduit; controlling the operation of a transducer emitting noise cancellation signals in said exhaust conduit in response to said tracking signal; and preconditioning said sound pressure pulses by introducing negative pressure pulses into said conduit in response to said tracking signal.
Claim 10
Independent Claim
66 words
A method for muffling engine exhaust conduits comprising: tracking engine speed to generate a tracking signal representative of sound pressure waveforms introduced to the exhaust conduit; controlling the operation of a transducer emitting noise cancellation signals in said exhaust conduit in response to said tracking signal; and preconditioning said sound pressure pulses by introducing negative pressure pulses into said conduit in response to said tracking signal.
Claim 11
Dependent Claim
34 words
The invention as defined in claim 5 wherein said preconditioning step comprises intermittently coupling a vacuum source in fluid communication with the exhaust conduit; and actuating said valve in response to said sensor signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-11-04 | 1995-05-06 | 1995-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-11-04 | 1999-05-06 | 1999-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-11-04 | 2003-05-06 | 2003-11-05 | $7700.00 | Window Closed / Lapsed |