Abstract:
An integrated intake manifold assembly including a first poppet valve assembly disposed at the air inlet to the manifold to regulate air flow into the manifold; a second poppet valve assembly disposed on the manifold to regulate exhaust gas flow into the air intake system; and a bi-directional camshaft with cams for operating simultaneously the manifold vacuum regulating the poppet valves. The valve bodies are integrally formed in the wall of the intake manifold. The cams are arranged on the shaft to provide optimum synchronized opening and closing of the related valves. When used on a diesel engine, the manifold assembly may further include a swirl valve plate disposed between the manifold and the engine head and having a plurality of ganged swirl valves actuated by levers, connected to the camshaft internally of the manifold and swirl plate, for coordinated motion with the MVR and EGR valves. The valve poppets of the MVR and EGR valves are actuated by finger followers actuated by the camshaft to eliminate side loading of the valve stems.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Patent Application No. 60/301,734, filed Jun. 28, 2001. 
    
    
     TECHNICAL FIELD 
     The present invention relates to systems and apparatus for managing gas flow through internal combustion engines; more particularly, to one or more valving devices associated with the intake manifold of an internal combustion engine; and most particularly, to an intake manifold assembly for an internal combustion engine wherein at least one of an exhaust gas recirculation valve and a manifold inlet air control valve is a poppet valve actuated by a finger follower responsive to a cam lobe on a camshaft. 
     BACKGROUND OF THE INVENTION 
     It is a characteristic of diesel engines and some variable valve lift gasoline engines that virtually no vacuum exists in the intake manifolds of such engines. The lack of vacuum creates problems in providing vacuum-assisted functions for applications such as automotive vehicles, marine vessels, and stationary power generators. A conventional gasoline-powered engine includes a throttle valve at the inlet to the intake manifold to control the flow of air into the engine and thereby to regulate the speed of the engine. Such throttling of the inlet variably creates a subatmospheric condition in the manifold. Recirculation of exhaust gas into the intake manifold uses a pressure drop between the exhaust manifold and the intake manifold to draw exhaust gas into the intake manifold. Such a pressure drop is virtually non-existent in an unmodified diesel engine and also in a gasoline engine wherein gas flow is controlled by varying the lift of the intake valves. 
     It is known to create manifold vacuum in a diesel intake manifold by providing an air control valve at the manifold inlet, typically a rotary butterfly-type valve. Such a valve is typically actuated by an electric motor and gear train or a stepper motor and is provided as a subassembly which must be attached to the manifold as by bolting and which requires its own power and control connections in a wiring harness. Disadvantageously, a rotary butterfly valve has a highly non-linear flow profile as a function of valve angle; is difficult to close completely without jamming; and typically passes significant air flow in the “closed” position. 
     It is further known to provide an exhaust gas recirculation (EGR) valve having its own actuator and valve body which also must be bolted to the intake manifold. EGR valves typically are actuated by an electric solenoid in either a position-modulated or time-modulated mode, requiring additional and separate power and control connections. Further, such solenoids are known to be vulnerable to failure from corrosion by permeated exhaust gas. Prior art EGR valves provide exhaust gas globally to the interior of the intake manifold which then distributes the gas along with intake air via runners to the individual cylinders. 
     It is further known to provide dual intake ports to each diesel cylinder, one such port being open at all times and the other such port being closable by a butterfly-type “swirl” valve. The ports are off-axis of the cylinders such that when the swirl valves are closed, as under low engine load conditions, air entering the cylinder is swirled advantageously to center the fuel charge in the cylinder. Typically, the individual swirl valves are actuated by, for example, electrically-powered rotary actuators similar to that known for a throttle valve. 
     It is a principal object of the present invention to simplify an air intake manifold and associated control valving for a diesel engine to reduce manufacturing cost, ease assembly, improve and integrate air control through an engine, and increase engine reliability. 
     It is a further object of the invention to reduce side-loading on a poppet valve in an air intake manifold by actuating such a valve via a rotatable cam lobe and a finger follower mounted on the manifold. 
     SUMMARY OF THE INVENTION 
     Briefly described, an integrated intake manifold assembly in accordance with the invention includes a poppet manifold vacuum regulating valve (MVR valve) disposed at the air inlet to the manifold to regulate air flow into the manifold; a poppet EGR valve disposed on the manifold to regulate exhaust gas flow into the air intake system; and a bi-directional camshaft and cams for operating simultaneously the MVR valve and the EGR valve. At least one of the poppet valves is actuated by an intermediary finger follower disposed between the cam lobe and the valve poppet, and pivotable from a mounting on the intake manifold. The valve bodies are integrally formed in the wall of the intake manifold. The camshaft is driven by a single brush DC motor and gear train. The cams are arranged on the shaft to provide optimum synchronized opening and closing of the related valves. The cams may also be individually shaped as needed to optimize the actuation profile of each valve. When used on a diesel engine, the assembly may further include a swirl valve plate disposed between the manifold and the engine head and having a plurality of ganged swirl valves actuated by linkage connected to the camshaft and internal to the manifold and swirl plate. Preferably, the swirl valve plate is also ported as a distribution rail to receive exhaust gas from the EGR valve and distribute it to the individual cylinders, bypassing altogether the interior of the intake manifold and obviating soot deposits in the manifold. 
     An integrated intake manifold assembly in accordance with the invention, when compared to prior art assemblies of stand-alone components, eliminates eight bolts and two gaskets; eliminates two actuators and related wiring; eliminates vacuum actuation and hoses; reduces soot in the air intake system, protecting air components; reduces electrical connections to two; simplifies manufacture and assembly; and reduces the overall size and mass of the air control system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the invention will be more fully understood and appreciated from the following description of certain exemplary embodiments of the invention taken together with the accompanying drawings, in which: 
     FIG. 1 is an isometric view from above of an embodiment of the invention, including an associated swirl plate; 
     FIG. 2 is an isometric view like that shown in FIG. 1 but taken from the opposite side of the embodiment, showing the swirl plate-and swirl valves; 
     FIG. 3 is a plan view of the embodiment from above, without the swirl plate; 
     FIG. 4 is a plan view of the embodiment from below, without the swirl plate; 
     FIG. 5 is an isometric view of the operative mechanism contained in the embodiment as shown in FIG. 1, taken from the same point of view with the manifold omitted; 
     FIG. 6 is an elevational cross-sectional view of the embodiment shown in FIGS. 1 through 5, taken along line  6 — 6  in FIG. 3; 
     FIG. 7 is an elevational view of the embodiment, showing the locations of various cross-sections taken in the following drawings; 
     FIG. 8 is an elevational cross-sectional view of a currently preferred arrangement of linkage between the camshaft and the swirl valve shaft contained within the intake manifold and the swirl plate, showing also the distribution of exhaust gas from the EGR valve through an exhaust gas distribution rail; 
     FIG. 9 is an elevational cross-sectional view of the manifold vacuum regulation valve, taken along line  9 — 9  in FIG. 7; 
     FIG. 10 is an elevational cross-sectional view of the exhaust gas recirculation valve, taken along line  10 — 10  in FIG. 7; 
     FIG. 11 is a detailed elevational cross-sectional view of the manifold vacuum regulation valve, showing the incorporation of a reciprocating yoke to limit side-loading of the valve stem in its sleeve bearing; 
     FIG. 12 is an elevational cross-sectional view of the motor and gear train which actuates the camshaft, taken along line  12 — 12  in FIG. 7; 
     FIG. 13 is an end view of the embodiment, taken from the electromechanical drive end; 
     FIG. 14 is a cross-sectional view taken along line  14 — 14  in FIG. 13, showing the relationships among the drive motor, gear train, and camshaft; 
     FIG. 15 is a graph showing actuation curves for the swirl valves, manifold vacuum regulation valve, and exhaust gas recirculation valve as optimized for an exemplary diesel engine; 
     FIGS. 16 through 19 are isometric views from above of the swirl valve control subassembly at four different stages of camshaft rotation; 
     FIG. 20 is an elevational cross-sectional view of a finger follower assembly for actuating a poppet valve head, such as the MVR valve head, in accordance with the invention; and 
     FIG. 21 is an elevational cross-sectional view of a finger follower assembly for actuating a poppet valve pintle, such as the EGR valve pintle, in accordance with the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description, the embodiment is assumed to be oriented such that an associated engine is beside, and an exhaust manifold below, the embodiment. The use of the terms up, down, upper, lower, above, and below assume such an orientation. 
     Referring to FIGS. 1 through 4, an integrated intake manifold assembly  10  in accordance with the invention includes an intake manifold element  12  preferably formed as by die casting of metal such as aluminum alloy. Formed integrally with element  12  are a first housing  14  for a MVR valve assembly  16 ; a second housing  18  for an EGR valve assembly  20 ; a third housing  22  for a drive motor (not visible in these drawings); a fourth housing  24  for a gear train (also not visible); a fifth housing  26  for a lever actuator  28  attached to a camshaft  82 ; a first mounting flange  30  for attaching assembly  10  to an engine block or head  32 ; a second mounting flange  34  for attaching assembly  10  to an exhaust manifold  36 ; and a receptacle  38  for mounting of a manifold vacuum sensor  40  having an electrical connector  42  for conventional connection to an engine control module (ECM) (not shown). Unlike prior art intake manifolds in which MVR valves and EGR valves are assembled onto a manifold and require independent electrical actuation, position sensing, and control, the present MVR and EGR valves are integrally formed into the manifold itself and mechanically actuated by a common camshaft, as described further below. 
     Attached to, but separate from, integrated intake manifold assembly  10  is a swirl valve plate  44  disposed between assembly  10  and engine  32 . Plate  44  includes first ports  46 , for distributing air from manifold  12  into each of four engine cylinders (not shown) under low engine load, and second ports  48  in flow parallel with first ports  46  for providing additional air under high load conditions. Air flow from manifold  12  through second ports  48  may be regulated by swirl control valves  50  which are ganged for unified action by being mounted on a single control shaft  52  extending through axially aligned bores  54  in plate  44 . A link  56  connects first lever actuator  28  with a similar second lever actuator  58  (FIGS. 8,  18 , and  19 ) attached to shaft  52 . When valves  50  are closed, air is introduced tangentially to the cylinders only via ports  46 , causing a swirling motion which tends to desirably center the fuel charge on the piston. Under high air and fuel volumes, when valves  50  are open, such swirling is unimportant and is eliminated. 
     Such linkage may be attached to actuator  28  either above the axis of rotation, as shown for example in FIGS. 1,  2 ,  5 , and  16 - 19 , or below the axis of rotation, as shown in FIG.  8 . The currently preferred arrangement shown in FIG. 8 allows for the actuation of a swirl-port system with no linkages external to the intake manifold. All of the components of this mechanism thus may be hidden internally, within the intake manifold and swirl plate, by appropriately configuring the manifold in known fashion. After the assembly is mounted to the engine, all moving parts are concealed and protected from the environment, providing a safe, robust assembly. 
     Preferably, plate  44  is also provided with a longitudinal channel  60  matable with a similar channel  62  formed in assembly  10  to form an exhaust gas distribution rail  64  supplied with exhaust gas via an exhaust gas conduit  66  from EGR valve assembly  20 . Rail  64  is connected via individual runners (not visible) to each of first ports  46  for dispensing exhaust gas into each of the cylinders of engine  32 . This arrangement thus accomplishes controlled exhaust gas recirculation to the cylinders without exposing the interior of the intake manifold to soot and corrosive oxides. Of course, for simplicity of construction, an integrated EGR valve assembly  20  in accordance with the invention may simply feed exhaust gas via a conduit  66 ′ analogous to conduit  66  directly into intake manifold  12  for distribution with air into the cylinders, as in the prior art. Further, in some applications of the invention to spark-ignited gasoline powered engines, the swirl plate is not needed and distribution of EGR to the individual cylinders is not required, in which case assembly  10  is mounted directly onto engine  32 , and conduit  66 ′ represents the preferred embodiment. 
     In gasoline engines throttled by variable valve lift, valve assembly  16  may function as a manifold vacuum regulating valve, substantially as in a diesel engine as described herein. However, in gasoline engines throttled conventionally by a manifold inlet valve, an integrated intake manifold assembly in accordance with the invention may be usefully adapted for conventional throttle control by valve assembly  16 . 
     Referring to FIGS. 5,  6 ,  13 , and  14 , the mechanism  68  of the invention is housed in the various integrated housings formed in manifold  12 , as recited above. 
     The power train is a conventional motor and reduction gear train. A single brush DC motor  70 , housed in third housing  22 , is provided with a first pinion gear  72  which meshes with first ring gear  74  mounted on an idle shaft  76 . Second pinion gear  78 , attached to first ring gear  74 , meshes with second ring gear  80  which is mounted on camshaft  82  via an output spring  84 . A camshaft position sensor  79  is disposed on the proximal end  81  of camshaft  82 . The gear train and position sensor are housed in a cover  83  boltable to the intake manifold. An electrical connector  85  provides power and operating signals to the motor and carries information from position sensor  79  to the ECM. 
     Camshaft  82  is journalled in three sets of ball bearings  87  retained in bearing mounts formed in intake manifold  12  and rotates about an axis  77 . MVR cam  86  and EGR cam  88 , having throughbores, are mounted on camshaft  82  at predetermined axial locations and at a predetermined angular relationship to each other. After the cams have been properly positioned during assembly, they are fixed in place by set screws  90 . Preferably, after assembly and testing, the cams are drilled and pinned  91  to the camshaft. 
     Referring also to FIGS. 9 and 11, manifold vacuum regulating valve assembly  16  includes a poppet valve head  92  for mating with seat  94  formed integrally with manifold  12 . Seat  94  is formed in a bore  96  defining an air inlet to manifold  12 . A valve pintle  98  extends from the underside of poppet head  92  and is received in a pintle bearing insert  100  disposed in a cylindrical boss  102  formed in manifold  12  for guiding the pintle and head along a first axis of motion  103  orthogonal to camshaft axis  77  during actuation of the valve. A return spring  104  surrounds boss  102  and is seated against a step in boss  102  for urging head  92  toward seat  94 , to a normally-closed position. Poppet valve head  92  is further provided with a slot and transverse bore for receiving a roller  106  and pin  107  for following the surface of MVR cam  86 . In FIGS. 5,  6 ,  9 , and  11 , MVR valve assembly  16  is shown in the open position, permitting the passage of air through inlet bore  96  into intake manifold  12 . 
     Preferably, spring  104  is selected and the valve head and seat are constructed such that assembly  16  is fully closed when the engine is shut down. This prevents entry of additional air into the engine, important for some gasoline engines in preventing the well-known “diesel” effect of continued compressive running after the ignition is off. Prior art butterfly-type manifold entry valves are incapable of providing this advantage. Additionally, the spring strength of spring  104  is preferably selected such that, in the event of valve control failure, the valve can be forced open by air compressed by a diesel supercharger and the engine can continue to run although non-optimally. 
     Referring again to FIGS. 5 and 6, and additionally FIG. 10, exhaust gas recirculation valve assembly  20  includes a poppet valve head  108  for mating with seat  110  inserted into a step  112  in a bell-shaped valve body  114  formed integrally with manifold  12 . Body  114  terminates at its lower end in flange  34 , as recited above, for mounting onto exhaust manifold  36 . A valve pintle  116  extends through poppet head  108  and is secured thereto by nut  109 , which sets the tolerance stack-up in the valve assembly. Further, pintle  116  extends from the upper side of poppet head  108  and is received in a stepped bore  118  formed in manifold  12  for guiding the pintle and head along a second axis of motion  119  orthogonal to camshaft axis  77  during actuation of the valve. A return spring  120  surrounds pintle  116  and is captured between a pintle bearing insert  122  and an annular flange  124  on pintle  116  for urging head  108  toward seat  110 , to a normally-closed position. The upper end of pintle  116  is further provided with a slot and transverse bore for receiving a roller  126  and pin  127  for following the surface of EGR cam  88 . Referring again to FIG. 8, first conduit  66  connects EGR valve assembly  20  to exhaust gas rail  64 . In FIGS. 5,  6 , and  10 , EGR valve assembly  20  is shown in the closed position, preventing the passage of exhaust gas through flange  34  into exhaust gas rail  64 . 
     Referring to FIG. 10, preferably EGR cam  88  is provided with a hook portion  128  which engages and captures roller  126  when cam  88  is rotated sufficiently counterclockwise, thereby mechanically locking assembly  20  in a closed position. 
     Referring again to FIGS. 5,  6 , and  11 , each of valve poppets in assemblies  16 ,  20  is provided with a yoke element  130  extending from either the valve head (MVR valve head  92 ) or the valve pintle (EGR valve pintle  116 ) toward camshaft  82  and terminating in flat fork tines  132  which embrace the camshaft and preferably are slidingly fitted against their respective cam lobes  86 , 88 . If desired, additional stiffness of the tines may be obtained by connecting the tines with a strap  134 , as shown in FIG.  11 . The tines thus provide lateral support to the valve pintles  98 ,  116  at their upper ends and thereby inhibit side loading of the pintles by the rotary action of the cam lobes. This reduces wear on the pintles and pintle bearings and increases the working life and reliability of the valves. 
     FIG. 15 shows the operation of an integrated intake manifold assembly in accordance with the invention. Exemplary actuation curves for the swirl valve shaft  52 , MVR valve  16 , and EGR valve  20  are shown for a typical diesel engine application. Also refer to FIGS. 16 through 19 wherein the accompanying action of the swirl valve control subassembly  138  is shown. Relative valve position is shown in FIG. 15 as a function of camshaft position. Arbitrarily, the curves represent full engine speed at the far left (270° of camshaft rotation) and engine shutdown at the far right (0° of camshaft rotation). 
     Beginning at maximum engine speed and air flow, shown at the far left of FIG. 15, the swirl valves  50  (FIG. 16) and the MVR are fully open. There is no exhaust gas recirculation. The EGR valve is both closed and locked shut by hook  128  to prevent its being forced open by high intake manifold pressures from the engine turbocharger which would limit the effectiveness of the turbocharger. 
     Because first lever actuator  28  has an arcuate slotted opening  136  for connection to link  56 , the camshaft and swirl control body  140  are able to rotate counterclockwise sufficiently (about 20°) to unlock the EGR valve before link  56  becomes engaged in controlling the swirl valves. First torsion spring  142  is disposed in torsional compression on body  140  between notch  144  and pin extension  146  (see also FIG.  5 ), thus urging link  56  toward the valve-closed position shown in FIGS. 16 and 17. Second torsion spring  148  is also disposed in torsional compression on body  140  between lever actuator  28  and a recess in manifold  12  (not shown) but is counter-wound from spring  142 . Spring  148  urges actuator  28  counterclockwise as seen in FIGS. 16-19 (springs omitted or partially omitted in FIGS. 17-19 for clarity). 
     Camshaft  82  is provided with a radial tang  150  which can engage an axial tang  152  extending from body  140 . In the 0° camshaft position shown in FIG. 16, body  140  and actuator  28  are are rotated by the camshaft such that the EGR valve is both closed and locked shut by hook  128 , as shown in FIG.  10 . 
     As engine load is decreased (camshaft begins to rotate counterclockwise), the EGR valve is unlocked in the first 25° of rotation. Because first lever actuator  28  has arcuate slotted opening  136  for connection to link  56 , the camshaft is able to rotate clockwise sufficiently to unlock the EGR valve without beginning to close the swirl valves, as shown in FIG.  17 . Link  56  becomes engaged by actuator  28  at the right end of slot  136 . 
     Between about 25° and 45° of rotation, link  56  is drawn counterclockwise by actuating lever  28 , closing the swirl valves completely, as shown in FIG. 18, and the engine thus becomes supplied with air solely through first ports  46  (FIG.  2 ). The link is now prevented by the closing of the swirl valves from traveling farther, so further rotation of body  140  is prevented; the camshaft, however, may continue to be rotated within body  140 , as body  140  is rotatably disposed on sealed bearings  141  (FIG. 6) mounted on camshaft  82 . As camshaft rotation continues, tang  150  separates from tang  152 , as shown in FIG.  19 . 
     At about 50° of camshaft rotation, the EGR valve begins to open, adding exhaust gas to the air entering the cylinders. The MVR valve remains wide open until about 90° of rotation, then begins to close. Because the MVR valve is a poppet valve rather than a conventional rotary butterfly valve, the open area of the valve between the seat and head is cylindrical and therefore flow through the valve is linear with respect to pintle motion, and the slope of the curve is readily controlled by appropriately shaping the MVR cam lobe. 
     The normal operating range of the engine is typically between cam positions of about 100° and 150°. Beyond about 180°, the MVR valve is fully closed (no fresh air is being admitted to the engine) and the EGR valve is fully open. Such a condition may be useful during non-combustive periods, such as going downhill, when fuel is withheld from the cylinders and recirculation of stale exhaust gas can progressively cool the engine cylinders. 
     Finally, at engine shutdown, the camshaft is rotated to about 270° to the position shown in FIG.  19  and the swirl, MVR, and EGR valves are closed. When the engine is restarted, the camshaft is automatically rotated clock wise through a predetermined angle to provide optimal opening settings for the MVR and EGR valves, the swirl valves remaining closed until high engine speed is again required. 
     Referring to FIGS. 20 and 21, side-loading of the valve poppets  155 ,  157  alternatively may be eliminated (instead of employing yokes  130  as described hereinabove) by displacing the axis of the valve assembly and poppet from intersecting the axis of the camshaft and installing a finger follower  154  between the cam lobe and the poppet, similar to the fashion in which engine intake valves are actuated. The pad  156  of the finger follower, because it is pivoted from a remote pivot  158 , preferably a conventional hydraulic lash adjuster  160 , has an actuation path which is essentially linear over the length of the valve stroke. Thus, substantially all side-loading of the poppet within its bearing, as shown in FIGS. 9 and 10, is eliminated. Preferably, finger follower  154  includes a roller  162 , analogous to rollers  106 ,  126 , for following the surface of the actuating cam lobe. Preferably, rollers  106 , 126  are excluded from this embodiment. MVR poppet  155  may include a pintle extension  164  for optimal positioning of said valve within said manifold  12 . 
     All the recited camshaft positions are programmed into a conventional engine control module in known fashion, which module receives various engine inputs including manifold pressure signals from sensor  40  and cam position signals from sensor  79 . The ECM controls the action of motor  70  responsive to these and other signals and algorithms stored therein. 
     While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.