Power plants – Internal combustion engine with treatment or handling of... – Pulsed – timed – tuned or resonating exhaust
Patent
1998-05-01
2000-01-04
Denion, Thomas
Power plants
Internal combustion engine with treatment or handling of...
Pulsed, timed, tuned or resonating exhaust
60274, 60322, 181229, 12318457, F02B 2702
Patent
active
060097051
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a noise attenuator for an air induction system or an exhaust system.
The present invention will be described with reference to its use in an air induction system or an exhaust system of an internal combustion engine in an automobile. However, the noise attenuator of the invention should not be considered limited to such a use and it should be appreciated that the invention could be used to attenuate noise in many gas flow systems, (e.g. air conditioning systems, car heater systems, fan systems or domestic appliances) many air induction systems or in many exhaust systems.
It is at present the generally accepted practice in attenuation of noise in air induction systems of internal combustion engines in automobiles to attach to the air induction conduit at separate points along the conduit Helmholtz resonators and quarter wave tube resonators, each resonator being a separate integer and a number of different integers being connected to the air inlet conduit along the length thereof. A summation of the volumes of the separate resonators typically gives a total volume of 12 liters. The different resonators are typically distributed about the engine bay.
In U.S. Pat. No. 5,014,816 there is described a silencer for an air induction system or an exhaust system of an internal combustion engine which comprises a number of quarter wave resonator tubes provided by multiple channels arranged in a single housing. The system is advantageous over certain prior art systems because it is more compact in nature than the previous prior art systems. However, the arrangement of U.S. Pat. No. 5,014,816 has a disadvantage in that very long quarter wave tubes must be used to attenuate low frequencies. Thus the designer must either design a quite large housing to incorporate a long quarter wave tube or alternatively the designer must accept that the induction system will not attenuate the lower frequencies.
The present invention provides a noise attenuator for an air induction system or an exhaust system comprising a housing having: gas outlet, and first gas flow passage, Helmholtz resonator which opens on to the first passage, whereby the Helmholtz resonator and the quarter wave resonator are together integrated in a single unit and the single unit is connectable in and deconnectable from the induction system or the exhaust system.
The housing of the noise attenuator has a Helmholtz resonator which can attenuate low frequency noise. The present invention thus has the advantage of providing in one housing all of the elements required for attenuation of noise of the air induction system or the exhaust system in a compact manner. Thus, the housing will not need to have a very long quarter wave tube to attenuate low frequency noise.
A Helmholtz resonator has significant advantages over a quarter wave tube resonator in attenuating low frequency noise. Whilst the volume of a Helmholtz resonator for attenuating for example 100 Hz frequency noise will be 2.4 liters and the volume of a quarter wave tube for attenuating the same frequency noise will be less, the quarter wave tube will need to be at least 1 meter long and thus will be harder to package than the Helmholtz resonator. Furthermore, the Helmholtz resonator will provide a better defined frequency band width of noise cancellation than a quarter wave resonator tube.
The present invention provides a noise attenuator as one completely integrated unit which has a number of advantages. First, there is a lower pressure loss across the integrated attenuator than there would be across a prior art system providing similar attenuation but with separate resonators distributed throughout the air induction system. This leads to an increase in the efficiency of the internal combustion engine downstream. Secondly, the applicant has found that a prior art system with a total of 12 liters of resonator volume made up of separate resonators distributed throughout the air intake system can be replaced with a noise attenuator according to the present invention which has
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Arnott Steven Peter
Hallam William
Lyddon Steven
Shepperson Anthony William
Denion Thomas
Tennex Europe Limited
Tran Binh
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