Abstract:
A modular intake manifold for an internal combustion engine that has a lower base member, a center runner section, and an upper shell. The lower base member has a series of outlets and witness marks formed within the outlets and attaches to an engine between right and left cylinder heads. The center runner section is situated within the base member for channeling incoming air into the series of outlets in the lower base member. The upper shell attaches to the lower base member, includes a throttle body mounting boss, seals and isolates the individual runner sections of the center runner section, and encloses the intake manifold. The intake manifold may be assembled and disassembled freely. Once disassembled, a different upper shell or center runner section, each having differing features from the components previously removed, may be reattached to the lower base member to alter the engine performance in some way.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an intake manifold for an internal combustion engine and, more particularly, to a manifold having interchangeable parts capable of disassembly and reassembly. 
     2. Discussion of Related Art 
     Internal combustion engines generally include an intake manifold. The intake manifold directs air or a fuel and air mixture into the cylinders of the engines where the fuel and air mixture is combusted, releasing mechanical energy to power the engine. 
     Traditionally, intake manifolds have been made by either casting metals into a single component or by forming plastics or polymers into several different pieces that are then permanently bonded together by, for example, friction welding. Any subsequent attempt to disassemble either of the traditional types results in severe damage to the intake manifold. Therefore, these construction types precluded the intake manifold from being tuned to alter engine performance in any way alterations such as clearing or removing excess metal or other material or removing and discarding the current intake manifold and obtaining and installing a new intake manifold. Such replacement is both costly and wasteful. Additionally, removal of the old intake manifold destroys the seal between the intake manifold and the engine. This exposes internal components of the engine to external debris and contamination. Currently, then, in order to tune engine performance by means of the intake manifold, a user must essentially purchase an entirely new intake manifold part and subject the engine to potential damage from external contamination. Therefore, tuning by manipulation of the intake manifold, i.e., intake runner length or intake diameter, becomes financially costly and prone to cause engine damage. 
     Prior art patents disclosing multipiece intake manifolds capable of being disassembled are known, such as U.S. Pat. No. 3,831,566 issued to Thomas and U.S. Pat. No. 4,279,224 issued to Szabo et al. However, none of these patents provides for a manifold comprising easily removed and replaced components having differing characteristics, such as air inlet size and internal runner shape, to alter engine performance. 
     SUMMARY OF THE INVENTION 
     The instant invention provides an improved intake manifold for an internal combustion engine that solves the above-described problems, as well as others, by having a construction that permits disassembly, replacement or substitution, and reassembly without detriment to the individual intake manifold components. 
     According to a first aspect of the invention, an intake manifold has a multiple piece construction comprising, for example, a lower base member, a center runner section, and an upper shell, wherein the upper shell and center runner section fixably attach, for example by the use of bolts, to the lower base member in such a way that the components can later be disassembled. This ability to disassemble the intake manifold without causing damage allows intake manifold tuning by reattaching to the lower base member a different upper shell or center runner section having different geometries. For example, the instant invention allows for transmittal of a larger volume of air through the intake manifold by replacing the upper shell with an upper shell having a larger inlet. Additionally, replacing the center runner section with a center runner section having runner cavities of a different shape changes the airflow within the intake manifold and, hence, the way in which the air is delivered to the engine. This also provides flexibility for engine tuning. Therefore, the interchangeability of the upper shell and the center runner section is advantageous from an engine tuning perspective and results in less waste compared to traditional intake manifolds that must be entirely replaced. Further, the modular construction of the intake manifold allows for the removal and replacement of the upper shell without detaching the lower base member from the engine. Hence the seal between the lower base member and the engine remains intact, thereby reducing the possibility of debris entering the engine. 
     A second aspect of the invention is the use of witness marks on interior surfaces of air outlets of the lower base member to provide visual indicators of the amount of material that can be safely removed from the interior surfaces before the intake manifold will no longer seal with the internal combustion engine. 
     Additional advantages and novel features of the invention will be partially set forth in the description that follows, and will also become apparent to those skilled in the art upon examination of the following or upon learning by practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Other aspects of the present invention will be better understood from the following description, along with the accompanying drawings, wherein: 
         FIG. 1  is an exploded view of an embodiment of the intake manifold in accordance with an embodiment of the present invention; 
         FIG. 2  is a view along line A—A in  FIG. 1 ; 
         FIG. 3  is a partial detail view of the mating face of the lower base member for the embodiment of  FIG. 1 ; 
         FIG. 4  is a view along line B—B in  FIG. 1 ; 
         FIG. 5  is a partial detail view of an outlet of a runner cavity of the center runner section for the embodiment of  FIG. 1 ; 
         FIG. 6  is a view along line C—C in  FIG. 1 ; 
         FIG. 7  is a section view along line D—D in  FIG. 1 ; 
         FIG. 8  is a view along line E—E in  FIG. 1 ; 
         FIG. 9  is an isometric view of the upper shell of an intake manifold, in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiment described below applies to a three-piece intake manifold for an eight-cylinder internal combustion engine. However, it is understood that the invention is applicable to an internal combustion engine having any number of cylinders.  FIG. 1  is an exploded view of a first embodiment of the intake manifold  10  of the present invention, having an upper shell  20 , a center runner section  30 , and a lower base member  40 . The center runner section  30  inserts into lower base member  40 . Upper shell  20  secures to an upper mating surface  50  of lower base member  40  and encloses the center runner section  30  between the upper shell  20  and the lower base member  40 . 
     Lower Base Member 
       FIG. 2  corresponds to view A—A of  FIG. 1  and is a bottom view of the lower base member  40 . Referring to  FIG. 2 , lower base member  40  includes right  60  and left  70  mating faces that abut mating surfaces on right  80  and left  90  cylinder heads of an engine  100 , as shown in  FIG. 1 . Air outlets  110  are provided within the lower base member  40 . As shown in  FIGS. 3 and 4  the air outlets  110  have an upper edge  120  and a lower edge  130 , as well as an interior surface  140  extending from the upper edge  120  to the lower edge  130 . Lower edges  130  of air outlets  110  correspond to inlet ports (not shown) provided in the cylinder heads  80  and  90 . Thus, the air outlets  110  are passages extending through the entire thickness of lower base member  40 , and allow communication between the interior of the intake manifold  10  and the inlet ports of cylinder heads  80  and  90 . Surfaces  150  are also provided within an outer periphery of the air outlets  110  near the outer periphery of the mating faces  60  and  70 . An opening  160  extends from each surface  150  through the entire thickness of lower base member  40 . 
     Referring to  FIG. 3 , two witness marks  170  are formed into the interior surfaces  140  of the air outlets  110 . The witness marks are formed, for example, by being cast into the lower base member  40  at the time of manufacturing or by a machining process after formation of the lower base member  40 . The function of the witness marks  170  will be explained further below. 
       FIG. 4  corresponds to view B—B of  FIG. 1  and is a top view of the lower base member  40 . Referring to  FIGS. 1 and 4 , a semicircular flange  180  having an upper surface  190  and rounded upper surfaces  200  is formed at the front of the lower base member  40  and creates a semicircular front opening  210 , as shown in  FIG. 1 . An upper surface  220  of the lower base member  40  along with the upper surface  190  of the flange  180  and rounded upper surfaces  225  comprise the upper mating surface  50 . A series of threaded openings  230  are formed in the upper mating surface  50 . The interior of lower base member  40  includes a large central cavity  240  having a base defined by an upper interior surface  250  of the lower base member  40 . The interior of lower base member  40  communicates with the exterior of the lower base member  40  by the front opening  210 , the air outlets  110 , and an opening formed by an inner edge of the upper surface  220 . A continuous groove  260  is formed in the upper mating surface  50 . 
     Turning to the interior of the lower base member  40 , the upper edges  120  of the air outlets  110  are provided on the upper interior surface  250  and are surrounded on three sides by a groove  270  formed in the upper interior surface  250 . Therefore, the grooves  270  form a U-shape leaving only the outermost edge of the upper edge  120  unbounded. The area between the grooves  270  and the upper edges  120  of the air outlets  110  form mating surfaces  280 . Additionally, a series of bosses  290  integrally formed on the upper interior surface  250  are proximate to the inner edge of upper surface  220 . A threaded opening  295  exists on each of the bosses  290  and extends into the lower base member  40 . 
     Center Runner Section 
       FIGS. 1 ,  5 , and  6  illustrate the center runner section  30 . The center runner section  30  is the base of the intake manifold and can comprise various types of materials, such as metal, plastic, or polymers. In a preferred embodiment, the center runner section  30  is a single piece component manufactured by any number of well known casting or molding techniques.  FIG. 5  is a partial detail of a portion of the center runner section  30 , and  FIG. 6  is a view along line C—C in  FIG. 1 . The center runner section  30  includes a series of runner cavities  300  having substantially a U-shaped cross-section defined by vertical walls  310  and a base  320 . Each runner cavity  300  has an outlet  330  at one end and an inlet  340  at an opposing end. It is understood that a surface of one vertical wall  310  forms an inner vertical surface of one runner cavity  300 , while an opposite surface of the same vertical wall  310  forms an inner vertical surface for an adjacent runner cavity  300 . In one embodiment, adjacent runner cavities  300  are oriented in opposite directions from one another, so that one runner cavity  300  extends to one side of the lower base member  40 , while an adjacent runner cavity  300  extends to the opposite side of lower base member  40 . An end surface  350  is formed at each outlet  330  by terminal ends of the vertical walls  310  and the base  320 . A flange  360  extends from the center of each end surface  350  and has a cross-section thickness less than the width of the end surface  350 . Therefore, the flanges  360  divide the end surfaces  350  into an inner mating surface  370  and an outer mating surface  380 . A groove  390  is formed on an upper surface of each vertical wall  310 . 
     As illustrated in  FIG. 1 , the center runner section  30  has a general arc shape defining an air intake and distribution chamber  395  below the runner cavities  300 . The air intake and distribution chamber  395  communicates with the runner cavities  300  via the inlets  340 . A wall  400  extends from a horizontal surface of each vertical wall  310  to an opposing horizontal surface of an adjacent vertical wall  310  enclosing the inlets  340 . An opening  410  extends through each wall  400  from a top surface. 
     Upper Shell 
     The upper shell  20 , which can be composed of various types of materials, such as metal, plastic, or polymers, encloses the manifold  10  from above. In a preferred embodiment, the upper shell  20  is formed as a single piece component manufactured by any number of well-known casting or molding techniques.  FIGS. 1 ,  7 ,  8 , and  9  illustrate the upper shell  20 , which is comprised of a throttle body mounting boss  420 , an inlet  430 , a peripheral mating flange  440 , a contoured upper portion  450 , and an interior cavity  460 . The inlet  430  communicates with the interior cavity  460 . Additionally, in one embodiment inlet  430  is secondly circular in shape. However, the inlet  430  of the instant invention can be of any shape. As illustrated in  FIG. 1 , a series of threaded openings  470  extend through the throttle body mounting boss  420  from a front face and accept bolts (not shown) or other fasteners used to attach a throttle body (not shown) to the upper shell  20 .  FIG. 8  is view E—E shown in  FIG. 1  and illustrates a series of openings  480  extending through the mating flange  440  from an upper surface. The upper portion  450  comprises a series of integrally formed semicircular covers  490  that are transverse to a longitudinal axis  500  and extend from an edge of the mating flange  440  to an opposing edge on the mating flange  440 . Each cover  490  corresponds to a runner cavity  300  of the center runner section  30  and is comprised of an upper surface  510  and opposing horizontal surfaces of vertical walls  520  extending from a lower surface of the upper portion  450 . A seal  525  extends into the interior cavity  460  from a bottom surface of each vertical wall  520 . 
       FIG. 9  is an isometric view of the upper shell  20  and illustrates a continuous lower mating surface  530 , comprised of a lower surface of the mating flange  440 , a lower semicircular surface  540 , and rounded surfaces  550 . A seal  560  is disposed on the lower mating surface  530 . 
     Manifold Assembly 
     According to  FIG. 1 , the lower base member  40  attaches to the engine  100  between the cylinder heads  80  and  90 . The mating faces  60  and  70  engage corresponding mating surfaces on the cylinder heads  80  and  90  with a series of gaskets  570  or other sealing mechanisms provided there between. When the lower base member  40  is properly positioned on the engine  100 , openings  160  align with corresponding threaded openings (not shown) in the cylinder heads  80  and  90  of the engine  100 . Bolts  580 , for example, insert through the openings  160  from above and screw into the corresponding threaded opening in the cylinder heads  80  and  90 , creating a seal at the interface of the mating faces  60  and  70 , the gaskets  570 , and the mating surfaces of the cylinder heads  80  and  90 . Further, as previously described, the lower edges  130  of the air outlets  110  align with corresponding inlet ports in the cylinder heads  80  and  90  of the engine  100 , allowing communication between the interior of both the intake manifold  10  and the engine  100 . 
     Next, the center runner section  30  inserts into and attaches to the lower base member  40 . Prior to attaching center runner section  30  to lower base member  40 , a sealant, such as silicone gel, is applied to the flanges  360  at the outlets  330  of the runner cavities  300  of the center runner section  30 . After insertion, the flanges  360  insert into the U-shaped grooves  270  provided in the lower base member  40 , causing contact between inner mating surfaces  370  of the runner cavities  300  and mating surfaces  280  of the lower base member  40 , and between the outer mating surfaces  380  and the upper interior surface  250  of the lower base member  40  adjacent to the grooves  270 . Once the center runner section  30  is inserted, the sealant creates a seal between the outlets  330  of the center runner section  30  and the air outlets  110  of the lower base member  40 . Further, openings  410  extending through the walls  400  of the center runner section  30  align with the threaded openings  295  provided on the bosses  290  integral to the upper interior surface  250  of the lower base member  40 . Bolts  590 , for example, insert through openings  410  from above and screw into threaded openings  295 , securely attaching the center runner section  30  to the lower base member  40 . Moreover, inner edges of the inner mating surface  370  at the outlets  330  align with the upper edges  120  of the air outlets  110  of the lower base member  40 , providing a smooth transition between the runner cavities  300  and the air outlets  110 . 
     Finally, upper shell  20  attaches to the lower base member  40  from above, completely enclosing the center runner section  30 . When properly oriented, the lower mating surface  530  of the upper shell  20  contacts upper mating surface  50  of the lower base member  40 , forcing the seal  560  into the groove  260 , creating a seal. Additionally, openings  480  in the mating flange  440  align with the threaded openings  230  in the upper mating surface  50 . Bolts  600 , for example, insert into openings  480  from above and screw into threaded openings  230 , providing a clamping force to hold the engine manifold  10  together. Further, when the upper shell  20  is placed down onto the assembly of the lower base member  40  and the center runner section  30 , the seals  525  provided on the lower surfaces of the vertical walls  520  align and insert into the corresponding grooves  390  formed in the upper surface of each vertical wall  310  of the center runner section  30 . Once attached, the upper shell  20  completely encloses and seals the runner cavities  300  of the center runner section  30  via the upper surfaces  510  and vertical walls  520  of the upper shell  20 . Therefore, both the center runner section  30  and the upper shell  20  attach directly to the lower base member  40 , thereby allowing assembly and disassembly of the upper shell  20  without disturbing the center runner section  30  or lower base member  40 . 
     When assembled, the interior of the intake manifold  10  communicates with the exterior via the inlet  430  of the upper shell  20  and air outlets  110  in the lower base member  40 . In operation, the intake manifold  10  accepts incoming air through inlet  430 . The air then travels into the air intake and distribution chamber  395  and is drawn into the enclosed runner cavities  300  through inlets  340 . From there, the air travels down a length of the respective enclosed runner cavities  300  and through the air outlets  110  formed in the lower base member  40 , at which time the air flows into the inlet ports in the cylinder heads  80  and  90  of the engine  100 . 
     The volume and velocity of air allowed through an intake manifold is limited by the size and shape of the inlet of the intake manifold. Generally speaking, the larger the inlet  430  of the intake manifold  10 , the larger the volume of air that can be directed into the engine  100 . Traditionally, intake manifold modification has been limited to altering only certain features, such as inlet size or air outlet size, because of the single component or permanently bonded types of construction. However, these features may be altered only to a degree, past which the part is no longer usable. Alternatively, intake manifold modification has constituted removing the installed intake manifold, obtaining an entirely new intake manifold with features of differing shapes or sizes, such a smaller or larger inlet, and attaching the new intake manifold to the engine. This process includes a substantial financial cost for both purchase of a new part and labor for installation. However, an intake manifold having the above-described construction solves these problems while, at the same time, adding two additional benefits. 
     First, the intake manifold  10  can be made to allow for a larger volume of air by simply removing the upper shell  20  having an inlet  430  of a given diameter, 78 mm for example, and replacing it with an upper shell  20  having an inlet  430  with a different diameter, 90 mm for example. Replacing only the upper shell  20  versus the entire intake manifold  10  results in a lower cost and less waste. Second, an added benefit of the present invention is the ability to change runner shape by removing and replacing the center runner section  30  with a new center runner section  30  having runner cavities  300  of a different shape. The shape of the runner cavities  300  directly affects how air flows within the intake manifold  10 , and hence, how the air is delivered to the engine  100 . Therefore, the interchangeability of the center runner section  30  is also advantageous from an engine tuning perspective. Third, by modular construction of the intake manifold, the upper shell  20  can be changed without having to disassemble the lower base member  40  from the engine  100 . Therefore the seals between the mating faces  40  and  50 , the gaskets  570 , and the mating surfaces of the cylinder heads  80  and  90  remain intact. Accordingly, there is less risk of debris entering into the engine  100  and, therefore, less risk of internal engine damage. 
     Another beneficial aspect of the present invention is the use of witness marks  170 . Intake manifolds  10  are commonly modified by a practice termed “porting”, wherein material is removed from the interior surfaces  140  of the air outlets  110  of the lower base member  40 . Porting improves airflow exiting the manifold  10 . However, a common risk associated with porting is removal of too much material from the interior surfaces  140 , eroding a surrounding portion of the right  60  or left  70  mating face abutted by the gasket  570 , causing the gasket  570  to be drawn into or otherwise interfere with the performance of the engine  100 . Therefore, two witness marks  170  are formed into opposing faces of the interior surface  140  of each air outlet  110 . The depth of the witness marks  170  define the depth of material that may be removed by porting without the risk of the gaskets  570  becoming dislodged and being drawn into the engine  100 . Therefore, the witness marks  170  provide a visual indicator as to how much material can be safely removed without causing the intake manifold  10  not to seal with the engine  100 . 
     While there has been described what are at present considered to be preferred embodiments of the present invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claims cover all such modifications as fall within the true spirit and scope of the invention. Other modifications will be apparent to those skilled in the art.