Abstract:
The subject invention is a throttle body for an intake manifold of a spark ignition internal combustion engine. The throttle body includes a throttle plate member comprising a shaft, a throttle plate and a lever. The throttle plate member is integrally molded as one piece from an engineering resin. The throttle body also includes an air intake portion and an air discharge portion. Either the air intake or the air discharge portions may be integrally attached to the intake manifold prior to assembly of the throttle plate member.

Description:
[0001]    This is a continuation of U.S. patent application Ser. No. 09/536,554, filed Mar. 28, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present application relates to throttle bodies for intake manifolds of a spark ignition internal combustion engine. More specifically, the present invention relates to an intake manifold for a spark ignition internal combustion engine that has an integrally molded plate, shaft and lever assembly.  
           [0003]    In the past, there has been a need for easy to assemble, lightweight and more reasonably priced components for fuel injected engines which require a throttle body. In the past, throttle bodies have typically been configured as a one-piece housing in which a plate, shaft and lever assembly were assembled in separate pieces of a housing. Typically, because of the one-piece construction of the housing, a somewhat time consuming assembly process was necessary in order to pivotally secure the plate member inside of the throttle body bore and thereafter connect the peripheral portions and/or control inputs along the shaft.  
           [0004]    Thus, in typical prior art constructions, a multi-step process was required for pressing bearings and then installing the shaft, springs, and lever assembly and the like. Typically with such constructions, the throttle control spring was inboard of the throttle lever assembly. Additionally, the throttle lever assembly, shaft and plate were all separate pieces which needed to be connected by way of rivets or the like in order to provide a finished throttle body for installation on an engine. As might be readily appreciated, most of these parts have been made from metal, which is heavy, and the steps necessary to assembly the throttle body made such units relatively expensive components of the vehicle engine.  
           [0005]    In recent years, there have been some advances in throttle body designs, such as providing a two-piece assembly. A two-piece throttle body makes it easier to install the plate member. However, there remains a need for making an inexpensive yet reliable throttle body housing.  
         SUMMARY OF THE INVENTION  
         [0006]    In accordance with the present invention, there is provided a throttle body assembly for an engine, which includes a throttle body housing having a central intake bore therethrough. In the present invention, a throttle plate member is rotatably disposed in said bore for metering air flow through the throttle body and to the engine. The throttle plate member of the present invention includes a shaft member, which is effective for pivoting the plate member about an axis. In the present invention, the throttle plate member and the shaft and lever assembly and the like are integrally formed by one-piece injection molding and installed in the throttle body as a single piece.  
           [0007]    Further understanding of the present invention will be had by reference to the detailed description of the preferred embodiments set forth below when taken in conjunction with the examples and claims appended hereto.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    The various advantages of the present invention will become apparent to one skilled in the art by reading the following specification and subjoined claims and by referencing the following drawings in which:  
         [0009]    [0009]FIG. 1 is a perspective view of an engine utilizing a throttle body in accordance with the present invention;  
         [0010]    [0010]FIG. 2 is a detailed perspective view of a throttle body in accordance with the present invention;  
         [0011]    [0011]FIG. 3 is an exploded perspective view of the throttle body of the present invention;  
         [0012]    [0012]FIG. 4 is a section taken along line  4 - 4  of FIG. 3;  
         [0013]    [0013]FIG. 5 is a section of an alternate embodiment of the plate, shaft and lever assembly of FIG. 3; and  
         [0014]    [0014]FIG. 6 is a detailed broken away perspective view of a connection assembly for the throttle body taken along line  6 - 6  of FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    In accordance with the present invention, there is provided a throttle body generally shown at  10  for use on an engine  12  of a vehicle  14 . Particular throttle bodies are typically used for attachment to an intake manifold  16  of a fuel injected engine. The throttle body of the present invention is unique in that it is entirely produced from injection molded portions. The throttle body of the present invention includes a throttle body housing generally indicated at  18 . The throttle body  18  includes a central intake bore  20  therethrough. The throttle body of the present application includes an upper throttle body member  22  (air intake portion), a throttle plate, shaft, and lever assembly member  24 , and a lower throttle body member  26  (air discharge portion). The throttle plate, shaft, and lever assembly member  24  is rotatably disposed in the bore  20  for metering of air flow through the throttle body, and thus controlling engine speed.  
         [0016]    The throttle plate, shaft, and lever assembly member  24  of the present invention is different form prior art devices in that it is a one-piece integrally molded assembly, such as shown in FIGS. 4 and 5. Prior throttle body designs required assembly of the throttle plate assembly and shaft in the throttle body after casting of the throttle body. This is labor intensive and the metal used in the castings adds undesirable weight to the vehicle.  
         [0017]    The throttle plate, shaft and lever assembly member  24  shown in FIG. 3 includes a central plate portion  28  (as shown in FIG. 4), bearing members  30  and  32 , a throttle cable connection portion  34 , and a position sensor end  36 . The plate member is thick in the center portion  38  and tapers outward to edge portions  40  and  42 . A series of strengthening ribs  44  is provided on the upper and lower surfaces of the plate member. The profile of these ribs also provides improved air flow over the plate surfaces, for increasing engine performance. However, other strengthening ribs or the like may be included for strengthening of the throttle plate.  
         [0018]    The throttle position sensor end engages the throttle position sensor  46  for sensing the position of the throttle plate, shaft, and lever assembly member  24 . The cable end  34  (or lever) connects to a cable  48  for throttle control of the throttle plate, shaft, and lever assembly member  24 . The cable end  34  includes a spring retaining shaft. The throttle return springs  52  and  54  engage the shaft  50  and are positioned by the spring positioning arm  56 . Cable end  34  is outboard of the bearings  30  and  32 , which provides an efficient assembly of the cable  48  to the plate assembly  24 . This also allows for the throttle return springs  52  and  54  to be installed on the outside of the assembly  24 , further streamlining the assembly process.  
         [0019]    Lower throttle body member  26  also includes an air idle bypass chamber  27 , which is connected to an air source in the clean side of the air filter. Idle bypasses are known and typically are operably connected to a control valve that controls a linear solenoid or stepper motor for positioning of the bypass control valve at idle. The present invention differs from prior art designs in that the reference air source is taken from the clean side of the air cleaner rather than directly from the throttle body inlet.  
         [0020]    Upon assembly, the bearings  30  and  32  rest in bearing surfaces  58  and  60  in the lower throttle body member and mating bearing surfaces  62  and  64  in the upper throttle body member. The throttle plate, shaft, and lever assembly member  24  is positioned between the upper and lower body members, and they are brought together and temporarily secured in place via clip or snap fit tab assemblies  66 , which are shown in more detail in FIG. 6. Bearing members are preferably integrally molded with the plate assembly. Alternatively, ball bearings may be used in their place. For instance, a sealed ball bearing unit could be overmolded into the throttle plate, shaft, and lever assembly member  24 .  
         [0021]    Each clip assembly  66  includes a spring arm  68 , which engages a ledge  70  during engagement of the two halves of the throttle body. This provides for assembly during shipping of the assembled throttle body. Bolt holes  78  are provided for final attachment of the throttle body into the intake manifold. The upper throttle body member  22  includes a concentric lip  72 , which fits in a portion  74  of lower throttle body member  26 . A seal  76  is provided around the perimeter other than at the bearing areas for sealing the throttle body opening.  
         [0022]    Upper throttle body member  22  is preferably produced from an injection moldable material which will allow strict tolerances to be maintained it the position where the edges  40  and  42  are located during the idle position (i.e., where the throttle plate, shaft, and lever assembly member  24  is substantially horizontal). In order to maintain the position, the edges  40  and  42  are positioned adjacent the lip  72 . Lip  72  is, in fact, designed with a reduced thickness at this location to ensure roundness and proper tolerances between the lip  72  and throttle plate edges  40  and  42  during molding. Materials used for the upper throttle body are preferably engineering resins such as glass reinforced polyether amide resins. A preferred resin is a 30% glass reinforced resin sold under the name ULTEM 2310, available from GE Plastics of Pittsfield, Mass.  
         [0023]    Typically, the throttle plate, shaft, and lever assembly member  24  may also be injection molded from an engineering resin such as a polythalamide, or preferably glass-filled polythalamide. A preferred resin is an AMODEL glass reinforced resin, such as A-1145 HS, available from B.P. Amoco Chemicals, having offices in Livonia, Mich. As shown in FIG. 5, the material can be overmolded around a steel support shaft  80  as an alternate embodiment for providing added rigidity and strength if necessary.  
         [0024]    Lower throttle body member  26  can be produced from any number of materials. Preferably, a strong inexpensive material such as nylon or the like can be used. Certainly, engineering resins would equally be useful for this component. In an alternate embodiment, the lower throttle body member  26  could also be manufactured as a part of the manifold. In this embodiment, the throttle plate, shaft, and lever assembly member  24  and upper throttle body  22  and other components would be installed in place on the manifold  16 , having the lower throttle body member  26  as an integral part. Alternatively, the upper throttle body  22  could be an integral part of the manifold  16  while the lower throttle body  26  and the throttle plate, shaft and lever assembly member  24  would be installed in place on the manifold  16 .  
         [0025]    Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited such other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification and following claims.