Abstract:
A valve to shaft assembly includes a butterfly-type valve, a pair of bushings receiving the valve and holding the valve in axial position within a housing, and a shaft engaging the valve and the bushings and rotating the bushings in the housing. The bushings include features to hold the valve in position in the bore prior to assembly of the valve and, furthermore, act as rotating bearing surfaces for the valve. The valve to shaft assembly process may be simplified, especially where multiple valves are assembled to a single common drive shaft, such as in a port face charge motion control valve. Furthermore, the valve to shaft assembly provides an axial degree of freedom between valve, drive shaft, and bore, which allows the valve to float on the axis of the drive shaft, to facilitate self centering of the valve in the valve housing.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to internal combustion engines; more particularly, to engine air control valves; and most particularly, to a valve to shaft assembly without fasteners and a method for assembling a butterfly-type valve within a housing. 
       BACKGROUND OF THE INVENTION 
       [0002]    Butterfly-type valves having a rotatable valve plate fixed to a shaft are generally well known in the art of internal combustion engine design. Such butterfly-type valves have traditionally been used on throttle bodies and carburetors, more recently on throttle bodies of fuel injected engines, and are currently used inside intake manifolds with greater frequency. Butterfly-type valves are typically used to regulate airflow in order to create a desired combustion mixture within the engine. Butterfly-type valves may be used, for example, in electronic throttle control bodies, mechanical throttle bodies, diesel electronic throttle control body housings, or intake manifolds, and may be used as, for example, electronic throttle control valves, mechanical throttle body valves, diesel intake throttle body valves, or charge motion control valves. 
         [0003]    Traditionally, throttle valves have been affixed to shafts by mechanical means, usually fasteners. Typically a flat is milled on the shaft, a valve having holes in it is positioned on the flat, and fasteners, such as screws, are used to secure the valve to the shaft. The screws may be staked to the shaft to keep them from coming off. Even though, a constant concern is the potential risk of a fastener loosing during vehicle operation. If a fastener was to come loose, the valve could dislodge form the desired position. This in turn may generate noise or may possibly cause the valve to bind with the bore and become inoperable. A loosened fastener may also become disengaged from the shaft and fall into the engine. An inoperable valve may lead to emission failures, an inoperable vehicle, unwanted acceleration, etc. Also, in the event of a fastener coming completely loose there is the danger of engine damage. 
         [0004]    In the prior art, various approaches have been made to prevent fasteners fromloosening. These approaches include, for example, application of adhesives, replacing threaded fasteners with rivets, and upsetting the threads on the fastener to prevent rotation. All of these options add additional steps during the valve assembly adding to the assembly cost. Furthermore, these various approaches may not prevent a fastener from loosening with time during operation. 
         [0005]    In further prior art, where multiple valves are assembled to a single common drive shaft, such as in a charge motion control valve, each of the intake runners may have a separate valve body, designed to split open or to include multiple parts, to receive valves and bearings or bushings manufactured as a single part or pre-assembled. Other prior art approaches include a multi-part bushing/bearing assembly that is inserted in the bores for receiving a drive shaft. During the assembly process, the drive shaft is fed through the bushing/bearing assembly and through sleeves integrated in the valve alternating until all valves are assembled to the common drive shaft. 
         [0006]    What is needed in the art is a low cost solution for affixing a valve to a shaft without using mechanical means, such as fasteners, when the shaft is positioned within a housing, whether as a single valve assembly or as a multiple valve assembly as in a charge motion control valve. It would further be desirable to simplify the assembly process of butterfly-type valves in intake manifolds. 
       SUMMARY OF THE INVENTION 
       [0007]    Briefly described, a valve to shaft assembly in accordance with the invention includes a pair of bushings for each intake manifold runner that retain a butterfly-type valve and receive a shaft. Contrary to the prior art, where the valve is typically affixed to the shaft using mechanical means, such as fasteners, the bushings in accordance with the present invention enable assembly of the valve to the shaft without using fasteners. Furthermore, the valve to shaft assembly in accordance with the invention ensures that there are no loose valves on the drive shaft that could generate noise or become dislodged. Also, by pivoting valves on molded non-metal bushings, a quiet operation in the rotational and axial directions is achieved. In another aspect of the invention, the bushings include features to hold the valve in position in the bore prior to assembly of the valve and, furthermore, act as rotating bearing surfaces for the valve. Consequently, the valve to shaft assembly process may be simplified, especially where multiple valves are assembled to a single common drive shaft, such as in a charge motion control valve serving multiple intake runners. Although detailed description of the preferred embodiment herein will be directed to a charge motion control valve, it is understood that the invention is useful with throttle bodies, carburetors, or any other application where a butterfly-type valve is assembled in a housing. 
         [0008]    In accordance with the present invention, variable airflow within an intake manifold runner tract for improved cold start emissions and fuel economy is accomplished by providing a notched, center pivot butterfly-type valve. By designing the valve, which may be stamped metal, to have an as thin as possible profile, low flow restrictions may be achieved when the valve is fully open. Furthermore, the valve to shaft assembly in accordance with the invention provides an axial degree of freedom between valve, drive shaft, and bore, which allows the valve to float on the axis of the drive shaft, to facilitate self centering of the valve in the valve housing, such as in a multiple valve intake manifold runner. This free floating design of the valve to shaft assembly provides that the manifold, in which multiple valves are installed, may be manufactured, for example, as a molded composite, a die-cast, or a sand-cast, whereas prior art manifolds need to be machined to maintain proper valve fit among a ganged set of multiple valves. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0010]      FIG. 1  is an exploded isometric view of a charge motion control valve assembly; 
           [0011]      FIG. 2  is a plan front view of a bushing; and 
           [0012]      FIG. 3  is a cross-sectional view taken along line  3 - 3  in  FIG. 2 . 
       
    
    
       [0013]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
       DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    Referring now to the drawings, there is seen in  FIG. 1  a preferred embodiment of the inventive valve to shaft assembly  10  incorporated into a charge motion control valve assembly  20  of a V6 internal combustion engine. It is understood that charge motion control valve assembly  20  is provided for purpose of description only and the invention is not limited to the particular charge motion control assembly  20  design shown in  FIG. 1 . Rather, the invention is applicable to any type of valve housing design and any application where a butterfly-type valve is assembled to a shaft within a housing, which could benefit from the advantages the present invention offers as further explained below. 
         [0015]    Referring to  FIG. 1 , a charge motion control valve assembly  20  of a V6 internal combustion engine includes a manifold runner set  26 . The manifold runner set  26  includes multiple runners  21 . As shown in  FIG. 1 , three of the runners  21  are lined up longitudinally along an axis  22  and three of the runners  21  are lined up longitudinally along an axis  23 , which is positioned parallel to axis  22 . More or less runners  21  may be used and, furthermore, the runners  21  may be any type of valve housing in accordance with the invention. Each runner  21  includes two shaft bores  24  positioned opposite from each other and extending longitudinally along axis  22  or axis  23 . Shaft bores  24  of multiple runners  21  are lined up in series along axis  22  or axis  23 . Axis  22  and axis  23  are axes of rotation. 
         [0016]    A valve to shaft assembly  10  includes butterfly-type valve  11 , a pair of bushings  30 , and a drive shaft  25 . One valve to shaft assembly  10  is inserted into each of the runners  21 . A single common drive shaft  25  is then fed through the multiple valve to shaft assemblies  10 . The drive shaft  25  rotates the bushings  30  and the bushings  30  turn the valves  11 . 
         [0017]    Drive shaft  25  may be a single piece of un-machined metal stock that has a non-round cross-section, preferably a square or rectangular cross-section. Drive shaft  25  is a compliant member and, as a result, may be flexed due to a small cross-section relative to its length. By being a compliant member, assembly of the drive shaft  25  does not require the shaft bores  24  of the manifold  26  to be perfectly aligned. Hence, it is not necessary to precisely drill bores  24  to assure close-to-perfect alignment relative to axes  22  or  23 . The drive shaft  25  engages the bushings  30  by its non-round cross section and may or may not directly engage valves  11 . Multiple valves  11  may be assembled to a single common shaft  25  as more fully described below. In the case of a single runner  21  or single valve housing, bores  24  receive a drive shaft  25  that may not be shared with an adjacent runner. 
         [0018]    Still referring to  FIG. 1 , the butterfly-type valve  11  may be a notched, center pivot butterfly valve. In a preferred embodiment, the valve  11  is a thin metal valve having an as thin as possible cross-section to minimize flow restrictions when valve  11  is fully open. The metal valve  11  may be, for example, manufactured during a stamping process by a progressive die. Valve  11  includes features that hold the valve  11  in place in an axial direction along axis  22  or  23  and that prevent the valve  11  from sliding underneath the shaft  25  and from falling out after assembly. Thus, the valve  11  becomes trapped on the shaft  25  without using fasteners. 
         [0019]    Alternating bands of metal  12  and  13  may be pushed in opposite directions during the valve forming process. For example, bands  12  may be pushed up in vertical direction while the middle band  13  may be pushed down. The pushed up bands  12  form a step  14 . The middle band  13  may further be shaped to match the cross-section of the shaft  25 . Together the alternating bands of metal  12  and  13  form a multi-sided non-round pattern as viewed along axes  22 ,  23  to surround the shaft to kept the valves from slipping past the bushings and falling out of the bores after assembly. In one aspect of the invention, the bands of metal  12  and  13  may form a multi-sided non-round pattern that matches the cross-section of shaft  25 . The multi-sided pattern is formed to be in alignment with the axis of rotation, such as axis  22  or  23 . The bands  12  and  13  are formed such that when the valve is viewed along the axis of rotation, such as axis  22  or  23 , the shaped bands  12  and  13  will appear as a fully closed geometric shape. As a variation, one of the bands, such as middle band  13  may have an open band pattern that is left unshaped until after insertion of the shaft  25 . The band  13  may be crimped onto the shaft  25  as a final assembly step. Alternatively, middle band  13  may be left in the open band pattern if not needed for gripping valve  11 . It may further be possible to push the middle band  13  in the same direction as the bands  12  to form step  14  in order to keep the valve from slipping past the bushings and falling out of the bore after assembly. Also, the bands  12  and  13  may be a single band that is shaped to form step  14 . Step  14  extends in axial direction and is positioned adjacent to shaft  25  once installed. 
         [0020]    It may further be possible to use valves  11  made from composite or other materials. In an alternative embodiment, valve  11  may be a molded plastic valve. 
         [0021]    Referring to  FIGS. 2 and 3 , bushing  30  has a cylindrical shape that extends along axis  22  (or  23 ), which is the axis of rotation, and an outer diameter  35  selected to fit closely into shaft bore  24 . Bushing  30  includes a center aperture  31  that receives the drive shaft  25  and, therefore, has the same non-round cross-section as the shaft  25 , for example, a rectangular cross-section as shown. Center aperture  31  may be designed to be closely conforming to the cross-section of the shaft  25 . By matching the cross-section of the center aperture  31  and of the shaft  25 , the bushing  30  may be rotated by the shaft  25 . 
         [0022]    Bushing  30  further includes at least one distinctive element, such as slot  32  shown in  FIG. 2 , that receives, in a close fitting manner, valve  11 , that firmly grips valve  11 , and that secures valve  11  in axial position within runner  21 . Bushing  30  may further include a pickup spring or any other depressible member to complement the purpose of bushing  30 , in accordance with the invention, at the root of the slot  32  that is depressed when the valve is assembled in a pair of bushings  30  and that then applies pressure to the inserted valve  11  ensuring a tight fit between valve  11  and the bushings  30 . 
         [0023]    Bushing  30  further includes a shoulder  33  that has a larger diameter  36  than the shaft bore  24  and that holds bushing  30  in an axial position in shaft bore  24  prior to assembly of valve  11  and shaft  25 . The diameter  36  of shoulder  33  is larger than the outer diameter  35 . 
         [0024]    Bushing  30  also includes a bearing surface  34  at the outer circumference and, therefore, functions as a rotating shaft bearing within shaft bore  24 . Consequently, the material for the bushing is selected for lubricity and wear characteristics, as well as in consideration of the material the bushing  30  is rotating against. Bushings  30  are preferably formed of a plastic material, such as commercial grade nylon, for example, nylon PA66GF, through injection molding. A polymer is the preferred material due to high resistance to engine heat, chemical resistance, and noise canceling properties. Other materials that complement the purpose of bushings  30 , in accordance with the invention, may be used; for example, oil impregnated bronze, aluminum, and brass. Bushing  30  may also be, for example, a powder-metal part, a die-cast, a sinter part, or a machined part if desired. 
         [0025]    Referring again to  FIG. 1 , during the assembly process of the charge motion control valve  20 , a pair of bushings  30  is placed into the shaft bores  24  of a first runner  21 . The shoulder  33  of the bushings  30  ensures that the bushings  30  are positioned correctly in the bores  24  preventing the bushings  30  from slipping too far or even completely inside the bores  24 . After slots  32  are aligned to receive the valve, valve  11  is inserted into slots  32  of a pair of bushings  30 . The bushings  30  retain valve  11  within runner  21  and, in turn, the valve retains the bushings within bore  24 . These steps are repeated for each runner  21 . Then the drive shaft  25  is inserted through the center aperture  31  of the bushings and along the step  14  of the valve  11 . The drive shaft  25  positively engages the bushings  30 . If a multi-sided non-round pattern that matches the cross-section of the shaft  25  was formed with the metal bands  12  and  13 , then the shaft  25  is inserted through that formed pattern as well. If the middle band  13  is left in open band position, it may by crimped around the shaft  25  after inserting the shaft  25  or the band  13  may remain in open band position. Since the valve  11  is tightly gripped by a pair of bushings  30  and secured in place by the bushings in the axial direction, step  14  incorporated in the valve  11  may be sufficient to keep valve  11  from sliding underneath the shaft  25  and from falling out. Thus, valve  11  is secured to shaft  25  without fasteners and multiple valves  11  may be assembled to a single common valve shaft  25  in a relatively simple assembly process that requires only low cost tooling. 
         [0026]    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.