Abstract: An outboard motor includes a lower portion including a propeller shaft, an upper portion including a drive source to provide a rotational force to rotate the propeller shaft, and a support portion to rotatably support the lower portion relative to the upper portion about a steering shaft and rotate integrally with the lower portion. The upper portion includes a water pump assembly to suck up water from the lower portion through the support portion and supply the water to the drive source. When viewed along a shaft line direction of the steering shaft, the water pump assembly overlaps the lower portion at a first rotation position of the lower portion with respect to the upper portion, and at least a portion of the water pump assembly does not overlap the lower portion at a second rotation position of the lower portion with respect to the upper portion.

Abstract: An outboard motor includes a driving gear that is driven and rotated, and a propeller shaft that extends in a front-rear direction below the driving gear. The outboard motor includes a first transmission gear that is engaged with the driving gear and surrounding the propeller shaft, a propeller-shaft bearing that rotatably supports the propeller shaft, a first-transmission-gear bearing that rotatably supports the first transmission gear, and a support including an intervening portion between the first transmission gear and the propeller shaft. The support supports the propeller-shaft bearing between the intervening portion and the propeller shaft, and supports the first-transmission-gear bearing at a more outward position than the intervening portion in a radial direction of the propeller shaft.

Abstract: An outboard motor includes a driving gear that is driven and rotated, and a propeller shaft that extends in a front-rear direction below the driving gear. The outboard motor includes a first transmission gear that is engaged with the driving gear and surrounding the propeller shaft, a propeller-shaft bearing that rotatably supports the propeller shaft, a first-transmission-gear bearing that rotatably supports the first transmission gear, and a support including an intervening portion between the first transmission gear and the propeller shaft. The support supports the propeller-shaft bearing between the intervening portion and the propeller shaft, and supports the first-transmission-gear bearing at a more outward position than the intervening portion in a radial direction of the propeller shaft.

Abstract: A marine propulsion device includes a motive force transmission system, a propeller shaft, a housing section, and a clutch. The motive force transmission system includes a crank shaft and a drive shaft which transmits a motive force from the crank shaft. The propeller shaft transmits the motive force from the drive shaft. The housing section houses the motive force transmission system. The clutch is attached between the motive force transmission system and the housing section. The clutch permits relative rotation between the motive force transmission system and the housing section by opening a connection between the motive force transmission system and the housing section during normal rotation of the motive force transmission system. The clutch prevents relative rotation between the motive force transmission system and the housing section by connecting the motive force transmission system and the housing section during a reverse rotation of the motive force transmission system.

Abstract: A marine propulsion device includes a motive force transmission system, a propeller shaft, a housing section, and a clutch. The motive force transmission system includes a crank shaft and a drive shaft which transmits a motive force from the crank shaft. The propeller shaft transmits the motive force from the drive shaft. The housing section houses the motive force transmission system. The clutch is attached between the motive force transmission system and the housing section. The clutch permits relative rotation between the motive force transmission system and the housing section by opening a connection between the motive force transmission system and the housing section during normal rotation of the motive force transmission system. The clutch prevents relative rotation between the motive force transmission system and the housing section by connecting the motive force transmission system and the housing section during a reverse rotation of the motive force transmission system.

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: 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 marine vessel propulsion unit includes an engine, a drive shaft, a single propeller shaft, a single propeller, and a planetary gear mechanism. The drive shaft is arranged to extend vertically. The propeller shaft is arranged to extend in a direction intersecting the drive shaft. The rotation of the engine is transmitted to the propeller shaft via the drive shaft. The propeller is arranged to rotate together with the propeller shaft. The planetary gear mechanism is arranged at the front relative to the drive shaft and coaxial to a central rotation axis of the propeller shaft. The planetary gear mechanism is arranged to decelerate the rotation from the drive shaft and transmit the decelerated rotation toward the propeller shaft.

Abstract: In an outboard motor having a power transmission mechanism for transmitting power of an engine to a propeller, the power transmission mechanism has a transmission ratio changing unit having a planetary gear train including a sun gear, planetary gears, and an internal gear. The internal gear is connected to an input side shaft on the engine side. The planetary gears are connected to an output side shaft on the propeller side. The sun gear is connected to a stationary portion via a one-way clutch. The planetary gears and the internal gear and/or the sun gear are connected by an on-off clutch. When the on-off clutch is disengaged, the one-way clutch is engaged and the speed from the input side shaft is outputted from the output side shaft with a reduced speed. When the on-off clutch is engaged, the speed from the input side shaft is outputted from the output side shaft with the same speed.

Abstract: A marine vessel propulsion unit includes an engine, a drive shaft, a propeller shaft, a propeller, an intermediate shaft, and a first reduction gear mechanism. The drive shaft is arranged to be rotated by the engine. The rotation of the drive shaft is transmitted to the propeller shaft. The propeller is arranged to be rotated together with the propeller shaft. The intermediate shaft is arranged on a central rotation axis of the propeller shaft or an extension of the central rotation axis. The intermediate shaft is arranged to transmit rotation between the drive shaft and the propeller shaft. The first reduction gear mechanism is arranged on a central rotation axis of the propeller shaft or the extension of the central rotation axis. The first reduction gear mechanism is arranged to decelerate the rotation of the intermediate shaft so as to transmit the decelerated rotation to the propeller shaft during both forward propulsion and backward propulsion.

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: A power transmission mechanism transferring a power output from an engine to a propeller includes a transmission planetary gear train that transforms the output power of the engine before it is transferred to the propeller. The transmission planetary gear train includes a transmission sun gear, a transmission double planetary gear set, and a transmission internal gear, in which the transmission sun gear is connected via the first clutch to the input end shaft extending into the engine, and the transmission sun gear is also connected via the second one-way clutch to the housing. In addition, the transmission double planetary gear set is connected via the second clutch to the input end shaft extending into the engine, and the transmission double planetary gear set is also connected via the first one-way clutch to the housing. Further, the transmission internal gear is connected to the output end shaft extending toward the propeller.

Abstract: A boat propulsion unit minimizes a shock upon switching of an engagement state of a clutch mechanism. The boat propulsion unit includes an upper clutch mechanism that is arranged on an axis of a lower drive shaft and that can be switched between an engagement state (first engagement state) in which driving force of an engine is transmitted to a downstream side, and a half clutch state in which the driving force of the engine is reduced and then is transmitted; and an advance-reverse drive that is disposed on an axis of a front propeller drive shaft and a rear propeller drive shaft and that can be switched between a forward travel engagement state and a reverse travel engagement state (second disengagement state) in which the driving force of the engine is transmitted to a front propeller and a rear propeller in order to propel a boat, and a disengagement state (second disengagement state) in which the driving force of the engine is disengaged.

Abstract: A marine vessel propulsion unit includes an engine, a drive shaft, a propeller shaft, a propeller, an intermediate shaft, a forward-reverse switching mechanism, and a shock reduction mechanism. The intermediate shaft is arranged on a central rotation axis of the propeller shaft. The intermediate shaft is arranged to transmit rotation between the drive shaft and the propeller shaft. The forward-reverse switching mechanism is arranged to switch a rotational direction of the propeller shaft to a forward drive direction or a reverse drive direction. The shock reduction mechanism includes a plurality of spring members and a pair of stopper portions. The shock reduction mechanism is arranged on the central rotation axis of the propeller shaft. The plurality of spring members are arranged to absorb a force in the rotational direction by elastically deforming in the rotational direction when the force in the rotational direction is applied to the intermediate shaft.

Abstract: A boat propulsion unit has a construction that prevents a structure near a drive shaft from becoming complicated and increased in size. The boat propulsion unit preferably in the form of an outboard motor includes a front propeller that is rotated together with a front propeller drive shaft during both forward travel and reverse travel of the boat, a rear propeller that is rotated together with a rear propeller drive shaft in an opposite direction of the front propeller during both of the forward travel and the reverse travel of the boat, and a forward-reverse drive that is arranged on an axis of the front propeller drive shaft and the rear propeller drive shaft, and that can be switched between a direction in which the front propeller drive shaft and the rear propeller drive shaft are rotated during the forward travel of the boat and a direction in which the front propeller drive shaft and the rear propeller drive shaft are rotated during the reverse travel of the boat.

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: 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.