Outboard motor and boat

Abstract

An outboard motor includes a drive source, a drive shaft, a steering shaft, a case, and an angle detection sensor. The drive shaft extends in an upper-lower direction and is rotatable by the driving force of the drive source. The hollow tubular steering shaft surrounds an outer circumference of the drive shaft. The case is located lower than the drive source, and an oil chamber is structured to store oil, and at least a portion of the steering shaft is housed in the oil chamber. The angle detection sensor is located higher than the oil chamber to detect the rotation angle of the steering shaft.

What is claimed is: 
     
         1 . An outboard motor comprising:
 a drive source;   a drive shaft extending in an upper-lower direction and rotatable by the driving force of the drive source;   a hollow tubular steering shaft to surround an outer circumference of the drive shaft;   a case located lower than the drive source and including an oil chamber to store oil and at least a portion of the steering shaft is housed in the oil chamber; and   an angle detection sensor located higher than the oil chamber to detect a rotation angle of the steering shaft.   
     
     
         2 . The outboard motor according to  claim 1 , wherein the angle detection sensor is located between the drive source and the oil chamber in the upper-lower direction. 
     
     
         3 . The outboard motor according to  claim 1 , further comprising:
 a primary reduction gear located lower than the drive source and higher than the oil chamber; wherein   the angle detection sensor is located between the primary reduction gear and the oil chamber in the upper-lower direction.   
     
     
         4 . The outboard motor according to  claim 2 , further comprising:
 a primary reduction gear located lower than the drive source and higher than the oil chamber; wherein   the angle detection sensor is located between the primary reduction gear and the oil chamber in the upper-lower direction.   
     
     
         5 . The outboard motor according to  claim 1 , further comprising:
 a rotatable body to rotate in conjunction with the rotation of the steering shaft and at least a portion of which is located higher than the oil chamber; wherein   the angle detection sensor is operable to detect the rotation angle of the steering shaft by measuring a rotation angle of the rotatable body.   
     
     
         6 . The outboard motor according to  claim 2 , further comprising:
 a rotatable body to rotate in conjunction with the rotation of the steering shaft and at least a portion of which is located higher than the oil chamber; wherein   the angle detection sensor is operable to detect the rotation angle of the steering shaft by measuring a rotation angle of the rotatable body.   
     
     
         7 . The outboard motor according to  claim 3 , further comprising:
 a rotatable body to rotate in conjunction with the rotation of the steering shaft and at least a portion of which is located higher than the oil chamber; wherein   the angle detection sensor is operable to detect the rotation angle of the steering shaft by measuring a rotation angle of the rotatable body.   
     
     
         8 . The outboard motor according to  claim 5 , wherein
 a portion of the steering shaft is located higher than the oil chamber; and   the rotation of the steering shaft is transmitted to the rotatable body at a location higher than the oil chamber.   
     
     
         9 . The outboard motor according to  claim 6 , wherein
 a portion of the steering shaft is located higher than the oil chamber; and   the rotation of the steering shaft is transmitted to the rotatable body at a location higher than the oil chamber.   
     
     
         10 . The outboard motor according to  claim 7 , wherein
 a portion of the steering shaft is located higher than the oil chamber; and   the rotation of the steering shaft is transmitted to the rotatable body at a location higher than the oil chamber.   
     
     
         11 . The outboard motor according to  claim 5 , wherein
 the rotatable body includes an offset shaft that is parallel or substantially parallel to the steering shaft; and   the outboard motor further comprises a transmission located higher than the oil chamber to transmit the rotation of the steering shaft to the offset shaft.   
     
     
         12 . The outboard motor according to  claim 8 , wherein
 the rotatable body includes an offset shaft that is parallel or substantially parallel to the steering shaft; and   the outboard motor further comprises a transmission located higher than the oil chamber to transmit the rotation of the steering shaft to the offset shaft.   
     
     
         13 . The outboard motor according to  claim 1 , wherein
 the drive source includes an electric motor; and   the outboard motor further comprises a waterproof case located higher than the oil chamber and housing the electric motor and the angle detection sensor.   
     
     
         14 . The outboard motor according to  claim 2 , wherein
 the drive source includes an electric motor; and   the outboard motor further comprises a waterproof case located higher than the oil chamber and housing the electric motor and the angle detection sensor.   
     
     
         15 . The outboard motor according to  claim 3 , wherein
 the drive source includes an electric motor; and   the outboard motor further comprises a waterproof case located higher than the oil chamber and housing the electric motor and the angle detection sensor.   
     
     
         16 . The outboard motor according to  claim 13 , further comprising:
 a rotatable body to rotate in conjunction with the rotation of the steering shaft and at least a portion of which is located inside the waterproof case; wherein   the angle detection sensor is operable to detect the rotation angle of the steering shaft by measuring a rotation angle of the rotatable body.   
     
     
         17 . The outboard motor according to in  claim 16 , wherein
 a portion of the steering shaft is located inside the waterproof case; and   the rotation of the steering shaft is transmitted to the rotatable body inside the waterproof case.   
     
     
         18 . The outboard motor according to  claim 16 , wherein
 the rotatable body includes an offset shaft that is parallel or substantially parallel to the steering shaft; and   the outboard motor further comprises a transmission inside the waterproof case to transmit the rotation of the steering shaft to the offset shaft.   
     
     
         19 . A boat comprising;
 a hull; and   the outboard motor according to  claim 1  mounted to a rear portion of the hull.   
     
     
         20 . An outboard motor comprising:
 a drive source;   a drive shaft extending in an upper-lower direction and rotatable by the driving force of the drive source;   a hollow tubular steering shaft to surround an outer circumference of the drive shaft; and   an angle detection sensor surrounded by air to detect a rotation angle of the steering shaft.