Abstract:
A throttle body for use in the air intake system of a motor vehicle comprising a throttle body defining a throttle bore. The throttle plate is rotatably mounted within the throttle bore, having an outside diameter smaller than an inside diameter of the throttle bore. A plurality of fins, located on the throttle plate, extend from the throttle plate in a direction generally perpendicular to a plane defined by said throttle plate. The fins are optimized in number, thickness, spacing, length, shape, and angle to reduce air-rush noise without impacting engine performance.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. provisional patent application No. 60/316.120, filed Aug. 30, 2001, and entitled “Method of Reducing Air-Rush Noise Created by Throttle Plate”. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention is directed to reducing noise in a motor vehicle, and in particular, a new throttle plate and method of design to reduce air rush noise generated as air moves past a partially opened throttle plate into the vehicle intake manifold.  
           [0004]    2. Background and Description of the Prior Art  
           [0005]    Electronic fuel injection systems in vehicles have replaced carburetor systems in an effort to reduce engine emissions and increase fuel efficiency. When the driver depresses the gas pedal on a fuel injected vehicle, the throttle valve opens inside the throttle body, letting in more air. The air travels through the engine intake manifold, where it mixes with fuel from the fuel injectors and enters the engine cylinders to increase power to the vehicle. When the air rushes through the throttle body into the manifold, increased turbulent air flow is created, which can make significant noise.  
           [0006]    Noise reduction has been a major goal of automakers in motor vehicles for the past several years. With global competition in vehicle sales, automakers often try to differentiate their vehicles from the competition by their “sound characteristics.” As major vehicle noises are reduced, other long-standing background noises must be addressed. Air rush noise through the intake system when the throttle plate is opened is one of those noises.  
           [0007]    High frequency flow noise can be created when a butterfly valve (the throttle plate) is opened from the fully closed position to some partially open position. Due to its inherent lower material density, this can be especially troublesome in composite-based air intake systems. The convergence of turbulent air streams through the openings created on either side of the throttle plate creates what is described as a ‘whoosh’ noise by customers. The condition can exist at ‘tip-in’ (the rapid opening of the fully closed throttle plate) or at a steady state, part-throttle condition.  
           [0008]    Several designs currently exist to reduce the air rush noise in a vehicle. One method is seen in U.S. Pat. No. 5,722,357 issued to Choi. This patent describes a gasket-like piece that is added between the throttle body and the manifold to diffuse the air flow downstream from the throttle plate. Vanes project from the interior of the circular opening to diffuse the air flow and reduce the noise. Since the vanes are not located at the source of noise, this method is less effective at reducing the noise. The addition of these protrusions can also act to partially impede the flow resulting in an increased pressure drop leading to a minor loss of power when the throttle plate is fully open. This method, however, requires an extra component to be installed on every vehicle. This is not cost-effective for mass production.  
           [0009]    The use of protrusions downstream of the throttle plate is also discussed in U.S. Pat. No. 5,970,963 issued to Nakase et al. Several different types of protrusions from the downstream side of the throttle valve are discussed. These protrusions severely complicate the die cast tooling necessary to make the throttle body. Slides will need to be added to the die cast tool and extra machining of the casting will be necessary. This adds cost to the component and reduces production volume. The addition of these protrusions can also act to partially impede the flow resulting in an increased pressure drop further leading to a minor loss of power when the throttle plate is fully open.  
           [0010]    Adding protrusions to the throttle plate to reduce the air rush noise has been addressed in U.S. Pat. No. 5,881,995 issued to Tse et al. and U.S. Pat. No. 5,465,756 issued to Royalty et al. Both patents describe noise reduction components added to the throttle plate to attenuate the noise. The fins on the designs, however, are of a fixed geometry to the throttle plate. While these will reduce some of the air rush noise, they may not eliminate it in all vehicle models. Manifolds and throttle bodies vary in shape, which changes the fluid dynamics and noise in the vehicles necessitating an adaptable throttle plate design. The subject matter of the above referenced patents may also have reduced power when the throttle plate is fully open due to the pressure drop caused by protrusions of these types. There still exists a need to optimize these protrusions. No optimization techniques are discussed.  
           [0011]    The need thus still exists for a flexible throttle plate design that reduces the air rush noise across vehicle models. There needs to be a method to accomplish the noise reduction while not causing a power loss when the throttle plate is fully open. There also needs to be a method of optimizing and customizing the design to reduce the air rush noise in each individual vehicle to accommodate the different manifold and throttle body designs.  
         SUMMARY OF THE INVENTION  
         [0012]    In accordance with the present invention, these and other objects are accomplished by providing an apparatus and a method for reducing the air rush noise in a variety of motor vehicles when the throttle plate is open. This reduction is for throttle plates that are gradually opened, held in a partially-open position or are rapidly opened.  
           [0013]    On a vehicle, the throttle plate opens when the engine needs to deliver more power. The air flow over the throttle plate inside the throttle bore can cause increased turbulence and vorticies. Fins added to the throttle plate can prevent the vorticies from being generated and act to straighten the flow, thus mitigating the turbulence in the flow downstream of the plate. The fins delay convergence of the turbulent air to a point further downstream when the energy has been dissipated. This, in turn, mitigates the source of the noise. With the fins attached to one or both sides of the throttle plate, the designer has the ability to tune the acoustical response as well as the restriction imposed by the fins minimizing the effect on the engine&#39;s power output. The fins may be of constant width and spaced consistently across the throttle plate, or the spacing and width may vary.  
           [0014]    The present invention uses fins in one or more orientations on the throttle plate to manage the flow of the air through the throttle bore to the manifold to mitigate the source of the noise. The throttle bore may be cylindrical, oval, elliptical, or a similar shape. A variety of computational fluid dynamics and other computer aided engineering methods, along with bench testing, can be used to simulate the flow of the air through the specific throttle body/manifold design to simulate the air flow and optimize the design of the fins of the throttle plate. This optimization depends upon many factors including the duct section geometry of the induction system, the airflow rate, and customer design specifications for pressure drop and radiated sound levels. The fins can be fabricated of various materials such as composite plastics or die cast aluminum. The fins can be attached to the throttle plate by various methods such as a mechanical joint, adhesive or welding. The fins could also be integrated into the plate as a one-piece design.  
           [0015]    Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a perspective view of the throttle body and manifold system showing the present invention;  
         [0017]    [0017]FIG. 2 is a sectional view cut through the throttle bore of FIG. 1  
         [0018]    [0018]FIG. 3 is an end view of the throttle plate of the present invention within the throttle body in the closed position;  
         [0019]    [0019]FIG. 4 is an end view of the throttle plate of the present invention within the throttle body in the open position;  
         [0020]    [0020]FIG. 4A is a cross-sectional view of the throttle plate of the present invention within the throttle body in the open position;  
         [0021]    [0021]FIG. 5 is a perspective view of the throttle plate according to another embodiment of the present invention;  
         [0022]    [0022]FIG. 6 is a side view of the embodiment shown in FIG. 5; and  
         [0023]    [0023]FIG. 7 is a perspective view of an embodiment of the throttle plate of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    Referring now in detail to the drawings, shown in FIG. 1, the throttle body  4  and intake manifold  11  portion of the air intake system of an electronically fuel injected vehicle is shown. The manifold  11  is the portion of the air intake system that interacts with the fuel components. Air enters the plenum portion  6  of the manifold  11  from the throttle body  4 . The plenum portion  6  of the manifold  11  evens out the pulses in the air to help fuel economy and emissions before the air enters the inlet tracks  7 . The air from the inlet tracks  7  mixes with the fuel spray from the fuel injectors mounted on a fuel rail at the exit of the inlet tracks  7  (not shown). Thereafter, the fuel-air mixture is combusted in the combustion chamber of the engine.  
         [0025]    The manifold  11  is attached to the throttle body  4  on the plenum  6  side of the manifold  11  at the manifold inlet  13 . The throttle body  4  mounts via a mounting flange  15  to a mounting surface  14  of the manifold inlet  13 . Fasteners, such as bolts, screws or other means, fastened through manifold attachment holes  17  and  19 , respectively formed in the mounting surface  14  and mounting flange  15 , secure the throttle body  4  to the manifold inlet  13  of the manifold  11 .  
         [0026]    The throttle body  4  determines how much air will flow into the plenum  6  and therefore the engine. A throttle plate  2  fits snugly inside a throttle bore  28  defined within a cylindrical ring  21  of the throttle body  4 . The throttle plate  2  is attached to a throttle shaft  12  by fasteners  18 , such as bolts, screws and other means. Rotation of the shaft  12  causes the throttle plate  2  to open and close to regulate the air stream. When the driver depresses the accelerator pedal of the automobile, the throttle shaft  12  is rotated, thus opening the throttle plate  2  and allowing air to flow into the manifold  11 . The air flows through the throttle bore  28  into the manifold inlet  13  in flow direction  20 .  
         [0027]    As seen in FIG. 2, attachment of the throttle plate  2  inside of the cylindrical ring  21 , to the throttle body  4  is shown in a sectional view as seen from the manifold  11  attachment side thereof. The throttle bore  28  has two rod holes  30  extending through its sides. The rod holes  30  extend along a common axis  31  and the throttle rod  12  fits through rod holes  30  in the throttle bore  28 . Attached to the throttle rod  12 , the throttle plate  2  fit snugly inside throttle bore  28  to substantially block air flow when the throttle plate  2  is in the closed position. As shown in FIG. 2, the throttle plate  2  is partially open.  
         [0028]    The throttle plate  2  may be attached to the throttle rod  12  by screws or bolts  18  extending through mounting rings  25  formed within the throttle rod  12  and into the throttle plate  2 . Formed on or mounted to the throttle plate  2  are fins  8 . Preferably, the fins  8  are on the trailing edge of the throttle plate  2 . As such, when the throttle rod  12  is turned and the throttle plate  2  is opened, the fins  8  operate to mitigate the noise by straightening the air flow in direction  20 .  
         [0029]    Referring now to FIG. 3, an end view from the mounting flange  15  of the throttle body  4  is shown. The throttle plate  2  in this view is in the closed position inside the throttle bore  28  and air flow is blocked by the snug fit between the throttle plate  2  and the throttle bore  28 . The fins  8  can be seen facing the mounting flange  15  of the throttle body  4 . When the throttle plate  2  is in this closed position, the fins  8  have no effect on the air intake system.  
         [0030]    [0030]FIG. 4 is a view from the mounting flange  15  of the throttle body  4 , similar to that seen in FIG. 3. In this view, the throttle rod  12  has been rotated almost to the open position inside the throttle bore  28 . Rotated as such, the fins  8  move away from an orientation facing the mounting flange  15  towards an angle perpendicular or 90° relative to the closed position (wide open throttle).  
         [0031]    Referring now to FIG. 4A, the partially open throttle plate  2  from FIG. 4 is shown in a cross-sectional view. The throttle rod  12  is rotated to open the throttle plate  2 . Air flows in air direction  20  through the throttle bore  28 . The fins  8  manage the air flow through the throttle bore  28  to reduce the air rush noise generated by the air flow over the throttle plate  2  which may be heard in the vehicle.  
         [0032]    When the throttle plate  2  is opened, as the air travels in air flow direction  20 , it travels through the fins  8 , which are aligned in the air flow direction  20  path. With the throttle plate  2  open, the fins  8  overhang the throttle plate  2  by overhang distance  26  or height. The intrusion of fins  8  by fin overhang distance  26  modifies the air flow by preventing the vortices from being produced from turbulent flow to laminar flow, quieting the air rush noise of the air flow through the throttle bore  28  into manifold  6 .  
         [0033]    Referring now to FIG. 5, a perspective view of one embodiment of the fins  8  of the throttle plate  2  is shown. The fins  8  themselves are formed on a separate fin attachment plate  50 . The fin attachment plate  50  is fastened, using an adhesive or a mechanical fastener, onto the rear side of the throttle plate  2  and on the lower side which forms the leading edge side  51 .  
         [0034]    After attachment, the fins  8  progress from approximately the center of the throttle plate  2  and rise from there until reaching the end of the throttle plate  2 , a fin tip height  22  at a fin angle  24 , calculated by using the fin start location  32  and measuring angle between a ray along the fin length  36  and a ray toward the fin tip height  22 . Because of the generally round shape of the throttle plate  2 , the fin length  36  will generally be different for each fin  8 . FIG. 6 is an opposing view of the fin attachment plate  50  to that of FIG. 5. The fins  8  are seen as being equally spaced  10  between each fin  8 . The fin width  24  is shown to be consistent throughout the fin attachment  50 .  
         [0035]    Seen in FIG. 7 is a perspective view of a further embodiment of the present invention. In this embodiment, the fins  8  are manufactured as a unitary part of the throttle plate  2 . The throttle plate  2  with the unitary fins  8  can be a one-piece die casting or made by another manufacturing method. There is no separate fin attachment piece with this embodiment.  
         [0036]    In this latter embodiment, the fins  8  start at fin start height  34 , generally along the diameter of the throttle plate  2 . The fins  8  then rise diagonally towards the outer edge of the throttle plate  2  to fin edge height  22 . The fins  8  are again equally spaced with fin spacing  10 . The throttle plate attachment holes  25  are shown near the center of the throttle plate  2 . Formed in this manner, the fins  8  extend completely across the opening created during rotation of the throttle plate  2 , regardless of the open angle of the throttle plate  2 .  
         [0037]    While the above description constitutes the preferred embodiments of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.