Abstract: An outboard motor includes an engine that generates power and a transmission device arranged to change the speed of rotation of the engine and to transmit the rotation to a propeller. The transmission device includes a planetary gear type transmission mechanism arranged to shift to any of a plurality of speed positions, and the planetary gear type transmission mechanism is controlled to shift such that a sun gear and planetary gears unitarily rotate when a speed position is a normally used speed position. The outboard motor achieves a reduction in load normally caused by engagements between gears in a normally used speed position and also achieves significant improvement in durability of the gears.

Abstract: A power transmission system of a marine propulsion system includes a transmission arranged to change the speed of an output from an engine and then to transmit the output to a propeller shaft. Wet-type multi-plate clutches provided in the transmission include a plurality of clutch plates fitted to a clutch rotating body for axial movement with the clutch rotating body. The clutch rotating body includes an oil reservoir in its inner bottom portion and arranged to hold lubricating oil and a peripheral wall arranged to cover the oil reservoir from the radial outside and fit to each of the clutch plates to permit axial movement of the clutch plates. Communicating holes are arranged on the peripheral wall such that they communicate the oil reservoir side to the outside of the clutch rotating body in the radial direction.

Abstract: An outboard motor includes an engine that generates power and a transmission device arranged to change the speed of rotation of the engine and to transmit the rotation to a propeller. The transmission device includes a planetary gear type transmission mechanism arranged to shift to any of a plurality of speed positions, and the planetary gear type transmission mechanism is controlled to shift such that a sun gear and planetary gears unitarily rotate when a speed position is a normally used speed position. The outboard motor achieves a reduction in load normally caused by engagements between gears in a normally used speed position and also achieves significant improvement in durability of the gears.

Abstract: In an outboard motor, a speed reduction mechanism includes an inner gear connected with an input shaft (i.e., second output shaft), a planetary gear that meshes with the inner gear and that rolls inside the inner gear, and a sun gear that meshes with the planetary gear and that is not rotatable. A shaft portion of a carrier that supports the planetary gear, and a shaft core portion of the sun gear, preferably have a cylindrical or substantially cylindrical shape. The shaft portion of the carrier is inserted and arranged to overlap with the shaft core portion of the sun gear in a direction perpendicular or substantially perpendicular to the shaft. The output shaft (i.e., drive shaft) is inserted and coupled to the shaft portion of the carrier. Accordingly, this provides an outboard motor that makes it possible to prevent the size of a speed change device from increasing in size when a speed reduction mechanism is added.

Abstract: A transmission device includes hydraulic type transmission mechanisms arranged to change the speed or the direction of rotation of an engine, and hydraulic pressure control valves arranged to control hydraulic pressure supplied to the hydraulic type transmission mechanisms. The hydraulic pressure control valves are disposed on one side or the other side in the watercraft width direction. The transmission device provides an outboard motor capable of securing cooling characteristics of a hydraulic pressure control valve without incurring complexity in structure and increase in cost.

Abstract: An oil supply device includes an axial oil passage and an intersecting oil passage provided in a propeller shaft, an axial oil passage and an intersecting oil passage provided in a drive shaft, and an oil guide passage. The intersecting oil passages allow oil inside the axial oil passages to be spouted radially of the shaft by centrifugal force generated as the shafts rotate. The oil is then supplied via the oil guide passage to an intermediate speed reduction device. As a result, it is possible to sufficiently lubricate an intermediate speed reduction device mounted on a drive shaft through a simple and compact arrangement.

Abstract: A power transmission system for a marine propulsion unit includes a case arranged to be supported on a hull; a propeller supported at the lower end portion of the case for rotation about an axis extending in a fore-and-aft direction; a transmission housed in the case and having an axis with planetary gear trains extending vertically to receive an output from an engine, and change the speed of the output prior to transmission thereof; and an interlocking device arranged to receive the output from the transmission and transmit the output to the propeller. A speed reduction device is arranged such that it is interposed between the transmission and the interlocking device, receives the output from the transmission, and decelerates the output to transmit it to the interlocking device. This arrangement reduces the weight of a transmission unit in a power transmission system of a marine propulsion unit and decreases an external size of the transmission unit.

Abstract: A power transmission system of a marine propulsion system includes a transmission arranged to change the speed of an output from an engine and then to transmit the output to a propeller shaft. Wet-type multi-plate clutches provided in the transmission include a plurality of clutch plates fitted to a clutch rotating body for axial movement with the clutch rotating body. The clutch rotating body includes an oil reservoir in its inner bottom portion and arranged to hold lubricating oil and a peripheral wall arranged to cover the oil reservoir from the radial outside and fit to each of the clutch plates to permit axial movement of the clutch plates. Communicating holes are arranged on the peripheral wall such that they communicate the oil reservoir side to the outside of the clutch rotating body in the radial direction.

Abstract: An outboard motor includes a transmission device disposed on a middle portion of a drive shaft driven by an engine. The transmission device includes a forward-reverse switching device housed in a transmission case. Lubricating oil for lubricating the forward-reverse switching device is stored in the transmission case. The transmission case has a drain hole arranged to discharge lubricating oil in the transmission case that is provided in a lower portion of a side wall and in a position in front of the drive shaft, and a drain bolt for opening or closing the drain hole. An exposed opening for exposing the drain hole is provided in an upper case that covers the transmission case. As a result, work efficiency in discharging or draining of lubricating oil is greatly improved without requiring dismantling of a main body of the outboard motor.

Abstract: A transmission device includes hydraulic type transmission mechanisms arranged to change the speed or the direction of rotation of an engine, and hydraulic pressure control valves arranged to control hydraulic pressure supplied to the hydraulic type transmission mechanisms. The hydraulic pressure control valves are disposed on one side or the other side in the watercraft width direction. The transmission device provides an outboard motor capable of securing cooling characteristics of a hydraulic pressure control valve without incurring complexity in structure and increase in cost.

Abstract: In an outboard motor, a speed reduction mechanism includes an inner gear connected with an input shaft (i.e., second output shaft), a planetary gear that meshes with the inner gear and that rolls inside the inner gear, and a sun gear that meshes with the planetary gear and that is not rotatable. A shaft portion of a carrier that supports the planetary gear, and a shaft core portion of the sun gear, preferably have a cylindrical or substantially cylindrical shape. The shaft portion of the carrier is inserted and arranged to overlap with the shaft core portion of the sun gear in a direction perpendicular or substantially perpendicular to the shaft. The output shaft (i.e., drive shaft) is inserted and coupled to the shaft portion of the carrier. Accordingly, this provides an outboard motor that makes it possible to prevent the size of a speed change device from increasing in size when a speed reduction mechanism is added.

Abstract: An oil supply device includes an axial oil passage and an intersecting oil passage provided in a propeller shaft, an axial oil passage and an intersecting oil passage provided in a drive shaft, and an oil guide passage. The intersecting oil passages allow oil inside the axial oil passages to be spouted radially of the shaft by centrifugal force generated as the shafts rotate. The oil is then supplied via the oil guide passage to an intermediate speed reduction device. As a result, it is possible to sufficiently lubricate an intermediate speed reduction device mounted on a drive shaft through a simple and compact arrangement.

Abstract: A water cooling apparatus in a power transmission system of a boat propulsion system includes a transmission unit that changes the speed of an output from an engine and then transmits the output to a propeller shaft. The transmission unit includes a cylindrical transmission case with an axis extending vertically, a transmission device housed in the transmission case and arranged to change the speed of an input, and a cooling water passage formed in the transmission case for flowing cooling water. In the plan sectional view of the transmission unit, the cooling water passage is formed in at least one of a side portion or a rear portion of the transmission case. As a result, strain on a rear portion of a hull that supports a boat propulsion unit is prevented and minimized, while a transmission unit is sufficiently cooled with cooling water.

Abstract: An outboard motor includes a transmission device disposed on a middle portion of a drive shaft driven by an engine. The transmission device includes a forward-reverse switching device housed in a transmission case. Lubricating oil for lubricating the forward-reverse switching device is stored in the transmission case. The transmission case has a drain hole arranged to discharge lubricating oil in the transmission case that is provided in a lower portion of a side wall and in a position in front of the drive shaft, and a drain bolt for opening or closing the drain hole. An exposed opening for exposing the drain hole is provided in an upper case that covers the transmission case. As a result, work efficiency in discharging or draining of lubricating oil is greatly improved without requiring dismantling of a main body of the outboard motor.

Abstract: An outboard motor includes an engine. A cowling body defines an internal cavity in which the engine is enclosed. A partition member divides the internal cavity into a first cavity and a second cavity. The first cavity communicates with outside through a first opening for introducing ambient air into the first cavity. The second cavity encloses the engine therein. The partition member has a second opening through which the air in the first cavity moves to the second cavity. The cowling body and the partition member are made of a nonferrous metal. The partition member is adhered to the cowling body.

Abstract: An outboard motor has a cowling structure that includes a top cowl and a bottom cowl. The top cowl has a hook mounting member which is bonded to an inner side of the top cowl. The hook mounting member has a top cowl hook configured to engage a bottom cowl hook mounted to the bottom cowl. The hook mounting member is formed by pressing a nonferrous metal plate. A hook fixing part of the housing mounting member is coupled to the top cowl hook and is formed by the way of drawing in the pressing process.

Abstract: An outboard motor has a cowling structure that includes a top cowl and a bottom cowl. The top cowl has a hook mounting member which is bonded to an inner side of the top cowl. The hook mounting member has a top cowl hook configured to engage a bottom cowl hook mounted to the bottom cowl. The hook mounting member is formed by pressing a nonferrous metal plate. A hook fixing part of the housing mounting member is coupled to the top cowl hook and is formed by the way of drawing in the pressing process.

Abstract: An outboard motor includes an engine. A cowling body defines an internal cavity in which the engine is enclosed. A partition member divides the internal cavity into a first cavity and a second cavity. The first cavity communicates with outside through a first opening for introducing ambient air into the first cavity. The second cavity encloses the engine therein. The partition member has a second opening through which the air in the first cavity moves to the second cavity. The cowling body and the partition member are made of a nonferrous metal. The partition member is adhered to the cowling body.