Abstract:
A throttle valve assembly is held within a passageway in a throttle body. The assembly includes a plate and a pivot shaft. The pivot shaft extends through the mounting receptacle and engages with the throttle body. A method of making a series of throttle bodies includes molding multiple like bodies having first and second passageway portions. The first portions are sized to receive butterfly valves of a standard size. The second portions, positioned downstream from the first portions, have cross sectional openings equal to or smaller than the first portions. The second portions are machined or molded to various sizes adapted to flow fluid into the in-take ports of various size engines.

Description:
PRIORITY CLAIM 
     This application is a divisional of U.S. application Ser. No. 11/106,941, filed Apr. 15, 2005. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to valve members for fluid flow systems and, more specifically, to air intake systems for internal combustion engines. 
     BACKGROUND OF THE INVENTION 
     A throttle plate for a throttle body or carburetor is conventionally constructed with a flat metal plate pivotally held in place with a pivot shaft. The shaft holds the plate within the throttle bore for control of air intake for mixing with fuel and burning after being compressed within the engine cylinder. The ends of the shaft are secured to, and extend through, the carburetor or throttle body. One end is coupled to the throttle controller to vary the opening of the throttle plate to increase or decrease the amount of air fed to the intake port of the cylinder. 
     As air passes over the throttle plate the flow is somewhat interrupted by the discontinuity introduced by the bulging shaft extending across the middle of the plate. A conventional shaft holding a throttle plate is “D” shaped and riveted or screwed to the throttle plate. Smooth air flow is disrupted with a consequent loss in total air flow possible at wide-open throttle (WOT) for a given throttle body size. Thus, a need exists for a smoother flowing, more efficient air intake system. 
     In the case of fuel delivery systems, a specific throttle body is sized for the needs of a particular engine&#39;s fuel requirements. For an engine of a different displacement, a differently sized throttle body is provided. The need for various sizes results in increased part counts for a series of engines with resultant increases in cost and complexity. Furthermore, carburetors, throttle bodies, and throttle plates are typically constructed of metals such as aluminum, brass, and steel. These materials add weight to a vehicle and also result in costly part construction and assembly. The shaft and rivet or screw assembly also introduces an unnecessary chance for failure. 
     SUMMARY OF THE INVENTION 
     The present invention improves throttle valve flow, decreases weight, improves durability, and reduces manufacturing costs for throttle bodies and carburetors. 
     The present invention provides numerous advantages through its throttle valve assembly for engagement with a throttle body. The throttle valve assembly is held within a passageway in the throttle body. The assembly includes a plate and a pivot shaft. The plate includes a contoured front surface, a contoured back surface, and a mounting receptacle. The mounting receptacle forms a smooth bulge at the side of the plate. At least one of the front and back surfaces is smoothly contoured to the bulge. The pivot shaft is mounted to the mounting receptacle and engageable with the throttle body. Preferably, both the front and back surfaces are smoothly contoured to the bulge to provide increased aerodynamics and efficiency of flow especially at wide open throttle. 
     In one preferred aspect of the invention, the plate is a molded butterfly valve. The plate includes a center aperture to receive the pivot shaft. The shaft is indexed to the aperture. At least a portion of the shaft has a D-shaped cross section for indexing with the aperture. Alternatively, other non-slip shapes are used. Possible examples include T-shapes, x-shapes, or keyed shafts. In one preferred aspect, the mounting receptacle forms bulges on both sides of the plate with the pivot shaft extending through both bulges to engage the throttle body. 
     The invention may also be defined as a throttle valve assembly including a throttle body, a plate, and a pivot shaft. The throttle body includes a passageway. The plate has a first face, a second face, and a peripheral edge. The plate includes a mounting receptacle at a portion of the peripheral edge. The receptacle is thicker than most of the peripheral edge, the first and second face being contoured for a smooth transition to the receptacle. The pivot shaft is mounted to the mounting receptacle. The pivot shaft extends to a mount with the throttle body to allow pivotal movement of the plate within the passageway. 
     In further preferred aspects of the invention, the plate is formed of molded thermoplastic material or die cast metal. The throttle body may also comprise a molded thermoplastic material or a metal. 
     In still a further preferred aspect of the invention, the throttle body passageway includes a valve portion and a second passageway portion. The plate is mounted within the valve portion. The second passageway portion is downstream of the valve portion and provides an equal-to or smaller flow channel for communication of fluid flow to an engine in-take port having a similar opening size. In the preferred embodiment, the second passageway portion is machined after molding such that it is sized to the in-take port of the engine. Alternatively, the second passageway portions may be molded with differing pin sizes to match various intake port sizes. The passageway is preferably a bore, circular in cross section. In one preferred embodiment, the throttle body is part of a carbureted fuel delivery system. In another preferred embodiment, the throttle body is part of a fuel injection fuel delivery system. 
     A method of making a series of throttle bodies for various internal combustion engine sizes is also part of the present invention. The method includes molding multiple like bodies having passageways including first portions and second portions. The first portions are sized to receive butterfly valves of a standard size. The second portions may have various cross sectional areas (equal to or smaller) and are positioned downstream from the first portions. The second portions are machined or molded to various sizes adapted to flow fluid into the in-take ports of various size engines. 
     The method further includes molding and inserting butterfly valves within the first portions. The butterfly valves are molded with front and back faces and mounting receptacles. The mounting receptacles are smoothly contoured with the faces. 
     A further preferred method of carrying out the invention for making throttle bodies with various internal combustion engine sizes includes providing a mold with a standard outer shape and a passageway first portion. A first pin is placed within the mold to form a passageway second portion size to fit a particular first engine. The first throttle body is molded with a flowable material and the part is removed. A second pin is then placed within the mold to form a passageway second portion sized to fit a particular second engine. A second throttle body is then molded with a flowable material and the part is removed. Thus, with a single standard mold, throttle bodies of various sizes for various engine sizes can be created. Preferably, the flowable material includes a thermoplastic material or a metal, formed for example by die casting. The first and second portions of the passageway are preferably co-axial. 
     In a further preferred aspect of the method, a first-size plate valve is placed within the first portion of the passageway of the throttle body that is molded for the first engine. A first-size plate valve is also placed within the first portion of the passageway of the throttle body molded for the second engine. Thus, part counts are reduced, assembly is simplified, and costs are decreased. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. 
         FIG. 1A  is a side-elevational view of the throttle body of the present invention coupled to an engine; 
         FIG. 1B  is a carburetor with an internal throttle plate of the present invention coupled to an engine; 
         FIG. 2A  is an exploded isometric view of the throttle body of the present invention with the rod and throttle plate assembly; 
         FIG. 2B  is an isometric view of the throttle plate assembly in an assembled configuration; 
         FIG. 3A  is a side-elevational end view of the throttle body with the throttle plate in a closed position; 
         FIG. 3B  is a side-elevational end view of the throttle body with the throttle plate in a wide open throttle position; 
         FIG. 4  is a cross-sectional view of an alternative throttle body with a reduced passage portion; and 
         FIG. 5  is an isometric view of a mold for forming a throttle body housing with a reduced housing portion. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to  FIGS. 1A and 1B , an engine  10  is provided for powering a machine, such as an all-terrain vehicle. The present invention is directed toward the fuel delivery system for engine  10 . Engine  10  used as an example herein has a basic configuration, including a crank case  12  and a cylinder  14  with a head  16 . The fuel delivery system of the present invention may be adapted to work with any internal combustion engine, for any motorized purpose. The advantages of more efficient fuel delivery and simpler, less expensive components may all be realized in such situations. 
     Engine  10  includes an inlet port  18  to feed a fuel-air mixture into cylinder  14 . An exhaust port  20  is also provided for exhaust gases to be channeled to an exhaust pipe  22 . Exhaust pipe  22  then optionally runs to a muffler or other exhaust treatment devices. The inlets and exhaust ports are all of standard configuration or may be of any necessary configuration. For example, in a two-stroke engine, the inlet ports may vary from that in a four-stroke engine. 
     The fuel mixing and delivery system, whether it be a fuel injection system or a carbureted system is coupled to inlet port  18 . Thus, for example, in  FIG. 1A , a throttle body  24  is provided. Throttle body  24  includes a throttle cable  26  for control of a throttle valve within throttle body  24 , as will be described in more detail below. A fuel injector  28  is also positioned downstream of throttle body  24 . Fuel injector  28  may alternatively inject fuel into throttle body  24  rather than downstream of throttle body  24 . Fuel injector  28  includes a fuel line  30  and a control line  32 . Fuel line  30  provides fuel supply to fuel injector  28 . Control line  32  preferably comprises wires for electrically controlling the operation of fuel injector  28 . Finally, an air hose  34  is connected to the upstream end of throttle body  24 . Air hose  32  extends, for example, from an air cleaner. Air hose  34  provides air to throttle body  24  for control by throttle body  24 . 
     Turning to  FIG. 1B , a carbureted arrangement is illustrated. In place of a fuel injector  28  and a throttle body  24 , a carburetor  36  is provided. Carburetor  36  includes a throttle valve therein for control of the air that is fed to engine  10 . 
     Referring now to  FIG. 2A , the details of throttle body  24 , a throttle plate  38 , and a rod assembly  40  will now be described. Throttle body  24  includes a central housing  42  of generally cylindrical configuration. An outlet mount  44  is disposed on the downstream end of central housing  42  and is configured for coupling to a hose or inlet port to feed a fuel-air mixture to cylinder  14  of engine  10 . Thus, outlet mount  44  may include a recess circumferentially within an outer portion thereof for receiving a clamp for securing a hose to lead to inlet port  18  of cylinder  14 . 
     An inlet mount  46  extends from the upstream end of central housing  42 . Inlet mount  46  includes an outward flange extending from central housing  42  to provide a surface for coupling air hose  34 . Alternatively, the outward flange is omitted and the airhose is clamped to inlet mount  46 . Inlet mount  46  also includes a flange member for securing a throttle position sensor as will be described below. Central housing  42  further includes a left rod sleeve  48  and a right rod sleeve  50  projecting outwardly on opposite sides thereof. Right and left rod sleeves  48  and  50  preferably have a common center axis and are somewhat cylindrical in shape to hold rod assembly  40  therein for control of throttle plate  38 . 
     Throttle plate  38  includes a front face  52 , a rear face  54 , and a peripheral edge  56  extending circumferentially around throttle plate  38 . Front and rear faces  52  and  54  bulge outwardly towards their middles and are gradually reduced in section as they approach peripheral edge  56 . However, plate receptacles  58  are provided on diametrically opposed sides at the peripheral edge  56  in order to accommodate rod assembly  40 . Contoured bulges  60  are provided in both front face  52  and rear face  54  of throttle plate  38  for smooth air flow over throttle plate  38 . In prior-art systems, a pivot rod was simply attached to a flat face of a throttle plate creating turbulent flow and thus decreasing the efficiency of the throttle plate in the system. In contrast, the present invention provides convex faces with contoured side bulges  60  for smooth flow over and around throttle plate  38  while providing a secure connection to a pivot rod completely through one side and out the other of throttle plate  38 . Even if the control rod or other device does not extend completely through the throttle plate, in an alternate embodiment, wherever such rod or control device is connected, may have an appropriate smooth contour for a smooth air flow. Preferably, throttle plate  38  is constructed of injection molded plastic material making it easy and inexpensive to manufacture in such contours and shapes as described above and as illustrated in the figures. Alternatively, throttle plate  38  may be machined, cast, or otherwise formed. It may alternatively be formed from metal rather than plastic. Other materials may alternatively be used. 
     Rod assembly  40  includes a pivot rod  62  that extends through left and right bushings  64  and  66  that are held within left and right rod sleeves  48  and  50 . Pivot rod  62  includes a cylindrical portion at one end and a D-shaped portion at the other end for proper engagement with the various elements of rod assembly  40 . Other shapes that resist rotation may alternatively be used as long as they resist bending and slipping relative to the parts to which they are coupled. The D-shaped end extends through throttle body  24  after passing through left bushing  64 . Left bushing  64  is generally cylindrical in shape with a smaller cylindrical projection on an inward end and a flange on the outer end. Right bushing  66  is similarly shaped. The outer flanges abut against the ends of rod sleeves  48  and  50  while the cylindrical portions fit within throttle body  24 . Bushings  64  and  66  properly position entire rod assembly  40  along the proper axis for turning of throttle plate  38  within central housing  42  of throttle body  24 . A D-plug  68  is provided to be secured over the D-shaped end of pivot rod  62  for mating engagement therewith within right bushing  66 . A D-receiver  70  abuts against D-plug  68  to also receive a further-most end of the D-shaped portion of pivot rod  62 . D-receiver  70  abuts against throttle position sensor  72 . Throttle position sensor  72  provides feedback as to the angular position of throttle plate  38  based on the position of pivot rod  62 . The cylindrical body of right bushing  66  is somewhat larger then that of left bushing  64  so as to contain the outer flange portions of D-plug  68  and D-receiver  70 . 
     The opposite end of pivot rod  62 , which is cylindrical in shape, receives a left end mount  74 . Left end mount  74  is generally cylindrical in shape with a flange at the inner end to abut the flange of left bushing  64 . Left end mount  74  is force-fit or otherwise positively secured to the cylindrical end of pivot rod  62 . Left end mount  74  preferably receives a spring and a control mechanism such that it is used to turn pivot rod  62  to control the angular position of throttle plate  38  within throttle body  24 . 
     All of the parts of rod assembly  40  are constructed of plastic materials in the preferred embodiment. Alternatively, other materials may be used for these individual components. 
       FIG. 2B  illustrates the assembled configuration of rod assembly  40  with throttle plate  38  and throttle body  24  completely removed. Thus, the completed coupling of these elements together is shown. Also, the smooth contours of throttle plate  38  are evident from this view. The abutment of the flanges of left bushing  64  and left end mount  74  are also illustrated. Note also that D-plug  68  and D-receiver  70  (not shown in  FIG. 2B ) are completely contained within right bushing  66  and throttle plate  38 . Throttle position sensor  72  is configured for attachment to the flange extending from the side of inlet mount  46  as illustrated in  FIGS. 3A and 3B . 
     Turning to  FIG. 3A , this view shows throttle plate  38  in a closed configuration substantially cutting off the air fed to the cyclinder. Note that the peripheral edge  56  of throttle plate  38  is configured to be adjacent the inner diameter of central housing  42  of throttle body  24 . 
       FIG. 3B  illustrates the smooth flow path that is provided when throttle plate  38  is positioned in a wide open throttle position. Note that the contouring of throttle plate  38  provides initially a relatively sharp peripheral edge  56  then followed by smooth flow path around throttle plate  38  including around the sides where pivot rod  62  (not shown in  FIG. 3B ) extends into and out of throttle plate  38 . Such contouring results in efficiency of air flow through throttle body  24 . A preliminary test on some embodiments have indicated at least a 5% improvement in air flow with this contoured throttle plate. 
       FIG. 4  illustrates a throttle body  24   a  that may be used with a family of engine sizes. Throttle body  24   a  includes a central housing  42   a  and is arranged to receive a throttle plate  38   a  with a pivot rod  62   a  therein. Throttle plate  38   a  is received within a valve passage  76   a . This valve passage  76   a  has a large internal diameter. In the preferred embodiment this diameter is constant throughout a family of throttle bodies used for various engines or engine sizes. However, a reduced passage  78   a  is provided that may be adapted to different engine sizes or different inlet port sizes. Note the dashed lines that indicate an alternative formed shape of passage  78   a . Thus passage  78   a  is preferably reduced, but may alternatively have a diameter equal to or even slightly larger than the valve passage  76   a . Reduced passage  78   a  is initially molded or otherwise formed, such as by boring, to a particular minimum size that is used on the smallest engine size in a series. Before assembly, reduced passage  78   a  may be bored or otherwise formed in a larger size to accommodate the larger engine size. Thus, parts and moldings are constant and reduce costs and part counts. The reduced passage  78   a  is modified depending on the engine size after initial forming to an initial standard size. 
     Turning now to  FIG. 5 , the method of molding as well as a mold for creating a throttle body will now be discussed. A mold  80  is provided and includes a left side  82 , a right side  84 , and a top  86 . These pieces are shown separated in  FIG. 5 . When placed together, they may be used for an injection mold or a pour molding operation to create a throttle body such as that discussed above. Left and right sides  82  and  84  include half each of a valve housing portion  88  and a reduced housing portion  90 . Both halves also include a pin opening  96  to receive a pin  94 . Valve housing portion  88  is a larger diameter portion that is used to create the housing portion to hold the plate valve therein. A plug  92  extends downwardly from top  86  to fit within valve housing portion  88  to create the inner walls of this cylindrical portion. Pin  94  is inserted within pin opening  96  and extends upwardly to meet the bottom of plug  92  to create the inner diameter of the cylindrical reduced housing portion  90 . 
     Thus, a finished product will be a stepped cylindrical body that includes a larger inner diameter portion at one end. Various size pins may be used that have different diameters at the upper end thereof to create different reduced housing portion inner diameters for various engine sizes. Plug  92  may also be used with different sizes. However, in the preferred embodiment, plug  92  maintains the same size such that the same plate valve may be used from one throttle body to the next. Thus, sizing the throttle body for various engine sizes is accomplished by placing a different size pin  94  within mold  80 . Thus, only a single set of molds need be cut and used with various pin sizes. The lower portion of pin  94  may maintain its outer diameter so as to fit tightly within pin-opening  96 . 
     While the preferred embodiments of the invention have been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.