Jet-propulsion watercraft

Abstract

A jet-propulsion watercraft comprises: an engine; an oil tank provided independently of the engine, for reserving engine oil; and a water jet pump driven by the engine, the water jet pump pressurizing and accelerating water taken in from outside of the watercraft and ejecting the water from the outlet port to propel the watercraft as a reaction of the ejecting water, and the muffler is provided behind the engine and on one of right and left sides of the watercraft and the oil tank is provided behind the engine and on the other side of the watercraft.

What is claimed is:  
     
         1 . A jet-propulsion watercraft comprising: 
 an engine;    an oil tank provided independently of the engine, for reserving engine oil; and    a water jet pump driven by the engine, the water jet pump pressurizing and accelerating water taken in from outside of the watercraft and ejecting the water from the outlet port to propel the watercraft as a reaction of the ejecting water, wherein    the muffler is provided behind the engine and on one of right and left sides of the watercraft and the oil tank is provided behind the engine and on the other side of the watercraft.    
     
     
         2 . The jet-propulsion watercraft according to  claim 1 , wherein 
 the oil tank is provided such that its longitudinal direction corresponds with a vertical direction.    
     
     
         3 . The jet-propulsion watercraft according to  claim 2 , wherein the oil tank is provided with an inner tube inside of the oil tank to form a vertically long closed space in the oil tank and cooling water is led into the closed space for water-cooling the oil tank.  
     
     
         4 . The jet-propulsion watercraft according to  claim 1 , wherein an outer plate of the muffler and an outer plate of the oil tank are identical components, and/or an end plate of the muffler and an end plate of the oil tank are identical components.  
     
     
         5 . The jet-propulsion watercraft according to  Claim 1 , wherein the jet-propulsion watercraft is a personal watercraft configured such that a straddle-type seat is provided to span between a center portion of a body and a rear portion of the body, a steering handle is provided in front of the seat, and the engine is mounted in a space below the seat.  
     
     
         6 . A jet-propulsion watercraft comprising: 
 an engine;    an oil tank provided independently of the engine, for reserving engine oil; and    a water jet pump driven by the engine, the water jet pump pressurizing and accelerating water taken in from outside of the watercraft and ejecting the water from the outlet port to propel the watercraft as a reaction of the ejecting water, wherein    the oil tank is provided with a cooling water passage, and    the engine oil reserved in the oil tank is cooled by water being supplied from the water jet pump to the cooling water passage.    
     
     
         7 . The jet-propulsion watercraft according to  claim 6 , wherein the oil tank is tubular and is provided with an inner tube inside of the oil tank as the cooling water passage.  
     
     
         8 . The jet-propulsion watercraft according to  Claim 7 , wherein the oil tank is cylindrical and the oil tank and the inner tube are provided such that their longitudinal directions correspond with a vertical direction.  
     
     
         9 . The jet-propulsion watercraft according to  claim 7 , wherein a breather pipe is provided inside of the inner tube such that a base end of the breather pipe is connected to an oil reserving portion formed between the inner tube and an inner face of the oil tank.  
     
     
         10 . The jet-propulsion watercraft according to  claim 9 , wherein the base end of the breather pipe is located at an upper end portion of the oil tank, and the breather pipe extends downwardly to a bottom of the inner tube, from which the breather pipe extends upwardly, and a tip end of the breather pipe protrudes from an upper end of the oil tank.  
     
     
         11 . The jet-propulsion watercraft according to  claim 8 , wherein a separating plate is provided in an oil reserving portion formed between the inner tube and an inner face of the oil tank such that the separating plate extends radially outwardly from an outer peripheral face of the inner tube.  
     
     
         12 . The jet-propulsion watercraft according to  claim 11 , wherein an oil introducing pipe of the oil tank is provided so as to be offset from a center axis of the oil tank.  
     
     
         13 . The jet-propulsion watercraft according to  claim 6 , wherein the jet-propulsion watercraft is a personal watercraft configured such that a straddle-type seat is provided to span between a center portion of a body and a rear portion of the body, a steering handle is provided in front of the seat, and the engine is mounted in a space below the seat.  
     
     
         14 . A jet-propulsion watercraft comprising: 
 an engine;    an oil tank provided independently of the engine, for reserving engine oil; and    a water jet pump driven by the engine, the water jet pump pressurizing and accelerating water taken in from outside of the watercraft and ejecting the water from the outlet port to propel the watercraft as a reaction of the ejecting water, wherein    the oil tank is tubular and is provided such that its longitudinal direction corresponds with a vertical direction, and the oil tank is provided at an upper portion with an inlet through which engine oil from the engine flows into the oil tank and at a lower portion with an outlet through which the engine oil to the engine flows to outside of the oil tank, wherein    the inlet is provided on a side wall of the oil tank such that the inlet is offset from a center axis of the oil tank to allow the engine oil flowing into the oil tank to swirl.    
     
     
         15 . The jet-propulsion watercraft according to  claim 14 , wherein the oil tank is cylindrical and the inlet is provided in a side face of the oil tank so as to be oriented along a tangential direction of the side face.  
     
     
         16 . The jet-propulsion watercraft according to  claim 15 , wherein a separating plate is provided inside of the oil tank such that the separating plate is orthogonal to the center axis of the oil tank.  
     
     
         17 . The jet-propulsion watercraft according to  Claim 16 , wherein the oil tank is provided with an inner tube inside of the oil tank in which water from the water jet pump flows.  
     
     
         18 . The jet-propulsion watercraft according to  claim 14 , wherein 
 the jet-propulsion watercraft is a personal watercraft configured such that a straddle-type seat is provided to span between a center portion of a body and a rear portion of the body, a steering handle is provided in front of the seat, and the engine is mounted in a space below the seat.