Abstract:
An in-line resonator for an air induction system of an internal combustion engine is provided. The system includes a resonator housing, an upstream duct, a downstream duct, a conduit, a partition, and a sleeve. The conduit extends through the resonator housing connecting the upstream duct and the downstream duct. The partition is moveable within the resonator housing and divides the housing into an upstream chamber and a downstream chamber. The downstream chamber, the conduit, and the downstream sleeve cooperate to form a first Helmholtz resonator that is in fluid communication with the downstream duct. The upstream chamber, the conduit, and the upstream sleeve cooperate to form a second Helmholtz resonator that is in fluid communication with the upstream duct. Further, a means is provided to axially move the partition to vary the volume of the chambers concurrently with the length and/or area of the passages.

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention generally relates to an in-line resonator for an air induction system. 
     2. Description of Related Art 
     Resonators for attenuating acoustic pressure pulsations in automotive applications are well known. The air induction systems of internal combustion engines produce undesirable noise in the form of acoustic pressure pulsations. This induction noise varies based on the engine configuration and engine speed. The induction noise is caused by a pressure wave that travels from the inlet valve towards the inlet of the air induction system. Further, the induction noise may be reduced by reflecting a wave toward the inlet valve 180° out of phase with the noise wave. As such, Helmholtz type resonators have been used to attenuate the noise wave generated from the inlet valve-opening event. In addition and more recently, resonators have been developed that change the volume of the resonator to adjust for varying frequencies of the noise wave, as engine speed changes. Previous designs, however, have not provided the control of multiple frequencies at the same engine speed, which is required for some applications. 
     To meet order based air induction noise targets, it is generally necessary to incorporate a tuning device, such as a resonator, into the air induction system. Traditional static resonators are tuned to a fixed frequency that will not change with engine speed. These resonators provide notch-type attenuation at their designated frequency, but introduce undesirable side band resonances at higher and lower frequencies. Even after the addition of multiple static devices, it may still not be possible to match the desired order based targets due to the notch-type attenuation and side band amplification caused by such devices. Resonators have been developed that change the volume of the resonator to adjust for the varying frequencies of the noise wave as engine speed changes. However, the acoustic pressure pulsations may be composed of several frequencies of significant amplitude that occur simultaneously at any given engine speed. 
     In view of the above, it is apparent that there exists a need for an improved resonator having broader flexibility to attenuate the various noise frequencies of the engine. 
     SUMMARY 
     In satisfying the above need, as well as overcoming the drawbacks and other limitations of the related art, the present invention provides an in-line resonator with multiple chambers for an air induction system of an internal combustion engine. 
     The system includes a resonator housing, an upstream duct, a downstream duct, a conduit, a partition, an upstream sleeve, and a downstream sleeve. The upstream duct and downstream duct are connected to opposite ends of the housing. The upstream duct connects the resonator to the air intake, and the downstream duct connects the resonator to the internal combustion engine. The conduit extends through the resonator housing providing an airflow path between the upstream duct and downstream duct. The partition divides the housing into an upstream chamber and a downstream chamber. Additionally, the partition, downstream sleeve, and upstream sleeve are fixed to each other so that these components always maintain the same relative position with respect to each other. The partition, downstream sleeve, and upstream sleeve are collectively referred to as the sliding unit of the resonator assembly. The downstream and upstream sleeves slide along the outside of the conduit while the airflow from the upstream duct to the downstream duct is bounded by the inner surface of the conduit. The downstream chamber, conduit, and downstream sleeve cooperate to form a downstream Helmholtz resonator that is in fluid communication with the downstream duct. The properties of the Helmholtz resonator are characterized by the volume of the downstream chamber and the length and cross-sectional area of the passage connecting the downstream duct to the downstream chamber. 
     In another aspect of the present invention, the conduit and the upstream sleeve may include overlapping openings that form a fluid communication path from the interior of the conduit to the upstream chamber. The upstream chamber and the overlapping openings of the upstream sleeve and conduit form an upstream Helmholtz resonator. The overlapping openings of the conduit and upstream sleeve may have a variety of shapes thereby varying the frequency of the second Helmholtz resonator as a function of the relative positions of the upstream duct and conduit. 
     In another aspect of the present invention, the downstream sleeve may be composed of an outer downstream sleeve and an inner downstream sleeve. The outer downstream sleeve is spaced apart from the inner downstream sleeve. The inner downstream sleeve slides about the conduit, and the outer downstream sleeve slides within the downstream duct. The gap between the inner and outer downstream sleeves defines the area of the passage connecting the downstream duct and the downstream chamber. 
     In a further aspect of the present invention, the outer downstream sleeve has an end that extends into the downstream chamber. The distance from the end of the conduit that terminates within the downstream duct and the end of the outer downstream sleeve that terminates within the downstream chamber defines the length of the passage between the downstream duct and the downstream chamber. 
     In another aspect of the present invention, the means for axially moving the sliding unit includes a motor mounted on the resonator housing and an actuator connecting the motor to the sliding unit. 
     In yet another aspect of the present invention, the conduit may contain a plurality of perforations. As a function of the position of the upstream sleeve, the upstream sleeve will act to cover or uncover a portion of the perforations in the conduit. The uncovered perforations form a fluid communication path to the upstream chamber. The upstream chamber and the uncovered perforations in the conduit form an upstream Helmholtz resonator. 
     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal sectional view of an in-line resonator embodying the principles of the present invention; 
         FIG. 2  is a chart depicting various hole configurations used to vary the frequency attenuation of the upstream chamber; 
         FIG. 3  is a graph showing the frequency attenuated by the upstream chamber for various conduit hole configurations as varied by the partition being moved across the resonator; 
         FIG. 4  is a sectional side view of another embodiment of a in-line resonator having perforations in the conduit; 
         FIG. 5  is a sectional side view of another embodiment of an in-line resonator having an extension of the downstream duct protruding into the downstream chamber; and 
         FIG. 6  is a sectional side view of yet another embodiment of an in-line resonator where the upstream and downstream ducts have extensions that protrude into the upstream and downstream chambers. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , an in-line resonator embodying the principles of the present invention is illustrated therein and designated at  10 . As its primary components, the in-line resonator  10  includes a resonator housing  12 , a conduit  20 , a partition  24 , a downstream sleeve  30 , and an upstream sleeve  31 . 
     The housing  12  of the in-line resonator  10  forms a compartment  13  having a fixed volume. Extending from the ends of the housing  12  are an upstream duct  16  and a downstream duct  18 . Positioned axially within the in-line resonator  10  and providing an airflow passage from the upstream duct  16  to the downstream duct  18  is the conduit  20 . The conduit  20  is centered on the axis  14  of the resonator housing  12  and air flows generally into the upstream duct  16 , through the conduit  20 , into the downstream duct  18 , and to the internal combustion engine (not shown). Acoustic pressure pulsations created by the air induction process travel from the engine into the downstream duct  18 . 
     Located axially around the conduit  20  and attached to the partition  24  for sliding therewith are a downstream sleeve  30  and an upstream sleeve  31 . The downstream sleeve  30 , the upstream sleeve  31 , the partition  24 , and the resonator housing  12  cooperate to form a first or downstream chamber  28  and second or upstream chamber  26 . The downstream sleeve  30  includes an outer downstream sleeve  46  that is spaced apart from the conduit  20  and that defines an outer downstream sleeve end  32  extending into the downstream duct  18  and downstream chamber  28 . The outer downstream sleeve end  32  in cooperation with the conduit end  22  defines an annular connector passage  48 . Further, a length  36  is defined from the conduit end  22  to the outer downstream sleeve end  32 . 
     To attenuate the acoustic pressure pulsations, the first chamber  28 , and the annular connector passage  48  form a first or downstream Helmholtz resonator  38 . As the acoustic pressure pulsations enter the downstream resonator  38 , the location of the partition  24 , the downstream sleeve  30 , and outer downstream sleeve  46  within the housing  12  are adjusted by the actuator  40  to create the necessary internal dimensions that will reflect the acoustic pressure pulsations back into the downstream duct with a 180° phase shift at the desired frequency, thereby attenuating the acoustic pressure pulsations. 
     To further attenuate the acoustic pressure pulsations, the second chamber  26 , the opening  42  in the conduit, and the opening  44  in the upstream sleeve cooperate to form a second or upstream Helmholtz resonator  39 . As the acoustic pressure pulsations travel through the conduit  20 , they enter the second chamber  26  through the overlapping areas of the conduit opening  42  and the upstream sleeve opening  44 . Both of the openings  42  and  44  are further defined below. The frequency attenuated by the upstream resonator  39  is controlled by the position of the partition  24 , the size and shape of the opening formed by the overlapping or relative positions of the conduit opening  42  and the sleeve opening  44 , and the wall thickness of the conduit  20  and upstream sleeve  31 . 
     The upstream resonator  39  offers greater flexibility to address additional frequencies in need of attenuation, while the first resonator  38  addresses a single dominant order. If the intake manifold is acoustically symmetric, then an acoustic pressure pulsation signature composed of the engine firing order and its harmonics will dominate the induction noise. As a result the downstream resonator  38  can address the dominant engine order, and the upstream resonator  39  can be tailored to address additional problematic frequencies, as described in the paragraphs below. 
     Controller  41  monitors engine parameters, such as engine speed, engine acceleration, throttle position, and pedal position. The controller  41  calculates the optimal position of the partition  24  based on the engine parameters. In doing this, controller  41  can utilize a lookup table of the partition position relative to both engine speed and performance characteristics. The lookup table could be developed from a series of induction noise tests to determine the optimal position for the partition at every engine speed. In addition, a position sensor  49  may be used to monitor the position of the partition  24  and provide feedback to the controller  41 . Based on the feedback from the position sensor  49  and the engine&#39;s operating conditions, the controller commands the actuator  40  to move the partition  24  to the predetermined optimal position. 
     Now referring to  FIG. 2  and  FIG. 3 , examples of various shaped conduit holes are provided along with graphs of the resulting frequency of attenuation achieved by each conduit hole as the upstream sleeve  31  slides along the conduit  20 . For reference, the attenuation provided by downstream resonator is designated by reference numeral  51 . Further, it is to be noted, that the opening formed by the cooperation of the conduit opening  42  together with the upstream sleeve opening  44  significantly varies the frequency attenuated by the second resonator  39 . Accordingly, either the conduit opening  42 , the upstream sleeve opening  44 , or both may be altered in size and shape along the length of the opening to obtain desired attenuation characteristics. Utilizing the oval shape of the upstream sleeve opening  44 , as shown in  FIG. 1 , a first wedge-shaped conduit opening  52  with the apex pointing towards the downstream duct  18  allows the attenuated frequency decrease while the volume of the second chamber  26  increases, as defined by the position of the partition  24 . The angle along the length of the first wedge shape  52  can be modified to vary the rate at which the frequency decreases as the volume of he second chamber  26  increases. 
     Utilizing a second wedge shape  54 , with the apex pointing towards the upstream duct  16 , the angle of the apex can be chosen to attenuate a constant frequency as the upstream sleeve  30  moves along the conduit  20 . The second wedge shape  54  essentially compensates for the increase in the volume of the second chamber  26  by changing the size and shape of the conduit opening, as shown by second wedge shape  54  and its corresponding graph. 
     In addition, non-linear transfer functions between the position of the partition  24  and the attenuated frequency can be created by changing the angle of the apex and shape of the sides in a non-linear manner. One example is provided in the violin-shaped wedge  56 . 
     In contrast to the first wedge shape  52 , the frequency may be increased using a third wedge shape  58  as the sleeve  30  moves along the conduit  32 . The third wedge shape  58  has an apex pointing towards the upstream duct  16 , however, the apex angle is wider than the second wedge shape  54 . 
     Referring now to  FIG. 4 , another embodiment of in-line resonator according to the principles of the present invention is illustrated therein and designated at  60 . It is noted that common components with the previously described exponent are referenced with common element numbers. 
     As its primary components, the in-line resonator  60  includes a resonator housing  12 , a conduit  20 , a partition  24 , a downstream sleeve  30 , and an upstream sleeve  65 . The housing  12  of the in-line resonator  60  forms a compartment  13  having a fixed volume. Extending from the ends of the housing  12  are an upstream duct  16  and a downstream duct  18 . Positioned axially within the in-line resonator  60  and providing a passage from the upstream duct  16  to the downstream duct  18  is the conduit  20 . Generally, air flows into the upstream duct  16 , through the conduit  20 , and out the downstream duct  18  to the internal combustion engine (not shown). Acoustic pressure pulsations created by the air induction process travel from the engine into the downstream duct  18 . 
     Located axially around the conduit  20  and attached to the partition  24 , for sliding therewith, are a downstream sleeve  30  and an upstream sleeve  65 . The downstream sleeve  30 , the upstream sleeve  65 , the partition  24 , and the resonator housing  12  cooperate to form a first or downstream chamber  28  and a second or upstream chamber  26 . The downstream sleeve  30  includes an outer downstream sleeve  46  that is spaced apart from the conduit  20  that defines an outer downstream sleeve end  32  extending into the downstream duct  18  and downstream chamber  28 . The outer downstream sleeve end  32  in cooperation with the conduit end  22  defines an annular connector passage  48 . Further, a length  36  is defined from the conduit end  22  to the outer downstream sleeve end  32 . 
     To attenuate the acoustic pressure pulsations, the first chamber  28 , and the annular connector passage  48  form a first or downstream Helmholtz resonator  38 . As the acoustic pressure pulsations enter the resonator  38 , the location of the partition  24 , the downstream sleeve  30 , and outer downstream sleeve  46  within the housing  12  are adjusted by the actuator  40  to create the necessary internal dimensions that will reflect the acoustic pressure pulsations back into the downstream duct with a 180° phase shift at the desired frequency, thereby attenuating the acoustic pressure pulsations. 
     To further attenuate the acoustic pressure pulsations, a second chamber  26 , the perforated openings  61  in the conduit  20 , and the position of the upstream sleeve  65  cooperate to form a second or upstream Helmholtz resonator  39 . As the acoustic pressure pulsations travel through the conduit  20 , perforations  61  in the conduit  20  allow the acoustic pressure pulsation to enter the second chamber  26 . The frequency attenuated by the upstream resonator  39  is controlled by the position of the partition  24 , the wall thickness of the conduit  20 , as well as the amount of perforations  61  not covered by the upstream sleeve  30  based on the position of the upstream sleeve  30 . 
     Controller  41  monitors engine parameters, such as engine speed, engine acceleration, throttle position, and pedal position. The controller  41  calculates the optimal position of the partition  24  based on the engine parameters. In doing this, controller  41  can utilize a lookup table of the partition position relative to both engine speed and performance characteristics. The lookup table could be developed from a series of induction noise tests to determine the optimal position for the partition at every engine speed. In addition, a position sensor  49  may be used to monitor the position of the partition  24  and provide feedback to the controller  41 . Based on the feedback from the position sensor  49  and the engine&#39;s operating conditions, the controller commands the actuator  40  to move the partition  24  to the predetermined optimal position. 
     Referring now to  FIG. 5 , another embodiment of in-line resonator according to the principles of the present invention is illustrated therein and designated at  62 . Again, common components to those of the preceding embodiments one designated with like reference numbers. As its primary components, the in-line resonator  62  includes a resonator housing  12 , a conduit  20 , a partition  24 , a downstream sleeve  30 , and an upstream sleeve  65 . 
     The housing  12  of the in-line resonator  62  forms a compartment  13  having a fixed volume. Extending from the ends of the housing  12  are an upstream duct  16  and a downstream duct  18 . Positioned axially within the in-line resonator  62  providing a passage from the upstream duct  16  to the downstream duct  18  is the conduit  20 . Generally, air flows into the upstream duct  16 , through the conduit  20 , and out the downstream duct  18  to the internal combustion engine (not shown). Acoustic pressure pulsations created by the air induction process travel from the engine into the downstream duct  18 . 
     Located axially around the conduit  20  and attached to the partition  24  for sliding therewith are a downstream sleeve  30  and an upstream sleeve  31 . The downstream sleeve  30 , the upstream sleeve  65 , the partition  24 , and the resonator housing  12  cooperate to form a first or downstream chamber  28  and second or upstream chamber  26 . The downstream sleeve  30  includes an outer downstream sleeve  64  that is spaced apart from the conduit  20  and that defines an outer downstream sleeve end  32  extending into the downstream chamber  28 . In addition, the downstream duct has an extension  63  that extends into the downstream chamber  28  around which the outer downstream sleeve  64  slides. The conduit end  22 , the downstream duct extension  63 , and the outer downstream sleeve  64  cooperate to define an annular passage  66 . Further, a length  36  is defined from the conduit end  22  to the outer downstream sleeve end  32 . 
     To attenuate the acoustic pressure pulsations, the downstream chamber  28  and the annular passage  66  cooperate to form a first or downstream Helmholtz resonator  38 . As the acoustic pressure pulsations enter the downstream resonator  38 , the location of the partition  24 , the downstream sleeve  30 , and outer downstream sleeve  46  within the housing  12  are adjusted by the actuator  40  to create the necessary internal dimensions that will reflect the acoustic pressure pulsations back into the downstream duct with a 180° phase shift at the desired frequency, thereby attenuating the acoustic pressure pulsations. 
     To further attenuate the acoustic pressure pulsations, a second chamber  26 , the perforated openings  61  in the conduit  20 , and the position of the upstream sleeve  65  cooperate to form a second or upstream Helmholtz resonator  39 . As the acoustic pressure pulsations travel through the conduit  20 , perforations  61  in the conduit  20  allow the acoustic pressure pulsation to enter the second chamber  26 . The frequency attenuated by the upstream resonator  39  is controlled by the position of the partition  24 , the wall thickness of the conduit  20 , as well as the amount of perforations  61  not covered by the upstream sleeve  30  based on the position of the upstream sleeve  30 . 
     Controller  41  monitors engine parameters, such as engine speed, engine acceleration, throttle position, and pedal position. The controller  41  calculates the optimal position of the partition  24  based on the engine parameters. In doing this, controller  41  can utilize a lookup table of the partition position relative to both engine speed and performance characteristics. The lookup table could be developed from a series of induction noise tests to determine the optimal position for the partition at every engine speed. In addition, a position sensor  49  may be used to monitor the position of the partition  24  and provide feedback to the controller  41 . Based on the feedback from the position sensor  49  and the engine&#39;s operating conditions, the controller commands the actuator  40  to move the partition  24  to the predetermined optimal position. 
     Referring now to  FIG. 6 , another embodiment of in-line resonator according to the principles of the present invention is illustrated therein and designated at  68 . Again, common components to those of the preceding embodiments one designated with like reference numbers. As its primary components, the in-line resonator  68  includes a resonator housing  12 , a conduit  20 , a partition  24 , a downstream sleeve  30 , and an upstream sleeve  71 . 
     The housing  12  of the in-line resonator  68  forms a compartment  13  having a fixed volume. Extending from the ends of the housing  12  are an upstream duct  16  and a downstream duct  18 . The conduit  20  is positioned axially within the in-line resonator  68  providing a passage from the upstream duct  16  to the downstream duct  18 . Generally, air flows into the upstream duct  16 , through the conduit  20 , and out the downstream duct  18  to the internal combustion engine (not shown). Acoustic pressure pulsations created by the air induction process travel from the engine into the downstream duct  18 . 
     Located axially around the conduit  20  and attached to the partition  24  for sliding therewith are a downstream sleeve  30  and an upstream sleeve  71 . The downstream sleeve  30 , the upstream sleeve  71 , the partition  24 , and the resonator housing  12  cooperate to form a first or downstream chamber  28  and second or upstream chamber  26 . The downstream sleeve  30  includes an outer downstream sleeve  64  that is spaced apart from the conduit  20  and that defines an outer downstream sleeve end  32  extending into the downstream chamber  28 . The downstream duct has an extension  63  that extends into the downstream chamber  28  around which the outer downstream sleeve  64  slides. The conduit end  22 , the downstream duct extension  63 , and the outer downstream sleeve  64  cooperate to define an annular passage  66 . Further, a length  36  is defined from the conduit end  22  to the outer downstream sleeve end  32 . 
     In addition, the upstream sleeve  71  includes an outer upstream sleeve  70  that is spaced apart from the conduit  20  and that defines an outer upstream sleeve end  74  extending into the upstream chamber  26 . The upstream duct has an extension  69  that extends into the downstream chamber  26  around which the outer upstream sleeve  70  slides. The conduit end  76 , the upstream duct extension  69 , and the outer upstream sleeve  70  cooperate to define an annular passage  72 . Further, a length  78  is defined from the conduit end  76  to the outer upstream sleeve end  74 . 
     To attenuate the acoustic pressure pulsations, the downstream chamber  28  and the annular passage  66  cooperate to form a first or downstream Helmholtz resonator  38 . As the acoustic pressure pulsations enter the downstream resonator  38 , the location of the partition  24 , the downstream sleeve  30 , and outer downstream sleeve  46  within the housing  12  are adjusted by the actuator  40  to create the necessary internal dimensions that will reflect the acoustic pressure pulsations back into the downstream duct with a 180° phase shift at the desired frequency, thereby attenuating the acoustic pressure pulsations. 
     To further attenuate the acoustic pressure pulsations, the upstream chamber  26  and the annular passage  72  cooperate to form a second or upstream Helmholtz resonator  39 . As the acoustic pressure pulsations enter the upstream resonator  39 , the location of the partition  24 , the upstream sleeve  71 , and outer upstream sleeve  70  within the housing  12  are adjusted by the actuator  40  to create the necessary internal dimensions that will reflect the acoustic pressure pulsations back into the upstream duct with a 180° phase shift at the desired frequency, thereby attenuating the acoustic pressure pulsations. 
     Controller  41  monitors engine parameters, such as engine speed, engine acceleration, throttle position, and pedal position. The controller  41  calculates the optimal position of the partition  24  based on the engine parameters. In doing this, controller  41  can utilize a lookup table of the partition position relative to both engine speed and performance characteristics. The lookup table could be developed from a series of induction noise tests to determine the optimal position for the partition at every engine speed. In addition, a position sensor  49  may be used to monitor the position of the partition  24  and provide feedback to the controller  41 . Based on the feedback from the position sensor  49  and the engine&#39;s operating conditions, the controller commands the actuator  40  to move the partition  24  to the predetermined optimal position. 
     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of the principles of this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.