Abstract: A base member mounted to a side of a cylinder block is formed with an inlet-side oil supply passage for supplying an oil to an oil filter, and an outlet-side oil supply passage for discharging the oil from the oil filter. As a result, it is unnecessary to increase the thickness of a wall of the cylinder block or to form a bulged portion in order to form the oil supply passages, thereby contributing to a decrease in weight of the cylinder block. Moreover, because the oil supply passages are formed in the base member, the layouts thereof can be determined freely without restrained by the shape of the cylinder block, thereby contributing an increase in degree of freedom for the design.

Abstract: In an outboard motor air intake system, there are equipped with a secondary air passage connected to an air intake pipe at a location downstream of the throttle valve in terms of intake air flow; a manual valve installed in the secondary air passage to be operable by the operator to regulate a sectional area of the secondary air passage, a knob positioned at a location remote from the outboard motor to be operable by the operator, and a wire connecting the knob to the manual valve, such that the sectional area of the secondary air passage can be regulated through the knob and the manual valve at the location remote from the outboard motor, thereby making it easy to realize fine regulation when the engine operates in a low-speed such as idling.

Abstract: An outboard motor steering system includes a hydraulic fluid supply mechanism connected to the steering hydraulic cylinder to supply hydraulic fluid thereto disposed in a space formed between the stern brackets and the swivel case. In other words, since the hydraulic fluid supply mechanism is incorporated into the outboard motor as a unit, the structure can be made simpler than that of the related art and the number of parts in the entire system can be reduced and moreover the work of installation into the boat's hull can be simplified. Also, operating efficiency is improved for an electric motor serving as the source of driving force for a hydraulic pump that supplies hydraulic fluid to the hydraulic cylinder used for steering, and power consumption is reduced.

Abstract: A water-cooled vertical engine is provided with an exhaust guide cooling water jacket and an exhaust manifold cooling water jacket formed in an engine compartment exhaust passage, a cylinder block cooling water jacket formed in a cylinder block, and a cylinder head cooling water jacket formed in a cylinder head. A first cooling path for supplying cooling water from a cooling water pump to the cylinder block cooling water jacket via the exhaust guide cooling water jacket and the exhaust manifold cooling water jacket is substantially independent from a second cooling path for supplying cooling water from the cooling water pump to the cylinder head cooling water jacket. Thermostats are provided in the cylinder block cooling water jacket and the cylinder head cooling water jacket, respectively.

Abstract: An outboard motor water-cooled vertical engine is provided in which a crankshaft is disposed substantially vertically, a timing chain for transmitting a driving force of the crankshaft to a camshaft is disposed in an upper part of the cylinder block and a cylinder head, and an upper part of the timing chain is covered with a chain cover. Provided in the chain cover are thermostats for controlling the flow of cooling water in a cylinder block cooling water jacket and a cylinder head cooling water jacket. Therefore, the thermostats can be accessed from the top of the engine for maintenance without being obstructed by the timing chain, and moreover it is easy to manipulate a drain pipe for discharging cooling water from the thermostats.

Abstract: There is provided an outboard motor (1), comprising: an intake valve (17) and an exhaust valve (18) provided to a cylinder head (14); a camshaft (20) arranged substantially vertically in the cylinder head to open and close the intake and exhaust valves; a valve operation characteristics changing device (29) hydraulically operated to change operation characteristics of at least one of the intake and exhaust valves; a selector valve (electromagnetic valve 27) for controlling an oil pressure provided to the valve operation characteristics changing device; and an exhaust passage component part (exhaust manifold 23) secured on a side of the cylinder head, wherein the selector valve is disposed at a position (space G) beside the cylinder head and overlapping with a top end surface of the exhaust passage component part.

Abstract: In a water-cooled multi-cylinder vertical engine for an outboard engine system, cooling water having passed through an exhaust-manifold cooling water jacket for cooling an exhaust passage within an engine room is supplied to a cylinder-block cooling water jacket provided in a cylinder block through water supply pipes, a branching member and two upper and lower couplings. In this case, the lower coupling is locked below the center of a lowermost cylinder to minimize unevenness in flow rate of the cooling water flowing through a water jacket on opposite left and right sides of a cylinder toward a cooling water outlet provided at an upper portion thereof, thereby making uniform the distribution of the temperature around a combustion chamber, leading to an enhancement in cooling effect.

Abstract: A water-cooled vertical engine includes: an exhaust guide cooling water jacket and an exhaust manifold cooling water jacket which are formed in an engine compartment; a cylinder block cooling water jacket formed in a cylinder block; and a cylinder head cooling water jacket formed in a cylinder head. Cooling water from a cooling water pump is supplied in parallel to an upper part and a lower part of the cylinder block cooling water jacket through the exhaust guide cooling water jacket and the exhaust manifold cooling water jacket.

Abstract: An outboard motor is provided with an engine compartment exhaust passage that is formed by joining via a joining part an exhaust manifold connected to a cylinder head and an exhaust guide connected to an exhaust passage of a mount case. By bending the portion of the exhaust manifold that is lower than the lowest combustion chamber so as to be farther away from the cylinder head than other portions of the exhaust manifold, the space in which the exhaust manifold is arranged can be minimized, and the joining part can be prevented from interfering with the cylinder head while minimizing any influence on the exhaust efficiency.

Abstract: An outboard motor equipped with a water-cooled engine includes an exhaust manifold cooling water jacket for cooling an exhaust manifold for discharging to the outside exhaust gas from a combustion chamber, the exhaust manifold cooling water jacket being supplied with cooling water from a cooling water pump. A water outlet provided in the highest part of the exhaust manifold cooling water jacket is made to communicate with a water check outlet for confirming the circulation of cooling water due to operation of the cooling water pump. Thus, it is possible to reliably discharge air residing within the exhaust manifold cooling water jacket through the water check outlet. Since the water check outlet is used as an opening for discharging air, it is unnecessary to provide a special air outlet.

Abstract: A water-cooled vertical engine is provided with an exhaust guide cooling water jacket and an exhaust manifold cooling water jacket formed in an engine compartment exhaust passage, a cylinder block cooling water jacket formed in a cylinder block, and a cylinder head cooling water jacket formed in a cylinder head. A first cooling path for supplying cooling water from a cooling water pump to the cylinder block cooling water jacket via the exhaust guide cooling water jacket and the exhaust manifold cooling water jacket is substantially independent from a second cooling path for supplying cooling water from the cooling water pump to the cylinder head cooling water jacket. Thermostats are provided in the cylinder block cooling water jacket and the cylinder head cooling water jacket, respectively.

Abstract: There is provided an outboard motor (1), comprising: an intake valve (17) and an exhaust valve (18) provided to a cylinder head (14); a camshaft (20) arranged substantially vertically in the cylinder head to open and close the intake and exhaust valves; a valve operation characteristics changing device (29) hydraulically operated to change operation characteristics of at least one of the intake and exhaust valves; a selector valve (electromagnetic valve 27) for controlling an oil pressure provided to the valve operation characteristics changing device; and an exhaust passage component part (exhaust manifold 23) secured on a side of the cylinder head, wherein the selector valve is disposed at a position (space G) beside the cylinder head and overlapping with a top-end surface of the exhaust passage component part.

Abstract: In an outboard engine system, a first opening communicating with a cooling water discharge passage and a second opening communicating with a cooling water supply passage are formed adjacent to each other in an upper wall of a cooling water passage forming member. A relief valve is provided in a first opening at a position remote from a tilt shaft. The relief valve includes a valve seat provided at the upper wall and facing downward. A valve body is seated on the valve seat from below. Accordingly, any cooling water staying in an upper portion of the relief valve leaks through gaps between the valve seat and the valve body to be discharged easily. When the outboard engine system is tilted upward about the tilt shaft, the opening provided with the relief valve is moved upward so that the cooling water is discharged smoothly through the other opening.

Abstract: In an outboard engine system, an exhaust manifold fixed to a cylinder head of a vertical engine by a bolt includes single pipe portions and a collecting portion through which an exhaust gas flow. A water jacket, through which cooling water flows, is formed to surround a periphery of the collecting portion. An exhaust characteristics sensor for detecting an oxygen content of exhaust gas is mounted to an upper surface of the exhaust manifold. A water temperature sensor for detecting temperature of the cooling water is mounted to a side surface of the exhaust manifold.

Abstract: Recesses are provided in portions of a head cover and a crankcase which are opposed to outer peripheries of a timing chain and a balancer-driving chain driven by a crankshaft of a vertical engine, whereby vertical walls and horizontal walls are formed to oppose to outer peripheral surfaces and lower surfaces of the timing chain and the balancer-driving chain. An oil scattered from the timing chain and the balancer-driving chain by a centrifugal force is caught on the vertical walls, and the oil flowing down along the vertical walls by gravitation is retained on the underlying horizontal walls, whereby the oil can be brought into contact with the chains without waste to effectively lubricate the chains.

Abstract: In a vertical engine, a bulged portion protrudes upwards, in conformity to a partially cylindrical outer wall of uppermost one of cylinders, on an upper surface of a cylinder block forming a bottom wall of a chain chamber accommodating a chain for driving a camshaft and a balancer shaft through a crankshaft. A pair of oil return bores for returning an oil in the chain chamber to an oil pan are provided in lower portions of the bottom wall on opposite sides of an axis of the bulged portion. The oil which has lubricated the chain in the chain chamber flows so that it is distributed to the opposite sides of the axis, and the oil is returned smoothly from the oil return bores formed in the bottom wall to the oil pan.

Abstract: A base member mounted to a side of a cylinder block is formed with an inlet-side oil supply passage for supplying an oil to an oil filter, and an outlet-side oil supply passage for discharging the oil from the oil filter. As a result, it is unnecessary to increase the thickness of a wall of the cylinder block or to form a bulged portion in order to form the oil supply passages, thereby contributing to a decrease in weight of the cylinder block. Moreover, because the oil supply passages are formed in the base member, the layouts thereof can be determined freely without restrained by the shape of the cylinder block, thereby contributing an increase in degree of freedom for the design.

Abstract: A first chain mechanism for transmitting the rotation of a crankshaft of an vertical engine to a camshaft and a second chain mechanism for transmitting the rotation of the crankshaft to a balancer shaft are forcibly lubricated by an oil injected by first, second and third oil jets mounted within a chain chamber. The first, second and third oil jets are disposed at locations closer to the crankshaft, the cam shaft and the balancer shaft, respectively, and the first and second oil jets are disposed inside a travel locus for a timing chain. Thus, the chain mechanisms disposed in a plane of the vertical engine can be lubricated effectively.

Abstract: Oil jets are mounted in upper two cylinders in a cylinder block of a 4-cylinder vertical engine to inject an oil to rear faces of pistons received in the two cylinders. Thus, although lower pistons are cooled more effectively by the oil dropped by gravitation through oil return bores provided in journal support walls, the upper pistons are forcibly cooled by the oil injected from the oil jets, so that the four pistons can be cooled equally to prevent insufficient cooling and excessive cooling, while minimizing the required amount of the oil.

Abstract: A water-cooled vertical engine includes: an exhaust guide cooling water jacket and an exhaust manifold cooling water jacket which are formed in an engine compartment; a cylinder block cooling water jacket formed in a cylinder block; and a cylinder head cooling water jacket formed in a cylinder head. Cooling water from a cooling water pump is supplied in parallel to an upper part and a lower part of the cylinder block cooling water jacket through the exhaust guide cooling water jacket and the exhaust manifold cooling water jacket.