Silencer for air induction system and high flow articulated coupling

An air induction silencer assembly includes an acoustic interference member disposed within a conduit. The acoustic interference member is tuned to acoustically cancel a selected noise energy frequency. An acoustic absorbing member is also disposed within the conduit. The acoustic absorbing member converts noise energy within the conduit into heat energy to attenuate noise energy within the air induction silencer assembly. The air induction silencer assembly connects to a flexible conduit that includes an inlet portion, an outlet portion, and a flexible joint that connects the inlet portion and the outlet portion together. The flexible joint includes a rolling lobe and a rolling surface. The rolling lobe moves along the rolling surface when the inlet portion moves relative to the outlet portion.

BACKGROUND OF THE INVENTION

This invention relates to air induction systems and, more particularly, to an air induction system that includes a silencer to attenuate noise within the air induction system and a flexible conduit that provides a low turbulence connection within the air induction system.

Air induction systems are often used in vehicles to intake air from a surrounding environment and supply the air to a combustion engine. Typically, the air from the surrounding environment is drawn through a conduit to an air filter. The air filter filters the air before the air is supplied to the combustion engine. Some engines use a turbocharger to boost the air pressure in the conduit.

Common turbochargers utilize a rotating fan or intermeshing rotating screws to compress and blow the air. The rotation of the fan or the intermeshing screws produces pulsations of compressed air at a frequency that corresponds to the speed of rotation. The pulsations of compressed air manifest within the air induction system as noise energy. Disadvantageously, the noise energy often results in an undesirable audible sound.

The conduit between the turbocharger and the air filter commonly includes a silencer to attenuate the noise energy and reduce the audible sound. Typical silencers employ chambers that receive the noise energy and reflect the noise energy to acoustically cancel the noise energy and reduce the audible sound. Disadvantageously, these silencers attenuate a relatively small portion of the noise energy, while a remaining portion of the noise energy still results in audible sound.

The conduit between the turbocharger and the air filter also commonly includes a flexible portion that allows the compressed air to travel along a curved flow path into the air filter. Typical flexible portions often include a convoluted tube to allow the flexible portion to bend. Disadvantageously, convoluted walls of the convoluted tube interfere with the flow of air through the flexible portion and produce turbulent air flow. The turbulent air flow often results in decreased amounts of air being supplied to the combustion engine and inefficient combustion.

Accordingly, there is a need for a silencer that more effectively attenuates noise energy and a flexible conduit that reduces turbulent air flow in an air induction system.

SUMMARY OF THE INVENTION

An example air induction silencer assembly according to the present invention includes an acoustic interference member disposed within a conduit. The acoustic interference member is tuned to acoustically cancel a selected noise energy frequency. An acoustic absorbing member is also disposed within the conduit. The acoustic absorbing member converts noise energy within the conduit into heat energy to attenuate noise energy within the air induction silencer assembly.

In another example according to the present invention, the air induction silencer assembly includes an acoustic absorbing member disposed within a first conduit. The acoustic absorbing member converts noise energy within the conduit into heat energy. A second conduit is fluidly connected to the first conduit. The second conduit includes an inlet portion, an outlet portion, and a flexible joint that connects the inlet portion and the outlet portion together. The flexible joint includes a rolling lobe and a rolling surface. The rolling lobe moves along the rolling surface when the inlet portion moves relative to the outlet portion.

An example flexible conduit according to the present invention includes an inlet portion, an outlet portion, and a flexible joint that connects the inlet portion and the outlet portion together. The flexible joint includes a rolling lobe and a rolling surface. The rolling lobe moves along the rolling surface when the inlet portion moves relative to the outlet portion.

Accordingly, this invention provides a silencer that more effectively attenuates noise energy and a flexible conduit that reduces turbulent air flow in an air induction system, while avoiding the shortcomings and drawbacks of the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1illustrates selected portions of an example air induction system10of a combustion engine vehicle for example. The air induction system10includes an air filter12connected to a flexible conduit14. The flexible conduit14connects to a silencer16that provides noise attenuation of noise energy. The silencer16connects to a duct18that leads into a turbocharger20. Connector members22secure the flexible conduit14, the silencer16, and the duct18together. During operation of the vehicle, air from a surrounding environment travels into the air filter12. The air filter12removes dirt, dust, and debris for example from the air before the air enters the flexible conduit14, silencer16, and duct18.

FIG. 2illustrates an exploded view of the silencer16ofFIG. 1. The silencer16includes an outer cover30that defines a conduit along a flow channel32through the outer cover30. In one example, the outer cover30is made of a molded plastic material. In the illustrated example, a cage34is disposed inside of the outer cover30. The cage34includes cage openings36, as described below, and securing members38. The securing members38contact an inner surface40and a lip42of the outer cover30. The securing members38secure the cage34within the outer cover30such that the cage34is prevented from moving laterally along the flow channel32.

The securing members38also space the cage34from the outer cover30to define an annular space44between the outer cover30and the cage34. An acoustic absorbing member46is disposed in the annular space44. The cage34restrains the acoustic absorbing member46such that the acoustic absorbing member46is prevented from protruding into the flow channel32and interfering with air flow through the silencer16. The cage34also provides the benefit of restraining and preventing portions of the acoustic absorbing member46from breaking loose into the flow channel32.

The cage openings36correspond to the type of material used for the acoustic absorbing member46. In the illustrated example, the acoustic absorbing member46is made of a foam material such that the acoustic absorbing member46is a single piece of foam. The single piece of foam requires minimal restraint from the cage34to prevent the single piece of foam from protruding into the flow channel32. In another example, the cage openings are smaller than illustrated inFIG. 2, and correspond to, for example, a mesh screen (seeFIG. 2a) to prevent relatively small, separable pieces of the acoustic absorbing member46from protruding or breaking off into the flow channel32. In the mesh screen example, the cage34is a mesh and the openings36′ correspond to openings in the mesh.

In the illustrated example, the cage34is acoustically porous such that noise energy traveling through the silencer16can impinge upon the acoustic absorbing material through the cage openings36.

An acoustic interference member48having a periphery49is disposed radially inward of the cage34and the acoustic absorbing member46(FIG. 3). The acoustic interference member48includes locking members50that interlock with one of the cage openings36to secure the acoustic interference member48within the cage34. In the illustrated example, the outer cover30therefore supports the cage34, and the cage34supports the acoustic interference member48. This feature provides the benefit of a tight fit between the outer cover30, the cage34, the acoustic absorbing member46, and the acoustic interference member48.

The acoustic interference member includes a first plate52and a second plate54configured in the shape of a cross. The first plate52and the second plate54are curved such that air flow is directed along the flow channel32. In the illustrated example, the first plate52and the second plate54are integrated (e.g., by injection molding) such that the acoustic interference member48is a single piece. However, it is to be understood that the first plate52and the second plate54could also be two or more separate pieces.

In the illustrated example, the first plate52includes a plurality of blind holes56. Each of the blind holes56has an associated depth that corresponds to a noise energy wavelength. The depths of the blind holes56are selected (i.e., tuned) to acoustically cancel selected wavelengths of noise energy that are expected to travel through the silencer16from the turbocharger20during operation of the vehicle. As is known, a wavelength of a frequency of noise energy will travel along the blind hole56and reflect off of an end of the blind hole56. The reflected noise energy is 180° out of phase with the noise energy entering the blind hole56and therefore acoustically cancels the entering noise energy. This provides the benefit of attenuating at least a portion of the noise energy from the turbocharger20.

In one example, the blind holes56include at least two different depths in order to attenuate at least two corresponding noise energy wavelengths. In another example, the depths are less than 15 mm in order to attenuate noise energy within a selected corresponding range.

In the illustrated example, the first plate52and the second plate54separate the flow channel32into four flow channel quadrants. The first plate52and the second plate54guide the air flow entering the silencer16. The separation and guidance of the air flow provide the benefit of preventing pressure build-ups and pressure drops within the silencer16.

The acoustic absorbing member46provides additional noise energy attenuation. The acoustic absorbing member46receives at least a portion of the noise energy that travels into the silencer16. The acoustic absorbing member46absorbs the noise energy. The noise energy causes movement (e.g., microscopic movement) of the acoustic absorbing member46, which results in internal friction between the chemical molecules of the acoustic absorbing member46. The internal friction results in the production of heat. The acoustic absorbing member46provides the benefit of absorbing noise energy within the silencer16, converting the noise energy to heat, and dissipating the heat to the surrounding environment. In one example, a noise energy wave W propagating through the silencer impinges upon the acoustic absorbing member46in an essentially perpendicular direction. The acoustic absorbing material absorbs a significant portion of the noise energy wave W to essentially eliminate the noise energy wave W.

The combination of the acoustic absorbing member46and the acoustic interference member48provides the benefit of more effective noise attenuation within the silencer16compared to previously known silencers. The acoustic interference member48attenuates a portion of the noise energy that travels within the air induction system10and the acoustic absorbing member46attenuates another portion of the noise energy within the air induction system (i.e., a portion not attenuated by the acoustic interference member48).

In the illustrated example, the acoustic absorbing member46includes a foam material. The foam material is flexible and therefore is receptive to receiving and absorbing the noise energy. In another example, the acoustic absorbing member includes woven fibers68, as illustrated inFIG. 4. In another example, the acoustic absorbing member46includes a non-woven fibers70, as illustrated inFIG. 5. The woven fibers68and non-woven fibers70absorb noise energy and convert the noise energy to heat, as described above for the foam material.

Air exiting the flexible conduit14enters the silencer16.FIG. 6illustrates a perspective view of the flexible conduit14ofFIG. 1. The flexible conduit14includes an inlet portion80, an outlet portion82, and a flexible joint84that define a flow channel85through the flexible conduit14. The flexible joint84allows the inlet portion80and the outlet portion82to move relative to each other. This provides the benefit of directing the compressed airflow through the flexible conduit14along a curved flow path from the air filter12.

In the illustrated example, the flexible conduit14is made from a flexible material such as an elastomer. In one example, the elastomer includes ethylene propylene diene methylene (EPDM) and resists temperatures at least between −40° C. and 120° C. The flexible conduit is injection molded in a known manner.

The configuration of the flexible joint84is shown schematically over the perspective view inFIG. 6. The flexible joint84includes a first conduit wall portion86that is folded relative to a second conduit wall portion88such that the first conduit wall portion86overlaps the second conduit wall portion88to form a first rolling lobe90. The first conduit wall portion86and the second conduit wall portion88are folded relative to a third conduit wall portion92to form a second rolling lobe94.

During movement of the inlet portion80relative to the outlet portion82, the first rolling lobe moves along a first rolling surface96in a direction D1. The second rolling lobe94moves along a second rolling surface98in a direction D2. The movement of the first rolling lobe90and the second rolling lobe94along one of the directional movements Doallows the inlet portion80to move relative to the outlet portion82, as will be described below.

In one example, the elastomer material of the flexible conduit14includes an internal lubricant. The internal lubricant reduces friction between the first rolling lobe90and the first rolling surface96and the second rolling lobe94and the second rolling surface98. This feature provides the advantage of reduced wear between the rolling lobes90and94and the respective rolling surfaces96and98. In one example, the internal lubricant includes a lubricious material such as a wax.

In the illustrated example, the flexible joint84includes an interior space108between the first conduit wall portion86and the second conduit wall portion88. An opening110connects the interior space108to the flow channel85. In one example, the interior space108receives noise energy from the turbocharger20. The noise energy enters the interior space108through the opening110. The interior space108includes a length L1. Although the length L1changes as the first and second rolling lobes90and94move, the length L1is relatively constant once the flexible conduit14is installed into a vehicle. That is, the length L1can be predetermined such that the length L1is about 25% of a selected noise energy wavelength to acoustically cancel the selected noise energy wavelength (as described above for the blind holes56). This provides the benefit attenuating at least a portion of the noise energy from the turbocharger20.

In another example, a size of the opening110corresponds to a selected noise energy wavelength and frequency. Together, the interior space108and the opening110form a Helmholtz resonator to dampen the selected noise energy wavelength and frequency. The principles of a Helmholtz resonator are known and hereby incorporated by reference.

The combination of the acoustic absorbing member46, the acoustic interference member48, and the interior space108of the flexible conduit14provides the benefit of more effective noise attenuation within the air induction system10compared to previously known air induction systems. In one example, each of the acoustic absorbing member46, the acoustic interference member48, and the interior space108are tuned to attenuate different noise energy frequencies. This results in attenuation over a wider range of frequencies compared to previously known air induction systems.

The flexible conduit14also provides a low turbulence connection between the turbocharger20and the air filter12compared to previously known convoluted flexible conduits. An interior surface112of the flexible conduit14is smooth and does not significantly interfere with compressed air flowing through the flow channel85. This provides a low turbulence connection into the air filter12while allowing the compressed air to flow along a curved path (i.e., flow channel85).

During movement of the flexible joint84from the configuration shown inFIG. 6to the configuration shown inFIG. 7, the length L1of the interior portion108near the top of the flexible joint84(top relative toFIG. 7) increases from L1to L2, for example, as the first rolling lobe90moves towards the inlet portion80along the first rolling surface96. As the first rolling lobe90moves, the first conduit wall portion86folds under and into the second conduit wall portion88. Likewise, the third conduit wall portion92folds into the second conduit wall portion88at the second rolling lobe94. The length L3of the interior portion108near the bottom of the flexible joint84decreases from L3to L4, for example, as the first rolling lobe90moves towards the inlet portion80.

It is to be recognized that opposite movement of the inlet portion80relative to the outlet portion82will cause, for example, the second conduit wall portion88to fold into the first conduit wall portion86. The folding (i.e., rolling) of the first conduit wall portion86relative to the second conduit wall portion88and folding of the third conduit wall portion92relative to the second conduit wall portion88allows the inlet portion80to move relative to the outlet portion82. It is to be recognized also that folding of either the first conduit wall portion86relative to the second conduit wall portion88or folding of the third conduit wall portion92relative to the second conduit wall portion88(i.e., rolling of only one of the first rolling lobe90or the second rolling lobe94) will allow movement of the inlet portion80relative to the outlet portion82.