Patent Publication Number: US-6662900-B2

Title: Cross-exit exhaust system

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to exhaust systems in general and to cross-exit exhaust systems utilizing cross coupling via a common chamber to interconnect different portions of the exhaust system for silencing purposes. 
     Prior art approaches to noise reduction, especially in higher performance engines, has been obtained by utilizing cross coupling passageways between left and right exhaust conduits coming from opposite sides of the engine block from manifolds associated with a particular bank of cylinders. Such approaches have been commonly referred to as “H-pipe” or “X-pipe” exhaust configurations. One example of the X-pipe approach, which essentially is a variation of the older H-pipe approach is shown in U.S. Pat. No. 4,800,719. 
     All the known prior approaches utilizing the H or X-pipe interconnection schemes involve passing exhaust gases and associated pressure pulses in the first and second (or left and right) exhaust pipes coming from the opposite sides of the engine past the common cross-over point wherein the exhaust and associated pressure pulses are flowing past that common chamber in the same direction. 
     We have found that improved cancellation of low frequency exhaust noise is attained in such cross coupling exhaust systems where the gases and related pressure pulses flow past the connection point, or common chamber, in opposite directions. 
     SUMMARY OF THE INVENTION 
     Accordingly, an exhaust system for use in a vehicle having an internal combustion engine with first and second cylinder banks, each having respective first and second exhaust manifolds, comprises a first conduit adapted to be coupled to the first manifold, a second conduit adapted to be coupled to the second manifold, said first and second conduits extending toward each other downstream of their respective manifolds to a cross-over point, and a common chamber in fluid communication with the first and second conduits substantially at the cross-over point, whereby exhaust gases and associated pressure pulses in the first conduit flow past the common chamber in a direction substantially opposite to flow of exhaust gases and associated pressure pulses in the second conduit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The objects and features of the invention will become apparent from the detailed description taken in conjunction with the drawing, in which: 
     FIG. 1 is a perspective view of a cross-over exhaust system arranged in accordance with the principles of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, a typical internal combustion engine  130  has first and second (or right and left) cylinder banks with exhaust ports each emptying into a first manifold  140  and a second manifold  150 . 
     The output of each manifold  140  and  150  is respectively fluidly coupled to exhaust conduits  118  and  120 . 
     Exhaust conduit  118  is coupled to an input of catalytic converter  114 . The output of converter  114  is coupled to exhaust conduit  110  which is, in turn, coupled to an input of muffler  106 . 
     Similarly, exhaust conduit  120  is coupled to an input of catalytic converter  116 . The output of converter  116  is coupled to exhaust conduit  112  which is, in turn, coupled to an input of muffler  108 . 
     Exhaust conduits  100  and  102 , respectively coupled to outputs of mufflers  106  and  108 , then turn inwardly toward a longitudinal axis of the vehicle where conduits  100  and  102  reach a cross-over point substantially at the longitudinal axis of the vehicle. At this cross-over point is located a common chamber  104  coupled for fluid communication with exhaust conduits  100  and  102 . 
     Once each tube  100  and  102  extends past the cross-over point and common chamber  104 , each conduit then extends further to a side of the vehicle where it terminates, thus providing cross exits for the exhaust system. 
     With the arrangement as shown, exhaust gases and their associated pressure pulses emanating from engine manifolds  140  and  150  cross over from their originating sides in the vicinity of the common chamber  104  which results in equalization of the pressure pulses from the gas stream traveling in opposite directions past chamber  104 . This has been found to substantially reduce low frequency exhaust noise. 
     It is believed that with the exhaust gases and associated pressure pulses flowing against each other in common chamber  104 , the mixing of the pulses and their sound streams is more thorough, resulting in improved noise reduction at the output of the exhaust system. 
     It should also be noted that the volume of chamber  104  may be chosen, for a particular application, to provide an optimum tuning chamber for that application. The choice is usually determined by experimenting with various cross sectional areas and lengths of chamber  104 . 
     The invention has been described with reference to an exemplary embodiment for the sake of example only. The scope and spirit of the invention are to be derived from appropriately interpreting the appended claims.