Abstract:
An exhaust manifold is provided with deflector members positioned between downstream gas inlets and a main gas passage. The deflector members redirect the flow of exhaust gas from the inlets into the general direction of the gas flowing in the main passage as the exhaust gas enters the main passage.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an exhaust manifold for controlling combustion gases and more particularly to arrangements for reducing pneumatic interaction between cylinders and optimizing exhaust flow in an exhaust manifold.  
       BACKGROUND OF THE INVENTION  
       [0002]     Prior to the present invention, various exhaust manifolds and methods of controlling exhaust gases have been disclosed in the prior art. U.S. Pat. No. 2,230,666 which issued on Feb. 4, 1941 and is entitled “Exhaust Gas Collector” discloses a plurality of laterally spaced exhaust pipes fluidly connected to the cylinders of an associated internal combustion engine open to a diverging funnel-like main exhaust tube providing reduced back pressure and thereby increasing the power of the engine. U.S. Pat. No. 4,288,988 which issued on Sep. 15, 1981 and is entitled “Method and Apparatus for Improving the Gas Flow in an Internal Combustion Engine Exhaust Manifold” discloses a method and apparatus for damping pressure oscillations in the exhaust manifold of an associated engine by throttling the exhaust gas near the outlet of the cylinders and then accelerating the gas flow in the manifold by providing a uniform flow section therein which is substantially smaller than the cylinder bore. U.S. Pat. No. 5,860,278 which issued on Jan. 19, 1999 and is entitled “Apparatus and Method for Providing a Compact Low Pressure Drop Exhaust Manifold” discloses a method and apparatus for improving flow through the manifold and decreasing pressure drop to enhance engine performance.  
         [0003]     While these and other prior manifold constructions control flow of engine exhaust gas as disclosed, one drawback is that such constructions can result in exhaust interference (i.e. a portion of the engine exhaust gas reflected back up the exhaust tube toward non-firing upstream engine cylinders) and reduced output depending on the exhaust order of the engine cylinders. It is therefore desirable to provide an exhaust manifold that is capable of reducing undesirable pneumatic interaction between cylinders and optimizing exhaust flow.  
         [0004]     It is known in the art that one solution for reducing undesirable pneumatic interaction is to provide an exhaust gas intake branch on the manifold adjacent to each cylinder of sufficient length (i.e. greater than eight inches) to permit the engine to fire the upstream cylinders prior to exhaust gas from downstream cylinders reaching the main exhaust tube. In this solution, exhaust gas entering the main exhaust passage of the manifold from upstream cylinders creates a sufficient downstream pressure on the exhaust gas previously emitted from downstream cylinders to prevent undesirable pneumatic interaction. However, the compact size of modern vehicle engine compartments makes such designs difficult due to their bulky configurations. It is therefore desirable to provide an exhaust manifold that requires a minimal amount of space within the engine compartment while reducing undesirable pneumatic interaction between cylinders.  
       SUMMARY OF THE INVENTION  
       [0005]     Accordingly, one aspect of the present invention is to provide an exhaust manifold that is capable of reducing undesirable pneumatic interaction between cylinders and optimizing exhaust flow.  
         [0006]     Another aspect of the present invention is to provide an exhaust manifold that requires a minimal amount of space within the engine compartment while reducing undesirable pneumatic interaction between cylinders.  
         [0007]     In accordance with the foregoing aspects of the invention, an exhaust manifold is shown comprising a housing with a generally rectangular outer wall and providing a longitudinally extending main exhaust gas passage terminating in an outlet at one end and a plurality of discrete inlet branch passages arranged to provide separate gas passages in fluid communication with an associated exhaust valve of an engine. An initial inlet branch passage and an inner wall of the housing are arranged to provide a ninety degree angular change of flow direction as exhaust gas exits an exhaust valve and enters the main exhaust gas passage. The remaining inlet branch passages are arranged to provide a deflector member between each inlet branch passage and the main exhaust gas passage which provides an angular change of flow direction requiring exhaust gas to enter the main exhaust gas passage in the downstream direction.  
         [0008]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0010]      FIG. 1  shows an elevational side view of an exhaust manifold looking toward the engine cylinder head in accordance with the present invention;  
         [0011]      FIG. 2  shows a planer and sectional view of an exhaust manifold looking in the direction  2 - 2  shown in  FIG. 1  in accordance with one embodiment of the present invention;  
         [0012]      FIG. 3  shows an elevational side view of an exhaust manifold looking away from the engine&#39;s cylinder head in accordance with the present invention; and  
         [0013]      FIG. 4  shows a planer and sectional view of an exhaust manifold looking in the direction  2 - 2  shown in  FIG. 1  in accordance with an alternative embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0015]     Turning now in greater detail to the drawings particularly  FIG. 1 , an exhaust manifold  1  according to an exemplary embodiment of the invention adapted for use with an internal combustion engine is shown. In the illustrated embodiment, an exhaust manifold  1  is adapted to be attached to a right cylinder assembly of a V-8 type internal combustion engine (not shown). The exhaust manifold  1  forms a plurality of exhaust gas inlet branch portions arranged in series. Referring to  FIGS. 2 and 4 , each exhaust gas inlet branch portion defines an inlet branch passage  10 ,  12 ,  14  and  16 , respectively, having exhaust gas openings  1   1 ,  13 ,  15  and  17  open to flow of exhaust gas from the passages of the cylinder head as is well known in the art. The inlet branch passages  10 ,  12 ,  14  and  16  each receive a discharge of exhaust gas from an associated exhaust opening (not shown) of the engine cylinder head.  
         [0016]     As best seen in  FIG. 3 , a housing  200  of the manifold  1  generally extends longitudinally with a closed forward end portion and an opened rearward end portion terminating in an outlet  18 . When attached to the associated engine cylinder head, the manifold  1  is secured so as to align its inlet branch passages  10 ,  12 ,  14  and  16 , respectively, with the outlet openings of the engine cylinder head. Specifically, the manifold  1  is attached to the cylinder head (not shown) by fasteners (not shown) extending through brackets  101 ,  102 ,  121 ,  122 ,  141 ,  142 ,  161  and  162 . An encircling flange  181  is provided to connect the outlet  18  of the housing  200  to an exhaust pipe (not shown) by means of fasteners (not shown).  
         [0017]     As best seen in  FIGS. 2 and 4 , manifold  1  defines a main exhaust gas passage  203  formed by the internal walls  205 ,  207 ,  227  of the housing  200 . As each exhaust valve opens for an associated combustion chamber, exhaust gas (such as  50  and  52  shown in  FIGS. 2 and 4 ) flows into the associated inlet branch passages  10 ,  12 ,  14  and  16  of the manifold  1 .  
         [0018]     The flow of exhaust gas through an initial inlet branch passage into the main exhaust gas passage  203  of the manifold  1  occurs in a manner known to those skilled in the art. For example, with respect to inlet branch passage  10 , the flow of exhaust gas performs an angular change of direction of approximately ninety degrees after the flow enters into the main exhaust gas passage  203 . Each of the internal walls  205 ,  207  of the housing  200  are formed to gradually turn to provide this angular change of direction as the flow proceeds downstream in the longitudinal direction, as represented by arrows  2 , toward the outlet end of the manifold  1 .  
         [0019]     In accordance with the present invention, a deflector member  125 ,  145  and  165  is provided to prevent exhaust gases entering the main exhaust passage from downstream inlet branch passages from backing up (i.e. flowing upstream) and pneumatically interacting with exhaust gases attempting to enter the main exhaust passage from upstream inlet branch passages. More specifically, beginning at the side wall of each inlet branch passage  12 ,  14  and  16  upstream of the outlet end  18  of the manifold  1 , a deflector member  125 ,  145  or  165  is formed as a curved wall within housing  200  extending into main exhaust gas passage  203  from a respective inlet branch passage  12 ,  14  or  16 . The deflector member  125  is as long as the inlet branch passage  12  is wide and the formed section area is no less than that of the inlet branch passage  12 . The terminal point of the deflector member  125  is shaped in a manner that exhaust gas flow  50  from the upstream inlet branch passages can not flow past the deflector member  125  at any appreciable angle, and provides at least the same section area as an upstream inlet branch passage. As a result, the exhaust gas flow  50  enters the main exhaust gas passage  203  at an angle θ relative to the main exhaust gas passage  203  that is less than ninety degrees.  
         [0020]     In a first exemplary embodiment of this invention as shown in  FIG. 4 , the deflector member  125  is formed with a substantially plumb end surface  127 .  
         [0021]     In a secondary exemplary embodiment of this invention as shown in  FIG. 2 , the deflector member  125  is formed with an inwardly sloping, or ramped, end surface, wherein the top and bottom portions of the wall  126  extend further into the main exhaust passage than the middle section of the wall. Such an arrangement can mitigate the potential formation of cracks in the deflector member  125  due to thermal stress.  
         [0022]     Therefore, the present invention advantageously provides a deflector member  125  is that controls any pressure waves from a downstream exhaust gas inlet branch by redirecting the flow from an inlet to be in the general direction of the main exhaust gas flow as it reaches the main exhaust gas passage  203 . Thus, exhaust gases can not reach the opening of any non-flowing inlet branch passage, irrespective of its sequential or mechanical position, thus reducing the probability of cylinder to cylinder pneumatic interaction.  
         [0023]     Another advantage of this deflector member  125  is the creation of a low-pressure area at the inlet branch passage/main exhaust passage juncture at each of the non-flowing inlet branch passages. As the upstream exhaust gas flow  50  passes by the outside surface of the deflector member  125 , a low pressure area is naturally created on the opposite side of the deflector member  125 . Since it is directionally correct for the cylinders&#39; exhaust cycle to enter the manifold  1  at the lowest possible conduit pressure, the deflector member  125  assists in the optimization of the exhaust gas flow within the manifold  1 .  
         [0024]     While only the exhaust manifold  1  associated with the right cylinder head (not shown) has been shown and referred to in  FIG. 1  and the text above, a similar left manifold would be provided for the left cylinder head of the V-8 engine. Other engines such as an I-4 (in-line four cylinder), or an I-6 engine would have only one single bank of cylinders and one cylinder head so that only a single exhaust manifold would be required. However, those skilled in the art will recognize that the specific exhaust gas control principles and construction of the exhaust manifold are applicable to other engine configurations.  
         [0025]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.