US20230151786A1 - Vessel propulsion apparatus, vessel, and vessel engine - Google Patents
Vessel propulsion apparatus, vessel, and vessel engine Download PDFInfo
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- US20230151786A1 US20230151786A1 US17/956,898 US202217956898A US2023151786A1 US 20230151786 A1 US20230151786 A1 US 20230151786A1 US 202217956898 A US202217956898 A US 202217956898A US 2023151786 A1 US2023151786 A1 US 2023151786A1
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- combustion chamber
- intake openings
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- 230000007423 decrease Effects 0.000 claims abstract description 20
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- 238000011144 upstream manufacturing Methods 0.000 claims description 15
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 210000000078 claw Anatomy 0.000 description 8
- 239000000446 fuel Substances 0.000 description 7
- 230000033001 locomotion Effects 0.000 description 6
- 230000008901 benefit Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
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- 229910052751 metal Inorganic materials 0.000 description 1
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- 230000007935 neutral effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
- F02B29/04—Cooling of air intake supply
- F02B29/0406—Layout of the intake air cooling or coolant circuit
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B61/00—Adaptations of engines for driving vehicles or for driving propellers; Combinations of engines with gearing
- F02B61/04—Adaptations of engines for driving vehicles or for driving propellers; Combinations of engines with gearing for driving propellers
- F02B61/045—Adaptations of engines for driving vehicles or for driving propellers; Combinations of engines with gearing for driving propellers for marine engines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
- F02M35/10—Air intakes; Induction systems
- F02M35/10006—Air intakes; Induction systems characterised by the position of elements of the air intake system in direction of the air intake flow, i.e. between ambient air inlet and supply to the combustion chamber
- F02M35/10078—Connections of intake systems to the engine
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
- F02M35/16—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines characterised by use in vehicles
- F02M35/165—Marine vessels; Ships; Boats
- F02M35/167—Marine vessels; Ships; Boats having outboard engines; Jet-skis
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Definitions
- the present invention relates to a vessel propulsion apparatus, a vessel, and a vessel engine.
- US 2002/0072281A1 discloses an outboard motor that is an example of a vessel propulsion apparatus.
- An engine for use in the outboard motor includes a cylinder block provided with a plurality of cylinders, a piston disposed in each of the cylinders, and a cylinder head connected to the cylinder block.
- Combustion concave portions which form a combustion chamber together with corresponding cylinders and pistons, are provided one by one at a portion, which faces each of the cylinders, of the cylinder head.
- a pair of intake valve openings and an exhaust valve opening are formed in each of the combustion concave portions.
- a pair of intake ports that extend from an intake manifold are connected to the pair of intake valve openings, respectively.
- An exhaust port is connected to the exhaust valve opening.
- air that has flowed into the intake manifold divides and flows into the pair of intake ports, and then flows from the pair of intake valve openings into the combustion chamber, and then is combusted together with fuel in the combustion chamber, and, as a result, turns into an exhaust gas, and then flows through the exhaust valve opening and the exhaust port, and then is discharged outwardly from the outboard motor.
- ⁇ swirl caused by air that has flowed from the pair of intake valve openings into the combustion chamber in the engine.
- the ⁇ swirl is a swirl making an ⁇ -shaped trace seen from a moving direction of the piston in such a manner that air that has flowed into the combustion chamber from each of the pair of intake valve openings flows toward the exhaust valve opening so that a distance between the flows of air becomes longer immediately after entering into the combustion chamber and then decreases while the flows of air are approaching each other. If it is possible to prevent the occurrence of the co swirl, it is possible to improve engine performance by increasing a combustion speed.
- the inventor of preferred embodiments of the present invention described and claimed in the present application conducted an extensive study and research regarding a vessel propulsion apparatus, a vessel, and a vessel engine, such as the one described above, and in doing so, discovered and first recognized new unique challenges and previously unrecognized possibilities for improvements as described in greater detail below.
- Preferred embodiments of the present invention provide vessel propulsion apparatuses each able to prevent the occurrence of an ⁇ swirl in a combustion chamber of an engine, vessels including the vessel propulsion apparatuses, and vessel engines included in the vessel propulsion apparatuses.
- a preferred embodiment of the present invention provides a vessel propulsion apparatus including an engine and a propulsion unit to be driven by the engine.
- the engine includes a cylinder head including a combustion chamber and a pair of intake openings to communicate with the combustion chamber and a pair of intake ports respectively connected to the pair of intake openings.
- the pair of intake ports include a pair of downstream portions respectively connected to the pair of intake openings. A distance between the pair of downstream portions decreases toward the pair of intake openings.
- the vessel propulsion apparatus further includes a pressure charger and an intercooler to cool air compressed by the pressure charger. Air cooled by the intercooler flows into the pair of intake ports.
- the pair of intake ports include a pair of independent intake ports that individually extend from the intercooler to the pair of intake openings.
- each of the pair of intake ports is an independent intake port, it is possible to easily arrange the distance between the downstream portions connected to the intake openings so as to decrease in proportion as the downstream portions approach the intake openings.
- a preferred embodiment of the present invention provides a vessel propulsion apparatus including an engine and a propulsion unit to be driven by the engine.
- the engine includes a cylinder head including a combustion chamber and a pair of intake openings to communicate with the combustion chamber and a pair of intake ports respectively connected to the pair of intake openings.
- the cylinder head includes a pair of inner surfaces that respectively extend from peripheral edges of the pair of intake openings and that face each other in an arrangement direction in which the pair of intake openings are arranged.
- the combustion chamber is defined between the pair of inner surfaces.
- the pair of inner surfaces include a pair of upstream portions respectively connected to the peripheral edges of the pair of intake openings. A distance between the pair of upstream portions decreases in a direction moving away from the peripheral edges of the pair of intake openings.
- the cylinder head includes a pair of exhaust openings to communicate with the combustion chamber and arranged side by side along the arrangement direction.
- the engine includes a pair of exhaust ports respectively connected to the pair of exhaust openings.
- a first inner surface of the pair of inner surfaces connects a peripheral edge of a first intake opening of the pair of intake openings and a peripheral edge of a first exhaust opening of the pair of exhaust openings.
- a second inner surface of the pair of inner surfaces connects a peripheral edge of a second intake opening of the pair of intake openings and a peripheral edge of a second exhaust opening of the pair of exhaust openings.
- the first inner surface and the second inner surface are curved toward each other.
- the distance between the upstream portions in the pair of inner surfaces of the cylinder head decreases in the direction moving away from the peripheral edges of the intake openings.
- the engine includes a crankshaft extending along a vertical direction.
- the vessel propulsion apparatus is an outboard motor that includes a drive shaft, a propeller shaft, a propeller, and a transmission.
- the drive shaft is joined to the crankshaft, and extends along the vertical direction.
- the propeller shaft extends along a horizontal direction.
- the propeller defines the propulsion unit, and is joined to the propeller shaft.
- the transmission transmits rotation of the drive shaft to the propeller shaft.
- a preferred embodiment of the present invention provides a vessel including a hull and the vessel propulsion apparatus mounted in the hull to provide a thrust to the hull.
- a preferred embodiment of the present invention provides a vessel engine including a cylinder head including a combustion chamber, a pair of intake openings to communicate with the combustion chamber, and a pair of intake ports respectively connected to the pair of intake openings.
- the pair of intake ports include a pair of downstream portions respectively connected to the pair of intake openings. A distance between the pair of downstream portions decreases toward the pair of intake openings.
- a preferred embodiment of the present invention provides a vessel engine including a cylinder head including a combustion chamber, a pair of intake openings to communicate with the combustion chamber, and a pair of intake ports respectively connected to the pair of intake openings.
- the cylinder head includes a pair of inner surfaces that respectively extend from peripheral edges of the pair of intake openings and that face each other in an arrangement direction in which the pair of intake openings are arranged.
- the combustion chamber is defined between the pair of inner surfaces.
- the pair of inner surfaces include a pair of upstream portions respectively connected to the peripheral edges of the pair of intake openings. A distance between the pair of upstream portions decreases in a direction moving away from the peripheral edges of the pair of intake openings.
- FIG. 1 is a schematic plan view of a vessel according to a preferred embodiment of the present invention.
- FIG. 2 is a schematic side view of an outboard motor included in the vessel.
- FIG. 3 is a schematic view shown to describe an air intake/exhaust system of the outboard motor.
- FIG. 4 is a perspective view of an air intake structure in the air intake/exhaust system.
- FIG. 5 is a rear view of a main portion in the air intake structure.
- FIG. 6 is a front view of the main portion in the air intake structure.
- FIG. 1 is a schematic plan view of a vessel 1 according to a preferred embodiment of the present invention.
- the vessel 1 includes a hull 2 , a vessel operation device 3 , and an outboard motor 4 , and the hull 2 is equipped with both the vessel operation device 3 and the outboard motor 4 .
- An example of the vessel operation device 3 includes a steering wheel 6 and a throttle lever 7 both of which are provided at an operational platform 5 around a vessel operation seat of the hull 2 , and a communication bus 9 by which an ECU (electronic control unit) 8 built into the outboard motor 4 , a steering wheel 6 , and the throttle lever 7 are connected together.
- a vessel operator turns the steering wheel 6 in a left-right direction to steer.
- the vessel operator turns the throttle lever 7 in a front-rear direction to adjust the output of the outboard motor 4 .
- a joystick 10 that is operated by the vessel operator to steer and adjust the output of the outboard motor 4 may be provided at the operational platform 5 .
- the outboard motor 4 is an example of a vessel propulsion apparatus that provides a thrust to the hull 2 , and is provided as a single outboard motor or as a plurality of outboard motors.
- the single outboard motor 4 is attached to a transom stern 2 A on a virtual center line C along the front-rear direction through the transom stern 2 A and a bow 2 B of the hull 2 .
- the plurality of outboard motors 4 are attached to the transom stern 2 A at bilaterally symmetrical positions with respect to the center line C.
- FIG. 2 is a schematic right side view of the outboard motor 4 .
- the left side in FIG. 2 is the front side of the outboard motor 4
- the right side in FIG. 2 is the rear side of the outboard motor 4 .
- the upper side in FIG. 2 is the upper side of the outboard motor 4
- the lower side in FIG. 2 is the lower side of the outboard motor 4 .
- An up-down direction is also a vertical direction.
- a direction perpendicular to the plane of paper of FIG. 2 is the left-right direction of the outboard motor 4 .
- a leftward or rightward direction of the outboard motor 4 is determined based on a direction given when the outboard motor 4 is seen from the front side.
- the near side in the direction perpendicular to the plane of paper of FIG. 2 is the right side of the outboard motor 4
- the far side in the direction perpendicular to the plane of paper of FIG. 2 is the left side of the outboard motor 4 .
- the outboard motor 4 includes a mount 11 to attach the outboard motor 4 to the transom stern 2 A and an outboard motor main body 12 .
- the mount 11 includes a clamp bracket 13 fixed to the transom stern 2 A and a swivel bracket 15 coupled to the clamp bracket 13 through a tilt shaft 14 horizontally extending in the left-right direction.
- the swivel bracket 15 is coupled to the outboard motor main body 12 through a steering shaft 16 extending in the up-down direction.
- the outboard motor main body 12 is attached to the transom stern 2 A by the mount 11 in a vertical or substantial vertical attitude.
- the outboard motor main body 12 and the swivel bracket 15 are turnable in the up-down direction around the tilt shaft 14 with respect to the clamp bracket 13 .
- the outboard motor main body 12 is turned around the tilt shaft 14 , and, as a result, the outboard motor main body 12 is tilted with respect to the hull 2 and the clamp bracket 13 .
- the outboard motor main body 12 is turnable in the left-right direction together with the steering shaft 16 with respect to the clamp bracket 13 and the swivel bracket 15 .
- the vessel 1 is steered.
- the outboard motor main body 12 includes a box-shaped engine cover 17 , a hollow casing 18 extending downwardly from the engine cover 17 , and a plate-shaped exhaust guide 19 attached to a lower end portion of the engine cover 17 so as to close an internal space of the casing 18 from above.
- a lower end portion of the casing 18 is a lower case 18 A.
- the outboard motor main body 12 includes an engine 20 mounted on an upper surface of the exhaust guide 19 in the engine cover 17 , a drive shaft 21 extending along the up-down direction in the casing 18 , and a propeller shaft 22 and a transmission 23 both of which are located in the lower case 18 A.
- the engine 20 is a vessel engine, and includes an internal combustion engine that burns fuel, such as gasoline, and generates power.
- the engine 20 includes a cylinder block 25 including a single or a plurality of cylinders 24 , a piston 26 located in the cylinder 24 one by one, and a crankshaft 27 extending along the up-down direction in the cylinder block 25 and that is coupled to the piston(s) 26 .
- the engine 20 in the present preferred embodiment is a straight-type four-cylinder engine in which four cylinders 24 are located in series along the up-down direction.
- An internal space of each of the cylinders 24 includes a circular cylindrical shape extending along the front-rear direction.
- a combustion chamber 28 is defined in a region behind the piston 26 in the internal space of each of the cylinders 24 .
- a front portion that houses the crankshaft 27 in the cylinder block 25 is a crank case 25 A.
- the engine 20 includes a cylinder head 29 attached to the cylinder block 25 from behind and a head cover 30 attached to the cylinder head 29 from behind.
- the cylinder head 29 and the head cover 30 may be regarded as elements of the cylinder block 25 .
- Concave portions 29 A each of which is rearwardly hollowed as a portion of the combustion chamber 28 are provided one by one at a portion, which faces the combustion chamber 28 of each of the cylinders 24 , of a front surface of the cylinder head 29 .
- the engine 20 includes an intake valve 31 and an exhaust valve 32 that are exposed to each of the concave portions 29 A and a camshaft 33 that extends along the up-down direction and that is rotatably supported by the head cover 30 .
- the camshaft 33 may be provided as a pair of camshafts in accordance with each of the intake valve 31 and the exhaust valve 32 .
- the crankshaft 27 has a crankshaft axis 27 A extending in the up-down direction. An upper end portion of the crankshaft 27 protrudes upwardly from the crank case 25 A. A lower end portion of the crankshaft 27 is joined to the upper end portion of the drive shaft 21 .
- the engine 20 includes a flywheel magneto 34 fixed to the upper end portion of the crankshaft 27 and a cam chain 35 connecting the lower end portion of the crankshaft 27 and a lower end portion of the camshaft 33 .
- the flywheel magneto 34 is located at a higher position than the crank case 25 A.
- the cam chain 35 is located below the four cylinders 24 in the cylinder block 25 .
- the piston 26 is rectilinearly reciprocated in the front-rear direction perpendicular to the crankshaft axis 27 A by combustion of an air-fuel mixture in each of the combustion chambers 28 .
- the crankshaft 27 is driven and rotated around the crankshaft axis 27 A along with the drive shaft 21 .
- the flywheel magneto 34 rotates and generates electricity, and the cam chain 35 moves in a circular motion.
- the camshaft 33 is rotated in accordance with the circular movement of the cam chain 35 .
- the intake valve 31 and the exhaust valve 32 are actuated interlockingly with the rotation of the camshaft 33 .
- intake/exhaust is performed in each of the combustion chambers 28 .
- the propeller shaft 22 horizontally extends along the front-rear direction in the lower case 18 A.
- a lower end portion of the drive shaft 21 is coupled to a front end portion of the propeller shaft 22 by the transmission 23 .
- a rear end portion of the propeller shaft 22 protrudes rearwardly from the lower case 18 A.
- a propeller 36 as an example of a propulsion unit that is an element of the outboard motor 4 is joined to the rear end portion of the propeller shaft 22 .
- the propeller shaft 22 rotates together with the propeller 36 around a rotational axis 22 A that extends in the front-rear direction.
- the transmission 23 is used to transmit the rotation of the drive shaft 21 to the propeller shaft 22 .
- the transmission 23 includes a driving gear 38 fixed to the lower end portion of the drive shaft 21 and a rotary body 39 and a dog clutch 40 both of which are attached to the front end portion of the propeller shaft 22 .
- the driving gear 38 is a bevel gear.
- the propeller shaft 22 is located below the driving gear 38 .
- the rotary body 39 includes a first rotary body 41 and a second rotary body 42 that are located side by side in the front-rear direction along the propeller shaft 22 .
- the first rotary body 41 and the second rotary body 42 are, for example, cylindrical bevel gears, respectively.
- the first rotary body 41 is located at a more forward position than the driving gear 38
- the second rotary body 42 is located at a more rearward position than the driving gear 38
- the front-rear positional relationship between the first rotary body 41 and the second rotary body 42 may be opposite to that of the present preferred embodiment.
- a tooth portion 41 A is provided at a tapered outer peripheral portion
- a claw portion 41 B is provided at an inner peripheral portion.
- a tooth portion 42 A is provided at a tapered outer peripheral portion
- a claw portion 42 B is provided at an inner peripheral portion.
- the first rotary body 41 surrounds a portion, which is at a more forward position than the driving gear 38 , of the front end portion of the propeller shaft 22
- the second rotary body 42 surrounds a portion, which is at a more rearward position than the driving gear 38 , of the front end portion of the propeller shaft 22
- the first rotary body 41 and the second rotary body 42 are located so that their tooth portions 41 A and 42 A face each other at a distance from each other in the front-rear direction, and engage with the driving gear 38 .
- the dog clutch 40 is located between the first rotary body 41 and the second rotary body 42 .
- the dog clutch 40 is, for example, cylindrical, and surrounds the front end portion of the propeller shaft 22 .
- a first claw portion 40 A is provided at a front end surface of the dog clutch 40
- a second claw portion 40 B is provided at a rear end surface of the dog clutch 40 .
- the dog clutch 40 is coupled to the front end portion of the propeller shaft 22 by, for example, a spline. Therefore, the dog clutch 40 rotates together with the front end portion of the propeller shaft 22 .
- the dog clutch 40 is movable in the front-rear direction with respect to the front end portion of the propeller shaft 22 . In other words, the dog clutch 40 is rotatable together with the propeller shaft 22 , and is movable along the front-rear direction relatively with the propeller shaft 22 .
- the transmission 23 also includes a shifter 43 located at a more forward position than the propeller shaft 22 in the lower case 18 A.
- the shifter 43 includes, for example, a shift rod 44 extending in the up-down direction and an electric shift actuator 45 joined to the shift rod 44 .
- a lower end portion of the shift rod 44 is coupled to the dog clutch 40 .
- the shift actuator 45 is operated by the control of the ECU 8 (see FIG. 1 )
- the shift rod 44 turns around an axis of the shift rod 44 .
- the shift rod 44 turns, and, as a result, the dog clutch 40 is moved along the front-rear direction between a disconnection position and a connection position.
- the disconnection position is a position in which the dog clutch 40 is spaced apart from the first rotary body 41 and the second rotary body 42 , and does not engage with either of these rotary bodies of the rotary body 39 as shown in FIG. 2 .
- each of the rotary body 39 to which the rotation of the drive shaft 21 is transmitted runs idle, and therefore the rotation of the drive shaft 21 is not transmitted to the propeller shaft 22 .
- the shift position of the outboard motor 4 at this time is referred to as “neutral.”
- the connection position is a position in which the dog clutch 40 engages with either one of the first rotary body 41 or the second rotary body 42 .
- the connection position includes a first connection position in which the first claw portion 40 A of the dog clutch 40 engages with only the claw portion 41 B of the first rotary body 41 and a second connection position in which the second claw portion 40 B of the dog clutch 40 engages with only the claw portion 42 B of the second rotary body 42 .
- the disconnection position is a position between the first connection position and the second connection position. The first connection position is more forward than the disconnection position, and the second connection position is more rearward than the disconnection position.
- the first rotary body 41 is a gear for forward movement
- the second rotary body 42 is a gear for reverse movement
- the first rotary body 41 may be a gear for reverse movement
- the second rotary body 42 may be a gear for forward movement.
- the outboard motor main body 12 includes an exhaust passage 46 provided inside the outboard motor main body 12 and connected to the engine 20 .
- the exhaust passage 46 passes through the exhaust guide 19 in the up-down direction, and extends downwardly in the casing 18 and rearwardly in the propeller 36 .
- the exhaust passage 46 includes an outlet 46 A provided at a rear end surface of the propeller 36 . In a state in which the vessel 1 is floating on water and in which the propeller 36 is located below a water surface, the outlet 46 A is located in the water, and therefore water that has passed through the outlet 46 A enters a downstream portion of the exhaust passage 46 .
- a steering rod 47 that forwardly extends is fixed to the outboard motor main body 12 .
- An electric steering actuator 48 that is controlled by the ECU 8 is joined to the steering rod 47 .
- the outboard motor main body 12 is able to turn around the steering shaft 16 by allowing the steering actuator 48 to operate, thus making it possible to perform steering.
- FIG. 3 is a schematic view shown to describe an air intake/exhaust system 49 of the outboard motor 4 .
- the air intake/exhaust system 49 includes the engine 20 , a pressure charger 50 that compresses air and supplies the air to the engine 20 , and an intercooler 51 that cools air compressed by the pressure charger 50 .
- the engine 20 includes the exhaust passage 46 , an air intake passage 52 , and an electric throttle valve 53 located in the air intake passage 52 .
- the exhaust passage 46 is connected to each of the combustion chambers 28 through a plurality of exhaust ports 54 provided in the cylinder head 29 of the engine 20 .
- the air intake passage 52 is connected to each of the combustion chambers 28 through a plurality of intake ports 55 provided in the cylinder head 29 .
- An inlet 52 A is provided at an end portion, which is opposite to the intake port 55 , of the air intake passage 52 .
- the ECU 8 controls the throttle valve 53 , and, as a result, the opening degree of the throttle valve 53 is adjusted.
- the pressure charger 50 is interposed between the ends of the air intake passage 52 .
- the pressure charger 50 is a supercharger driven by the rotation of the crankshaft 27 of the engine 20 .
- the pressure charger 50 includes a housing 50 A including an internal space defining a portion of the air intake passage 52 , a compressor wheel 50 B located in the housing 50 A, and a rotational shaft 50 C coaxially fixed to the compressor wheel 50 B.
- An end portion, which is spaced apart from the compressor wheel 50 B, of the rotational shaft 50 C is located outside the housing 50 A, and a rotor 56 is coaxially fixed to this end portion.
- the air intake/exhaust system 49 includes a power transmission by which the crankshaft 27 and the pressure charger 50 are joined together.
- An example of the power transmission includes the rotor 56 , another rotor 57 attached to the crankshaft 27 , and a belt 58 by which the rotor 56 and the rotor 57 are connected together.
- An example of each of the rotors 56 and 57 is a pulley.
- the rotor 57 is attached to a portion, which is located at a higher position than the flywheel magneto 34 , of the upper end portion of the crankshaft 27 (see FIG. 2 ).
- the pressure charger 50 When the pressure charger 50 operates in a state in which the throttle valve 53 has been opened, air that has been taken from the inlet 52 A and that flows through the air intake passage 52 is compressed by the compressor wheel 50 B rotating in the housing 50 A.
- Another arrangement such as a Lysholm-type device, may be used as the pressure charger 50 without being limited to the centrifugal-type device shown in FIG. 3 .
- the intercooler 51 is interposed between each of the intake ports 55 of the engine 20 and the pressure charger 50 in the air intake passage 52 .
- the intercooler 51 includes a housing 51 A including an internal space defining a portion of the air intake passage 52 and a cooling fin (not shown). Either of an air-cooled intercooler or a water-cooled intercooler may be used as the intercooler 51 .
- the intercooler 51 includes an intake manifold 51 B that extends from the housing 51 A and is connected to the intake port 55 .
- the intake manifold 51 B is integral with the housing 51 A.
- Air compressed by the compressor wheel 50 B in the housing 50 A of the pressure charger 50 continuously flows through the air intake passage 52 , and thus is guided to the intercooler 51 , and is cooled by heat exchange with the cooling fin in the housing 51 A of the intercooler 51 .
- the air cooled by the intercooler 51 flows through the intake manifold 51 B, and then is turned into an air-fuel mixture, supplied from the intake port 55 to the combustion chamber 28 in the cylinder 24 , and combusted.
- Exhaust gas generated by the combustion flows from the exhaust port 54 through the exhaust passage 46 , and then is discharged from the outlet 46 A into the water as described above.
- FIG. 4 is a perspective view of an air intake structure 60 , seen from the right front side, which excludes the exhaust passage 46 in the air intake/exhaust system 49 .
- the intercooler 51 is located lateral to (more specifically, on the left side of) the cylinder block 25 of the engine 20 .
- the housing 51 A of the intercooler 51 is made of metal, such as aluminum, and is a hollow body elongated in the up-down direction.
- the intake manifold 51 B integral with the housing 51 A extends rearwardly from the housing 51 A, and is bent rightwardly.
- the pressure charger 50 is located in front of the cylinder block 25 .
- An upstream region 52 B, that is closer to the inlet 52 A than the pressure charger 50 , of the air intake passage 52 extends downwardly from the housing 50 A of the pressure charger 50 , and then extends right-rearwardly, and is bent on the right side of the cylinder block 25 , and extends upwardly.
- the inlet 52 A is provided at an upper end portion of the upstream region 52 B and faces forwardly.
- a filter 61 made of mesh, etc., is provided at the inlet 52 A.
- a portion, which is located on the right side of the cylinder block 25 , of the upstream region 52 B may be referred to as an air intake duct.
- the rotor 56 is located at an upper surface of the housing 50 A of the pressure charger 50 .
- FIG. 5 is a rear view of a main portion of the air intake structure 60 .
- a portion of the cylinder head 29 and a pair of the intake ports 55 are shown in FIG. 5 .
- the concave portion 29 A i.e., a portion of the combustion chamber 28 is provided at the cylinder head 29 as a single or a plurality of concave portions whose number is the same as the number of cylinders 24 , and, in the present preferred embodiment, four concave portions 29 A are arranged side by side in the up-down direction (see FIG. 2 ).
- the intake port 55 is a circular tubular pipe passage provided as a pair for each combustion chamber 28 , and extends rightwardly from the intake manifold 51 B (in a rear view, leftwardly), and is connected to a corresponding combustion chamber 28 .
- a valve guide 62 that supports the intake valve 31 (see FIG. 2 ) is provided at each of the intake ports 55 .
- the intake valve 31 and the exhaust valve 32 are omitted and are not shown in FIG. 5 and in the drawings subsequent to FIG. 5 .
- the exhaust port 54 is a circular tubular pipe passage provided as a pair for each combustion chamber 28 (see FIG. 6 ).
- a pair of air intake openings 63 and a pair of exhaust openings 64 are provided in a region, which coincides with each of the combustion chambers 28 in a rear view, of a rear surface of the cylinder head 29 .
- Each of the air intake opening 63 and the exhaust opening 64 is a round hole that passes through the cylinder head 29 in the front-rear direction or substantially in the front-rear direction (see also FIG. 6 ).
- a single intake valve 31 is located in a single air intake opening 63
- a single exhaust valve 32 is located in a single exhaust opening 64 (not shown).
- a through-hole 29 B that exposes an ignition plug (not shown) to each of the combustion chambers 28 is also provided in the cylinder head 29 .
- an arrangement relative to each of the combustion chambers 28 will be hereinafter described with reference to a single combustion chamber 28 .
- the pair of air intake openings 63 arranged side by side along the up-down direction are located on the left side (in a rear view, on the right side) closer to the intake manifold 51 B than the pair of exhaust openings 64 arranged side by side along the up-down direction.
- an arrangement direction in which the pair of air intake openings 63 are arranged is the up-down direction (the arrangement direction)
- an arrangement direction in which the pair of exhaust openings 64 are arranged is likewise the up-down direction (the arrangement direction).
- the pair of air intake openings 63 communicate with a first region 28 A, which occupies substantially a left half of the combustion chamber 28 , from behind, and the pair of exhaust openings 64 communicate with a second region 28 B, which occupies substantially a right half of the combustion chamber 28 , from behind.
- a region surrounded by the pair of air intake openings 63 and by the pair of exhaust openings 64 in a rear view is a central region 28 C of the combustion chamber 28 .
- the central region 28 C is a boundary region between the first region 28 A and the second region 28 B.
- the through-hole 29 B is located at a position that coincides with the central region 28 C in a rear view.
- an upper one of the pair of air intake openings 63 will be referred to as a first air intake opening 63 A if necessary, and a lower one of the pair of air intake openings 63 will be referred to as a second air intake opening 63 B if necessary.
- an upper one of the pair of exhaust openings 64 i.e., the exhaust opening 64 located on the first air intake opening 63 A side in the up-down direction
- a lower one of the pair of exhaust openings 64 i.e., the exhaust opening 64 located on the second air intake opening 63 B side in the up-down direction will be referred to as a second exhaust opening 64 B if necessary.
- a pair of intake ports 55 are respectively connected to the pair of air intake openings 63 communicating with the single combustion chamber 28 .
- a pair of exhaust ports 54 are respectively connected to the pair of exhaust openings 64 communicating with this combustion chamber 28 (see FIG. 6 ).
- Each of the pair of intake ports 55 is an independent intake port that individually extends from the intake manifold 51 B integral with the intercooler 51 to the air intake opening 63 .
- a portion, which is connected to the air intake opening 63 , i.e., a portion closer to the air intake opening 63 , of each of the pair of intake ports 55 is referred to as a downstream portion 55 A.
- a distance D between the downstream portions 55 A of the pair of intake ports 55 decreases toward the air intake opening 63 .
- a virtual line passing through the center of the intake port 55 (more specifically, the center in a flow-passage cross section of the intake port 55 ) is referred to as a tube axis 55 B.
- a distance D′ between the tube axes 55 B in the downstream portions 55 A of the pair of intake ports 55 likewise decreases toward the air intake opening 63 in the same way as the distance D between the downstream portions 55 A.
- a distance between the entire areas of the pair of intake ports 55 may also become shorter toward the air intake opening 63 without being limited to the distance D between the downstream portions 55 A.
- Air cooled by the intercooler 51 divides and flows into each of the pair of intake ports 55 in the engine 20 of the outboard motor 4 .
- the air that has been divided and flowed into each of the pair of intake ports 55 flows into a corresponding one of the combustion chambers 28 from each of the pair of air intake openings 63 , and is combusted in the combustion chamber 28 together with fuel.
- the engine 20 generates a driving force
- the propeller 36 is driven in the outboard motor 4 , and therefore the outboard motor 4 generates a thrust.
- the distance D between the downstream portions 55 A connected to the air intake openings 63 decreases toward the air intake openings 63 as described above.
- This arrangement enables air immediately after having flowed into the combustion chamber 28 from each of the pair of air intake openings 63 to flow toward the central region 28 C side of the combustion chamber 28 (i.e., toward the ignition plug exposed through the through-hole 29 B) so that the distance between the air flows does not increase (see the thick solid arrow in FIG. 5 ).
- each of the pair of intake ports 55 is an independent intake port, it is possible to easily arrange the distance D between the downstream portions 55 A connected to the air intake openings 63 so as to become shorter toward the air intake openings 63 .
- FIG. 6 is a front view of a main portion of the air intake structure 60 .
- a portion of a front surface 29 C, at which the combustion chamber 28 (concave portion 29 A) is provided, of the cylinder head 29 and the pair of exhaust ports 54 are shown in FIG. 6 .
- the pair of exhaust ports 54 extend rightwardly.
- a pair of inner surfaces 65 facing each other in an arrangement direction in which the pair of air intake openings 63 are arranged (in the present preferred embodiment, in the up-down direction) and another pair of inner surfaces 66 facing each other in the left-right direction perpendicular to the arrangement direction are provided for each of the combustion chambers 28 in the cylinder head 29 .
- an upper inner surface 65 which is located on the first air intake opening 63 A side in the up-down direction, of the pair of inner surfaces 65 will be referred to as a first inner surface 65 A if necessary
- a lower inner surface 65 which is located on the second air intake opening 63 B side in the up-down direction, of the pair of inner surfaces 65 will be referred to as a second inner surface 65 B if necessary.
- a left inner surface 66 which is located on the pair of air intake ports 63 side in the left-right direction, of the pair of inner surfaces 66 will be referred to as a first inner surface 66 A if necessary
- a right inner surface 66 which is located on the pair of exhaust openings 64 side in the left-right direction, of the pair of inner surfaces 66 will be referred to as a second inner surface 66 B if necessary.
- the single combustion chamber 28 is defined between the pair of inner surfaces 65 and between the pair of inner surfaces 66 .
- the combustion chamber 28 includes a rectangular or substantially rectangular shape whose four corners are rounded in a front view. Either the pair of air intake openings 63 or the pair of exhaust openings 64 are located one by one at the four corners of the combustion chamber 28 in a front view.
- a circular arc, by which a left end portion of the first inner surface 65 A and an upper end portion of the first inner surface 66 A are connected together, of a circular peripheral edge 63 AA fringing the first air intake opening 63 A is referred to as a peripheral edge 63 AB.
- a circular arc, by which a left end portion of the second inner surface 65 B and a lower end portion of the first inner surface 66 A are connected together, of a circular peripheral edge 63 BA fringing the second air intake opening 63 B is referred to as a peripheral edge 63 BB.
- a circular arc, by which a right end portion of the first inner surface 65 A and an upper end portion of the second inner surface 66 B are connected together, of a circular peripheral edge 64 AA fringing the first exhaust opening 64 A is referred to as a peripheral edge 64 AB.
- a circular arc, by which a right end portion of the second inner surface 65 B and a lower end portion of the second inner surface 66 B are connected together, of a circular peripheral edge 64 BA fringing the second exhaust opening 64 B is referred to as a peripheral edge 64 BB.
- the first inner surface 65 A connects the peripheral edge 63 AB of the first air intake opening 63 A and the peripheral edge 64 AB of the first exhaust opening 64 A together.
- the second inner surface 65 B connects the peripheral edge 63 BB of the second air intake opening 63 B and the peripheral edge 64 BB of the second exhaust opening 64 B together.
- the pair of inner surfaces 65 extend from the peripheral edge 63 AB and the peripheral edge 63 BB of the pair of air intake openings 63 to the peripheral edge 64 AB and the peripheral edge 64 BB of the pair of exhaust openings 64 , respectively.
- a portion, which is connected to the peripheral edge 63 AB or the peripheral edge 63 BB of a corresponding air intake opening 63 , of each of the pair of inner surfaces 65 i.e., a portion, which is substantially a left half closer to the air intake opening 63 , of each of the pair of inner surfaces 65 is referred to an upstream portion 65 C.
- the first inner surface 65 A and the second inner surface 65 B of the pair of inner surfaces 65 are curved so as to approach each other. Therefore, a distance E between the upstream portions 65 C of the pair of inner surfaces 65 decreases in a direction moving rightwardly away from the peripheral edge 63 AB and from the peripheral edge 63 BB.
- the pair of inner surfaces 66 may be curved so as to approach each other in the same way as the pair of inner surfaces 65 , or may extend linearly in a parallel or substantially parallel manner, or one of the pair of inner surfaces 66 may be curved while the other inner surface 66 may extend linearly.
- an arrangement in which the distance D decreases toward the air intake opening 63 may be used in combination with each other, or only one of the arrangements may be used.
- the pressure charger 50 includes only the supercharger in the above-described preferred embodiments.
- the outboard motor 4 may be provided with a turbocharger (not shown) driven by exhaust gas passing through the exhaust passage 46 .
- the pressure charger 50 may include only a turbocharger, or may include both a supercharger and a turbocharger.
- an inboard/outboard motor, or an inboard motor, or a waterjet drive may be used as an example of a vessel propulsion apparatus other than the outboard motor 4 .
- a vessel engine arranged in the same way as the engine 20 is located inside the vessel, and a drive unit including a propulsion unit (propeller 36 , etc.) and a steering assembly is located outside the vessel.
- the inboard motor is a vessel engine and a drive unit that are built into the hull 2 and in which the propeller 36 is attached to a propeller shaft extending from the drive unit and outwardly from the vessel.
- the steering assembly is separately provided.
- the waterjet drive is arranged to accelerate water taken in from a vessel bottom by a pump, and jet the water from a jet nozzle of a transom stern, and thus obtain a thrust.
- the pump is driven by the vessel engine, and the steering assembly includes the jet nozzle and a mechanism that turns the jet nozzle along a horizontal plane.
- a plurality of cylinders 24 may be located in series along the horizontal direction, etc., so that the crankshaft 27 extends in the front-rear direction.
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Abstract
A vessel propulsion apparatus includes an engine and a propulsion unit to be driven by the engine. The engine includes a cylinder head including a combustion chamber and a pair of intake openings to communicate with the combustion chamber. The engine further includes a pair of intake ports respectively including a pair of downstream portions respectively connected to the pair of intake openings. A distance between the pair of downstream portions decreases toward the pair of intake openings.
Description
- This application claims the benefit of priority to Japanese Patent Application No. 2021-185986 filed on Nov. 15, 2021. The entire contents of this application are hereby incorporated herein by reference.
- The present invention relates to a vessel propulsion apparatus, a vessel, and a vessel engine.
- US 2002/0072281A1 discloses an outboard motor that is an example of a vessel propulsion apparatus. An engine for use in the outboard motor includes a cylinder block provided with a plurality of cylinders, a piston disposed in each of the cylinders, and a cylinder head connected to the cylinder block. Combustion concave portions, which form a combustion chamber together with corresponding cylinders and pistons, are provided one by one at a portion, which faces each of the cylinders, of the cylinder head. A pair of intake valve openings and an exhaust valve opening are formed in each of the combustion concave portions. A pair of intake ports that extend from an intake manifold are connected to the pair of intake valve openings, respectively. An exhaust port is connected to the exhaust valve opening. With respect to intake/exhaust in the each of the cylinders, air that has flowed into the intake manifold divides and flows into the pair of intake ports, and then flows from the pair of intake valve openings into the combustion chamber, and then is combusted together with fuel in the combustion chamber, and, as a result, turns into an exhaust gas, and then flows through the exhaust valve opening and the exhaust port, and then is discharged outwardly from the outboard motor.
- In a vessel propulsion apparatus, such as the outboard motor disclosed by US 2002/0072281A1, it is necessary to consider a so-called ω swirl caused by air that has flowed from the pair of intake valve openings into the combustion chamber in the engine. The ω swirl is a swirl making an ω-shaped trace seen from a moving direction of the piston in such a manner that air that has flowed into the combustion chamber from each of the pair of intake valve openings flows toward the exhaust valve opening so that a distance between the flows of air becomes longer immediately after entering into the combustion chamber and then decreases while the flows of air are approaching each other. If it is possible to prevent the occurrence of the co swirl, it is possible to improve engine performance by increasing a combustion speed.
- The inventor of preferred embodiments of the present invention described and claimed in the present application conducted an extensive study and research regarding a vessel propulsion apparatus, a vessel, and a vessel engine, such as the one described above, and in doing so, discovered and first recognized new unique challenges and previously unrecognized possibilities for improvements as described in greater detail below.
- Preferred embodiments of the present invention provide vessel propulsion apparatuses each able to prevent the occurrence of an ω swirl in a combustion chamber of an engine, vessels including the vessel propulsion apparatuses, and vessel engines included in the vessel propulsion apparatuses.
- In order to overcome the previously unrecognized and unsolved challenges described above, a preferred embodiment of the present invention provides a vessel propulsion apparatus including an engine and a propulsion unit to be driven by the engine. The engine includes a cylinder head including a combustion chamber and a pair of intake openings to communicate with the combustion chamber and a pair of intake ports respectively connected to the pair of intake openings. The pair of intake ports include a pair of downstream portions respectively connected to the pair of intake openings. A distance between the pair of downstream portions decreases toward the pair of intake openings.
- With this structural arrangement, in the engine of the vessel propulsion apparatus, air divides and flows into the pair of intake ports, flows into the combustion chamber from the pair of intake openings, and is combusted in the combustion chamber together with fuel. Thus, the engine generates a driving force, the propulsion unit is driven in the vessel propulsion apparatus, and therefore the vessel propulsion apparatus generates a thrust. The distance between the downstream portions connected to the intake openings of the pair of intake ports decreases toward the intake openings, and therefore air immediately after having flowed into the combustion chamber from the pair of intake openings is able to flow so that the distance between each other does not increase. This makes it possible to prevent the occurrence of an ω swirl in the combustion chamber of the engine.
- In a preferred embodiment of the present invention, the vessel propulsion apparatus further includes a pressure charger and an intercooler to cool air compressed by the pressure charger. Air cooled by the intercooler flows into the pair of intake ports. The pair of intake ports include a pair of independent intake ports that individually extend from the intercooler to the pair of intake openings.
- With this structural arrangement, as each of the pair of intake ports is an independent intake port, it is possible to easily arrange the distance between the downstream portions connected to the intake openings so as to decrease in proportion as the downstream portions approach the intake openings.
- A preferred embodiment of the present invention provides a vessel propulsion apparatus including an engine and a propulsion unit to be driven by the engine. The engine includes a cylinder head including a combustion chamber and a pair of intake openings to communicate with the combustion chamber and a pair of intake ports respectively connected to the pair of intake openings. The cylinder head includes a pair of inner surfaces that respectively extend from peripheral edges of the pair of intake openings and that face each other in an arrangement direction in which the pair of intake openings are arranged. The combustion chamber is defined between the pair of inner surfaces. The pair of inner surfaces include a pair of upstream portions respectively connected to the peripheral edges of the pair of intake openings. A distance between the pair of upstream portions decreases in a direction moving away from the peripheral edges of the pair of intake openings.
- With this structural arrangement, in the engine of the vessel propulsion apparatus, air divides and flows into the pair of intake ports, flows into the combustion chamber from the pair of intake openings, and is combusted in the combustion chamber together with fuel. Thus, the engine generates a driving force, the propulsion unit is driven in the vessel propulsion apparatus, and therefore the vessel propulsion apparatus generates a thrust. In the pair of inner surfaces that respectively extend from the peripheral edges of the pair of intake openings in the cylinder head and that face each other across the combustion chamber in an arrangement direction of the pair of intake openings, the distance between the pair of upstream portions connected to the peripheral edges of the intake openings decreases in the direction moving away from the peripheral edge of the intake openings. Therefore, air immediately after having flowed into the combustion chamber from the pair of intake openings is able to flow so that the distance between the air flows does not increase. This makes it possible to prevent the occurrence of an ω swirl in the combustion chamber of the engine.
- In a preferred embodiment of the present invention, the cylinder head includes a pair of exhaust openings to communicate with the combustion chamber and arranged side by side along the arrangement direction. The engine includes a pair of exhaust ports respectively connected to the pair of exhaust openings. A first inner surface of the pair of inner surfaces connects a peripheral edge of a first intake opening of the pair of intake openings and a peripheral edge of a first exhaust opening of the pair of exhaust openings. A second inner surface of the pair of inner surfaces connects a peripheral edge of a second intake opening of the pair of intake openings and a peripheral edge of a second exhaust opening of the pair of exhaust openings. The first inner surface and the second inner surface are curved toward each other.
- With this structural arrangement, the distance between the upstream portions in the pair of inner surfaces of the cylinder head decreases in the direction moving away from the peripheral edges of the intake openings.
- In a preferred embodiment of the present invention, the engine includes a crankshaft extending along a vertical direction. The vessel propulsion apparatus is an outboard motor that includes a drive shaft, a propeller shaft, a propeller, and a transmission. The drive shaft is joined to the crankshaft, and extends along the vertical direction. The propeller shaft extends along a horizontal direction. The propeller defines the propulsion unit, and is joined to the propeller shaft. The transmission transmits rotation of the drive shaft to the propeller shaft.
- With this structural arrangement, in the outboard motor, the rotation of the crankshaft of the engine is transmitted to the propeller shaft through the drive shaft and the transmission, and, as a result, the propeller shaft rotates together with the propeller, and therefore the propeller generates a thrust. In the combustion chamber of the engine of the outboard motor, it is possible to prevent the occurrence of an ω swirl as described above.
- A preferred embodiment of the present invention provides a vessel including a hull and the vessel propulsion apparatus mounted in the hull to provide a thrust to the hull.
- With this structural arrangement, in the combustion chamber of the engine of the vessel propulsion apparatus included in the vessel, it is possible to prevent the occurrence of an ω swirl as described above.
- A preferred embodiment of the present invention provides a vessel engine including a cylinder head including a combustion chamber, a pair of intake openings to communicate with the combustion chamber, and a pair of intake ports respectively connected to the pair of intake openings. The pair of intake ports include a pair of downstream portions respectively connected to the pair of intake openings. A distance between the pair of downstream portions decreases toward the pair of intake openings.
- With this structural arrangement, in the combustion chamber of the vessel engine, it is possible to prevent the occurrence of an ω swirl as described above.
- A preferred embodiment of the present invention provides a vessel engine including a cylinder head including a combustion chamber, a pair of intake openings to communicate with the combustion chamber, and a pair of intake ports respectively connected to the pair of intake openings. The cylinder head includes a pair of inner surfaces that respectively extend from peripheral edges of the pair of intake openings and that face each other in an arrangement direction in which the pair of intake openings are arranged. The combustion chamber is defined between the pair of inner surfaces. The pair of inner surfaces include a pair of upstream portions respectively connected to the peripheral edges of the pair of intake openings. A distance between the pair of upstream portions decreases in a direction moving away from the peripheral edges of the pair of intake openings.
- With this structural arrangement, in the combustion chamber of the vessel engine, it is possible to prevent the occurrence of an ω swirl as described above.
- The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.
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FIG. 1 is a schematic plan view of a vessel according to a preferred embodiment of the present invention. -
FIG. 2 is a schematic side view of an outboard motor included in the vessel. -
FIG. 3 is a schematic view shown to describe an air intake/exhaust system of the outboard motor. -
FIG. 4 is a perspective view of an air intake structure in the air intake/exhaust system. -
FIG. 5 is a rear view of a main portion in the air intake structure. -
FIG. 6 is a front view of the main portion in the air intake structure. -
FIG. 1 is a schematic plan view of avessel 1 according to a preferred embodiment of the present invention. Thevessel 1 includes ahull 2, avessel operation device 3, and anoutboard motor 4, and thehull 2 is equipped with both thevessel operation device 3 and theoutboard motor 4. An example of thevessel operation device 3 includes asteering wheel 6 and athrottle lever 7 both of which are provided at anoperational platform 5 around a vessel operation seat of thehull 2, and acommunication bus 9 by which an ECU (electronic control unit) 8 built into theoutboard motor 4, asteering wheel 6, and thethrottle lever 7 are connected together. A vessel operator turns thesteering wheel 6 in a left-right direction to steer. The vessel operator turns thethrottle lever 7 in a front-rear direction to adjust the output of theoutboard motor 4. Ajoystick 10 that is operated by the vessel operator to steer and adjust the output of theoutboard motor 4 may be provided at theoperational platform 5. - The
outboard motor 4 is an example of a vessel propulsion apparatus that provides a thrust to thehull 2, and is provided as a single outboard motor or as a plurality of outboard motors. The singleoutboard motor 4 is attached to a transom stern 2A on a virtual center line C along the front-rear direction through the transom stern 2A and abow 2B of thehull 2. The plurality ofoutboard motors 4 are attached to the transom stern 2A at bilaterally symmetrical positions with respect to the center line C. -
FIG. 2 is a schematic right side view of theoutboard motor 4. The left side inFIG. 2 is the front side of theoutboard motor 4, and the right side inFIG. 2 is the rear side of theoutboard motor 4. The upper side inFIG. 2 is the upper side of theoutboard motor 4, and the lower side inFIG. 2 is the lower side of theoutboard motor 4. An up-down direction is also a vertical direction. A direction perpendicular to the plane of paper ofFIG. 2 is the left-right direction of theoutboard motor 4. In the following description, a leftward or rightward direction of theoutboard motor 4 is determined based on a direction given when theoutboard motor 4 is seen from the front side. Therefore, the near side in the direction perpendicular to the plane of paper ofFIG. 2 is the right side of theoutboard motor 4, and the far side in the direction perpendicular to the plane of paper ofFIG. 2 is the left side of theoutboard motor 4. - The
outboard motor 4 includes amount 11 to attach theoutboard motor 4 to the transom stern 2A and an outboard motormain body 12. Themount 11 includes aclamp bracket 13 fixed to the transom stern 2A and aswivel bracket 15 coupled to theclamp bracket 13 through atilt shaft 14 horizontally extending in the left-right direction. Theswivel bracket 15 is coupled to the outboard motormain body 12 through a steeringshaft 16 extending in the up-down direction. Thus, the outboard motormain body 12 is attached to the transom stern 2A by themount 11 in a vertical or substantial vertical attitude. - The outboard motor
main body 12 and theswivel bracket 15 are turnable in the up-down direction around thetilt shaft 14 with respect to theclamp bracket 13. The outboard motormain body 12 is turned around thetilt shaft 14, and, as a result, the outboard motormain body 12 is tilted with respect to thehull 2 and theclamp bracket 13. The outboard motormain body 12 is turnable in the left-right direction together with the steeringshaft 16 with respect to theclamp bracket 13 and theswivel bracket 15. When the outboard motormain body 12 turns in the left-right direction, thevessel 1 is steered. - The outboard motor
main body 12 includes a box-shapedengine cover 17, ahollow casing 18 extending downwardly from theengine cover 17, and a plate-shapedexhaust guide 19 attached to a lower end portion of theengine cover 17 so as to close an internal space of thecasing 18 from above. A lower end portion of thecasing 18 is alower case 18A. The outboard motormain body 12 includes anengine 20 mounted on an upper surface of theexhaust guide 19 in theengine cover 17, adrive shaft 21 extending along the up-down direction in thecasing 18, and apropeller shaft 22 and atransmission 23 both of which are located in thelower case 18A. - The
engine 20 is a vessel engine, and includes an internal combustion engine that burns fuel, such as gasoline, and generates power. Theengine 20 includes acylinder block 25 including a single or a plurality ofcylinders 24, apiston 26 located in thecylinder 24 one by one, and acrankshaft 27 extending along the up-down direction in thecylinder block 25 and that is coupled to the piston(s) 26. Theengine 20 in the present preferred embodiment is a straight-type four-cylinder engine in which fourcylinders 24 are located in series along the up-down direction. - An internal space of each of the
cylinders 24 includes a circular cylindrical shape extending along the front-rear direction. Acombustion chamber 28 is defined in a region behind thepiston 26 in the internal space of each of thecylinders 24. A front portion that houses thecrankshaft 27 in thecylinder block 25 is acrank case 25A. - The
engine 20 includes acylinder head 29 attached to thecylinder block 25 from behind and ahead cover 30 attached to thecylinder head 29 from behind. Thecylinder head 29 and thehead cover 30 may be regarded as elements of thecylinder block 25.Concave portions 29A each of which is rearwardly hollowed as a portion of thecombustion chamber 28 are provided one by one at a portion, which faces thecombustion chamber 28 of each of thecylinders 24, of a front surface of thecylinder head 29. Theengine 20 includes an intake valve 31 and an exhaust valve 32 that are exposed to each of theconcave portions 29A and acamshaft 33 that extends along the up-down direction and that is rotatably supported by thehead cover 30. Thecamshaft 33 may be provided as a pair of camshafts in accordance with each of the intake valve 31 and the exhaust valve 32. - The
crankshaft 27 has a crankshaft axis 27A extending in the up-down direction. An upper end portion of thecrankshaft 27 protrudes upwardly from thecrank case 25A. A lower end portion of thecrankshaft 27 is joined to the upper end portion of thedrive shaft 21. Theengine 20 includes aflywheel magneto 34 fixed to the upper end portion of thecrankshaft 27 and acam chain 35 connecting the lower end portion of thecrankshaft 27 and a lower end portion of thecamshaft 33. Theflywheel magneto 34 is located at a higher position than the crankcase 25A. Thecam chain 35 is located below the fourcylinders 24 in thecylinder block 25. - The
piston 26 is rectilinearly reciprocated in the front-rear direction perpendicular to the crankshaft axis 27A by combustion of an air-fuel mixture in each of thecombustion chambers 28. When thepiston 26 is rectilinearly reciprocated, thecrankshaft 27 is driven and rotated around the crankshaft axis 27A along with thedrive shaft 21. In accordance with the rotation of thecrankshaft 27, theflywheel magneto 34 rotates and generates electricity, and thecam chain 35 moves in a circular motion. Thecamshaft 33 is rotated in accordance with the circular movement of thecam chain 35. The intake valve 31 and the exhaust valve 32 are actuated interlockingly with the rotation of thecamshaft 33. Thus, intake/exhaust is performed in each of thecombustion chambers 28. - The
propeller shaft 22 horizontally extends along the front-rear direction in thelower case 18A. A lower end portion of thedrive shaft 21 is coupled to a front end portion of thepropeller shaft 22 by thetransmission 23. A rear end portion of thepropeller shaft 22 protrudes rearwardly from thelower case 18A. Apropeller 36 as an example of a propulsion unit that is an element of theoutboard motor 4 is joined to the rear end portion of thepropeller shaft 22. Thepropeller shaft 22 rotates together with thepropeller 36 around arotational axis 22A that extends in the front-rear direction. - The
transmission 23 is used to transmit the rotation of thedrive shaft 21 to thepropeller shaft 22. Thetransmission 23 includes adriving gear 38 fixed to the lower end portion of thedrive shaft 21 and arotary body 39 and adog clutch 40 both of which are attached to the front end portion of thepropeller shaft 22. Thedriving gear 38 is a bevel gear. Thepropeller shaft 22 is located below thedriving gear 38. Therotary body 39 includes a firstrotary body 41 and a secondrotary body 42 that are located side by side in the front-rear direction along thepropeller shaft 22. The firstrotary body 41 and the secondrotary body 42 are, for example, cylindrical bevel gears, respectively. - In the present preferred embodiment, the first
rotary body 41 is located at a more forward position than the drivinggear 38, and the secondrotary body 42 is located at a more rearward position than the drivinggear 38, and yet the front-rear positional relationship between the firstrotary body 41 and the secondrotary body 42 may be opposite to that of the present preferred embodiment. In a rear surface of the firstrotary body 41, atooth portion 41A is provided at a tapered outer peripheral portion, and aclaw portion 41B is provided at an inner peripheral portion. In a front surface of the secondrotary body 42, atooth portion 42A is provided at a tapered outer peripheral portion, and aclaw portion 42B is provided at an inner peripheral portion. - The first
rotary body 41 surrounds a portion, which is at a more forward position than the drivinggear 38, of the front end portion of thepropeller shaft 22, and the secondrotary body 42 surrounds a portion, which is at a more rearward position than the drivinggear 38, of the front end portion of thepropeller shaft 22. The firstrotary body 41 and the secondrotary body 42 are located so that theirtooth portions driving gear 38. When thedriving gear 38 rotates together with thedrive shaft 21 in response to the driving of theengine 20, the rotation of thedriving gear 38 is transmitted to the firstrotary body 41 and to the secondrotary body 42. Thus, the firstrotary body 41 and the secondrotary body 42 rotate around therotational axis 22A of thepropeller shaft 22 in mutually opposite directions. - The
dog clutch 40 is located between the firstrotary body 41 and the secondrotary body 42. Thedog clutch 40 is, for example, cylindrical, and surrounds the front end portion of thepropeller shaft 22. Afirst claw portion 40A is provided at a front end surface of thedog clutch 40, and asecond claw portion 40B is provided at a rear end surface of thedog clutch 40. Thedog clutch 40 is coupled to the front end portion of thepropeller shaft 22 by, for example, a spline. Therefore, thedog clutch 40 rotates together with the front end portion of thepropeller shaft 22. Additionally, thedog clutch 40 is movable in the front-rear direction with respect to the front end portion of thepropeller shaft 22. In other words, thedog clutch 40 is rotatable together with thepropeller shaft 22, and is movable along the front-rear direction relatively with thepropeller shaft 22. - The
transmission 23 also includes ashifter 43 located at a more forward position than thepropeller shaft 22 in thelower case 18A. Theshifter 43 includes, for example, ashift rod 44 extending in the up-down direction and anelectric shift actuator 45 joined to theshift rod 44. A lower end portion of theshift rod 44 is coupled to thedog clutch 40. When theshift actuator 45 is operated by the control of the ECU 8 (seeFIG. 1 ), theshift rod 44 turns around an axis of theshift rod 44. Theshift rod 44 turns, and, as a result, thedog clutch 40 is moved along the front-rear direction between a disconnection position and a connection position. - The disconnection position is a position in which the
dog clutch 40 is spaced apart from the firstrotary body 41 and the secondrotary body 42, and does not engage with either of these rotary bodies of therotary body 39 as shown inFIG. 2 . In a state in which thedog clutch 40 is located in the disconnection position, each of therotary body 39 to which the rotation of thedrive shaft 21 is transmitted runs idle, and therefore the rotation of thedrive shaft 21 is not transmitted to thepropeller shaft 22. In the following description, the shift position of theoutboard motor 4 at this time is referred to as “neutral.” - The connection position is a position in which the
dog clutch 40 engages with either one of the firstrotary body 41 or the secondrotary body 42. The connection position includes a first connection position in which thefirst claw portion 40A of thedog clutch 40 engages with only theclaw portion 41B of the firstrotary body 41 and a second connection position in which thesecond claw portion 40B of thedog clutch 40 engages with only theclaw portion 42B of the secondrotary body 42. The disconnection position is a position between the first connection position and the second connection position. The first connection position is more forward than the disconnection position, and the second connection position is more rearward than the disconnection position. - In a state in which the
dog clutch 40 is located in the first connection position and is coupled to only the firstrotary body 41, the rotation of the firstrotary body 41 is transmitted to thepropeller shaft 22, and therefore the shift position of theoutboard motor 4 is shifted into “forward.” Thereupon, the rotation of thedrive shaft 21 is transmitted to thepropeller shaft 22 through the firstrotary body 41 and thedog clutch 40, and, as a result, thepropeller 36 rotates in a forward rotational direction (for example, a clockwise direction when seen from the rear side). Thus, thepropeller 36 is driven by theengine 20, and a forward thrust is generated. - In a state in which the
dog clutch 40 is located in the second connection position and is coupled to only the secondrotary body 42, the rotation of the secondrotary body 42 is transmitted to thepropeller shaft 22, and therefore the shift position of theoutboard motor 4 is shifted into “reverse.” Thereupon, the rotation of thedrive shaft 21 is transmitted to thepropeller shaft 22 through the secondrotary body 42 and thedog clutch 40, and, as a result, thepropeller 36 rotates in a reverse rotational direction opposite to the forward rotational direction. Thus, thepropeller 36 is driven by theengine 20, and a reverse thrust is generated. As thus described, in the present preferred embodiment, the firstrotary body 41 is a gear for forward movement, and the secondrotary body 42 is a gear for reverse movement. Of course, the firstrotary body 41 may be a gear for reverse movement, and the secondrotary body 42 may be a gear for forward movement. - The outboard motor
main body 12 includes anexhaust passage 46 provided inside the outboard motormain body 12 and connected to theengine 20. Theexhaust passage 46 passes through theexhaust guide 19 in the up-down direction, and extends downwardly in thecasing 18 and rearwardly in thepropeller 36. Theexhaust passage 46 includes anoutlet 46A provided at a rear end surface of thepropeller 36. In a state in which thevessel 1 is floating on water and in which thepropeller 36 is located below a water surface, theoutlet 46A is located in the water, and therefore water that has passed through theoutlet 46A enters a downstream portion of theexhaust passage 46. On the other hand, when theengine 20 rotates at a high speed, water in theexhaust passage 46 is pushed by the pressure of an exhaust gas emitted from theengine 20, and is discharged from theoutlet 46A together with the exhaust gas. Thus, the exhaust gas generated by theengine 20 is discharged into the water. - A steering
rod 47 that forwardly extends is fixed to the outboard motormain body 12. Anelectric steering actuator 48 that is controlled by theECU 8 is joined to the steeringrod 47. The outboard motormain body 12 is able to turn around the steeringshaft 16 by allowing thesteering actuator 48 to operate, thus making it possible to perform steering. -
FIG. 3 is a schematic view shown to describe an air intake/exhaust system 49 of theoutboard motor 4. The air intake/exhaust system 49 includes theengine 20, apressure charger 50 that compresses air and supplies the air to theengine 20, and anintercooler 51 that cools air compressed by thepressure charger 50. - With respect to the air intake/
exhaust system 49, theengine 20 includes theexhaust passage 46, anair intake passage 52, and anelectric throttle valve 53 located in theair intake passage 52. Theexhaust passage 46 is connected to each of thecombustion chambers 28 through a plurality ofexhaust ports 54 provided in thecylinder head 29 of theengine 20. Theair intake passage 52 is connected to each of thecombustion chambers 28 through a plurality ofintake ports 55 provided in thecylinder head 29. Aninlet 52A is provided at an end portion, which is opposite to theintake port 55, of theair intake passage 52. TheECU 8 controls thethrottle valve 53, and, as a result, the opening degree of thethrottle valve 53 is adjusted. - The
pressure charger 50 is interposed between the ends of theair intake passage 52. Thepressure charger 50 is a supercharger driven by the rotation of thecrankshaft 27 of theengine 20. Thepressure charger 50 includes ahousing 50A including an internal space defining a portion of theair intake passage 52, acompressor wheel 50B located in thehousing 50A, and arotational shaft 50C coaxially fixed to thecompressor wheel 50B. An end portion, which is spaced apart from thecompressor wheel 50B, of therotational shaft 50C is located outside thehousing 50A, and arotor 56 is coaxially fixed to this end portion. - The air intake/
exhaust system 49 includes a power transmission by which thecrankshaft 27 and thepressure charger 50 are joined together. An example of the power transmission includes therotor 56, anotherrotor 57 attached to thecrankshaft 27, and abelt 58 by which therotor 56 and therotor 57 are connected together. An example of each of therotors rotor 57 is attached to a portion, which is located at a higher position than theflywheel magneto 34, of the upper end portion of the crankshaft 27 (seeFIG. 2 ). - When the
crankshaft 27 rotates, therotor 57 rotates together with thecrankshaft 27. The rotation of therotor 57 is transmitted to therotor 56 through thebelt 58. Thereupon, therotational shaft 50C rotates together with thecompressor wheel 50B, and, as a result, thepressure charger 50 is driven. A sprocket may be used as each of therotors belt 58. - When the
pressure charger 50 operates in a state in which thethrottle valve 53 has been opened, air that has been taken from theinlet 52A and that flows through theair intake passage 52 is compressed by thecompressor wheel 50B rotating in thehousing 50A. Another arrangement, such as a Lysholm-type device, may be used as thepressure charger 50 without being limited to the centrifugal-type device shown inFIG. 3 . - The
intercooler 51 is interposed between each of theintake ports 55 of theengine 20 and thepressure charger 50 in theair intake passage 52. Theintercooler 51 includes ahousing 51A including an internal space defining a portion of theair intake passage 52 and a cooling fin (not shown). Either of an air-cooled intercooler or a water-cooled intercooler may be used as theintercooler 51. Theintercooler 51 includes anintake manifold 51B that extends from thehousing 51A and is connected to theintake port 55. Theintake manifold 51B is integral with thehousing 51A. - Air compressed by the
compressor wheel 50B in thehousing 50A of thepressure charger 50 continuously flows through theair intake passage 52, and thus is guided to theintercooler 51, and is cooled by heat exchange with the cooling fin in thehousing 51A of theintercooler 51. The air cooled by theintercooler 51 flows through theintake manifold 51B, and then is turned into an air-fuel mixture, supplied from theintake port 55 to thecombustion chamber 28 in thecylinder 24, and combusted. Exhaust gas generated by the combustion flows from theexhaust port 54 through theexhaust passage 46, and then is discharged from theoutlet 46A into the water as described above. -
FIG. 4 is a perspective view of anair intake structure 60, seen from the right front side, which excludes theexhaust passage 46 in the air intake/exhaust system 49. Theintercooler 51 is located lateral to (more specifically, on the left side of) thecylinder block 25 of theengine 20. Thehousing 51A of theintercooler 51 is made of metal, such as aluminum, and is a hollow body elongated in the up-down direction. Theintake manifold 51B integral with thehousing 51A extends rearwardly from thehousing 51A, and is bent rightwardly. - The
pressure charger 50 is located in front of thecylinder block 25. Anupstream region 52B, that is closer to theinlet 52A than thepressure charger 50, of theair intake passage 52 extends downwardly from thehousing 50A of thepressure charger 50, and then extends right-rearwardly, and is bent on the right side of thecylinder block 25, and extends upwardly. Theinlet 52A is provided at an upper end portion of theupstream region 52B and faces forwardly. Afilter 61 made of mesh, etc., is provided at theinlet 52A. A portion, which is located on the right side of thecylinder block 25, of theupstream region 52B may be referred to as an air intake duct. Therotor 56 is located at an upper surface of thehousing 50A of thepressure charger 50. -
FIG. 5 is a rear view of a main portion of theair intake structure 60. A portion of thecylinder head 29 and a pair of theintake ports 55 are shown inFIG. 5 . Theconcave portion 29A, i.e., a portion of thecombustion chamber 28 is provided at thecylinder head 29 as a single or a plurality of concave portions whose number is the same as the number ofcylinders 24, and, in the present preferred embodiment, fourconcave portions 29A are arranged side by side in the up-down direction (seeFIG. 2 ). Theintake port 55 is a circular tubular pipe passage provided as a pair for eachcombustion chamber 28, and extends rightwardly from theintake manifold 51B (in a rear view, leftwardly), and is connected to acorresponding combustion chamber 28. Avalve guide 62 that supports the intake valve 31 (seeFIG. 2 ) is provided at each of theintake ports 55. The intake valve 31 and the exhaust valve 32 are omitted and are not shown inFIG. 5 and in the drawings subsequent toFIG. 5 . Theexhaust port 54 is a circular tubular pipe passage provided as a pair for each combustion chamber 28 (seeFIG. 6 ). - A pair of
air intake openings 63 and a pair ofexhaust openings 64 are provided in a region, which coincides with each of thecombustion chambers 28 in a rear view, of a rear surface of thecylinder head 29. Each of theair intake opening 63 and theexhaust opening 64 is a round hole that passes through thecylinder head 29 in the front-rear direction or substantially in the front-rear direction (see alsoFIG. 6 ). A single intake valve 31 is located in a singleair intake opening 63, and a single exhaust valve 32 is located in a single exhaust opening 64 (not shown). A through-hole 29B that exposes an ignition plug (not shown) to each of thecombustion chambers 28 is also provided in thecylinder head 29. - An arrangement relative to each of the
combustion chambers 28 will be hereinafter described with reference to asingle combustion chamber 28. For theair intake opening 63 and theexhaust opening 64 corresponding to thesingle combustion chamber 28, the pair ofair intake openings 63 arranged side by side along the up-down direction are located on the left side (in a rear view, on the right side) closer to theintake manifold 51B than the pair ofexhaust openings 64 arranged side by side along the up-down direction. In other words, in the present preferred embodiment, an arrangement direction in which the pair ofair intake openings 63 are arranged is the up-down direction (the arrangement direction), and an arrangement direction in which the pair ofexhaust openings 64 are arranged is likewise the up-down direction (the arrangement direction). - The pair of
air intake openings 63 communicate with afirst region 28A, which occupies substantially a left half of thecombustion chamber 28, from behind, and the pair ofexhaust openings 64 communicate with asecond region 28B, which occupies substantially a right half of thecombustion chamber 28, from behind. A region surrounded by the pair ofair intake openings 63 and by the pair ofexhaust openings 64 in a rear view is acentral region 28C of thecombustion chamber 28. Thecentral region 28C is a boundary region between thefirst region 28A and thesecond region 28B. The through-hole 29B is located at a position that coincides with thecentral region 28C in a rear view. - In the following description, an upper one of the pair of
air intake openings 63 will be referred to as a firstair intake opening 63A if necessary, and a lower one of the pair ofair intake openings 63 will be referred to as a secondair intake opening 63B if necessary. Additionally, an upper one of the pair ofexhaust openings 64, i.e., theexhaust opening 64 located on the firstair intake opening 63A side in the up-down direction will be referred to as afirst exhaust opening 64A if necessary, and a lower one of the pair ofexhaust openings 64, i.e., theexhaust opening 64 located on the secondair intake opening 63B side in the up-down direction will be referred to as asecond exhaust opening 64B if necessary. - A pair of
intake ports 55 are respectively connected to the pair ofair intake openings 63 communicating with thesingle combustion chamber 28. A pair ofexhaust ports 54 are respectively connected to the pair ofexhaust openings 64 communicating with this combustion chamber 28 (seeFIG. 6 ). - Each of the pair of
intake ports 55 is an independent intake port that individually extends from theintake manifold 51B integral with theintercooler 51 to theair intake opening 63. A portion, which is connected to theair intake opening 63, i.e., a portion closer to theair intake opening 63, of each of the pair ofintake ports 55, is referred to as adownstream portion 55A. A distance D between thedownstream portions 55A of the pair ofintake ports 55 decreases toward theair intake opening 63. - A virtual line passing through the center of the intake port 55 (more specifically, the center in a flow-passage cross section of the intake port 55) is referred to as a
tube axis 55B. A distance D′ between the tube axes 55B in thedownstream portions 55A of the pair ofintake ports 55 likewise decreases toward theair intake opening 63 in the same way as the distance D between thedownstream portions 55A. A distance between the entire areas of the pair ofintake ports 55 may also become shorter toward theair intake opening 63 without being limited to the distance D between thedownstream portions 55A. - Air cooled by the
intercooler 51 divides and flows into each of the pair ofintake ports 55 in theengine 20 of theoutboard motor 4. The air that has been divided and flowed into each of the pair ofintake ports 55 flows into a corresponding one of thecombustion chambers 28 from each of the pair ofair intake openings 63, and is combusted in thecombustion chamber 28 together with fuel. Thus, theengine 20 generates a driving force, and thepropeller 36 is driven in theoutboard motor 4, and therefore theoutboard motor 4 generates a thrust. - In the pair of
intake ports 55, the distance D between thedownstream portions 55A connected to theair intake openings 63 decreases toward theair intake openings 63 as described above. This arrangement enables air immediately after having flowed into thecombustion chamber 28 from each of the pair ofair intake openings 63 to flow toward thecentral region 28C side of the combustion chamber 28 (i.e., toward the ignition plug exposed through the through-hole 29B) so that the distance between the air flows does not increase (see the thick solid arrow inFIG. 5 ). This makes it possible to prevent the occurrence of an ω swirl (see the thick alternate long and two short dashed line arrow inFIG. 5 ) in thecombustion chamber 28 of theengine 20. If the occurrence of an ω swirl is prevented, it is possible to prevent the occurrence of knocking, and it is possible to raise a combustion speed particularly during ignition advance, thus making it possible to improve the performance of theengine 20. Additionally, if each of the pair ofintake ports 55 is an independent intake port, it is possible to easily arrange the distance D between thedownstream portions 55A connected to theair intake openings 63 so as to become shorter toward theair intake openings 63. -
FIG. 6 is a front view of a main portion of theair intake structure 60. A portion of afront surface 29C, at which the combustion chamber 28 (concave portion 29A) is provided, of thecylinder head 29 and the pair ofexhaust ports 54 are shown inFIG. 6 . The pair ofexhaust ports 54 extend rightwardly. - A pair of
inner surfaces 65 facing each other in an arrangement direction in which the pair ofair intake openings 63 are arranged (in the present preferred embodiment, in the up-down direction) and another pair ofinner surfaces 66 facing each other in the left-right direction perpendicular to the arrangement direction are provided for each of thecombustion chambers 28 in thecylinder head 29. - In the following description, an upper
inner surface 65, which is located on the firstair intake opening 63A side in the up-down direction, of the pair ofinner surfaces 65 will be referred to as a firstinner surface 65A if necessary, and a lowerinner surface 65, which is located on the secondair intake opening 63B side in the up-down direction, of the pair ofinner surfaces 65 will be referred to as a secondinner surface 65B if necessary. Additionally, a leftinner surface 66, which is located on the pair ofair intake ports 63 side in the left-right direction, of the pair ofinner surfaces 66 will be referred to as a firstinner surface 66A if necessary, and a rightinner surface 66, which is located on the pair ofexhaust openings 64 side in the left-right direction, of the pair ofinner surfaces 66 will be referred to as a secondinner surface 66B if necessary. - Left ends of the pair of
inner surfaces 65 are provided between the firstinner surfaces 66A, and right ends of the pair ofinner surfaces 65 are provided between the secondinner surfaces 66B. Thesingle combustion chamber 28 is defined between the pair ofinner surfaces 65 and between the pair ofinner surfaces 66. Thecombustion chamber 28 includes a rectangular or substantially rectangular shape whose four corners are rounded in a front view. Either the pair ofair intake openings 63 or the pair ofexhaust openings 64 are located one by one at the four corners of thecombustion chamber 28 in a front view. - A circular arc, by which a left end portion of the first
inner surface 65A and an upper end portion of the firstinner surface 66A are connected together, of a circular peripheral edge 63AA fringing the firstair intake opening 63A is referred to as a peripheral edge 63AB. A circular arc, by which a left end portion of the secondinner surface 65B and a lower end portion of the firstinner surface 66A are connected together, of a circular peripheral edge 63BA fringing the secondair intake opening 63B is referred to as a peripheral edge 63BB. A circular arc, by which a right end portion of the firstinner surface 65A and an upper end portion of the secondinner surface 66B are connected together, of a circular peripheral edge 64AA fringing thefirst exhaust opening 64A is referred to as a peripheral edge 64AB. A circular arc, by which a right end portion of the secondinner surface 65B and a lower end portion of the secondinner surface 66B are connected together, of a circular peripheral edge 64BA fringing thesecond exhaust opening 64B is referred to as a peripheral edge 64BB. - The first
inner surface 65A connects the peripheral edge 63AB of the firstair intake opening 63A and the peripheral edge 64AB of the first exhaust opening 64A together. The secondinner surface 65B connects the peripheral edge 63BB of the secondair intake opening 63B and the peripheral edge 64BB of the second exhaust opening 64B together. In other words, the pair ofinner surfaces 65 extend from the peripheral edge 63AB and the peripheral edge 63BB of the pair ofair intake openings 63 to the peripheral edge 64AB and the peripheral edge 64BB of the pair ofexhaust openings 64, respectively. - A portion, which is connected to the peripheral edge 63AB or the peripheral edge 63BB of a corresponding
air intake opening 63, of each of the pair ofinner surfaces 65, i.e., a portion, which is substantially a left half closer to theair intake opening 63, of each of the pair ofinner surfaces 65 is referred to anupstream portion 65C. The firstinner surface 65A and the secondinner surface 65B of the pair ofinner surfaces 65 are curved so as to approach each other. Therefore, a distance E between theupstream portions 65C of the pair ofinner surfaces 65 decreases in a direction moving rightwardly away from the peripheral edge 63AB and from the peripheral edge 63BB. Likewise, this arrangement enables air immediately after having flowed into thecombustion chamber 28 from each of the pair ofair intake openings 63 to flow so that the distance between each other does not increase (see the thick solid arrow inFIG. 6 ). This makes it possible to prevent the occurrence of an ω swirl (see the thick alternate long and two short dashed line arrow inFIG. 6 ) in thecombustion chamber 28 of theengine 20. The pair ofinner surfaces 66 may be curved so as to approach each other in the same way as the pair ofinner surfaces 65, or may extend linearly in a parallel or substantially parallel manner, or one of the pair ofinner surfaces 66 may be curved while the otherinner surface 66 may extend linearly. - Preferred embodiments of the present invention have been described above, and yet the present invention is not limited to the contents of the above-described preferred embodiments, and various modifications can be made within the scope of the present invention.
- For example, an arrangement in which the distance D decreases toward the air intake opening 63 (see
FIG. 5 ) and an arrangement in which the distance E decreases in a direction moving away from the peripheral edge 63AB and the peripheral edge 63BB of the pair of air intake openings 63 (seeFIG. 6 ) may be used in combination with each other, or only one of the arrangements may be used. - For example, the
pressure charger 50 includes only the supercharger in the above-described preferred embodiments. Theoutboard motor 4 may be provided with a turbocharger (not shown) driven by exhaust gas passing through theexhaust passage 46. Thepressure charger 50 may include only a turbocharger, or may include both a supercharger and a turbocharger. - Additionally, an inboard/outboard motor, or an inboard motor, or a waterjet drive may be used as an example of a vessel propulsion apparatus other than the
outboard motor 4. In the inboard/outboard motor, a vessel engine arranged in the same way as theengine 20 is located inside the vessel, and a drive unit including a propulsion unit (propeller 36, etc.) and a steering assembly is located outside the vessel. The inboard motor is a vessel engine and a drive unit that are built into thehull 2 and in which thepropeller 36 is attached to a propeller shaft extending from the drive unit and outwardly from the vessel. In this case, the steering assembly is separately provided. The waterjet drive is arranged to accelerate water taken in from a vessel bottom by a pump, and jet the water from a jet nozzle of a transom stern, and thus obtain a thrust. In this case, the pump is driven by the vessel engine, and the steering assembly includes the jet nozzle and a mechanism that turns the jet nozzle along a horizontal plane. In the vessel engine, a plurality ofcylinders 24 may be located in series along the horizontal direction, etc., so that thecrankshaft 27 extends in the front-rear direction. - Various features described above may be appropriately combined together.
- While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
Claims (8)
1. A vessel propulsion apparatus comprising:
an engine including a cylinder head including a combustion chamber, a pair of intake openings to communicate with the combustion chamber, and a pair of intake ports respectively including a pair of downstream portions respectively connected to the pair of intake openings; and
a propulsion unit to be driven by the engine; wherein
a distance between the pair of downstream portions decreases toward the pair of intake openings.
2. The vessel propulsion apparatus according to claim 1 , further comprising:
a pressure charger and an intercooler to cool air compressed by the pressure charger; wherein
air cooled by the intercooler flows into the pair of intake ports; and
the pair of intake ports include a pair of independent intake ports that individually extend from the intercooler to the pair of intake openings.
3. A vessel propulsion apparatus comprising:
an engine including a cylinder head including:
a combustion chamber;
a pair of intake openings to communicate with the combustion chamber;
a pair of inner surfaces respectively extending from peripheral edges of the pair of intake openings, facing each other in an arrangement direction in which the pair of intake openings are arranged, and defining the combustion chamber therebetween; and
a pair of intake ports respectively connected to the pair of intake openings; and
a propulsion unit to be driven by the engine; wherein
the pair of inner surfaces include a pair of upstream portions respectively connected to the peripheral edges of the pair of intake openings, and a distance between the pair of upstream portions decreases in a direction moving away from the peripheral edges of the pair of intake openings.
4. The vessel propulsion apparatus according to claim 3 , wherein
the cylinder head includes a pair of exhaust openings to communicate with the combustion chamber and arranged side by side along the arrangement direction;
the engine includes a pair of exhaust ports respectively connected to the pair of exhaust openings;
a first inner surface of the pair of inner surfaces connects a peripheral edge of a first intake opening of the pair of intake openings and a peripheral edge of a first exhaust opening of the pair of exhaust openings;
a second inner surface of the pair of inner surfaces connects a peripheral edge of a second intake opening of the pair of intake openings and a peripheral edge of a second exhaust opening of the pair of exhaust openings; and
the first inner surface and the second inner surface are curved toward each other.
5. The vessel propulsion apparatus according to claim 1 , wherein
the engine includes a crankshaft extending in a vertical direction; and
the vessel propulsion apparatus is an outboard motor including a drive shaft joined to the crankshaft and extending in the vertical direction, a propeller shaft extending along a horizontal direction, a propeller defining the propulsion unit joined to the propeller shaft, and a transmission to transmit rotation of the drive shaft to the propeller shaft.
6. A vessel comprising:
a hull; and
the vessel propulsion apparatus according to claim 1 mounted to the hull to provide a thrust to the hull.
7. A vessel engine comprising:
a cylinder head including a combustion chamber and a pair of intake openings to communicate with the combustion chamber; and
a pair of intake ports respectively connected to the pair of intake openings; wherein
the pair of intake ports include a pair of downstream portions respectively connected to the pair of intake openings, and a distance between the pair of downstream portions decreases toward the pair of intake openings.
8. A vessel engine comprising:
a cylinder head including:
a combustion chamber;
a pair of intake openings to communicate with the combustion chamber;
a pair of inner surfaces that respectively extend from peripheral edges of the pair of intake openings, that face each other in an arrangement direction in which the pair of intake openings are arranged, and that define the combustion chamber therebetween; and
a pair of intake ports respectively connected to the pair of intake openings; wherein
the pair of inner surfaces include a pair of upstream portions respectively connected to the peripheral edges of the pair of intake openings, and a distance between the pair of upstream portions decreases in a direction moving away from the peripheral edges of the pair of intake openings.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US18/536,327 US20240102434A1 (en) | 2021-11-15 | 2023-12-12 | Vessel propulsion apparatus, vessel, and vessel engine |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2021-185986 | 2021-11-15 | ||
JP2021185986A JP2023073137A (en) | 2021-11-15 | 2021-11-15 | Ship propulsion machine, ship and ship engine |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US18/536,327 Division US20240102434A1 (en) | 2021-11-15 | 2023-12-12 | Vessel propulsion apparatus, vessel, and vessel engine |
Publications (1)
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US20230151786A1 true US20230151786A1 (en) | 2023-05-18 |
Family
ID=86324286
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
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US17/956,898 Abandoned US20230151786A1 (en) | 2021-11-15 | 2022-09-30 | Vessel propulsion apparatus, vessel, and vessel engine |
US18/536,327 Pending US20240102434A1 (en) | 2021-11-15 | 2023-12-12 | Vessel propulsion apparatus, vessel, and vessel engine |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
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US18/536,327 Pending US20240102434A1 (en) | 2021-11-15 | 2023-12-12 | Vessel propulsion apparatus, vessel, and vessel engine |
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JP (1) | JP2023073137A (en) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4958604A (en) * | 1988-02-10 | 1990-09-25 | Toyota Jidosha Kabushiki Kaisha | Direct fuel injection type spark ignition internal combustion engine |
US6196185B1 (en) * | 1997-12-18 | 2001-03-06 | Nissan Motor Co., Ltd. | Fuel direct injection spark ignition type internal combustion engine |
US20090159041A1 (en) * | 2006-05-11 | 2009-06-25 | Honda Motor Co., Ltd. | Intake port structure for engine |
US20200318533A1 (en) * | 2019-04-04 | 2020-10-08 | Cox Powertrain Limited | Marine outboard motor with improved flow sensing |
-
2021
- 2021-11-15 JP JP2021185986A patent/JP2023073137A/en active Pending
-
2022
- 2022-09-30 US US17/956,898 patent/US20230151786A1/en not_active Abandoned
-
2023
- 2023-12-12 US US18/536,327 patent/US20240102434A1/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4958604A (en) * | 1988-02-10 | 1990-09-25 | Toyota Jidosha Kabushiki Kaisha | Direct fuel injection type spark ignition internal combustion engine |
US6196185B1 (en) * | 1997-12-18 | 2001-03-06 | Nissan Motor Co., Ltd. | Fuel direct injection spark ignition type internal combustion engine |
US20090159041A1 (en) * | 2006-05-11 | 2009-06-25 | Honda Motor Co., Ltd. | Intake port structure for engine |
US20200318533A1 (en) * | 2019-04-04 | 2020-10-08 | Cox Powertrain Limited | Marine outboard motor with improved flow sensing |
Also Published As
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JP2023073137A (en) | 2023-05-25 |
US20240102434A1 (en) | 2024-03-28 |
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