Abstract:
An improved throttle body includes an offset axis drum valve and shaped throat. The offset axis and shaped throat provide gradual initial opening for better throttle control and the drum valve includes a lower face matching the profile of the air path through the throttle body when rotated to a fully open throttle position, providing an optimal flow at full throttle. The offset axis drum further includes a slightly decreasing radius. As the drum opens, the surface of the drum retreats from the throttle body wall providing clearance for dusty environments and reducing tolerances for reduced manufacturing cost. A fuel injector pocket position provides a spray pattern aligned with an initial air flow as the throttle body opens providing better mixing at part throttle. The throttle body further creates a cavity under the drum in the closed position providing an increased volume in the intake tract which improves throttle response.

Description:
[0001]    The present application claims the priority of U.S. Provisional Patent Application Ser. No. 61/499,045 filed Jun. 20, 2011, which application is incorporated in its entirety herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to internal combustion engines and in particular to an improved throttle body for Otto cycle engines. 
         [0003]    There is a continuing quest to improve the performance of internal combustion engines, both in terms of efficiency and power output. One essential element of internal combustion Otto cycle engines is a throttle body which controls the amount of air entering the engine. Engines produce power by converting chemical energy from reacting (i.e., burning) a mixture of liquid fuel and air into mechanical energy. While only about one third of the chemical energy is converted into mechanical energy, the amount of mechanical energy produced is roughly proportional to the amount of chemical energy released, which in turn is roughly proportional to the amount of air taken into the engine. Because the throttle body limits the amount of air taken into the engine, the throttle body also controls the amount of mechanical energy produced by the engine. 
         [0004]    Various throttle bodies are known in the art, these include butterfly type throttle bodies and slide type throttle bodies. Butterfly type throttle bodies are common in many automobiles and are fairly simple, but include a shaft through the center of the throttle body throat which creates some restriction even when fully open. A plate rotated by the shaft to open and close the throttle body also restricts air flow through the throttle body. 
         [0005]    Slide type throttle bodies require an extension of the throttle body housing to receive the slide as it opens and may become jammed due to dirt or gavel being captured between the slide and housing in some environments. Further, known butterfly type throttle bodies provide a very non-linear relationship between throttle position and air flow, especially upon initial opening of the throttle. Known fuel injection control units commonly use throttle position as an input and are programmed based on the behavior of the known butterfly type throttle bodies. Other throttle body types, for example, slide type throttle bodies, do not produce a similar non-linear relationship between throttle position and air flow, and difficulties arise when another throttle body type is substituted for a butterfly type throttle body. Unfortunately, the known fuel injection control units often allow only a narrow adjustment which is not adequate when another throttle body type is substituted for a butterfly type throttle body. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present invention addresses the above and other needs by providing an improved throttle body including an offset axis drum valve and shaped throat. The offset axis and shaped throat provide gradual initial opening for better throttle control and the drum valve includes a lower face matching the profile of the air path through the throttle body when rotated to a fully open throttle position, providing an optimal flow at full throttle. The offset axis drum further includes a slightly decreasing radius. As the drum opens, the surface of the drum retreats from the throttle body wall providing clearance for dusty environments and reducing tolerances for reduced manufacturing cost. A fuel injector pocket position provides a spray pattern aligned with an initial air flow as the throttle body opens providing better mixing at part throttle. The throttle body further creates a cavity under the drum in the closed position providing an increased volume in the intake tract which improves throttle response. 
         [0007]    In accordance with one aspect of the invention, there is provided a throttle body having an offset axis drum valve. The offset axis drum valve provides a more gradual initial opening for better throttle control. 
         [0008]    In accordance with another aspect of the invention, there is provided a throttle body having a drum valve which includes a lower face matching the profile of the air path through the throttle body providing an optimal air flow at fully open throttle. 
         [0009]    In accordance with still another aspect of the invention, there is provided a throttle body having a drum with a slightly decreasing radius. As the drum opens, the surface of the drum retreats from the throttle body wall providing clearance for dusty environments and reducing tolerances for reduced manufacturing cost. 
         [0010]    In accordance with one yet another aspect of the invention, there is provided a throttle body providing an initial air flow directed toward a fuel injector spray pattern. A trailing edge of the drum meets the throttle body throat wall above the injector spray pattern. At initial and partial throttle opening, the air flow is concentrated on the fuel injector spray pattern providing better fuel/air mixing and more efficient combustion. 
         [0011]    In accordance with still another aspect of the invention, there is provided a throttle body having a drum cavity providing an increased volume below the drum at closed throttle. As the throttle opens the drum rotates into the cavity. As the throttle is closed, the cavity adds volume to the intake path improving the volumetric efficiency of the motor. 
         [0012]    In accordance with another aspect of the invention, there is provided a throttle body having a shaped throat contoured to reduce the area provided for air flow at partial throttle opening. Butterfly throttles are known to provide a desirable throttle opening response. Other known designs, for example slide throttles, generally open to quickly or suffer from poor response at partial throttle. The shaped throat may be shaped to provide a more gradual opening of the air passage. 
         [0013]    In accordance with still another aspect of the invention, there is provided a throttle body having a shaped throat is contoured to direct air flow towards an injector spray pattern. The shaped throat opens a small area directly above the injector spray pattern. Initial tests have shown increased power for the same air and fuel flow, indicating that more efficient combustion is taking place. 
         [0014]    In accordance with another aspect of the invention, there is provided a throttle body having a shaped throat providing an air flow very close to the air flow of a butterfly type throttle body at initial throttle opening. Nearly all motorcycles fuel injection systems use throttle position as a fuel management input. The shaped throat closely duplicates the butterfly throttle body air flow, thus allowing retention of the original fuel injection system. 
         [0015]    In accordance with yet another aspect of the invention, there is provided a slide throttle body having shaped throats. At initial opening, the air flow is reduced to be more like a butterfly throttle, and the air flow is directed towards the injector spray pattern to improve part throttle combustion. 
         [0016]    In accordance with another aspect of the invention, there is provided a slide throttle body having shaped slide plate passages. The known slide plate is replaced by a slide plate with an extended narrowed opening aligned with fuel injector nozzles. At initial opening, the air flow is reduced to be more like a butterfly throttle, and the air flow is directed towards the injector spray pattern to improve part throttle combustion. 
         [0017]    In accordance with still another aspect of the invention, there is provided a method for matching the initial throttle opening air flow of a shaped throttle body to a butterfly type throttle body. The method includes constructing a shaped throttle body with additional material in the throttle body throat blocking air flow at initial throttle opening, measuring the air flow of an original throttle body at a minimum 1st throttle opening, opening the shaped throttle body to the 1st throttle opening position, removing some of the additional material from the throat of the shaped throttle body to match the air flow of the original throttle body at the 1st throttle opening position, measuring the air flow of an original throttle body at a slightly greater 2nd throttle opening position, opening the shaped throttle body to the same 2nd throttle opening position, removing some of the additional material from the throat of the shaped throttle body to match the air flow of the original throttle body at the 2nd throttle opening position, and repeating the previous three steps for several greater throttle opening positions. The flow through the shaped throttle body is measured at each throttle position as material is removed incrementally. Material is preferably removed near the center of the throttle opening to direct the air flow towards a fuel injector spray pattern below the throttle opening, and the additional material removed at each step is selected to avoid affecting the air flow at smaller throttle opening positions. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0018]    The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
           [0019]      FIG. 1  is a compact “V” engine. 
           [0020]      FIG. 2A  is a cross-sectional view of a throttle body according to the present invention in a closed position. 
           [0021]      FIG. 2B  is a cross-sectional view of the throttle body according to the present invention in a partially open position. 
           [0022]      FIG. 2C  is a cross-sectional view of the throttle body according to the present invention in a fully open position. 
           [0023]      FIG. 3A  is a side view of a first embodiment of the throttle body according to the present invention. 
           [0024]      FIG. 3B  is a top view of the first embodiment of the throttle body according to the present invention. 
           [0025]      FIG. 3C  is a first perspective view of the first embodiment of the throttle body according to the present invention. 
           [0026]      FIG. 3D  is a second perspective view of the first embodiment of the throttle body according to the present invention. 
           [0027]      FIG. 4  is an exploded view of the first embodiment of the throttle body according to the present invention. 
           [0028]      FIG. 5A  shows the throttle body with the drum valve fully closed. 
           [0029]      FIG. 5B  shows a cross-sectional view of the throttle body with the drum valve fully closed taken along line  5 B- 5 B of  FIG. 5A . 
           [0030]      FIG. 6A  shows the throttle body with the drum valve partially open. 
           [0031]      FIG. 6B  shows a cross-sectional view of the throttle body with the drum valve partially open taken along line  6 B- 6 B of  FIG. 6A . 
           [0032]      FIG. 7A  shows the throttle body with the drum valve fully open. 
           [0033]      FIG. 7B  shows a cross-sectional view of the throttle body with the drum valve fully open taken along line  7 B- 7 B of  FIG. 7A . 
           [0034]      FIG. 8  shows a perspective view of the drum valve according to the present invention. 
           [0035]      FIG. 9A  shows a cross-sectional view of the throttle body with a shaped throat for limiting and/or directing air flow at partial throttle opening according to the present invention. 
           [0036]      FIG. 9B  shows a top view of the throttle body with the shaped throat for limiting and/or directing air flow at the partial throttle opening according to the present invention. 
           [0037]      FIG. 10A  shows a cross-sectional view of the throttle body with a shaped throat for limiting and/or directing air flow at a second partial throttle opening according to the present invention. 
           [0038]      FIG. 10B  shows a top view of the throttle body with the shaped throat for limiting and/or directing air flow at the second partial throttle opening according to the present invention. 
           [0039]      FIG. 11A  shows a top view of a slide plate throttle according to the present invention. 
           [0040]      FIG. 11B  shows a side view of a slide plate throttle according to the present invention. 
           [0041]      FIG. 12  shows a top view of a shaped slide plate according to the present invention. 
           [0042]      FIG. 13  shows the overlap of a partially open slide plate throttle according to the present invention. 
           [0043]      FIG. 14  shows the overlap of a prior art slide plate. 
           [0044]      FIG. 15  shows the overlap of one throat of the shaped slide plate according to the present invention. 
           [0045]      FIG. 16  shows the overlap of one throat of an un-shaped slide plate with a shaped runner according to the present invention. 
           [0046]      FIG. 17  is a method for matching the initial throttle opening air flow of a shaped throttle body to a butterfly type throttle body according to the present invention. 
       
    
    
       [0047]    Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0048]    The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
         [0049]    A side view of a motorcycle engine  10  is shown in  FIG. 1 . The motorcycle engine  10  includes cylinder head  12 , cylinder  16 , block  18 , air cleaner  14 , exhaust pipes,  19 , and throttle body  20 . The throttle body  20  controls the amount of air entering the engine  10  and thereby the amount of power produced by the engine  10 . 
         [0050]    A cross-sectional view of a throttle body  20  according to the present invention in a closed position is shown in  FIG. 2A , a cross-sectional view of the throttle body  20  in a partially open position is shown in  FIG. 2B , and a cross-sectional view of the throttle body  20  in a fully open position is shown in  FIG. 2C . The throttle body  20  includes a housing  22  providing an air path  24  into the engine  10 . A drum valve  26  rotates on an offset axis  28  into and out of a drum cavity  30  to open and close the throttle body  20 , moving proximal to a cavity lip  31 . The axis  28  is offset from the centerline of the air path  24 . The offset axis drum valve  26  provides gradual initial opening for better throttle control. 
         [0051]    In the closed position, the cavity  30  is created inside the housing  22  and under the drum valve  26  when the drum is in a closed and partially closed position. Some engine builders have found that increasing the volume under the throttle body, improves engine performance. 
         [0052]    The face (or upper surface)  27  of the drum valve  26  has a first radius R 1  along a leading edge  27   a  and a second radius R 2  at a trailing edge  27   b . The radius R 2  is slightly smaller than the radius R 1  to allow a close fit between the leading edge  27   a  and the interior of the housing  22  to seal the air path  24  through the throttle body when an idle air passage  34  and idle control valve  36  are present to control idle, and to facilitate fine adjustment of idle when the drum valve  26  is adjusted to control the idle. The increasing clearance between the drum valve  26  and the housing  22  as the throttle is opened helps reduce the potential for dust and the like to jam the drum valve  26  when a motorcycle is operated in a dusty environment. 
         [0053]    An injector pocket  32  is positioned in the housing under the initial opening of the drum valve  26 . As a result, a part throttle air flow through the housing will intersect fuel sprayed by a fuel injector to provide better mixing at part throttle. 
         [0054]    A side view of a first embodiment of the throttle body  20  according to the present invention is shown in  FIG. 3A , a top view of the throttle body  20  is shown in  FIG. 3B , a first perspective view of the throttle body  20  is shown in  FIG. 3C , a second perspective view of the throttle body  20  is shown in  FIG. 3D , and an exploded view of the throttle body  20  is shown in  FIG. 4 . The drum valve  26  is seen to have a concave vertical face  40  which blends with air path  24  through the housing  22  at fully open throttle. A throttle cable housing  42  attached to the side of the housing  22  and contains a cable drum  44  to which a throttle cable may be attached to operate the throttle body  20 . 
         [0055]    The throttle body  20  with the drum valve  26  is shown fully closed in  FIG. 5A  and a cross-sectional view of the throttle body  20  with the drum valve  26  fully closed taken along line  5 B- 5 B of  FIG. 5A  is shown in  FIG. 5B . The throttle body  20  with the drum valve  26  is shown partially open in  FIG. 6A  and a cross-sectional view of the throttle body  20  with the drum valve  26  partially open taken along line  6 B- 6 B of  FIG. 6A  is shown in  FIG. 6B . The throttle body  20  with the drum valve  26  is shown fully open in  FIG. 7A  and a cross-sectional view of the throttle body  20  with the drum valve  26  fully open taken along line  7 B- 7 B of  FIG. 7A  is shown in  FIG. 7B . The drum valve  26  is seen to blend into the throat  21  of the throttle body  20  in the fully open position providing a smooth passage for air entering the engine  10 . The drum valve  26  is seen in  FIG. 6B  to allow part throttle air flow along a side of the air path  24  passing over the injector pocket  32 . 
         [0056]    A perspective view of the drum valve  26  according to the present invention is shown in  FIG. 8 . 
         [0057]    A cross-sectional side view of the throttle body  20  with a shaped throat  58  for limiting and/or directing air flow at partial throttle opening according to the present invention is shown in  FIG. 9A , a top view of the throttle body  20  with the shaped throat  58  for limiting and/or directing air flow at the partial throttle opening is shown in  FIG. 9B , a cross-sectional view of the throttle body  20  with the shaped throat  58  for limiting and/or directing air flow at a second partial throttle opening is shown in  FIG. 10A , and a top view of the throttle body  20  with the shaped throat  58  for limiting and/or directing air flow at the second partial throttle opening is shown in  FIG. 10B . The shaped throat  58  is contoured to reduce the areas  56   a  and  56   b  at partial throttle opening providing a response preferred by most motorcycle riders, and similar to the response provided by butterfly type throttle bodies. Further, the initial opening of the drum valve  26  provides a narrow “squeeze” opening aligned with the fuel injector  50 . The air flow  24  is thus directed towards the fuel spray  52  from the injector  50 . Tests performed have shown an increase in power, compared to a butterfly type throttle body, at an identical air and fuel flow, indicating improved combustion. 
         [0058]    The unshaped throat  21  is shown as a dashed line. The shaped throat  58  provides reduced openings  54   a  and  54   b  (shown with double cross hatch shading), and unshaped throat  21  provides the larger and wider additional openings  56   a  and  56   b  (shown with single cross hatch shading). The openings  54   a  and  54   b  are both smaller and narrower than the openings created by the throat  21  at the same throttle position, providing the desired throttle response and directing the air flow to the fuel spray  52 . 
         [0059]    The shaped throat  58  is formed by narrowing the throat at the area of initial opening and/or above the injector  50 . The narrowing may take the form of a rounded “V” shape. Nearly all motorcycles fuel injection systems use throttle position as a fuel management input. The shaped throat  58  closely matches butterfly throttle body air flow at small throttle opening, thus allowing retention of the original fuel injection system on motors designed for butterfly throttle bodies. Although some fuel injection systems allow editing parameters, there are often small limits on such editing, and the software does not allow changes to accommodate changing an original butterfly type throttle body to a different style throttle body. 
         [0060]    Alternatively, the drum valve  26  may have a shaped trailing edge having an indentation at the center, thus providing a reduced air flow at initial opening and directing the air flow towards the fuel spray  52 . 
         [0061]    A top view of a four throat slide plate throttle  70  according to the present invention is shown in  FIG. 11A  and a side view of the slide plate throttle  70  is shown in  FIG. 11B . The slide plate throttle  70  includes four runners  74  in fluid communication with a cylinder head, and preferably one runner  74  in fluid communication with each cylinder of a motor, which motor may be a one or more cylinder motor. A slide plate assembly  72  cooperates with each of the runners  74  to control air flow through the slide plate throttle  70 , and an injector  50  provides fuel to each runner  74 . 
         [0062]    A top view of a shaped slide plate  80  according to the present invention, residing in the slide plate assembly  72 , is shown in  FIG. 12  and the partial throttle overlap  76  of the slide plate  80  with the runners  74  is shown in  FIG. 13 . The shaped slide plate  80  slides in the slide plate assembly  72  to open and close the slide plate throttle  70 . The shaped slide plate  80  includes shaped passages  72  having a narrowed leading edge  72   a . The overlap  78  of a prior art slide plate throttle is shown in  FIG. 14 , and the overlap  76  of one throat  74  of the shaped slide plate is shown in  FIG. 15 . During initial opening of the slide plate throttle  70 , the narrowed leading edge  72   a  attenuates the throttle response and directs the air flow towards the injector  50 , thus providing the desired throttle response and improved combustion efficiency at partial throttle. 
         [0063]    While the slide plate throttle  70  is shown having four runners in line, when space between the runners must be reduced, the runners may be offset. Further, the slide plate throttle may comprise round passages  72   a , and the runners may be shaped runners  74   a  in the same manner as the shaped throat  58  at the area of initial opening  76   a  to reduce initial air flow and direct the air flow towards the injectors as shown in  FIG. 16 . 
         [0064]    A method for matching the initial throttle opening air flow of a shaped throttle body to a butterfly type throttle body according to the present invention is shown in  FIG. 17 . The method includes constructing a shaped throttle body with additional material in the throttle body throat blocking air flow at initial throttle opening at step  100 ; measuring the air flow of an original throttle body at a minimum 1st throttle opening position at step  102 ; opening the shaped throttle body to the same 1st throttle opening position at step  104 ; removing some of the additional material from the throat of the shaped throttle body to match the air flow of the original throttle body at the 1st throttle opening at step  106 ; measuring the air flow of an original throttle body at a slightly greater 2nd throttle opening position at step  108 ; opening the shaped throttle body to the same 2nd throttle position at step  110 ; removing some of the additional material from the throat of the shaped throttle body to match the air flow of the original throttle body at the 2nd throttle opening position at step  112 ; and repeating steps  108 ,  110  and  112  for several greater throttle opening positions. The flow through the shaped throttle body is measured at each throttle opening position as material is removed incrementally. Material is preferably removed near the center of the throttle opening to direct the air flow towards a fuel injector spray pattern below the throttle opening, and the additional material removed at each step is selected to avoid affecting the air flow at smaller throttle opening positions. 
         [0065]    While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.