Outboard engine

Claim 1

In an outboard engine comprising an internal combustion engine having a crankshaft, a propeller on a driving shaft, and an automatic clutch provided between said crankshaft of said engine and said driving shaft of said propeller, the improvement wherein: said automatic clutch comprises a main centrifugal clutch mechanism which is engaged at a revolutional speed close to the rated revolutional speed of the engine and an auxiliary centrifugal clutch mechanism which transmits the revolutional torque of said engine with a frictional slip between said crankshaft and said driving shaft at a revolutional speed of the engine lower than said rated revolutional speed or at an idling speed; said main centrifugal clutch mechanism comprising a clutch drum coupled with said driving shaft of said propeller; a supporting disc mounted interior of said clutch drum and rotatably coupled with said crankshaft of said engine so as to rotate with said crankshaft; and a plurality of main centrifugal clutch shoes which are mounted on said supporting disc and which are engageable with said clutch drum by means of a centrifugal force acting thereon when the engine revolutional speed reaches close to said rated revolutional speed; and said auxiliary centrifugal clutch mechanism comprising a plurality of auxiliary centrifugal clutch shoes mounted on the outer periphery of said supporting disc and interior of said clutch drum; said respective auxiliary centrifugal clutch shoes each including a plate spring having a first end portion which is mounted on the outer periphery of said supporting disc, and a second end portion spaced from said first end portion; said auxiliary clutch shoes each further including a pad on the outer facing surface of said second end portion thereof and adapted to frictionally and slideably engage the inner surface of said clutch drum by means of a centrifugal force acting on said auxiliary clutch shoes at a revolutional speed of the engine lower than that required for engaging said main centrifugal clutch mechanism, the engagement pressure of said auxiliary clutch shoes against said clutch drum being a function of the amount of said centrifugal force, whereby the revolutional torque of said crankshaft is reduced by the resultant slip effect between said auxiliary clutch shoes and said clutch drum to transmit rotation to said propeller driving shaft at a lower speed than the revolutional speed of said crankshaft.