Abstract:
An induction system for a multi valve engine that facilitates operation in a lean burn mode over a large range of speeds and loads by employing a smaller cross sectional branch passages in several induction passages serving a common combustion chamber and a valve arrangement that progressively opens flow first through the branch passages and finally through both the main and branch passages so that maximum power can also be obtained.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an internal combustion engine and more particularly to an improved induction system for such an engine having improve performance particularly at low and mid range speeds without adversely affecting high speed performance. 
     It is well known that the induction system for an engine is a compromise between the obtaining of maximum performance and good running and fuel consumption at low speeds. It has also been proposed to provide an induction system induces turbulence in the combustion chamber in the form of swirl or tumble to improve low speed running and particularly to permit lean combustion. Examples of this are shown in U.S. Pat. No. 5,671,712 and Japanese Published Application 05-026135. 
     In the noted the United States Patent, the induction system includes a control valve which controls the flow of air to three intake valves provided for each combustion chamber. At low speeds, the control valve is operated so that the flow is directed through a restricted passageway toward one of the side intake valves. This also directs the flow into the combustion chamber in a direction of the to improve tumble and/or swirl. However, the flow also tends to go toward the other intake valves and diminishes the overall effect. 
     In the Japanese publication, on the other hand, the intake system cooperates with two intake valves and is designed so as to promote an increased flow to one of the intake valves by restricting the flow area. This will generate some turbulence. However, the arrangement restricts the overall ability of the engine to breath and thus reduces high speed performance. 
     In addition to the noted problems, in each approach in addition to the higher velocity flow through the restricted passage there is still a slower flow through the remainder of the valve opening through which the restricted opening passes. Thus even this added turbulence is reduced. 
     It is therefor a principal object to this invention to provide an induction system for an engine that will produce turbulence when desired and the desired flow directions without restricting maximum power output. In addition when the turbulence is generated this is done in such a way as to maintain the air flow in the direction or directions desired in the combustion chamber without dissipation of the effect. 
     SUMMARY OF THE INVENTION 
     A feature of this invention is adapted to be embodied in an internal combustion engine comprised of a pair of relatively moveable components defining a combustion chamber that varies in volume cyclically as the components move. A pair of intake passages supply of at least an air charge to the combustion chamber through respective valved openings communicating with the combustion chamber. A throttle valve is positioned in a common inlet to the intake passages for controlling the air flow thereto. A branch passage is formed in each of the intake passages and has an upstream inlet opening in communication with the common inlet and a discharge opening communicating directly with the valved opening of the respective intake passage in a direction to induce a swirling motion in the air delivered to the combustion chamber from the respective branch passage. A control valve precludes the flow through one of the branch passages when in a first position and permits flow through both of the branch passages in a second position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a partial cross sectional view take through a single cylinder of an internal combustion engine constructed in accordance with a first embodiment of the invention. 
         FIG. 2  is a cross section view taken along a plane perpendicular to the plane of  FIG. 1  looking from below and shows the configuration the induction system and its relation to an associated combustion chamber 
         FIG. 3  is a cross sectional view, in part similar to  FIG. 1 , and shows a second embodiment of the invention. 
         FIG. 4  is a cross section of view, in part similar to  FIG. 2 , and shows the construction of the embodiment of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring and now in detail to the drawing and initially to the embodiment of  FIGS. 1 and 2 , these show a portion of an internal combustion engine constructed in accordance with a first embodiment of the invention. In this embodiment and the other embodiment of  FIGS. 3 and 4  to be describes shortly, only a portion of the engine, identified generally by the reference numeral  11 , is illustrated. The portion of the engine that is shown is the combustion chamber and the induction and exhaust systems associated with it. The complete engine is not shown in as much as those skilled in the art will readily understand from the following description how the invention can be practiced with engines having any desired number of cylinders and cylinder configuration. 
     The engine  11  is comprised of the a cylinder block  12  that forms one or more cylinder bores  13  in which pistons (not shown) are supported for reciprocation. As is well known in the art, these pistons are connected to a crankshaft by means of connecting rods (none of which are shown). The cylinder bores  13  are closed at their upper ends by means of one or more cylinder head assemblies  14 , depending upon the configuration of the engine. That is, if the engine is of the V or opposed type, there will be provided a cylinder head  14  for each bank of the cylinder block  12 . 
     The surface of the cylinder head  14  that closes the cylinder bore  13  is formed with a recess  15 . These recesses  15 . the cylinder bores  13  and the head of the pistons each form a combustion chamber, indicated at  16 , of volume that varies cyclically as the engine crankshaft rotates. The combustion chamber is supplied with an air charge of by an induction system indicated generally at  17 . This induction system includes an air inlet device  18  that communicates with the atmosphere through an air intake opening in which a butterfly type operator control throttle valve  19  is positional. The induction device  18  may include tuning and silencing arrangements and so on of any desired types. 
     Since a single combustion chamber  16  is shown it should be understood the induction device  18  may form a part of an intake manifold that has branch sections or runners that communicate with the individual combustion chambers  16 . As illustrated these branch selections or runners have portions, indicated generally by the reference numeral  21  that sealingly engaged with the outer surface of the cylinder head  14 . 
     The manifold runner  21  as a generally open passageway, indicated generally by the reference numeral  22 , terminating in a large discharge opening  23  that communicates with a common inlet opening, indicated generally at  24 , of a cylinder head intake passage. The cylinder head intake passage is Siamesed and a pair of branch passages  25  and  26 , separated by a wall  27  extend from the common inlet  24 . 
     Each intake passage branch  25  and  26  terminates at a respective valve seat  28  and  29 , respectively, formed in the cylinder head recess  15 . Poppet type intake valves  31  and  32  are slidably supported in any desired manner by the cylinder head  14  and control the opening and closing of the these valve seats  28  and  29 . These intake valves  31  and  32  are operated by an overhead mounted cam shaft  33  journalled in the cylinder head  14 . Any suitable operating mechanism may be provided such as the rocker follower type of arrangement shown in the figures and indicated by the reference numeral  34 . 
     The charge which is formed in the combustion chambers  16 , in a manner to be described, is fired by means of a pair of spark plugs  35  and  36 . The spark plug  35  is mounted centrally in the combustion chamber  16  while the spark plug  36  is mounted adjacent the valved seat  29  adjacent the periphery of the cylinder bore  13 . 
     The burn charge is discharged from the combustion chamber  16  through a pair of a Siamese exhaust passage  37  which originates from exhaust valve seats  38  and  41  and is discharged to the atmosphere through a suitable exhaust system (not shown). Like the intake valves  31  and  32 , poppet type exhaust valves  39  and  41  are slidably supported in the cylinder head  14  in a suitable manner and are operated by means of an exhaust cam shaft  42 , suitably journalled in the cylinder head  14 , through a suitable mechanism such as rocker followers  43 . 
     Each intake valve seat  28  and  29  is served by a respective branch passage  44  and  45 . These branch passages  44  and  45  have respective inlet openings  46  and  47  that are formed in a curved surfaces  48  at the outlet end of the manifold runner end  21 . The curved surface  48  is complementary in shape to the peripheral edge of a butterfly type control valve  49  that is journalled on a control valve shaft  51  that extends transversely across the manifold runner end  21 . 
     The branch passages  44  and  45  extend also through the cylinder head  14  and terminate in respective discharge openings  52  and  53  that are directed transversely across the valve seats  28  and  29  and directed toward the opposite side thereof. 
     This embodiment employs direct cylinder fuel injection. To this end, a fuel injector  54  is mounted in the cylinder head  14  in the area adjacent the dividing wall  27  and below it. This fuel injector  54  has a spray pattern indicated by the broken lines F in the figures. The fuel sprayed from the fuel injector  54  will pass from one side of the cylinder bore  14  toward the opposite side and in proximity to the intake valve seats  28  and  29 . 
     The operation of this embodiment will now be described. It should be noted that regardless of the position of the flow control valve  49 , the A inlet opening  46  of the passage branch passage  44  will always be open. Thus, when the engine is operating at idle, all of the air flow will pass into the combustion chamber through the passageway  44  and specifically its opening  52 . As may be seen from  FIG. 2 , this is in direct registry with part of the discharge of fuel from the injector  54 . Also as has been noted, the discharge of opening  52  is directed toward the side of the of valve seat  29  closer to the axes of the cylinder bore  14 . Thus, this fuel will be subjected to a high velocity swirling motion around the axes of a cylinder bore  14  and ignition least by the spark plug  36  will be insured even though there is only a small amount of fuel in the combustion chamber  16 . 
     It should be understood back the flow control valve  49  may be operated either through a sequence through a linkage system with the operator control throttle valved  14  or maybe operated by means of a sensor of engine conditions such as engines speed/and or load. The condition described in the previous paragraph is the condition when operating at idle. 
     As the operator demands greater power by opening the throttle valved  19 , the flow control valve  49  is open progressively as shown by the arrows in  FIG. 1  from the position indicated in solid lines, toward the position indicated at A. When this position is reached, inlet opening  47  of the branch passage  46  associated with the intake valve  32  will be opened. As a result of this, there will be a high velocity air flows through both of the branch passages  45  and  46  and these flows will cause a tumble operation to occur in the combustion chamber  16 . In addition, the fuel be well mixed and can be ignited by either or both of the spark plugs  35  and  36 . Thus, even in mid range performance, lean operation is possible to improve fuel economy and good exhaust emission control. 
     In the embodiment as thus far described, the fuel injector  54  has been positioned to inject directly into the combustion chamber  16  resulting in what is referred to as “direct injection”. However, the invention also may be employed in conjunction with manifold type fuel injection and such an embodiment is shown in  FIGS. 3 and 4 . In this embodiment, the only difference from the previously described the embodiment is in conjunction with the location of the fuel injector  54 . Therefore, where components are the same as those in the previously described embodiment they have been identified by the same reference numerals and will be described again only in so far as is necessary to understand the construction and operation of this embodiment. 
     Referring now specifically to this embodiment it will be seen that the fuel injector  54  is mounted in the upper portion of the cylinder head  14  above the intake passages  25  and  26 . Actually, the actually the injector  54  is positioned upstream of the dividing wall  27  so that it&#39;s spray, I indicated by the arrows F., will be directed toward discharge openings  52  and  53  of the branch passages  25  and  26 . The discharge is, however, downstream of the branch passage openings  52  and  53  so that these same motion will be generated in the combustion chamber  16 . That is, when operating at idle, fuel will be discharged into the combustion chamber  16  due to the opening of both of the intake valves  31  and  32  and all of the air will introduced through both of the branch passage discharge openings  52  and  53  to provide the same form of motions in combustion chamber  16  has already described. 
     Also, the operation at part throttle and full throttle will also will be as previously described. Thus it is not believed necessary to repeat this description again. Of course, it should be understood that the foregoing description is that of some specific embodiments of the invention. Those skilled in the art will, however, understand readily than the spirit and scope and invention is not limited to specific environments described and that various modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.