Induction system for watercraft engine

Abstract

An induction system employed in an engine of a small watercraft includes the first intake chamber communicating with the combustion chambers within the engine and a second intake chamber communicating with the first intake chamber. At least one auxiliary air aperture is provided in the first intake chamber so as to allow an auxiliary flow of air into the first intake chamber during, for example, sudden acceleration.

What is claimed is:  
     
         1 . An engine induction system for a watercraft comprised of a hull defining an engine compartment, an internal combustion engine having a least one combustion chamber and being supported within the engine compartment, and a propulsion device supported by the hull and driven by the engine to propel the watercraft, the induction system comprising a first intake air chamber having a plurality of walls defining an interior volume and having an air inlet, the first intake air chamber communicating with the least one combustion chamber, a second intake air chamber having an air inlet and an air outlet, the air inlet of the first intake air chamber communicating with the air outlet of the second intake air chamber, and at least one auxiliary air aperture formed in at least one of the plurality of walls.  
     
     
         2 . An engine induction system as set forth in  claim 1  additionally comprising a first cross sectional air flow area defined in the induction system upstream from the first intake air chamber, the at least one auxiliary air aperture defining a total cross sectional air flow area into the first intake air chamber that is from 5-25% of the first cross sectional air flow area.  
     
     
         3 . An engine induction system as set forth in  claim 2 , wherein the total cross sectional air flow area of the at least one auxiliary air aperture is from 10-20% of the first cross sectional air flow area.  
     
     
         4 . An engine induction system as set forth in  claim 3 , wherein the total cross sectional air flow area of the at least one auxiliary air aperture is approximately 15% of the first cross sectional air flow area.  
     
     
         5 . An engine induction system as set forth in  claim 2  additionally comprising a conduit through which the air inlet of the first intake air chamber communicates with the air outlet of the second intake air chamber, the conduit defining the first cross sectional air flow area at a minimum cross sectional passage formed in the conduit.  
     
     
         6 . An engine induction system as set forth in  claim 1 , wherein the plurality of walls includes at least one inner wall formed between the interior of the first intake air chamber and the engine, the at least one auxiliary air aperture being formed in the inner wall.  
     
     
         7 . An engine induction system as set forth in  claim 6 , wherein the at least one auxiliary air aperture is arranged in an upper portion of the inner wall.  
     
     
         8 . An engine induction system as set forth in  claim 6  additionally comprising at least one induction port formed on the inner of wall, the first intake air chamber communicating with the at least one combustion chamber through the at least one induction port.  
     
     
         9 . An engine induction system as set forth in  claim 8 , wherein the at least one induction port comprises at least one pair of induction ports, the at least one auxiliary air aperture being arranged between the induction ports of each pair of induction ports.  
     
     
         10 . An engine induction system as set forth in  claim 9 , wherein the at least one auxiliary air aperture comprises at least a pair of auxiliary air apertures formed between each pair of induction ports.  
     
     
         11 . An engine induction system as set forth in  claim 8 , wherein the at least one auxiliary air aperture is formed on a portion of the wall above the induction port.  
     
     
         12 . An engine induction system as set forth in  claim 1 , wherein the at least one auxiliary air aperture connects the first intake air chamber to a space formed between the first intake air chamber and the engine.  
     
     
         13 . An induction system as set forth in  claim 1  additionally comprising an exhaust conduit communicating with the least one combustion chamber and extending over the first intake air chamber.  
     
     
         14 . An engine induction system as set forth in  claim 13  additionally comprising at least one fuel charge former positioned between the induction port and the engine, the exhaust conduit extending above the at least one fuel charge former.  
     
     
         15 . An engine induction system as set forth in  claim 1  additionally comprising a conduit through which the air inlet of the first intake air chamber communicates with the air outlet of the second intake air chamber, the first intake air chamber defining a first cross-sectional flow area, and the conduit defining a second cross-sectional flow area being smaller than the first cross-sectional flow area.  
     
     
         16 . An engine induction system according to  claim 15 , wherein the at least one auxiliary air aperture defines a cross-sectional air flow area the smaller than the first cross-sectional flow area.  
     
     
         17 . An engine induction system according to  claim 1  additionally comprising a projection formed adjacent the at least one auxiliary air aperture and being configured to shield the at least one auxiliary air aperture from splashing water.  
     
     
         18 . An engine induction system for a watercraft comprised of a hull defining an engine compartment, an internal combustion engine having a least one combustion chamber and being supported within the engine compartment, a propulsion device supported by the hull and driven by the engine to propel the watercraft, and a fuel tank supported by the hull, the induction system comprising a first intake air chamber having a plurality of walls defining an interior volume and having an air inlet, the first intake air chamber communicating with the least one combustion chamber, a second intake air chamber having an air inlet and an air outlet, the air inlet of the first intake air chamber communicating with the air outlet of the second intake air chamber, and means for allowing an auxiliary flow of air to flow into the first intake air chamber.  
     
     
         19 . An engine induction system according to  claim 18  additionally comprising means for shielding the means for allowing from splashing water.  
     
     
         20 . An engine induction system according to  claim 18  additionally comprising at least one projection formed adjacent the means for allowing, the projection being configured to shield the means for allowing from splashing water.  
     
     
         21 . An engine induction system as set forth in  claim 18 , wherein the plurality of walls includes at least one inner wall formed between the interior of the first intake air chamber and the engine, the means for allowing being formed in the inner wall.  
     
     
         22 . An engine induction system as set forth in  claim 21 , wherein the means for allowing is arranged in an upper portion of the inner wall.  
     
     
         23 . An engine induction system as set forth in  claim 21  additionally comprising at least one induction port formed on the inner of wall, the first intake air chamber communicating with the at least one combustion chamber through the at least one induction port.  
     
     
         24 . An engine induction system as set forth in  claim 23 , wherein the at least one induction port comprises at least one pair of induction ports, the means for allowing being arranged between the induction ports of each pair of induction ports.  
     
     
         25 . An engine induction system as set forth in  claim 18  additionally comprising an exhaust conduit communicating with the least one combustion chamber and extending over the first intake air chamber, the means for allowing being positioned below the exhaust conduit.  
     
     
         26 . An engine induction system as set forth in  claim 25 , wherein the plurality of walls includes at least one inner wall formed between the interior of the first intake air chamber and the engine, the means for allowing being formed in the inner wall.