JP2000213363A - Outboard motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the difference between combustion efficiency of an upper cylinder and combustion efficiency of a lower cylinder. SOLUTION: In an outboard motor, an engine 9 is cooled by cooling water sucked from the lower part. A crankshaft 10 of the engine is vertically arranged, a plurality of cylinders are vertically arranged behind the crankshaft, and the combustion chamber sides of the cylinders are covered with a cylinder head. Intake passages 53 are provided between a silencer 51 and an intake port 33 of the cylinder head. Injectors 56 for injecting fuel are attached to the intermediate parts of the intake passages. On the upstream side from the injector 56, the inclination of the intake passages on the lower side is larger than the intake passage on the upper side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an engine for cooling an engine by cooling water sucked from a lower portion, and supplying air to a combustion chamber of the engine through an intake passage. The present invention relates to an outboard motor that injects fuel.

[0002]

2. Description of the Related Art An intake passage of a conventional engine is disposed between an intake port of a combustion chamber and a surge tank, and a throttle body is provided at an air inflow portion of the surge tank. Then, the amount of air flowing into the surge tank is adjusted by the throttle body, and this air is supplied from the surge tank to the combustion chamber via the intake passage. An injector for injecting fuel into the air in the intake passage is provided near the intake port of the combustion chamber. The engine is cooled by cooling water sucked from a lower part of the outboard motor.

[0003]

By the way, the cooling water sucked from the lower part of the outboard motor flows meandering up and down from the lower part of the engine, and the temperature of the lower part of the engine becomes lower than the temperature of the upper part. ing. Therefore, the fuel injected from the injector is
It is easier to evaporate than the lower intake passage, diffuses and mixes better with air, and improves combustion efficiency. As a result, the output of the upper cylinder tends to be higher than that of the lower cylinder, and the engine output may be relatively different depending on the cylinder.

[0004] The present invention has been made to solve the above problems, and has as its object to provide an outboard motor in which the difference between the combustion efficiency of the upper cylinder and the combustion efficiency of the lower cylinder is small. .

[0005]

In the outboard motor of the present invention, the engine (9) is cooled by cooling water sucked from below, and the engine is covered by the cowlings (1, 2). And the crankshaft of the engine (1
0) are arranged vertically, a plurality of cylinders (11) are arranged vertically behind the crankshaft, and the combustion chamber (11a) side of the cylinder is the cylinder head (2).
It is covered with 2). The cylinder head is provided with an intake port (33) opening to the combustion chamber of the cylinder for each combustion chamber, and a silencer (51) is provided at a front portion in the cowling, and the silencer and the cylinder head are provided. An intake passage (53) is provided for each combustion chamber. An injector (56) for injecting fuel is attached to an intermediate portion of the intake passage.
On the downstream side of the injector, the inclination of the lower intake passage is larger than the inclination of the upper intake passage, and the distance between the injector and the intake port in the lower intake passage is smaller than that in the upper intake passage. It is longer than the distance between the injector and the intake.

In some cases, a throttle body (41) is provided at an intermediate portion of the intake passage, and an injector is attached to the throttle body.

Further, there is a case where a pair of upper and lower intake ports are formed for each combustion chamber.

At the rear of the crankshaft, a plurality of cylinders are arranged in a substantially V-shape on the left and right, and a plurality of cylinders are arranged vertically, and a throttle body is provided in an intermediate portion of the intake passage. An injector for injecting fuel is attached to the throttle body, and a throttle valve (4
The valve shaft of 2) is arranged vertically, the valve shaft of the uppermost throttle valve protrudes above the engine case, and the upper ends of the valve shafts of the left and right throttle valves are higher than the engine case. Interlocking mechanism (6
6, 67).

In this specification, the side on which the cylinder is disposed with respect to the crankshaft is referred to as the "rear side".

[0010]

Next, a first embodiment of an outboard motor according to the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of an outboard motor according to the present invention as viewed from the side.
FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a plan sectional view of an upper portion of the outboard motor according to the first embodiment. FIG. 4 shows the first embodiment.
It is a top view of the inside of the outboard motor of the form of FIG. FIG. 5 is a schematic diagram of the flow of the cooling water. FIG. 6 is an enlarged view of a main part of the intake passage. FIG. 7 is a plan view of the drive mechanism of the throttle valve, and FIG.
Is a diagram of the first embodiment, and (b) is a diagram of a modification.
1 and 2, the engine is shown in a partially cutaway side view. In FIGS. 3 and 4, the vapor separator tank is shown by a broken line. In FIG. 4, the illustration of the drive mechanism of the throttle valve is omitted.

The outboard motor is covered by a housing consisting of an upper cowling 1, a lower cowling 2, an upper casing 3 and a lower casing 4 in this order from the upper side. The lower casing 4 has a cooling water inlet 5 formed therein. A mounting bracket 6 for mounting the outboard motor to a small boat is mounted and fixed to a transom 7 of the small boat. An outboard motor main body is rotatably attached to a rear portion of the mounting bracket 6 via a pivot shaft 8 or the like.

Inside the cowlings 1 and 2 including the upper cowling 1 and the lower cowling 2, a fuel-injection V-type six-cylinder four-cycle engine 9 as an internal combustion engine is provided.
Is arranged. The axis of the crankshaft 10 of the four-cycle engine 9 is provided substantially vertically, that is, in the vertical direction. Behind the crankshaft 10, a pair of left and right cylinders 11 are distributed so as to form a V-shape in the horizontal direction. Are located. This pair of left and right cylinders 11
Are provided vertically in three stages, and the cylinders 11 are arranged in a total of six cylinders. Also, the crankshaft 10 has 6
Each of the pistons 13 is connected via a connecting rod 14, and the piston 13 is slidably disposed inside each cylinder 11. The case 17 of the engine 9 includes a cylinder block 20 forming the above-described six cylinders 11, a crankcase 21 covering the crankshaft 10 side of the cylinder block 20, and a combustion chamber 11a side of the cylinder block 20. It comprises a pair of left and right cylinder heads 22 to be closed.

The lower end of the crankshaft 10 is
The drive shaft 2 extending from the engine case 17 and disposed in the upper casing 3
6. The rotation of the drive shaft 26 is transmitted to a propeller 28 rotatably provided at the rear end of the lower casing 4 via a bevel gear or the like. A cooling water pump 29 is provided at an intermediate portion of the drive shaft 26 and is driven by rotation of the drive shaft 26.

The cylinder head 22 has an intake passage 31 for supplying air to the cylinder 11 and a cylinder 11.
An exhaust path 32 for exhausting the combustion gas is formed for each cylinder 11. The intake port 33 at the tip of each intake path 31 is
A pair of upper and lower members are provided and open to the combustion chamber 11a. Similarly, a pair of upper and lower exhaust ports 34 at the end of each exhaust path 32 are provided and open to the combustion chamber 11a. And combustion chamber 1
An intake valve 35 is connected to the intake port 33 of the combustion chamber 11a.
An exhaust valve 36 opens and closes the exhaust port 34. In addition, each intake path 31 has a bifurcated branch at the intake port 33 side, that is, the downstream side, and each of the intake paths 31 communicates with the intake port 33. On the other hand, the upstream side merges into one. The exhaust passage 32 of the cylinder head 22 communicates with a collective exhaust passage 38 extending vertically, and the combustion gas flowing through the upper and lower exhaust passages 32 flows into the collective exhaust passage 38 and joins. The collective exhaust passage 38 is provided in a pair on the left and right, and is disposed at the rear of the cylinder head 22.

Each intake passage 3 of the cylinder head 22
A throttle body 41 is connected to an end on the upstream side of 1 via an intake manifold 37. The throttle body 41 is provided with a throttle valve 42 with a valve shaft arranged in a vertical direction to adjust the amount of flowing air. The rear end portion of a resin intake pipe 46 is connected to the throttle body 41. The intake pipe 46 extends forward from the throttle body 41, and has a front end connected to a resin silencer 51 disposed at the front of the cowlings 1, 2. Three intake pipes 46 are provided on each of the left and right sides in the vertical direction. The resin-made intake pipe 46 and the silencer 51 are assembled to the engine main body after being connected by welding, fitting, adhesive or the like.

In this manner, the intake passage 31, the intake manifold 37, the throttle body 41, and the intake pipe 46 of the cylinder head 22 constitute an intake passage 53 from the silencer 51 to the intake port 33 of the combustion chamber 11a. The intake passage 53 extends outward from the intake port 33 of the combustion chamber 11a once in a plan view (that is, when viewed from the tip end side of the crankshaft 10) to form a projecting passage portion 53a. A connection passage portion 53 b extending toward 51 and having a front end connected to the silencer 51. And the overhanging passage 53
“a” is constituted by the intake passage 31 of the cylinder head 22 and the intake manifold 37. Connection passage 53b
Is composed of a throttle body 41 and an intake pipe 46.

In the side view of the intake passage 53, the overhang passage portion 53a is inclined upward and forward from the intake port 33 of the combustion chamber 11a, is substantially horizontal in the throttle body 41, and the intake pipe 46 is From the front. The inclination of the overhang passage portion 53a and the intake pipe 46 is smaller in the upper intake passage 53 than in the lower intake passage 53.

The throttle body 41 is provided with an electronically controlled injector 56 for each intake passage 53. The injector 56 has an injection port communicating with the intake passage 53 and the engine case 1.
7 and an intake passage 53. Then, fuel such as gasoline is supplied to the air in the intake passage 53 from the injector 56. By the way, as described above, on the downstream side of the injector 56, the intake passage 53 is inclined backward and downward, and the inclination is larger in the lower intake passage 53 than in the upper intake passage 53. Therefore, the distance between the injector 56 and the intake port 33, that is, the length of the flow path, is smaller in the lower intake passage 53 than in the lower intake passage 53.
It is longer than the upper intake passage 53. The vertical distance between the axes of the injectors 56 is determined by the length of the combustion chamber 11.
The distance between the centers of the intake ports 33 for each a is smaller than the vertical distance.

An ISC, which is an intake system component for adjusting the flow rate of air to reduce rotation fluctuations during idling,
(Idle speed control) 57 is attached to the upper side of the engine case 17, and an air supply passage 58 from the ISC 57 is connected to each throttle body 41. At the time of idling, air is supplied from the ISC 57 into the throttle body 41. In addition,
Reference numeral 61 denotes a starter motor, reference numeral 62 denotes a vapor separator tank, and reference numeral 63 denotes a spark plug.

The three throttle bodies 41 are vertically arranged on the left and right sides of the engine case 17, respectively. The valve shafts of the throttle valves 42 of the upper and lower throttle bodies 41 are connected to each other and are interlocked. The upper end of the valve shaft of the uppermost throttle valve 42 is mounted on the engine case 1.
7, and a lever 65 is fixed, and the lever 65 is connected to a rotating plate 67 via a link 66 or the like. This rotating plate 67 is
It is rotatably mounted on the upper side of the engine case 17. Then, when a throttle lever (not shown) is operated, as shown in FIG. 5A, the rotation is performed via a throttle cable 101, a cam lever 102, an L-shaped sliding lever 103, a rod 104, and the like, which are drive mechanisms. The moving plate 67 is rotated. The rotation of the rotation plate 67 is transmitted to the lever 65 fixed to the valve shafts of the left and right throttle valves 42 via the left and right links 66, and the valve shaft of the throttle valve 42 rotates. In this way, the throttle valve 4
When the second valve shaft rotates, the amount of air flowing through the throttle body 41 is adjusted. Further, a modified example of the driving mechanism is as follows.
This is illustrated in FIG. In this variation,
When the throttle lever is operated, the rotating plate 67 is rotated via the throttle cable 101, the cam lever 102, the sliding lever 106, the pair of wires 107, and the like.

A drive pulley 71 for a camshaft is provided at an upper end of the crankshaft 10, and a driven pulley 73 is provided at an upper end of a camshaft 72 for driving the exhaust valve 36. A belt 76 is stretched between the camshaft driving pulley 71 and the driven pulley 73. Also, a tensioner 78 is provided,
The tension is applied to the belt 76. The link 66, which constitutes a part of the throttle interlocking member that drives the valve shaft of the throttle valve 42, is connected to the engine case 1
It is arranged in the space between the belt 7 and the belt 76.

In the outboard motor configured as described above,
When the crankshaft 10 rotates, the cowlings 1, 2
The air inside is sucked into the silencer 51, and the sucked air is taken into the intake pipe 46, the throttle body 41,
Intake manifold 37 and cylinder head 22
, And flows into the combustion chamber 11 a of the cylinder 11. Then, in the throttle body 41, fuel such as gasoline injected from the injector 56 is mixed with air flowing through the throttle body 41, the intake manifold 37 and the intake passage 31.
Further, the fuel gas mixture flowing into the combustion chamber 11a is ignited by the ignition plug 63 and burned, and the exhaust gas generated at this time is exhausted by the exhaust path 32 of the cylinder head 22, the collective exhaust path 38, Through the propeller 2
8 and are discharged from the boss. The piston 13 reciprocates due to the expansion force when the fuel gas mixture burns, and the crankshaft 10 rotates via the connecting rod 14 by the reciprocation of the piston 13.

The rotation of the crankshaft 10 activates the cooling water pump 29, as shown in FIG.
Water outside the outboard motor, that is, cooling water, is drawn in from the cooling water intake port 5 of the lower casing 4. The sucked cooling water rises toward the engine 9 through the upflow channel 81. A pressure control valve 83 is provided in communication with the upward flow path 81.
When the pressure of the cooling water becomes equal to or higher than the set pressure, the pressure control valve 83 discharges the cooling water in the upflow channel 81 and sets the pressure in the upflow channel 81 to the set pressure. Then, the cooling water flowing into the engine 9 is cooled by the cooling water passage 86 for the exhaust passage around the exhaust passage 32 for each combustion chamber 11 a in the cylinder head 22,
, A cooling water passage 87 for the combustion chamber around the combustion chamber 11a of the cylinder head 22, a V bank jacket 89 inside the cylinder block 20,
It flows through a cylinder cooling water passage 91 around the cylinder 11 of the cylinder block 20 and reaches a thermostat 93. The thermostat 93 allows the flow of the cooling water when the temperature of the cooling water becomes equal to or higher than the set temperature, and substantially shuts off the flow of the cooling water when the temperature of the cooling water is lower than the set temperature (a small amount flows. ). The thermostat 93 prevents the engine 9 from being excessively cooled by the cooling water. The relatively high temperature (for example, 60 ° C. or higher) cooling water flowing out of the thermostat 93 is discharged to the outside of the outboard motor through the water passage 96 after cooling. In this way, the relatively low-temperature cooling water sucked in from the outside of the outboard motor flows in from the lower part of the engine 9, meanders up and down, and is then drained out of the outboard motor. Therefore, the temperature of the engine 9 is lower at the lower portion than at the upper portion.

As described above, in the first embodiment, the distance from the injection port of the injector 56 to the intake port 33 of the combustion chamber 11a, that is, the length of the flow path is equal to the uppermost intake path 53. It is the shortest, and it gets longer as you go down. Therefore, the time required for the fuel injected from the injector 56 to reach the intake port 33 depends on the upper intake passage 5.
3 is shorter than the lower intake passage 53. Further, in the engine 9, the cooling water flows in from the lower side and meanders up and down. The temperature of the upper part of the engine 9 is higher than the temperature of the lower part of the engine 9, and the upper intake passage 53 Is easier for the fuel to evaporate. Therefore, the ratio of the fuel injected from the injector 56 diffusing into the air per unit time is larger in the upper intake passage 53 than in the lower intake passage 53. However, as described above, the arrival time at the intake port 33 is shorter in the upper intake passage 53 than in the lower intake passage 53, and the diffusion time of the fuel when reaching the intake port 33 is reduced. The ratio reduces a large difference between the upper intake passage 53 and the lower intake passage 53. As a result, a large difference between the output of the upper cylinder 11 and the output of the lower cylinder 11 can be prevented, and the engine 9 can operate stably.

Further, a pair of upper and lower intake ports 33 of the combustion chamber 11a are provided, and the inclination of the upper intake passage 53 is smaller than that of the lower intake passage 53. Therefore, as shown in FIG. 6, the upper intake port 3 in each combustion chamber 11a
The difference in air volume between 3a and the lower intake port 33b is smaller in the upper intake passage 53. Therefore, the combustion chamber 1
1a from the upper intake port 33a to the lower intake port 3
The spiral flow (so-called swirl) toward 3b is smaller in the upper intake passage 53. The larger the swirl, the higher the fuel combustion efficiency in the combustion chamber 11a of the cylinder 11. Therefore, considering only the swirl, the combustion efficiency of the lower cylinder 11 is higher than that of the upper cylinder 11. Due to this difference in swirl, a difference in combustion efficiency between the cylinders 11 due to a temperature difference between the upper part and the lower part of the engine 9 can be compensated as much as possible.

Further, on the downstream side of the throttle body 41, the intake passage 53 is inclined rearward and downward, and the inclination is such that the lower intake passage 53 is closer to the upper intake passage 53.
Greater than. Therefore, the upper and lower intervals of the throttle body 41 can be reduced as compared with the case where the upper intake passage 53 and the lower intake passage 53 are arranged substantially in parallel with the arrangement of the intake ports 33. As a result, the height of the entire throttle body assembly from the lowermost throttle body 41 to the uppermost throttle body 41 can be reduced, and the throttle body assembly becomes compact.

Further, the intake pipe 46 is inclined backward and downward, and the inclination of the lower intake pipe 46 is larger than the inclination of the upper intake pipe 46. , A relatively large space can be formed. Therefore, components such as the vapor separator tank 62 can be arranged below the front part of the intake pipe 46. As a result, the space below the intake pipe 46 can be effectively used.

A throttle body 41 is provided at an intermediate portion of the intake passage 53, and a resin intake pipe 46 and a silencer 51 are attached to the front side, that is, the upstream side of the throttle body 41. Thus, the throttle body 41 for adjusting the amount of flowing air is provided.
Is arranged on the downstream side of the intake pipe 46 and the silencer 51, so that even if external air flows into the intake pipe 46 or the silencer 51 from the connection portion between the intake pipe 46 and the silencer 51, Also, the air flow rate on the downstream side hardly fluctuates. Therefore, the mounting accuracy of the intake pipe 46, the silencer 51, and the like can be reduced, and the mounting operation and the processing operation are facilitated.

After assembling the intake pipe 46 and the silencer 51, the assembled intake pipe 46 and silencer 51 are attached to the engine body. Therefore, the intake pipe 46 and the silencer 51 are unitized, and the assembling work of the engine 9 becomes easy.

Further, since the injector 56 is attached to the throttle body 41, the throttle body 41 and the injector 56 can be unitized. Therefore, the injector 56 and the throttle body 41 can be mounted in a unitized state, and the time required for assembling the engine 9 can be reduced. As a result, man-hours in the engine assembly line can be reduced.

Then, the ISC 57 is mounted on the engine case 17.
And the air supply passage 5 from the ISC 57.
Air is supplied to each of the left and right throttle bodies 41 through the same. Therefore, one ISC 57 can supply air to many throttle bodies 41 at idle.

Further, the valve shafts of the throttle valves 42 of the throttle body 41 are vertically arranged, and the valve shafts of the upper left and right uppermost throttle bodies 41 are connected to an interlocking mechanism (rotating plate 67 or link) above the engine case 17. 66 etc.). Therefore, the interlocking mechanism is less likely to protrude from the lateral side of the engine 9 to the outside, and the lateral width of the cowlings 1 and 2 can be made compact.

Next, the second embodiment of the outboard motor according to the present invention will be described.
The embodiment will be described. FIG. 8 is a plan sectional view of an upper portion of the outboard motor according to the second embodiment. In the description of the second embodiment, the same reference numerals are given to components corresponding to the components of the first embodiment, and a detailed description thereof will be omitted.

FIG. 8 is a view corresponding to FIG. 3 of the first embodiment, in which an injector 56 is mounted not on the throttle body 41 but on the intake pipe 46. In the first embodiment, the injection port of the injector 56 communicates with the intake passage 53 on the downstream side of the throttle valve 42. However, in the second embodiment, the injection port is located upstream of the throttle valve 42. The injector 56 injects fuel toward a gap between the inner surface of the throttle body 41 and the throttle valve 42. In the gap between the inner surface of the throttle body 41 and the throttle valve 42, the air flow is fast, so that the fuel injected from the injector 56 can be scattered efficiently. Further, the injection direction of the injector 56 does not face upward, and fuel or the like does not accumulate near the injection port of the injector 56.

The ISC 57 is provided on each throttle body 41. Further, the injector 56
Is mounted on the intake pipe 46, so that the injector 56 and the intake pipe 46 can be unitized.
Therefore, the injector 56 and the intake pipe 46 can be mounted in a unitized state, and the engine 9
The time required for the assembling work can be reduced.
Note that other points such as a point relating to the arrival time from the injection port of the injector 56 to the intake port 33 and a point relating to swirl are substantially the same as those in the first embodiment.

Next, a third embodiment of the outboard motor according to the present invention will be described.
The embodiment will be described. FIG. 9 is a plan sectional view of the upper part of the outboard motor according to the third embodiment. In the description of the third embodiment, the same reference numerals are given to components corresponding to the components of the first embodiment, and a detailed description thereof will be omitted. Also, in FIG. 9, the vapor separator tank is shown by a broken line.

FIG. 9 is a view corresponding to FIG. 3 of the first embodiment. In the third embodiment, the intake manifold 37 is formed integrally with the cylinder head 22. Further, in a plan view (that is, when viewed from the distal end side of the crankshaft 10), the intake passage 53 temporarily extends outward from the intake port 33 of the combustion chamber 11a to form a projecting passage portion 53a. A drawn-in passage portion 53c is formed to extend inward while being curved, and includes a side passage portion 53d extending from the drawn-in passage portion 53c toward the silencer 51. The projecting passage 53a is constituted by the intake passage 31 of the cylinder head 22. The retraction passage 53c is constituted by the throttle body 41 and the wall 49 of the cylinder 11.
, And are arranged so as to be more outward as going backwards. The side passage portion 53d is constituted by the intake pipe 46, and is disposed substantially along the outer wall 48 of the crank chamber 47 (that is, substantially in the front-rear direction).

The injector 56 is attached to the throttle body 41, and its axis is disposed in the front-rear direction (ie, substantially parallel to the outer wall 48 of the crank chamber 47), and the injector 56 projects outward. Not. Therefore, cowling 1,
2 can be reduced in width.

The injector 56 is connected to the intake passage 53
It is disposed outside the main body so that maintenance such as replacement can be easily performed. In addition, the injector 56
Points about the arrival time from the injection port to the intake port 33,
Other points, such as those relating to swirl, are substantially the same as in the first embodiment.

Next, the fourth embodiment of the outboard motor according to the present invention will be described.
The embodiment will be described. FIG. 10 is a plan sectional view of an upper portion of an outboard motor according to a fourth embodiment. In addition, the fourth of this implementation
In the description of the embodiment, the same reference numerals are given to the components corresponding to the components of the third embodiment, and the detailed description is omitted. Also, in FIG. 10, the vapor separator tank is shown by a broken line.

FIG. 10 is a view corresponding to FIG. 9 of the third embodiment. In the fourth embodiment, the injector 56 is attached to the intake pipe 46 instead of the throttle body 41. . In addition, injector 5
In the third embodiment, the injection port No. 6 is a throttle valve 4
The second embodiment communicates with the intake passage 53 downstream of the throttle valve 42, but in the fourth embodiment, communicates with the upstream of the throttle valve 42. The injector 56 is connected to the inner surface of the throttle body 41 and the throttle valve. The fuel is injected toward a gap between the fuel cell and the fuel cell. This throttle body 4
In the gap between the inner surface of the throttle valve 1 and the throttle valve 42, the air flow is fast, so that the fuel injected from the injector 56 can be scattered efficiently. Further, the injection direction of the injector 56 does not face upward, and fuel or the like does not accumulate near the injection port of the injector 56.
Other points such as a point relating to the arrival time from the injection port of the injector 56 to the intake port 33 and a point relating to swirl are substantially the same as those in the first embodiment.

Next, the fifth embodiment of the outboard motor according to the present invention will be described.
The embodiment will be described. FIG. 11 is a schematic diagram of the flow of cooling water according to the fifth embodiment. In the description of the fifth embodiment, the same reference numerals are given to components corresponding to the components of the first embodiment, and a detailed description thereof will be omitted.

FIG. 11 is a view corresponding to FIG. 5 of the first embodiment. In the fifth embodiment, the V bank jacket 89 is divided into right and left by a partition wall 121.
A pair of left and right flow paths 89a and 89b are formed. Therefore, the left and right thermostats 93 can control the temperature of the cylinder 11 independently of each other. The pair of left and right flow paths 89a and 89b communicate with each other at an upper portion and a lower portion. In addition, this V bank jacket 89
When the pilot water channel 122 is connected and the cooling water is normally supplied, a small amount of water flows out from the end of the pilot water channel 122. As described above, the fact that the water is flowing out from the end of the pilot water channel 122 indicates that the cooling water is normally supplied. For example, if the cooling water pump 29 breaks down or a flow path such as the upward flow path 81 is clogged, the outflow from the pilot water path 122 stops, indicating that the supply of cooling water is abnormal.

Further, air vent passages 123a, 123b and water vent passages 124a, 124b, 124c are formed so that water can be drained from the cooling water passages 86, 87, 88, 89, 91 when the engine 9 is stopped. . The air vent passages 123a and 123b and the water vent passage 12
4a, 124b, 124c are cooling water passages 86, 87, 8
The cross section is smaller than 8, 89, 91.
The first air vent passage 123a communicates the upper part of the combustion chamber cooling water passage 88 with the upper part of the cylinder cooling water passage 91, and the second air vent passage 123b communicates with the combustion chamber cooling water passage 8
8 and the upper part of the cooling water passage 87 for the collective exhaust passage. The first drain passage 124a communicates the lower part of the combustion chamber cooling water passage 88 with the lower part of the cylinder cooling water passage 91, and the second water drain passage 124b communicates with the cylinder cooling water passage 9
The lower portion 1 communicates with the after-cooling water passage 96, and the third drain passage 124 c communicates the lower portion of the V bank jacket 89 with the upflow passage 81. An exhaust pipe cooling water passage 126 is connected to the upward flow passage 81, and the cooling water in the exhaust pipe cooling water passage 126 cools the exhaust pipe 127. The exhaust pipe 127 is provided in a vertical space formed at the center of the oil pan 128. The fifth embodiment is substantially the same as the first embodiment except for the cooling water passage.

The embodiment of the present invention has been described above in detail.
The present invention is not limited to the above embodiment,
Within the gist of the present invention described in the claims,
Various changes can be made. Modification examples of the present invention are exemplified below. (1) In the above embodiment, the engine is a V-type six-cylinder four-cycle engine, but the type, the number of cylinders, and the like can be changed as appropriate. For example, it may be an L-type engine.

(2) The relationship of the arrangement in the left-right direction can be reversed. (3) The material of the silencer 51 and the intake pipe 46 does not necessarily need to be resin, but may be formed by aluminum die casting or the like. (4) The drive mechanism is one of the right and left throttle valves 4
2 is directly connected to the valve shaft 2 and has a throttle cable 1
It is also possible that the driving force from 01 is transmitted to the valve shaft of the right or left throttle valve 42 and then transmitted to the valve shaft of the other throttle valve 42 via the interlocking mechanisms 66 and 67. .

[0047]

According to the present invention, the engine is cooled by the cooling water sucked from the lower part of the outboard motor, and the temperature of the lower part of the engine is lower than the temperature of the upper part of the engine. Therefore, the fuel injected from the injector has a lower diffusion efficiency in the lower intake passage than in the upper intake passage. However, on the downstream side of the injector, the distance between the injector and the intake port in the lower intake passage is longer than the distance between the injector and the intake port in the upper intake passage. The time to reach the mouth is longer in the lower intake passage. Therefore, the time during which the fuel is spreading is longer,
The amount of diffusion can be increased. As a result, the difference in the amount of diffusion due to the difference in temperature between the upper part and the lower part of the engine can be minimized. And the difference in combustion efficiency between cylinders can be made as small as possible.

When a throttle body is provided at an intermediate portion of the intake passage and an injector is attached to the throttle body, the injector and the throttle body can be unitized.
Engine assembly becomes easier.

Further, a pair of upper and lower intake ports may be formed for each combustion chamber. And, on the downstream side of the injector, the inclination of the lower intake passage is greater than the inclination of the upper intake passage, and the swirl of the combustion chamber communicating with the lower intake passage communicates with the upper intake passage. It becomes larger than the swirl of the combustion chamber, and the combustion efficiency can be improved. Due to this difference in swirl, the difference in combustion efficiency between cylinders due to the temperature difference between the upper and lower parts of the engine can be compensated as much as possible.

When the V-type engine is employed as the outboard motor, the upper ends of the left and right throttle shafts are connected and interlocked by an interlocking mechanism disposed above the engine case. In this case, an interlocking mechanism for interlocking the valve shafts of the left and right throttle valves is less likely to protrude laterally, and the lateral width of the cowling of the outboard motor can be minimized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an outboard motor according to the present invention as viewed from the side.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a plan sectional view of an upper portion of the outboard motor according to the first embodiment;

FIG. 4 is a plan view of the inside of the outboard motor according to the first embodiment;

FIG. 5 is a schematic diagram of a flow of cooling water.

FIG. 6 is an enlarged view of a main part of an intake passage.

FIG. 7 is a plan view of a drive mechanism of a throttle valve.
(A) is a diagram of the first embodiment, and (b) is a diagram of a modification.

FIG. 8 is a plan sectional view of an upper portion of an outboard motor according to a second embodiment.

FIG. 9 is a plan sectional view of an upper portion of an outboard motor according to a third embodiment.

FIG. 10 is a plan sectional view of an upper portion of an outboard motor according to a fourth embodiment.

FIG. 11 is a schematic diagram of a flow of cooling water according to a fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper cowling 2 Lower cowling 9 Engine 10 Crankshaft 11 Cylinder 11a Combustion chamber 22 Cylinder head 33 Intake port 41 Throttle body 42 Throttle valve 51 Silencer 53 Intake passage 56 Injector 66 Link (interlocking mechanism) 67 Rotating plate (interlocking mechanism)

Claims (4)

[Claims] In an outboard motor in which an engine is cooled by cooling water sucked from a lower portion and a cowling covers the engine, a crankshaft of the engine is disposed in an up-down direction, and a rear of the crankshaft is provided. A plurality of cylinders are vertically arranged, and the combustion chamber side of the cylinder is covered with a cylinder head. In the cylinder head, an intake port opened to the combustion chamber of the cylinder is formed for each combustion chamber, A silencer is provided at a front portion in the cowling, and an intake passage is provided for each combustion chamber between the silencer and an intake port of the cylinder head. Fuel is provided at an intermediate portion of the intake passage. The injector that injects is installed, and the lower intake passage is inclined downstream of the injector so that the upper intake passage is inclined. Is larger than the inclination of the passage, the distance between the injector and the intake port at the lower side of the intake passage, the outboard motor, characterized in that longer than the distance between the injector and the intake port in the upper of the intake passage. 2. A throttle body is provided at an intermediate portion of the intake passage, and an injector is attached to the throttle body.
Outboard motor as described. 3. The outboard motor according to claim 1, wherein a pair of upper and lower intake ports are formed for each combustion chamber. 4. An outboard motor in which an engine is cooled by cooling water sucked from a lower portion and a cowling covers the engine, wherein a crankshaft of the engine is arranged in a vertical direction, and , The cylinder is approximately V
The cylinders are arranged in the shape of a letter, and are arranged in a plurality in the vertical direction. The combustion chamber side of this cylinder is covered with a cylinder head, and the cylinder head has an intake port that opens to the combustion chamber of the cylinder. A silencer is provided at a front portion inside the cowling, and an intake passage is provided between the silencer and an intake port of a cylinder head for each combustion chamber. A throttle body is provided at an intermediate portion of the passage, and an injector for injecting fuel is attached to the throttle body. The throttle shaft of the throttle body of the throttle body is arranged vertically and the uppermost stage is provided. The valve shafts of the throttle valves protrude above the engine case, and the upper ends of the left and right throttle valve shafts are It is connected and interlocked by an interlocking mechanism that is located above the lower intake passage, and the inclination of the lower intake passage is greater than the inclination of the upper intake passage downstream of the throttle body. An outboard motor characterized in that a distance between an injector and an intake port in a side intake passage is longer than a distance between an injector and an intake port in an upper intake passage.