Patent Application
20050284692
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.
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.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.
The securing members 38 also space the cage 34 from the outer cover 30 to define an annular space 44 between the outer cover 30 and the cage 34. An acoustic absorbing member 46 is disposed in the annular space 44. The cage 34 restrains the acoustic absorbing member 46 such that the acoustic absorbing member 46 is prevented from protruding into the flow channel 32 and interfering with air flow through the silencer 16. The cage 34 also provides the benefit of restraining and preventing portions of the acoustic absorbing member 46 from breaking loose into the flow channel 32.
The cage openings 36 correspond to the type of material used for the acoustic absorbing member 46. In the illustrated example, the acoustic absorbing member 46 is made of a foam material such that the acoustic absorbing member 46 is a single piece of foam. The single piece of foam requires minimal restraint from the cage 34 to prevent the single piece of foam from protruding into the flow channel 32. In another example, the cage openings are smaller than illustrated in
In the illustrated example, the cage 34 is acoustically porous such that noise energy traveling through the silencer 16 can impinge upon the acoustic absorbing material through the cage openings 36.
An acoustic interference member 48 having a periphery 49 is disposed radially inward of the cage 34 and the acoustic absorbing member 46 (
The acoustic interference member includes a first plate 52 and a second plate 54 configured in the shape of a cross. The first plate 52 and the second plate 54 are curved such that air flow is directed along the flow channel 32. In the illustrated example, the first plate 52 and the second plate 54 are integrated (e.g., by injection molding) such that the acoustic interference member 48 is a single piece. However, it is to be understood that the first plate 52 and the second plate 54 could also be two or more separate pieces.
In the illustrated example, the first plate 52 includes a plurality of blind holes 56. Each of the blind holes 56 has an associated depth that corresponds to a noise energy wavelength. The depths of the blind holes 56 are selected (i.e., tuned) to acoustically cancel selected wavelengths of noise energy that are expected to travel through the silencer 16 from the turbocharger 20 during operation of the vehicle. As is known, a wavelength of a frequency of noise energy will travel along the blind hole 56 and reflect off of an end of the blind hole 56. The reflected noise energy is 180° out of phase with the noise energy entering the blind hole 56 and therefore acoustically cancels the entering noise energy. This provides the benefit attenuating at least a portion of the noise energy from the turbocharger 20.
In one example, the blind holes 56 include 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 plate 52 and the second plate 54 separate the flow channel 32 into four flow channel quadrants. The first plate 52 and the second plate 54 guide the air flow entering the silencer 16. The separation and guidance of the air flow provide the benefit of preventing pressure build-ups and pressure drops within the silencer 16.
The acoustic absorbing member 46 provides additional noise energy attenuation. The acoustic absorbing member 46 receives at least a portion of the noise energy that travels into the silencer 16. The acoustic absorbing member 46 absorbs the noise energy. The noise energy causes movement (e.g., microscopic movement) of the acoustic absorbing member 46, which results in internal friction between the chemical molecules of the acoustic absorbing member 46. The internal friction results in the production of heat. The acoustic absorbing member 46 provides the benefit of absorbing noise energy within the silencer 16, 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 member 46 in 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 member 46 and the acoustic interference member 48 provides the benefit of more effective noise attenuation within the silencer 16 compared to previously known silencers. The acoustic interference member 48 attenuates a portion of the noise energy that travels within the air induction system 10 and the acoustic absorbing member 46 attenuates another portion of the noise energy within the air induction system (i.e., a portion not attenuated by the acoustic interference member 48).
In the illustrated example, the acoustic absorbing member 46 includes 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 fibers 68, as illustrated in
Air exiting the flexible conduit 14 enters the silencer 16.
In the illustrated example, the flexible conduit 14 is 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 joint 84 is shown schematically over the perspective view in
During movement of the inlet portion 80 relative to the outlet portion 82, the first rolling lobe moves along a first rolling surface 96 in a direction D1. The second rolling lobe 94 moves along a second rolling surface 98 in a direction D2. The movement of the first rolling lobe 90 and the second rolling lobe 94 along one of the directional movements Do allows the inlet portion 80 to move relative to the outlet portion 82, as will be described below.
In one example, the elastomer material of the flexible conduit 14 includes an internal lubricant. The internal lubricant reduces friction between the first rolling lobe 90 and the first rolling surface 96 and the second rolling lobe 94 and the second rolling surface 98. This feature provides the advantage of reduced wear between the rolling lobes 90 and 94 and the respective rolling surfaces 96 and 98. In one example, the internal lubricant includes a lubricious material such as a wax.
In the illustrated example, the flexible joint 84 includes an interior space 108 between the first conduit wall portion 86 and the second conduit wall portion 88. An opening 110 connects the interior space 108 to the flow channel 85. In one example, the interior space 108 receives noise energy from the turbocharger 20. The noise energy enters the interior space 108 through the opening 110. The interior space 108 includes a length L1. Although the length L1 changes as the first and second rolling lobes 90 and 94 move, the length L1 is relatively constant once the flexible conduit 14 is installed into a vehicle. That is, the length L1 can be predetermined such that the length L1 is about 25% of a selected noise energy wavelength to acoustically cancel the selected noise energy wavelength (as described above for the blind holes 56). This provides the benefit attenuating at least a portion of the noise energy from the turbocharger 20.
In another example, a size of the opening 110 corresponds to a selected noise energy wavelength and frequency. Together, the interior space 108 and the opening 110 form 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 member 46, the acoustic interference member 48, and the interior space 108 of the flexible conduit 14 provides the benefit of more effective noise attenuation within the air induction system 10 compared to previously known air induction systems. In one example, each of the acoustic absorbing member 46, the acoustic interference member 48, and the interior space 108 are 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 conduit 14 also provides a low turbulence connection between the turbocharger 20 and the air filter 12 compared to previously known convoluted flexible conduits. An interior surface 112 of the flexible conduit 14 is smooth and does not significantly interfere with compressed air flowing through the flow channel 85. This provides a low turbulence connection into the air filter 12 while allowing the compressed air to flow along a curved path (i.e., flow channel 85).
During movement of the flexible joint 84 from the configuration shown in
It is to be recognized that opposite movement of the inlet portion 80 relative to the outlet portion 82 will cause, for example, the second conduit wall portion 88 to fold into the first conduit wall portion 86. The folding (i.e., rolling) of the first conduit wall portion 86 relative to the second conduit wall portion 88 and folding of the third conduit wall portion 92 relative to the second conduit wall portion 88 allows the inlet portion 80 to move relative to the outlet portion 82. It is to be recognized also that folding of either the first conduit wall portion 86 relative to the second conduit wall portion 88 or folding of the third conduit wall portion 92 relative to the second conduit wall portion 88 (i.e., rolling of only one of the first rolling lobe 90 or the second rolling lobe 94) will allow movement of the inlet portion 80 relative to the outlet portion 82.
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
This application claims priority to U.S. Provisional Application No. 60/583,556, filed on Jun. 28, 2004.
| Number | Date | Country | |
|---|---|---|---|
| 60583556 | Jun 2004 | US |
