Patent Application
20200018272
The disclosed inventive concept relates generally to air intake systems for internal combustion engines. More particularly, the disclosed inventive concept relates to sound absorbing and silencing systems for use with such air intake systems. The sound absorbing and silencing system of the disclosed inventive concept incorporates a resistive foam element preferably of the closed cell type.
Automobile designers are today challenged by a broad range of requirements externally imposed by customer demands at one extreme and by government regulation at the other. One such customer demand is for the reduction of overall vehicle noise, vibration and harshness (NVH). A known source of vehicle noise in the internal combustion engine is air induction noise created by the engine and controlled by the air induction system.
In an effort to minimize air induction noise, automotive designers and engineers incorporated an acoustic absorbing material in the air intake passage. The common sound absorbing material is loose non-woven polyester batting. A fine mesh screen is required in the design of the material supporting structure such as a plastic retainer cage retain or restrict the entrainment of the loose polyester fiber from the air stream into the turbocharger inlet. Contaminating debris can damage the turbocharger at an expense to the manufacturer or to the end customer. The fine meshed screen is insert-molded to a plastic retainer cage. The retainer cage with its insert molded screen is assembled to the interior of an engine intake air duct.
The fine meshed screen has been found to be sensitive to mechanical cycling fatigue. Accordingly, a premium screen material must therefore be used. This method and combination of materials is effective for vehicle life durability.
However, use of the plastic retainer cage and screen to contain the loose non-woven polyester batting is cost-prohibitive due to the material cost (largely due to the expense of fine mesh screen) and the cost involved in the requisite over-molding operation of the screen material to the plastic cage. In addition, the installation of a specific amount of the loose polyester fiber batting is a labor-intensive undertaking.
Once in operation, the loose polyester fiber batting material can become soaked with liquid, typically oil or water, which can compact the loose acoustic material over time. The compaction of the batting can create voids in the resonator volume as it moves out of its intended original position. This reduces the acoustic performance of the resistive silencer component assembly. The loose batting acoustic material does not recover its position, size or shape if or when the polyester is dried over time.
Accordingly, known approaches to attenuating air induction noise associated with the operation of an internal combustion engine have not provided completely satisfactory results. As in so many areas of vehicle technology, there is always room for improvement related to air induction noise reduction.
The disclosed inventive concept provides a noise-attenuating resistive silencer assembly for use with an internal combustion engine. The resistive silencer assembly incorporates a resistive silencer material. The type, amount, and shape of the silencer material may be adapted for a particular use, thereby offering to the vehicle designer a high degree of tunability so as to achieve the desired level of noise emitted through the air induction system.
The noise-attenuating resistive silencer assembly of the disclosed inventive concept includes an intake duct having air inlet and outlet ends, an acoustic absorbing material support structure operatively associated with the intake duct and positioned between the air inlet end and the air outlet end, and an acoustic absorbing element supported by the acoustic absorbing material support structure. The acoustic absorbing element has a defined and non-amorphous shape. The intake duct may be of any of several shapes adapted for use in any one of several arrangements in relation to any of several internal combustion engines. However, regardless of the application, the air enters the air inlet end, passes by the acoustic absorbing material, and exits the air outlet end.
The acoustic absorbing element is formed from a shaped foam material which has a defined shape that is not subject to becoming loose or dissembling, unlike known batting. The shape of the foam material is defined to be placed in an acoustic absorbing element support structure. It may be a single layer or may be multiple layers. The foam material may be open cell foam or closed cell foam. A combination of open cell foam materials and closed cell foam materials may be utilized. In the case of open cell foam, the material may be, as a non-limiting example, either a low density or high density polyurethane foam. In the case of closed cell foam, the material may be, as non-limiting examples, crushed, closed-celled ethylene propylene dieme or polyvinyl nitrile foam.
The noise-attenuating resistive silencer assembly of the disclosed inventive concept provides an effective and efficient response to the need to reduce air induction noise in the internal combustion engine. The noise-attenuating resistive silencer assembly is relatively inexpensive to produce, install, and maintain.
The above advantages and other advantages and features will be readily apparent from the following detailed description of the preferred embodiments when taken in connection with the accompanying drawings.
For a more complete understanding of this invention, reference should now be made to the embodiments illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention wherein:
In the following figures, the same reference numerals will be used to refer to the same components. In the following description, various operating parameters and components are described for different constructed embodiments. These specific parameters and components are included as examples and are not meant to be limiting.
The accompanying figures and the associated description illustrate a resistive silencer assembly that may be adapted for use in any number of applications beyond the automotive industry. Particularly,
In general, the disclosed inventive concept provides superior short and long term performance over the known technologies in large part due to the advantages of incorporating a foam block of acoustic absorbing material into the resistive silencer assembly. The foam block of acoustic absorbing material of the disclosed inventive concept has a defined and non-amorphous form that does not lose its shape over time and does not degrade or release particles that could damage intake components, such as the vehicle's turbocharging system. Use of the foam block of acoustic absorbing material as part of the resistive silencer assembly results in significant material and production cost savings without compromising acoustic performance when compared with conventional acoustic batting. Air enters the system, passes by (but not through) the acoustic absorbing material, and exits the system for entrance into the induction unit, such as a turbocharger.
Referring to
The internal combustion engine 10 conventionally includes an air intake system 12. The air intake system 12 draws fresh ambient air at one end, passes the air, and exhausts the fresh air into the engine's intake. Particularly, a turbocharger 14 or a similar forced air induction device is fitted to the air intake of the internal combustion engine 10. The turbocharger 14 receives air from the air intake system 12. An incoming air box 16 is fitted to an air intake duct 18. The incoming air box 16 conventionally includes an air filter. The air intake duct 18 includes an air intake end 20 and an air output end 22. The incoming air box 16 is attached to the air intake end 20 of the air intake duct 18 while the turbocharger 14 is attached to the air output end 22 of the air intake duct 18.
An air inlet duct silencer 24 is formed as part of the air intake system 12. The air inlet duct silencer 24 includes a resistive silencer material that is restrained in a support frame or other structure that restrains the resistive silencer material at one side of the air duct work of the air intake system 12. By being positioned off to the side of the airflow, the incoming air passes by but not through the resistive silencer material, thereby minimizing any interference with airflow while providing superior noise absorbing characteristics.
The acoustic absorbing material used as silencing material in the disclosed inventive concept may be any of several elastomeric materials including, but not limited to, any of several open cell or closed cell foam materials. Non-limiting examples of such materials include any of several closed-cell polyurethane foam materials. Both types of foam materials have air pockets defining individual cells. Non-limiting examples of open cell foam materials include open cell polyurethane foam. The open cell foam may be high density or low density.
Non-limiting examples of closed cell foam include any of several polyurethane foam materials. A preferred material is crushed, closed-celled EPDM (ethylene propylene dieme) which is a synthetic rubber that is capable of withstanding extremes of cold and heat. Crushed, closed-cell EPDM foam is preferred as it is highly flexible and is capable of filling voids. Another closed cell foam material suitable for use in the disclosed inventive concept is closed cell polyvinyl nitrile foam (PVN).
The block of acoustic absorbing material 60 illustrated in
Referring to
The resistive silencer assembly 44 is illustrated in exploded view in
With reference thereto, the resistive silencer assembly 44 includes a resistive silencer housing 46 having a housing inlet 48 to which is attached a housing inlet hose 50. The resistive silencer housing 46 further includes a housing outlet to which is attached a housing outlet hose 54. A removable resistive silencer housing cover 56 is adapted for enclosing the resistive silencer housing 46.
Within the resistive silencer housing 46 is provided an acoustic absorbing material support frame 58 that provides support to a block of acoustic absorbing material 60. The acoustic absorbing material support frame 58 may be made of any suitable polymerized material that resists extreme temperatures and petroleum products.
The block of acoustic absorbing material 60 may be selected from any one of several materials including, but not limited to, any of several open cell foam materials or closed cell foam materials. Both types of foam materials have air pockets defining individual cells. Non-limiting examples of open cell foam materials include open cell polyurethane foam. The open cell foam may be high density or low density.
Non-limiting examples of closed cell foam include any of several polyurethane foam materials. A preferred material is crushed, closed-celled EPDM (ethylene propylene dieme) which is a synthetic rubber that is capable of withstanding extremes of cold and heat. Crushed, closed-cell EPDM foam is preferred as it is highly flexible and is capable of filling voids. Another closed cell foam material suitable for use in the disclosed inventive concept is closed cell polyvinyl nitrile foam (PVN).
Regardless of its composition, the block of acoustic absorbing material 60 offers several advantages over known batting. First, a predetermined block of foam material may be standardized for each application, thereby minimizing or virtually eliminating variations in the amount of sound absorbing material required. Second, because the foam block does not have a significant amount of loose fine particles, the requirement for a fine mesh screen to be added to the absorbing material support frame is eliminated thus saving both material and production costs related to the application of the screen to the support frame. Third, unlike batting which is subject to changes in size, shape, and position over its life, the foam block of acoustic absorbing material 60 can be relied upon to maintain its original configuration for the life of the vehicle.
Referring to
Referring to
Within the resistive silencer assembly 76 is provided an acoustic absorbing support frame similar in both structure and function to the acoustic absorbing material support frame 58 of
With reference to
Formed in the acoustic material absorbing support frame 80 is a plurality of windows 90. The windows permit the acoustic absorption of sound as the intake air passes by the acoustic material absorbing support frame 80.
The noise attenuating intake assembly of the disclosed inventive concept provides a solution to the difficulty of controlling noise in the air induction system of an internal combustion engine. The intake assembly set forth herein is of relatively low cost for not only initial production and installation but also provides virtually no needed maintenance over the life of the vehicle. In addition, the noise attenuating intake assembly of the disclosed inventive concept provides a high degree of tunability for controlling noise levels. Such tunability is enabled through the selection of specific types of resistive silencer material. Selections include the desired density of the material and whether or not the material is of the closed cell or open cell type. Accordingly, optimum air induction noise tuning is customizable according to vehicle and engine package.
One skilled in the art will readily recognize from the above discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.
