Abstract:
An active intake manifold system includes at least one flap cartridge assembly having a unitary cartridge housing including one or more flap valve housings. A flap valve is rotatable in the aperture of the flap valve housing between an open state and a closed state. A shaft is provided extending through the mounting ear apertures of the flap valves so that the flap valves change state in unison. A plurality of air intake runners provides air flow communication between the outlets of the flap valve housings and the cylinder intake valves of the engine. Each intake runner includes a main runner portion that then splits into a plurality of tracts of differing lengths with each tract tuned to a different predetermined engine speed and having a length and volume selected to optimize engine performance at the predetermined speed. The flap valves may be automatically operated by an actuator under control of an engine control system.

Description:
TECHNICAL FIELD 
     The present invention relates to an air intake manifold for internal combustion engines and, more particularly, to active air intake manifold systems. 
     BACKGROUND OF THE INVENTION 
     The main function of an intake manifold is to distribute clean air—as far as possible, without pressure loss—from the air filter into the combustion chamber of the engine. As well as the throttle body, further components such as an air mass meter, sensors, EGR ducts, fuel rail and injection valves may be integrated into the complete air intake system. 
     A typical intake manifold may be mounted to a cylinder head of an engine includes a plenum and may include a one runner for each engine cylinder that distributes air flow from the manifold to the intake ports of each cylinder. For a given air intake manifold, engine performance (e.g., the location of the engine&#39;s torque peak in the RPM band) is a function of the volume of the plenum, the cross-sectional area of the runners and, to a lesser extent, the length of the runners. 
     Conventional intake manifolds employed on engines generally have fixed runner geometry. With a fixed intake system, the speed at which intake tuning occurs is also fixed. Since the engine operates over a broad RPM range, and since a different geometry may be ideal for different engine speeds, fixed geometry intake systems are designed with a geometry which is only optimal for a limited engine speed range, thus the engineer is forced to design a compromise between torque at low speeds and horsepower at high engine speeds. 
     In a tuned manifold, for example, the plenum volume, the length of the runners and the cross-sectional area of the runners may be selected so that a pressure wave formed within the runners has a resonant frequency that optimizes (or elevates) the intake pressure at each intake port when the corresponding intake valve opens, providing increased mass air flow to the cylinder. 
     One variable used to select the size and dimension of both the plenum and the runners is the engine size (i.e. the engine displacement). The total volume of an air intake manifold, which includes the volume of the plenum and the volume within the runners, is typically about twice the total engine displacement. 
     The performance and torque of internal combustion engines are significantly improved through the development of variable air intake manifolds which can switch between different runner lengths. A short runner optimizes performance at higher speeds, while a long runner provides favorable torque in the lower and medium speed ranges. 
     An active air intake manifold optimizes incoming airflow through a valve provided in the intake manifold. The valve controls flow to the intake tracts that correspond to desired engine-performance parameters. At low engine rotational speeds (RPMs), the valve creates a longer path for intake air, enhancing combustion efficiency and torque output. At higher engine rotational speeds, the valve opens, creating a shorter path for maximum engine power. 
     Active air intakes are particularly useful in adapting the intake manifold to significantly increase low speed engine torque, giving the engine a broader torque curve that retains higher specific torque output across the engine speed range. 
     Some intake system designs have been created to allow for variable intake geometry and have met with varying degrees of success. With these designs, the cost may be excessive for certain applications due to complex and costly design, either in fabrication or assembly. An example of a suitable but relatively more costly solution is disclosed in European Patent publication EP1135584. 
     Other lower cost designs may utilize slide valves or air flaps. Either type is typically driven by a vacuum actuator or an electric motor, usually under the control of an Engine Control Unit (ECU) computer. Designs of this type close and open only the short runner, closing the short runner at low speeds to improve engine low speed torque. 
     SUMMARY OF THE INVENTION 
     In one aspect of the invention, an active intake manifold system includes at least one flap cartridge assembly having a unitary (one piece formed) cartridge housing. The unitary cartridge housing includes one or more flap valve housings, each having an airflow aperture therethrough connecting a housing inlet and outlet. A flap valve is provided within and rotatable within the aperture of the flap valve housing. Each flap valve includes at least one mounting ear having an aperture therethrough. The mounting ears are secured to the flap valve. The flap valve in the flap valve housing is rotatable between an open state and a closed state, wherein when in the closed state the flap valve substantially prevents airflow through the flap valve housing aperture. The flap valves of a single flap cartridge assembly share a common axis of rotation. A shaft is provided extending through the mounting ear apertures of the flap valves to rotatably operate the flap valves. The mounting ears rotationally lock the flap valves to the shaft so the flap valves change state in unison. A plurality of air intake runners are provided to provide air flow communication between the outlets of the flap valve housings and the cylinder intake valves of the engine. Each intake runner includes a main runner portion that divides into a plurality of tracts of differing lengths with each tract tuned to a different predetermined engine speed and having a length and volume selected to optimize engine performance at the predetermined speed. Each tract is in air flow communication with a different flap valve housing outlet so that it may be individually controlled. For any intake runner only one associated flap valve at a time is in the open state, which is to say that only one tract of the air intake runner is in air flow communication between the flap cartridge assembly/air intake duct and the engine cylinder intake valve or valves. The flap valves, through the rotary shaft, may be automatically operated by an actuator which may be under the control of an engine management system. 
     In another aspect of the invention, the inlets of the flap valve housings are secured to and in air flow communication with an air intake duct. 
     In another aspect of the invention, the flap valve housings of each unitary cartridge housing are arranged linearly side by side in alignment with the flap valve axis of rotation. 
     In another aspect of the invention, when a portion of said flap valves on the shaft are in the closed state, a different portion of the flap valves are in the open state. 
     In another aspect of the invention, each tract of the intake runner is connected to a different flap cartridge assembly. The flap valves in the flap cartridge assemblies are synchronized such that for any given intake runner only one tract has a flap valve in the open state at a time. 
     In another aspect of the invention, synchronization between different flap cartridge assemblies is provided by a mechanical linkage connecting the shafts of the flap cartridge assemblies such that the shafts rotate in unison. 
     In another aspect of the invention, the plurality of tracts to a particular engine cylinder intake include a long tract and a short tract. 
     In another aspect of the invention, at least one bearing cartridge is sized and configured to be inserted into bearing receptacles provided in the unitary cartridge housing. The bearing cartridge includes a bearing aperture sized and configured to permit the shaft to supportively pass through and rotate in the bearing, thereby rotatably supporting the flap valves in the flap valve housings. 
     In another aspect of the invention, the bearing cartridge includes an elastomeric material which resiliently contacts the bearing receptacle walls thereby preventing air leakage around the bearing cartridge. 
     In another aspect of the invention, the bearing receptacles are arch-shaped and the bearing cartridges are shaped and configured to be received into the arch-shaped bearing receptacles. 
     In another aspect of the invention, each of the tracts is ultrasonic welded to a different one of the flap valve housing. 
     In another aspect of the invention, the flap valves of each flap valve cartridge assembly are configured to be positioned in alternating open-closed states along the common axis of shaft rotation. 
     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  presents a schematic diagram of an active intake manifold interfaced to an internal combustion engine, consistent with the present invention; 
         FIG. 2A  is an exploded view of an exemplary embodiment of a flap cartridge assembly, consistent with the present invention; 
         FIG. 2B  depicts an exemplary embodiment of a bearing assembly for the flap cartridge assembly of  FIG. 2A , consistent with the present invention; 
         FIG. 3A  is a perspective view of two exemplary fully assembled flap cartridge assemblies previously shown as exploded components in  FIGS. 2A and 2B , consistent with the present invention; and 
         FIG. 3B  is a side view with a partial cutaway illustrating an exemplary two tract intake runner for connection between a flap cartridge assembly and an engine cylinder head intake valve connection, consistent with the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An improved active intake manifold flap cartridge system is disclosed. A method of assembling a flap cartridge system is also disclosed. The active intake manifold flap cartridge system of the present invention is adapted to effectively switch intake air flow between intake tracts of varying lengths while blocking off the unused tracts while further providing a system that is low in cost. The invention is particularly useful in automotive and commercial vehicle applications where an active manifold is desirable to optimize engine performance at higher speeds, while providing favorable torque in the lower and medium speed ranges. 
     The invention differs from the prior art by providing a low cost active manifold system without resorting to the use of more costly and complex designs such as barrel valves and complex rotary tract length tuning systems. 
     The invention further differs from the prior art by providing a low cost switchable dual flap valve cartridge assembly that effectively switches between the longer and shorter intake tracts of an air intake runner while closing off the unused intake tract or tracts. Prior art designs provide valve assemblies utilizing a barrel valve or single flap that does not close off the long intake runner when the short runner is activated. From an intake runner tuning and engine performance standpoint, it is desirable to close off, for example, the long intake runner when the short runner is active. This is an object of the present invention. 
     The present invention includes innovative insertable elastomeric bearing cartridges that support the shaft and flap valves while effectively preventing leakage between neighboring runners around the bearing cartridges. 
       FIG. 1  presents a schematic diagram of an active intake manifold interfaced to an internal combustion engine, consistent with the present invention. In  FIG. 1 , intake air  118  is provided through an air intake duct  106  to a distribution chamber  120 . Intake air  118  is typically filtered upstream by an air filter/air cleaner assembly (not shown). Distribution chamber  120  may be a separate member to which the air intake duct  106  is in air flow communication, or alternately the distribution chamber  120  may be realized as a portion of the air intake duct  106 . 
     One or more flap cartridge assemblies  108  may be provided on the distribution chamber. Each cartridge assembly  108  includes at least one flap valve housing  122  including a rotationally actuated flap valve  130  rotatably actuated by a shaft  126 . In exemplary embodiments of the invention, the shaft  126  may extend through a plurality of adjacent flap valve housings  122  that make up the flap cartridge assembly  108 . The shaft  126  synchronizes the actuation of a plurality of flap valves  130  in the flap cartridge assembly  108 . 
     In an exemplary embodiment schematically illustrated in  FIG. 1 , two flap cartridge assemblies  108  are illustrated, each having four synchronized sets of flap valves  130  provided in a unitary cartridge housing  240  (see  FIG. 2 ). To illustrate the inventive concept in the drawing, a specific configuration for the illustration was chosen. It is to be understood that the present invention is not limited to flap cartridge assemblies having four synchronized flap valves  130 , but instead any number of flap valves  130  may be included in a single flap cartridge assembly  108 . 
     A plurality of air intake runners  128 A-D extends between the flap cartridge assemblies  108  and the cylinder heads (not shown) of internal combustion engine  116 . Typically each runner is designed to supply filtered intake air to a designated cylinder (not shown) through the engine cylinder head intake valve or valves (not shown). In the illustrated specific embodiment of the present invention, each runner  128 A-D bifurcates into corresponding long tract  102 A-D and short tract  104 A-D portions. It is to be understood that, in general, air intake runners may split in any number of differing length tracts without deviating from the present invention. 
     As discussed earlier, the air intake runners  128 A-D together with the flap valves  130  are configured to optimize engine performance. Depending typically on engine speed, the flap valves  130  direct intake airflow to either the long intake tract  102 A-D or alternately the short intake tract  104 A-D. At low engine rotational speeds (RPMs), the long tract  102 A-D is utilized to enhance combustion efficiency and torque output. At higher engine rotational speeds the short tract  104 A-D is utilized to create a shorter path with a higher resonant air wavefront frequency for maximum engine power. 
     The flap valves  130  are synchronized such that, for each air intake runner  128 A-D, only one of the corresponding short tract  104 A-D or long tract  102 A-D is open for air flow at a given time. For example, runner  128 A has a short tract  104 A and a long tract  102 A.  FIG. 1  illustrates flap valve  130  at long tract  102 A in the open position (see Legend) while the short tract  104 A flap valve  130  is illustrated in the closed position (see Legend). Similarly, the flap valves  130  are synchronized such that all runners  128 A-D switch between the short tract  104 A-D and the long tract  102 A-D simultaneously, as is illustrated in  FIG. 1 . 
     A shaft  126  extends through the flap valves  130  of the flap valve assembly  108  and synchronizes operation of all flap valves  130  of the assembly. Where a portion of the flap valves  130  are provided on additional flap cartridge assemblies (ex: two assemblies  108  illustrated in  FIG. 1 , corresponding to two tracts per engine cylinder of the illustrated embodiment), the shafts  126  may be synchronized by a mechanical linkage  112  interconnecting the shafts  126  of the flap cartridge assemblies  108 . The flap valves  130  may be actuated by a actuator  114  which may be a vacuum actuator (as illustrated), an electric motor, solenoid actuator or other types of actuators as would be known to those skilled in the art. 
       FIG. 2A  is an exploded view of an exemplary embodiment of a flap cartridge assembly  208 , consistent with the present invention.  FIG. 2B  depicts an exemplary embodiment of a bearing cartridge  246  for the flap cartridge assembly  208  of  FIG. 2A , consistent with the present invention. Flap cartridge assembly  208  is one illustratory exemplary embodiment of the flap cartridge assembly  108  discussed with  FIG. 1 . Other aspects of the invention may differ in the number of flap valves  230 , the flap valve housing  242  shape as well as the general arrangement of flap valve housings  242  in the flap cartridge assembly  208 . The assembly view of flap cartridge  208  illustrates several features of the invention. As will be discussed and shown in further detail with other Figures, the flap cartridge assembly includes a unitary cartridge housing  240  integrating a plurality of flap valve housings  242 . The unitary cartridge housing  240  may be provided from a moldable plastic material and formed in one piece using a technology such as injection molding. As illustrated in  FIG. 2A , the flap valves  230  each include one or more mounting ears  244  having an aperture therethrough, the mounting ears configured to mount the flap valves  230  to the shaft  210 . Bearing cartridges  246  are configured and adapted to be received into arch shaped bearing receptacles  248  provided in the cartridge housing  240 . In an exemplary embodiment the bearing cartridges  246  are made of an elastomeric material with a plastic or metallic bearing  250  secured to the bearing cartridge  246 , and have an aperture  252  sized and configured to receive, support and provide an air flow seal around the shaft  210 . The elastomer based bearing cartridge  246  advantageously prevents the shaft  210  from binding as the elastomeric bearing cartridge  246  is able to flex to compensate for tolerance and alignment issues and its elastomeric properties additionally provide a seal between the flap valve housings  242  and the bearing cartridge  246 . The mounting ears  244  may be secured to the shaft  210  by any means know to those skilled in the art including laser welding, gluing, etc. such that the flap valves  230  are configured to rotate in lock step with the shaft  210 . 
     The flap cartridge assembly  208  may be assembled as follows. First the bearing cartridges  246  are positioned into the bearing receptacles  248  of the cartridge housing  240 . The flap valves  230  are then set into the cartridge housing  240  and the shaft  210  is then inserted through the bearings  250  and the mounting ears  244  of the flap valves  230 . The mounting ears may be locked to the shaft using any method including press fit design of the ear apertures on the shaft, gluing or laser welding the mounting ears onto the shaft, or any other method as would be known to one skilled in the art. The assembled flap cartridge assembly  208  may then be secured to the air intake manifold  106  or distribution chamber  120  (see schematic illustration  FIG. 1 ) using any known technique including vibration welding, ultrasonic welding, adhesives or other techniques as known to one skilled in the art such that inlets of the flap valve housings  122  are in air flow communication with the air intake duct  106 . 
       FIG. 3A  is a perspective view of two exemplary fully assembled flap cartridge assemblies  208 , previously shown as exploded components in  FIGS. 2A and 2B . The rotary position of the shafts  210  (and therefore the position of the flap valves  230 ) are synchronized by a linkage member  212  rotationally linking the two shafts  210  so as to rotate in unison. 
       FIG. 3B  is a side view with a partial cutaway illustrating an exemplary two tract intake runner  228  (shown schematically as  128 A-D in  FIG. 1 ) for air flow connection between an outlet of flap valve housing  242  of flap cartridge assemblies  208  and the cylinder head intake valve of an engine  116  (see  FIG. 1 ). In particular,  FIG. 3B  illustrates a two tract intake runner  228  having its short tract  204  connected to an outlet of the flap valve housing  242 A (see also  FIG. 2A ) and its long tract connected to an outlet of the flap valve housing  242 B (see also  FIG. 2A ). As is depicted in  FIG. 3A , the flap valve  230 B is depicted in the closed position (closing off long tract  202 ) and the flap valve  230 A is depicted in the open position (open to short tract  204 ). As discussed earlier with  FIG. 1 , either the long tract  202  or the short tract  204  is in an open state as the flap valves are positioned  90  degrees out of phase with each other on the shafts  210 . In an exemplary embodiment, the short tract  204  and long tract  202  are ultrasonic welded to outlets of flap valve housings  242 A and  242 B respectively. The tracts may be secured to the flap valve housings using any other means as would be known to one skilled in the art, including hot plate welding, laser welding, ultrasonic welding, adhesives and other means. The remaining two tract intake runners would be positioned in alternating left-right fashion and secured to their respective flap valve housings as described above and as illustrated schematically in  FIG. 1 . 
     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.