Patent Publication Number: US-7584821-B2

Title: Adjustable helmholtz resonator

Description:
TECHNICAL FIELD 
     The present invention relates to an adjustable Helmholtz resonator configured for use with an internal combustion engine. 
     BACKGROUND OF THE INVENTION 
     Various methods may be employed to reduce the intake noise of an internal combustion engine. One method is to use a Helmholtz resonator on an intake air pipe configured to communicate intake air to the internal combustion engine. The intake air pipe is typically disposed upstream from an intake manifold and is configured to communicate intake air to the intake manifold of the internal combustion engine. A Helmholtz resonator includes a resonance volume or chamber having a small opening, typically referred to as a neck. The neck is operable to enable communication between the resonance chamber and the intake air pipe. Sound waves generated by components within the internal combustion engine travel along the intake air pipe where their acoustic pressure impinges on the neck and excites a mass of air within the neck. The acoustic pressure within the resonance chamber reacts against the air mass within the neck and produces an out-of-phase acoustic pressure at the intake air pipe to cause cancellation of intake noise at the resonant frequency. In this way, some of the engine noise is eliminated as the out-of-phase acoustic pressures in the intake air pipe cancel each other. 
     SUMMARY OF THE INVENTION 
     A Helmholtz resonator assembly is provided having a housing partially defining at least one volume and a first generally cylindrical sleeve member disposed within the housing and further defining the at least one volume. A second generally cylindrical sleeve member is generally coaxially disposed within the generally cylindrical first sleeve member and defines a passage through which a gas may pass. The second generally cylindrical sleeve member is selectively and variably movable between a first position and a second position with respect to the first generally cylindrical sleeve member. At least one orifice is defined by the first generally cylindrical sleeve member and at least one other orifice is defined by the second generally cylindrical sleeve member. The second generally cylindrical sleeve member is operable to substantially block the at least one orifice to prevent communication between the at least one volume and the passage when the second generally cylindrical sleeve member is in the first position. The at least one other orifice of the second generally cylindrical sleeve member is operable to unblock the at least one orifice to allow communication between the at least one volume and the passage when the second generally cylindrical sleeve member is in the second position. The at least one orifice, the at least one other orifice, and the at least one volume cooperate to form at least one Helmholtz resonator when the at least one orifice is unblocked by the second generally cylindrical sleeve member. An actuator responsive to signals from a controller may be provided. The actuator is preferably configured to selectively and variably move the second sleeve member between the first position and the second position. 
     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagrammatic illustration of an internal combustion engine having an intake system with an adjustable Helmholtz resonator assembly disposed therein; 
         FIG. 2  is a perspective three quarter sectional view of the adjustable Helmholtz resonator assembly, schematically depicted in  FIG. 1 , illustrating the Helmholtz resonator assembly in an inactive state; and 
         FIG. 3  is a perspective three quarter sectional view of the adjustable Helmholtz resonator assembly of  FIG. 2  illustrating the Helmholtz resonator assembly in an active state. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings wherein like reference numbers correspond to like or similar components throughout the several figures there is schematically depicted in  FIG. 1  an internal combustion engine  10 . The internal combustion engine  10  may be configured to operate in one of a spark-ignited or compression-ignited mode of operation. The internal combustion engine  10  includes an intake system  12  operable to communicate a gas, such as intake air  14  to a plurality of cylinders  16  defined by an engine block  18  of the internal combustion engine  10 . The internal combustion engine  10  further includes an exhaust system  20  operable to exhaust or extract products of combustion  22  from the cylinders  16 . 
     The intake system  12  includes an air box  24  configured to hold a filter element  26  operable to filter or remove particulate matter from the intake air  14  prior to introduction to a Helmholtz resonator assembly  28 . The Helmholtz resonator assembly  28  is configured to mount to a supercharger assembly  29 . The supercharger assembly  29  operates to increase the volume of intake air  14  communicated to an intake manifold  30  thereby increasing the volumetric efficiency of the internal combustion engine  10 . The intake manifold  30  is operable to distribute or communicate intake air  14  to the cylinders  16 . 
     The Helmholtz resonator assembly  28  is adjustable, that is, can be switched from an active state, wherein noise producing pressure pulsations within the intake air  14  are substantially attenuated, to an inactive state, wherein the noise producing pressure pulsations within the intake air  14  are not attenuated. This is especially beneficial in instances where the internal combustion engine  10  is supercharged. The supercharger  29  may produce a high pitched “whine” which may be objectionable to some individuals, but not others. The Helmholtz resonator assembly  28  allows the flexibility to selectively attenuate this whine should the vehicle operator find it objectionable. An actuator  32  is configured to adjust the Helmholtz resonator assembly  28  in response to signals received from a controller  34 . The construction and operation of the Helmholtz resonator  28  will be described in greater detail hereinbelow with reference to  FIGS. 2 through 3 . 
     Referring now to  FIGS. 2 and 3 , there is shown a three quarter sectional view of the Helmholtz resonator assembly  28 . The Helmholtz resonator assembly  28  includes a housing  36  partially defining a first, second, third, fourth, fifth, and sixth chamber or volume  38 ,  40 ,  42 ,  44 ,  46 , and  48 , respectively. A first generally cylindrical sleeve member  50  is disposed within the housing  36  and further defines each of the first, second, third, fourth, fifth, and sixth volumes  38 ,  40 ,  42 ,  44 ,  46 , and  48 . A second generally cylindrical sleeve member  52  is coaxially disposed within the first sleeve member  50 . The second sleeve member  52  is rotatably movable within the first sleeve member  50 , as indicated by arrows  54 . The second sleeve member  52  defines a passage  56  through which the intake air  14  passes. 
     The first sleeve member  50  defines a first, second, third, fourth, fifth, and sixth plurality of orifices  58 ,  60 ,  62 ,  64 ,  66 , and  68 , respectively, while the second sleeve member  52  defines a first, second, third, fourth, fifth, and sixth plurality of orifices  70 ,  72 ,  74 ,  76 ,  78 , and  80 , respectively. The second sleeve member  52  is movable between a first position, as shown in  FIG. 2 , and a second position, as shown in  FIG. 3 . With the second sleeve member  52  in the first position, the second sleeve member substantially blocks the first, second, third, fourth, fifth, and sixth volumes  38 ,  40 ,  42 ,  44 ,  46 , and  48  from communicating with the passage  56  through the first, second, third, fourth, fifth, and sixth plurality of orifices  58 ,  60 ,  62 ,  64 ,  66 , and  68 . Therefore, with the second sleeve member  52  in the first position the Helmholtz resonator assembly  28  is in an inactive state and no attenuation of noise producing pressure pulsations within the intake air  14  occurs. 
     With the second sleeve member  52  in the second position the first, second, third, fourth, fifth, and sixth plurality of orifices  58 ,  60 ,  62 ,  64 ,  66 , and  68  of the first sleeve member  50  are aligned with the first, second, third, fourth, fifth, and sixth plurality of orifices  70 ,  72 ,  74 ,  76 ,  78 , and  80  of the second sleeve member  52 . Therefore, the second sleeve member  52  allows the communication between the first, second, third, fourth, fifth, and sixth volumes  38 ,  40 ,  42 ,  44 ,  46 , and  48  and the passage  56 . As such, respective first, second, third, fourth, fifth, and sixth plurality of orifices  58 ,  60 ,  62 ,  64 ,  66 , and  68 ; first, second, third, fourth, fifth, and sixth plurality of orifices  70 ,  72 ,  74 ,  76 ,  78 , and  80 ; and first, second, third, fourth, fifth, and sixth volumes  38 ,  40 ,  42 ,  44 ,  46 , and  48  cooperate to form first, second, third, fourth, fifth, and sixth Helmholtz resonators  82 ,  84 ,  86 ,  88 ,  90 , and  92 , respectively, as shown in  FIG. 3 . Therefore, with the second sleeve member  52  in the second position the Helmholtz resonator assembly  28  is in an active state to allow the attenuation of noise producing pressure pulsations within the intake air  14  to occur. 
     The first, second, third, fourth, fifth, and sixth plurality of orifices  70 ,  72 ,  74 ,  76 ,  78 , and  80 , defined by the second sleeve member  52 , may include slot-like orifices to permit the second sleeve member  52  to unblock the first, second, third, fourth, fifth, and sixth plurality of orifices  58 ,  60 ,  62 ,  64 ,  66 , and  68  in a staggered or step-like fashion as the second sleeve moves from the first position to the second position thereby enabling variable tuning of the Helmholtz resonator assembly  28 . This is illustrated in  FIG. 3  by orifices  74 A and  76 A which are not in rotational alignment with one another. Therefore, as the second sleeve member  52  is rotated orifice  74 A will align with orifice  64  prior to orifice  76 A aligning with orifice  66 . As illustrated in  FIGS. 2 and 3 , the first, second, third, fourth, fifth, and sixth volumes  38 ,  40 ,  42 ,  44 ,  46 , and  48  are of different sizes; therefore, a plurality of frequencies may be attenuated by the Helmholtz resonator assembly  28  when in the active state. The housing  36  and the first and second sleeve members  50  and  52  are preferably formed from plastic. The housing is configured to be mounted within the intake system  12  of the internal combustion engine  10 , shown schematically in  FIG. 1 , by a coupling member  94 . The coupling member  94  is preferably formed from an elastomeric material such as rubber. Preferably, the actuator  32 , shown in  FIG. 1 , would effect movement of the second sleeve member  52 , through the coupling member  94 . In this way, a seal is maintained within the intake system  12  to prevent the leakage of ambient air into the intake air  14 . Actuation may be effected by pressing a lever, not shown, attached to the second sleeve member  52  through the coupling member  94 . Additionally, actuation may be effected via a solenoid, not shown, acting on the second sleeve member  52  via a ferrous plunger, not shown, or lever, not shown. Although the second sleeve member  52  is shown in  FIGS. 2 and 3  to rotate within the first sleeve member  50  between the first and second position, movement of the second sleeve member  52  in the axial position is also envisioned. In a preferred embodiment, the housing  36  and the first and second sleeve members  50  and  52  are formed from plastic; however, those skilled in the art will recognize other materials may be used, such as aluminum, while remaining within the scope of that which is claimed. 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.