JPH1179085A - Suction passage structure for outboard motor engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To wastelessly and effectively use fuel by feeding the fuel spitted back and returned in engine operation to an engine mainbody again without being discharged into the air and stored in a surge tank and to prevent environmental pollution by preventing the discharge of the fuel to the outside. SOLUTION: In an outboard motor engine, suction pipes for cylinders arranged in parallel to the lateral direction are extended from a longitudinal surge tank arranged in front of an engine mainbody, in which the cylinders are arranged in the vertical direction so that crank axial lines can be in the vertical direction of a motor body and cylinder axial lines be in the longitudinal direction of the motorbody, to the cylinder heads at the rear side of the engine mainbody. A suction port 31a is open upward and sideways from the bottom of the surge tank 31 and the bottom of the surge tank 31 is smoothly continued with the bottoms of the suction pipes 32 at the lowest positions without forming drain holes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-cylinder engine mounted on an outboard motor of a small boat, and more particularly, to an intake passage structure from a surge tank to an intake pipe in such an outboard engine. About.

[0002]

2. Description of the Related Art With respect to a multi-cylinder engine mounted on an outboard motor of a small boat, the direction of the axis of the cylinder of each cylinder is generally set in the front-rear direction of the fuselage so that the crankcase side is forward and the cylinder head side is rearward. With the crankshaft common to each cylinder as the vertical direction of the fuselage, the cylinders of the engine main body are installed in the top cowling at the top of the outboard motor in a vertically installed state with the cylinders arranged vertically. From the vertical surge tank located on the front side of the
The intake pipe of each cylinder arranged at intervals in the vertical direction,
The carburetors extend in a substantially horizontal direction toward the cylinder head at the rear of the engine body so that the carburetor is installed in the middle.

[0003] In such an outboard motor engine, the fuel (gasoline) returned through each intake pipe by the blowback from the carburetor during operation of the engine is conventionally released to the atmosphere or It is designed to accumulate at the bottom of the surge tank, and if it accumulates at the bottom of the surge tank, a drain hole is formed on the bottom of the intake passage from the lower part of the surge tank to the intake pipe at the lowest position, It is practiced that the fuel thus returned and accumulated is discharged from the drain hole to the outside of the machine through a drain hose.

[0004]

By the way, in the conventional outboard motor engine as described above, the accumulated fuel returned by the blowback during the operation of the engine is discharged to the atmosphere or discharged from the drain hole. Since the fuel is discharged outside through the drain hose, not only fuel is wasted, but also the problem of environmental pollution is caused by dispersing the fuel around the outboard motor.

An object of the present invention is to solve the above-mentioned problems. More specifically, the present invention relates to an intake passage structure for an outboard motor engine, in which fuel returned by blow-back during engine operation is supplied to the atmosphere. By sending it back into the engine without discharging it into the tank or storing it in the surge tank, fuel can be used effectively without waste, and the fuel is not discharged outside the machine to prevent environmental pollution. It is possible to aim at.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, as described in claim 1, the crank axis is in the vertical direction of the fuselage and the cylinder axis is in the longitudinal direction of the fuselage. From the vertically long surge tank arranged in front of the engine main body in which the cylinders are arranged vertically so that the intake pipe of each cylinder arranged vertically at the rear of the engine main body is arranged at the rear of the engine main body. In an engine for an outboard motor that extends toward the cylinder head, an intake port is opened to the side above the bottom of the surge tank, and the bottom of the surge tank and the lowermost position The bottom portion of the intake pipe is formed so as to continue smoothly without having a drain hole.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an intake passage structure for an outboard motor engine according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an outboard motor on which an engine having an intake passage structure according to the present invention is mounted.
The upper cowl 2a, the bottom cowl 2b, and the air duct cover 2 are attached to the housing of the body in which the top cowling 2, the upper case 3, and the lower case 4 are connected.
The multi-cylinder engine 5 in which the cylinders are arranged in the vertical direction is installed in the top cowling 2 composed of the cylinders c and c so that the axis of the crankshaft 6 is in the vertical direction of the body.

A drive shaft 7 connected to the lower end of the crankshaft 6 of the engine 5 extends vertically through the upper case 3 to the lower case 4 and rotates the screw via a shift mechanism 8 using bevel gears. By being linked to the shaft 9, the screw 10 mounted on the lower rear side of the lower case 4 is configured to rotate by driving of the engine 5.

FIGS. 2 to 7 show the engine 5 installed in the top cowling 2 of the outboard motor 1 as described above. FIG. 2 is a view from the left side, and FIG. Is
4 is a view from the front, FIG. 5 is a view cut away from the rear, and FIG. 6 is an engine along the cylinder axis. FIG. 7 is a top view of a cross section of the main body and a cross section of the intake passage viewed from above, and FIG. 7 is a top view of a cross section of the engine body and a cross section of the intake passage along the cylinder partition wall.

The engine 5 is a four-stroke, four-cylinder engine in which the cylinders are arranged in a longitudinal direction. The engine 5 has a head cover 11, a cylinder head 12, a cylinder block 13, and a crankcase 14 which are sequentially integrated along the longitudinal direction of the hull. The main body portion is formed by such connection, and the crankcase 14 is arranged so as to be on the front side, and the head cover 11 is arranged so as to be on the rear side.

An intake port 15 for each cylinder is formed on the left side of the cylinder head 12 so as to overlap with an interval in the vertical direction, and on the right side of the cylinder head 12 so as to overlap with an interval in the vertical direction. An exhaust port 16 is formed for each cylinder, and an intake valve 17 is provided for each intake port 15 and an exhaust valve 18 is provided for each exhaust port.

An intake camshaft 19 and an exhaust camshaft 20 for driving the intake valve 17 and the exhaust valve 18 of each cylinder are respectively connected to the cylinder head 12 in a cam chamber 21 covered by the head cover 11. In the state of being sandwiched by the cam caps 22, they are pivotally supported so that the rotation axis direction is up and down, and cam pulleys 23 and 24 are fixed to the upper ends of the cam shafts 19 and 20, respectively. .

Cylinder block 13 and crankcase 1
A crankshaft 6 common to each cylinder is rotatably supported in a crank chamber 25 defined by the crankshaft 4 such that a rotation axis direction is a vertical direction. Is fixed, and extends over the timing pulley 27 and each of the cam pulleys 23 and 24 fixed below the flywheel 26 of the crankshaft 6.
A timing belt 28 for transmitting the rotation of the crankshaft 6 to each of the camshafts 19 and 20 is stretched.

Incidentally, for the timing belt 28,
Although not shown, a tensioner is provided to prevent the slack of the timing belt 28 by constantly biasing the timing belt 28 inward, and the flywheel 26, the cam pulleys 23 and 24, the timing belt 28, and the like are provided. A cover member 29 is further provided inside the top cowling 2 so as to cover from above.

A surge tank 3 serving as an air introduction portion of an intake passage is provided forward of the crankcase 14 of the engine body.
1 is installed, and a vertically formed surge tank 3
1, a vertically long intake port 31a is opened to the right at a position slightly above the bottom of the surge tank 31. From the rear left side of the surge tank 31, it passes through the left side of the engine body and Four intake pipes 32 arranged in parallel in the horizontal direction at an interval in the vertical direction toward each intake port 15 opened on the left side face are respectively arranged in a substantially horizontal direction so as to overlap when viewed from above. Has been extended.

Each intake pipe 32 extending from the surge tank 31
Are connected to the intake upstream side of the carburetors 33, respectively. The intake downstream side of each carburetor 33 is connected to the four short curved intake pipes extending from the carburetor 33 to the intake port 15 in the vertical direction. Are connected to the respective intake ports 15 of the cylinder head 12 by an intake manifold 34 connected in parallel with a gap therebetween, so that the intake port 31 of the surge tank 31 is
The intake passage of each cylinder is formed from a to the combustion chamber 35 from the intake port 15 to the combustion chamber 35 through the intake pipe 32, the carburetor 33, and the intake manifold 34.

In the present embodiment, as shown in FIG. 8, the portion between the surge tank 31 and each intake pipe 32 extends from the surge tank 31 to a part (upstream portion) of each intake pipe 32 along the center line of the intake passage. The two members are separately and integrally formed of a synthetic resin so as to be divided into right and left along a (center line in the width direction viewed from above), and then the members are joined together. The bottom of the surge tank 31 and the intake pipe 3 at the lowest position
As shown in FIG. 9, the bottom portion of each of the intake pipes 32 is formed so as to continue smoothly without having a drain hole, and is a cylindrical portion integrally formed with one of the members. Are integrally connected at their ends at intervals in the vertical direction.

As shown in FIG. 9, the surge tank 31 and the intake pipes 32 integrally connected as described above are
Furthermore, each carburetor 33 and intake manifold 34
And the intake passages of the respective cylinders from the surge tank 31 to the intake manifold 34 are integrally assembled as a single unit in advance, and such a unit is mounted on the left side of the engine body. Becomes

At this time, the procedure for mounting the unit is as follows. First, the unit is suspended and moved by the hanger portion 32a integrally formed with the intake pipe 32 at the uppermost position so as to approach the engine body. Positioning is performed with respect to the engine body by positioning pins 51 (and correspondingly, pin holes formed at each position of the cylinder head 12) fixed at respective positions near the upper end and the lower end of the base of the base 34. After that, the bolt 52 at the mounting portion located at the base of the intake manifold 34, and the bolt 53 at the mounting portion located between the intake pipes 32 near the surge tank 31, respectively, to the engine body. It will stick.

As shown in FIGS. 8 and 9, the uppermost intake pipe 32 includes a hanger portion 32a as well as a hanger portion 32a.
Code guide portions 32b, 3 provided with holes for code guidance
2c are integrally formed, and the hanger portion 32a is located near and above the center of gravity of the entire unit, and is integrated with one cord guide portion 32b.
After the unit is attached to the engine body, the hanger portion 32a itself can be used as a cord guide.

On the other hand, on the right side of the cylinder head 12, exhaust ports 16 of each cylinder are formed at an interval in the vertical direction so that one end is opened in the combustion chamber 35 of each cylinder. An exhaust passage 36 for collecting the exhaust gas at the other end of the port 16 and discharging the exhaust gas below the engine body is integrated with the cylinder block 13 on the right side of each cylinder hole 37. The exhaust passage 36 which is formed in the cylinder block 13 and extends vertically in the cylinder block 13 has an exhaust guide 41
Connected to the exhaust passage.

On the left side (intake side) of the engine body opposite to the exhaust passage 36, as shown in FIG. 7, from the cylinder block 13 to the cylinder head 12 at the positions of the partition walls of the vertically adjacent cylinders. Over, crankcase 2
5 and the cam chamber 21 so as to communicate with each other.
8, 39 are formed.

A blow-by hose 43 for returning blow-by gas to the intake passage is provided from a blow-by chamber 42 provided on the exhaust side of the head cover 11 so as to communicate with the cam chamber 21 on the right side of the engine body. The end of the blow-by hose 43 is connected from above to the upper end of a vertically long intake port 31 a opened to the side of the surge tank 31.

Thus, the combustion chamber 35 is moved from the crank chamber 2
The blow-by gas leaked to the side 5 passes through the blow-by gas passages 38 and 39 formed on the intake side of the cylinder block 13 and the cylinder head 12 of the engine body, and flows through the cam chamber 21 from the intake side to the exhaust side. Is returned from above from the blow-by chamber 42 to the upper end of the intake port 31a of the surge tank 31 through the blow-by hose 43.

In the engine 5, two fuel pumps 44 for pumping fuel to each of the carburetors 33 are vertically arranged in the head cover 11 on the intake side in a vertical direction. A control unit 46 and a rectifier regulator 47 are installed on the front surface of the unit with its front side (between the surge tank 31) covered by a cover member 45, and the side on which the intake pipe 32 and the carburetor 33 are installed. Is the other side (right side)
In addition, a starter motor 48 and an oil filter 49 are provided.

As described above, the surge tank 31 having the intake port 31a serving as an air introduction portion of the intake passage is connected to the intake passage of the engine 5 for an outboard motor as described above. It is located forward of the case 14, which makes the intake pipe 32 relatively long compared to one in which the surge tank is located on the front side of the crankcase.

A vertically long surge tank 31 is also provided.
Has a suction port 31a opened to the side above the bottom thereof, and the bottom of the surge tank 31 and the bottom of the suction pipe 32 at the lowest position are provided with a fuel reservoir, a drain hole, and the like. It is formed so as to continue smoothly without any.

According to the outboard motor engine 5 of the present embodiment having the above-described intake passage structure, even if fuel (gasoline) is blown back from the carburetor 33 during operation of the engine, the surge tank 31 is moved forward. And the intake pipes 32 are relatively long, so that the fuel is rarely returned to the surge tank 31.

Even if the fuel is returned from each intake pipe 32 to the surge tank 31, it is unlikely that the fuel leaks directly into the atmosphere from the intake port 31 a of the surge tank 31. Along the bottom of the lowermost intake pipe 32, which continues in a smoother,
Most of the air is sucked into the intake pipe 32 at the lowest position,
The fuel is sent to the combustion chamber 35 of the lowermost cylinder and burned, so that it does not accumulate at the bottom of the surge tank 31 and is discharged from the drain hole to the outside of the machine.

[0031]

According to the intake passage structure for an outboard motor engine of the present invention as described above, the fuel returned by the blowback during engine operation is not released into the atmosphere or stored in the surge tank. The fuel can be sent to the engine body again effectively, and the fuel can be effectively used without waste. In addition, the fuel can be prevented from being discharged outside the machine, thereby preventing environmental pollution.

[Brief description of the drawings]

FIG. 1 is a left side view schematically showing an outboard motor on which an engine having an intake passage structure of the present invention is mounted.

FIG. 2 is a side view showing the engine housed in the top cowling of the outboard motor shown in FIG. 1 as viewed from the left side.

FIG. 3 is a side view of the engine shown in FIG. 2 as viewed from the right side.

FIG. 4 is a front view of the engine shown in FIG. 2 as viewed from the front.

FIG. 5 is a partially cutaway rear view of the engine shown in FIG. 2 as viewed from the rear.

FIG. 6 is a partial cross-sectional top view showing a cross section of the engine main body and a cross section of an intake passage along a cylinder axis of the engine shown in FIG. 2;

7 is a partial cross-sectional top view showing a cross section of an engine body and a cross section of an intake passage along a cylinder partition wall of the engine shown in FIG. 2;

FIG. 8 is a partially cutaway top view showing an intake passage unit attached to the engine shown in FIG. 2;

FIG. 9 is a partially cutaway side view of the unit of the intake passage shown in FIG. 8;

[Explanation of symbols]

 Reference Signs List 1 outboard motor 5 engine 6 crankshaft 11 head cover (engine body) 12 cylinder head (engine body) 13 cylinder block (engine body) 14 crankcase (engine body) 31 surge tank 31a intake port 32 intake pipe

Claims (1)

[Claims] An engine body in which cylinders are vertically arranged such that a crank axis is in a vertical direction of the body and a cylinder axis is in a longitudinal direction of the body. In an engine for an outboard motor in which the intake pipes of the cylinders that are spaced apart in the direction are respectively extended toward the cylinder head at the rear of the engine body, the side is located above the bottom of the surge tank. An outboard opening, and the bottom of the surge tank and the bottom of the lowest intake pipe are formed so as to continue smoothly without having a drain hole. Engine intake passage structure.