Marine jet propulsion arrangement

Abstract

A jet propulsion arrangement, including a jet propulsion unit ( 32 ) having a housing ( 38 ) which includes an inlet ( 40 ) through which liquid is received, an outlet ( 34 ) through which liquid is discharged, a liquid path ( 39 ) between the inlet ( 40 ) and the outlet ( 34 ) and an impeller ( 41 ) disposed in the liquid path ( 39 ) to drive liquid for discharge. The housing can define a gear chamber ( 45 ) which accommodates a gear arrangement ( 46 ), with a first drive shaft ( 44 ) extending from the gear arrangement ( 46 ) in direct connection to the impeller ( 41 ) and a second drive shaft ( 54 ) extending from the gear arrangement ( 46 ) to an engine ( 31 ). Alternatively, a single shaft can extend in direct connection between the impeller ( 41 ) and the engine ( 31 ).

1 . A jet propulsion arrangement, including a jet propulsion unit having a housing which includes an inlet through which liquid is received at a first end thereof, an outlet through which liquid is discharged at a second end thereof, a liquid path between said inlet and said outlet and an impeller disposed in said liquid path to drive liquid for discharge, said housing defining a gear chamber generally in the region above said inlet which accommodates a gear arrangement, a first drive shaft extends from said gear arrangement in direct connection to said impeller and a second drive shaft extends from said gear arrangement to an inboard engine said first and second drive shafts extending substantially parallel to each other and in substantially opposite directions.  
   
   
       2 . A jet propulsion arrangement according to  claim 1 , said jet propulsion unit being generally elongate, with said outlet disposed at one end thereof and said gear chamber disposed at an opposite end.  
   
   
       3 . A jet propulsion arrangement according to  claim 1 , said liquid path being defined by housing walls which form a conduit that extends between said inlet and said outlet, wherein said first drive shaft extends through a housing wall of said conduit and into said liquid path for connection to said impeller.  
   
   
       4 . A jet propulsion arrangement according to  claim 1 , wherein said first drive shaft extends substantially horizontally between said gear arrangement and said impeller.  
   
   
       5 . A jet propulsion arrangement according to  claim 1 , wherein the axis of rotation of said first drive shaft is below the axis of rotation of said second drive shaft.  
   
   
       6 . A jet propulsion arrangement according to  claim 1 , wherein said gear arrangement includes a pair of meshing helical gears which provide a rotational speed reduction between the first and second drive shafts.  
   
   
       7 . A jet propulsion arrangement according to  claim 6 , said helical gears being in substantially vertically spaced meshing engagement.  
   
   
       8 . A jet propulsion arrangement according to  claim 6 , a first of said helical gears being fixedly connected to an end of said first drive shaft, and in second of said helical gears being flexibly connected to an end of said second drive shaft, said flexible connection accommodating axial misalignment between said engine and said gear arrangement.  
   
   
       9 . A jet propulsion arrangement according to  claim 1 , wherein said gear chamber is formed as an integral part of said housing, and defines an opening for access to within said chamber which is closed by a removable plate.  
   
   
       10 . A jet propulsion arrangement according to  claim 1 , wherein said housing is cast in at least two sections which are subsequently connected together.  
   
   
       11 . A jet propulsion arrangement according to  claim 1 , wherein said gear chamber is separately connected to said housing.  
   
   
       12 . A jet propulsion unit for use in a jet propulsion arrangement according to  claim 1 .  
   
   
       13 . A jet propulsion arrangement according to  claim 1  wherein said arrangement includes a couple for connection to the inboard engine said couple including a pair of projections which extend from a plate through which said second drive shaft extends and each said projection includes a bore, said projections being arranged to overly or underly complementary mounting projections of the inboard engine, said mounting projections each including a bore and said respective bores being arranged for alignment and to accept a fastener for fastening the respective projections of said couple and the inboard engine together.  
   
   
       14 . A jet propulsion arrangement according to  claim 13  said pair of projections of said couple extending from opposite sides of the said second drive shaft.  
   
   
       15 . A jet propulsion arrangement according to  claim 13 , wherein said couple is rotational so that the arrangement can be coupled to the inboard engine at an angle.  
   
   
       16 . A jet propulsion arrangement according to  claim 15 , said rotational couple having an arc of rotation of about 45°.  
   
   
       17 . A jet propulsion arrangement according to  claim 1 , said engine having a rear end region and a forward end region and said rear end region being closer to said jet propulsion unit than said forward end region, said engine being supported at each of said forward and rear end regions and said rear end region support being provided by connection between said engine and said jet propulsion unit.  
   
   
       18 . A jet propulsion arrangement including a jet propulsion unit having a housing which includes an inlet through which liquid is received at a first end thereof, an outlet through which liquid is discharged at a second end thereof, a liquid path between said inlet and said outlet and an impeller disposed in said liquid path to drive liquid for discharge, a drive shaft extending from said impeller for connection to an engine, said engine having a rear end region and a forward end region and said rear end region being closer to said jet propulsion unit than said forward end region, said engine being supported at each of said forward and rear end regions and said rear end region support being provided by said connection to said jet propulsion unit.  
   
   
       19 . A jet propulsion unit having a housing which includes an inlet through which liquid is received at a first end thereof, an outlet through which liquid is discharged at a second end thereof, a liquid path between said inlet and said outlet and an impeller disposed in said liquid path to drive liquid for discharge, said housing defining a gear chamber generally I the region above said inlet which accommodates a gear arrangement, a first drive shaft extends from said gear arrangement in direct connection to said impeller and a second drive shaft extends from said gear arrangement for connection to an inboard engine said first and second drive shafts extending substantially parallel to each other and in substantially opposite directions.  
   
   
       20 . A marine vessel including an engine and a jet propulsion unit according to  claim 19.