JP2002147306A - Fuel supply system for four-cycle engine for outboard motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel supply system for a four-cycle engine for an outboard motor having high degree of freedom on the arranging position of a high-pressure fuel pump and capable of miniaturizing an outboard motor by reducing a necessary arranging space. SOLUTION: This fuel supply system is used for a four-cycle engine for an outboard motor mounted on a hull by directing a crankshaft 8 in the longitudinal direction. A vapor separator tank 25 and the high-pressure pump 21 for fuel injection are so disposed as to establish a height relationship allowing the fuel in the vapor separator tank 25 to be fed to the high-pressure fuel pump by gravitation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for a four-stroke engine for an outboard motor, and more particularly to a fuel supply system suitable for a so-called four-cycle direct injection engine configured to directly inject and supply fuel into a combustion chamber. Related to the device.

[0002]

2. Description of the Related Art An outboard motor is generally mounted on a hull with a crankshaft directed vertically and a cylinder head directed rearward in the longitudinal direction of the hull. As this type of engine for an outboard motor, it has been considered to employ a so-called direct injection engine configured to directly inject and supply fuel into a combustion chamber.

[0003]

In the direct injection engine, a high-pressure fuel pump for supplying high-pressure fuel to the fuel injection valve is required. A high-pressure fuel pump is arranged at the upper end of the shaft, and the pump is driven by the upper end of the crankshaft. Therefore, the degree of freedom in the arrangement position of the high-pressure fuel pump is low, and a low-pressure fuel pump for supplying fuel to the high-pressure fuel pump is required. It is feared that it will be an obstacle to planning.

The present invention has been made in view of the above-mentioned conventional problems, and has a high degree of freedom in the arrangement position of a high-pressure fuel pump, and also requires a small arrangement space to reduce the size of an outboard motor. It is an object of the present invention to provide a fuel supply device for a four-stroke engine for an outboard motor that can perform the above-described operation.

[0005]

According to a first aspect of the present invention, there is provided a fuel supply device for a four-stroke engine for an outboard motor mounted on a hull with a crankshaft directed in a vertical direction. The pump and the pump are arranged so that the fuel in the vapor separator tank has a height relationship capable of being supplied to the high-pressure fuel pump by gravity.

According to a second aspect of the present invention, in the first aspect, the high-pressure fuel pump is disposed so as to be driven by a lower portion of a camshaft provided in parallel with the crankshaft, and the vapor separator tank is provided with It is disposed so that the bottom of the tank is located higher than the suction port of the high-pressure pump,
The fuel cell system is characterized in that the bottom of the vapor separator tank and the suction port of the high-pressure pump are connected by a fuel supply passage.

[0007]

According to the first aspect of the present invention, the vapor separator tank and the fuel injection high-pressure pump are in a height relationship such that the fuel in the vapor separator tank can be supplied to the high-pressure fuel pump by gravity. This arrangement eliminates the need for a low-pressure pump to supply the fuel in the vapor separator tank to the high-pressure fuel pump.Thus, the vapor separator tank can be downsized, the outboard motor can be downsized accordingly, and the fuel supply can be reduced. The system can be simplified and costs can be reduced.

According to the second aspect of the present invention, the high-pressure fuel pump is disposed so as to be driven by a lower portion of a camshaft disposed in parallel with the crankshaft, that is, the camshaft is disposed in a vertical direction. Since the structure unique to the outboard motor is used, it is easy to dispose the vapor separator tank such that the bottom surface of the tank is located higher than the suction port of the high-pressure pump. A specific structure for supplying the fuel in the tank to the high-pressure pump by gravity can be realized.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 to 5 are views for explaining a fuel supply device for a four-stroke engine for an outboard motor according to one embodiment of the present invention. FIG. Is a cross-sectional plan view of the engine, FIG. 3 is a bottom view of the cylinder head seen from the cylinder block side,
FIG. 4 is a side view of the cylinder head, and FIG. 5 is a plan view of the cylinder head as viewed from the head cover side. The terms front, rear, left, and right in the present embodiment mean front, rear, left, and right, respectively, in a state of facing the front side in the hull longitudinal direction.

In FIG. 1, reference numeral 1 denotes a four-cycle V-type six-cylinder engine for an outboard motor. It is mounted to be able to swing between. A crankcase 3 is connected to a front mating surface a of a cylinder block 2 of the engine 1, and a cylinder head 4 is connected to a rear mating surface b.
The cam chamber side opening of the cylinder head 4 is covered with a head cover 5. In the engine, the head cover 5 and the cylinder head 4 face rearward in the hull longitudinal direction when the engine is in the traveling state.

The head cover 5 is made of an aluminum alloy casting in which an intake-side cover 5a and an exhaust-side cover 5b, which are substantially cup-shaped in cross section and extend in the direction of the crankshaft 8, are integrally connected at a middle part and a lower end in the longitudinal direction. Things.

In the cylinder block 2, left and right cylinders (cylinder bores) 2a and 2b are formed such that their axes form a V bank having a sandwich angle of 60 degrees and are deviated in the direction of the crankshaft 8. Have been. The left and right cylinders 2a,
2b are formed of three sets each of which includes a left bank A by a left cylinder block 2, a left cylinder head 4, and a left head cover 5 composed of the three sets of left cylinders 2a, and the three sets of right cylinders 2b. A right bank B is formed by a right cylinder block 2, a right cylinder head 4, and a right head cover 5 each composed of:

In this embodiment, the right cylinder 2b on the right bank B side is displaced above the left cylinder 2a on the left bank A side. A piston 6 slidably inserted into each of the cylinders 2a and 2b is connected to a crank pin 8a of a crank shaft 8 by a connecting rod 7.

A combustion recess 4a, which forms a combustion chamber with the cylinder and piston, is formed in the cylinder head 4 on the side of the cylinder block 2 facing the cylinder head 4. The combustion recess 4a is formed with two intake valve openings 4b, 4b per cylinder and exhaust valve openings 4c, 4c smaller in diameter than the intake valve openings. An ignition plug 9 is screwed into the center of the cylinder of the combustion recess 4a, and the electrode 9a is exposed inside the combustion recess 4a.

The exhaust valve openings 4c, 4c are connected to the exhaust port 4
The exhaust gas is discharged into the V bank by d, and communicates with the exhaust manifold 4e of each bank so as to be collected. The exhaust gas is discharged into the water below the engine by the exhaust manifold 4e. 4f is an exhaust manifold 4e
Is a jacket cover that forms a water-cooled jacket 4g on the back side.

The intake valve openings 4b, 4b are respectively led out to the side wall of the cylinder head 4 by independent intake ports 4h, 4h, and the intake manifolds are connected to the external connection openings 4i, 4i of the intake ports 4h, 4h. Ten branch portions 10a, 10a are connected. The intake manifold 10 is made of an aluminum alloy casting in which three forked junctions 10b branched into the branch portions 10a, 10a are integrally formed.

Each junction 10 of the intake manifold 10
A throttle body 11 having a built-in throttle valve (not shown) is connected upstream of the throttle body b. An intake silencer 12 having a predetermined volume is provided upstream of the throttle body.
Is connected.

In this manner, as shown in FIG. 2, each branch 1 of the intake port 4h and the intake manifold 10 is provided.
0a, a bent portion 13a bent forward of the hull is formed from the intake valve opening 4a so as to form a substantially arcuate shape. Is configured.

The adjacent bent portion 13a of the intake passage 13
A fuel injection valve 14 that injects and supplies fuel into the combustion chamber is interposed between them. More specifically, a valve mounting hole 4j is formed in a portion between the upper and lower intake ports 4h, 4h constituting a part of the bent portion 13a in each cylinder of the cylinder head 4, and the valve mounting hole 4j is formed. A nozzle hole 4k is formed to penetrate from the bottom surface so as to communicate with the combustion recess 4a.

The fuel injection valve 14 is inserted into the valve mounting hole 4j. When viewed in the direction of the crankshaft 8, the fuel injection valve 14 is disposed so as to extend obliquely outward at the center between the bent portions 13a such that the axis c thereof obliquely intersects the cylinder axis d. I have. The injection nozzle 14a of the fuel injection valve 14 faces the inner surface of the combustion recess 4a, and the fuel inlet 14b is located outside the bent portion 13a.

Further, a cylindrical fuel supply rail 15 is provided so as to face the direction of the crankshaft 8 and to be located outside the bent portion 13a. As shown in FIG. 2, the fuel supply rail 15 is disposed so as to pass through a concave portion D formed by a front bent portion 13a having an intake passage shape peculiar to an outboard motor and a side wall of the cylinder head 4. Have been.

The fuel supply rail 15 is formed so that three fuel supply ports 15a are branched, and each fuel supply port 15a is connected to each fuel introduction port 14 of the fuel injection valve 14.
b.

The exhaust valve 16 and the intake valve 17 for opening and closing the exhaust valve opening 4c and the intake valve opening 4b are arranged so that their axes obliquely intersect with the cylinder axis d.
6, the intake valve 17 is opened and closed by an exhaust camshaft 18 and an intake camshaft 19 arranged in parallel with the crankshaft 8. The camshafts 18 and 19 are arranged on the mating surface of the cylinder head 4 on the cover side, and are rotatably supported by a cam cap 20.

A high pressure pump 21 for fuel injection is provided under the intake side cover 5a of the left head cover 5 on the left bank A side.
Is inserted from the outside toward the inside, and the intake side cover 5a
Is fixed to the mounting seat 5c. A plunger drive pin 21 a at the tip of the high-pressure pump 21 is in sliding contact with a pump drive cam nose 19 a of the intake cam shaft 19.

Here, the high-pressure pump 21 is arranged at a height of about 1/3 of the lower side when viewed in the height direction of the engine 1. The pump drive cam nose 19a is formed between a lower cylinder and an adjacent cylinder so as to correspond to the position of the high-pressure pump 21. Since the camshaft is arranged in the vertical direction in this way, the high-pressure pump 21 can freely set the height position within the range of the camshaft length, and is arranged below the cam nose for the lower cylinder. It is also possible.

In the high-pressure pump 21, the pump axis e is orthogonal to the axis f of the intake camshaft 19 when viewed in the direction of the crankshaft 8, ie, the intake camshaft 19, and the center side of the V bank of the engine 1 It is arranged so as to be inclined toward.

The high-pressure pump 19 and the fuel injection valve 14 are arranged so that their axes e and c form a triangle with the cylinder axis d. In this case, it is desirable to tilt the high-pressure pump 19 toward the center of the V bank so that the angle between the axis e and the cylinder axis d is as large as possible. By doing this,
The projecting amount of the high-pressure pump 19 to the rear of the engine can be reduced.

A gas-liquid separation chamber (not shown) is formed at the upper end of the intake side cover 5a of the head cover 5 on the right bank B side. In the present embodiment, the right bank B side is deviated so as to be located higher than the left bank A side. Therefore, the gas-liquid separation chamber is located at the highest point when viewed as a whole camshaft arrangement chamber. I have. With this configuration, the oil mist in the blow-by gas can be more reliably separated, and the oil mist can be prevented from being discharged to the atmosphere.

The fuel system 22 for supplying the fuel to the fuel injection valve 14 is configured as follows, mainly as shown in FIG. A fuel filter 23, a fuel supply low-pressure pump 24, and a vapor separator tank 25 are attached to a front portion of the side wall of the engine 1, and these are connected to each other by a fuel supply low-pressure hose 26. The fuel filter 23 is disposed below the side wall, the vapor separator tank 25 is disposed above the side wall, and the low pressure pump 24 is disposed near the bottom wall of the vapor separator tank 25. The vapor separator tank 25 separates vapor (bubbles) mixed in the fuel, and the separated vapor is introduced into the intake passage from a top wall of the vapor separator tank 25 via a vapor hose (not shown). Is burned.

The fuel outlet 25a on the bottom wall of the vapor separator tank 25 is connected to a fuel inlet 21d of the high-pressure pump 21 by a fuel hose 27.
Here, the height relationship between the vapor separator tank 25 and the high-pressure pump 21 is set so that a head difference (water head) H is generated between the fuel outlet 25a and the fuel inlet 21d. Thereby, the fuel in the vapor separator tank 25 is supplied to the high-pressure pump 21 by gravity.

In the fuel system 22, the fuel in the fuel tank mounted on the hull is supplied to the vapor separator tank 25 by the low pressure pump 24 through the low pressure hose 26 and the fuel filter 23. When the fuel level in the vapor separator tank 25 reaches a predetermined level, the fuel discharged from the low-pressure pump 24 returns to the return hose 24.
The liquid is returned to the suction port of the low-pressure pump 24 via a.

The fuel in the vapor separator tank 25 is supplied by gravity to the high-pressure pump 21 via a fuel hose 27, and the fuel pressurized by the high-pressure pump 21 is supplied from a discharge port 21e to a high-pressure hose 28 and left and right sides. The left and right fuel rails 1 are connected via branch hoses 28a and 28b.
5, 15 are supplied to the lower end. Then, while the injection nozzle 14a of the fuel injection valve 14 is open, the fuel is directly injected and supplied into the combustion chamber.

The high-pressure pump 21 has first and second return ports 21b and 21c for adjusting the discharge pressure and the flow rate. The first return port 21b is connected to the vapor separator tank 25 by a first return hose 30 routed along the left side wall of the engine 1.
Specifically, the first return hose 30 rises upward from the first return port 21b, extends forward over the engine, extends downward on the front side of the vapor separator tank 25 and the low-pressure pump 24, and further extends. The fuel gas passes through the vicinity of the lower end of the engine 1 and is connected to the return port 25b of the vapor separator tank 25.

A regulator 31 for adjusting pressure is connected to the upper end of the fuel supply rail 15, and a return passage 31a of the regulator 31 is connected to the middle of the first return hose 30 (FIG. 2). Not shown). When the pressure in the fuel supply rail 15 exceeds a set value, the regulator 31 opens, and excess fuel is supplied to the return passage 31a.
Is returned to the return port 25b of the vapor separator tank 25 via the first return hose 30.

The second return port 21c is connected to the engine 1
Is connected to the vapor separator tank 25 by a second return hose 29 routed along the left side wall of the tank. Specifically, the second return hose 20 rises obliquely forward and upward from the second return port 21c to the outside of the intake passage 13 through the lower part of the engine, and returns to the return port 25c of the top wall of the vapor separator tank 25. Is connected to the

Next, the operation and effects of the present embodiment will be described. In the engine 1 of this embodiment, in the fuel system 22, the fuel in the fuel tank mounted on the hull side is supplied to the vapor separator tank 25 by the low pressure pump 24 via the low pressure hose 26 and the fuel filter 23. . Since there is a head difference H between the fuel outlet 25a of the vapor separator tank 25 and the fuel inlet 21d of the high-pressure pump 21, the vapor separator tank 2
The fuel in 5 is supplied to the high-pressure pump 21 through the fuel hose 27 by gravity. The fuel pressurized by the high-pressure pump 21 is supplied through the high-pressure hose 28 to the fuel rail 15.
Supplied to Then, while the injection nozzle 14a of the fuel injection valve 14 is open, the fuel is directly injected and supplied into the combustion chamber.

As described above, in the fuel supply system 22 of the present embodiment, the structure unique to the four-stroke engine for the outboard motor is effectively used, so that the head difference H between the vapor separator tank 25 and the high-pressure pump 21 is obtained. It was able to be arranged so that it could be. That is, the four-stroke engine for an outboard motor is mounted on the hull with the crankshaft directed vertically, and the camshaft is also directed vertically. The pump driving cam nose 19a is provided below the vertically arranged intake cam shaft 19, thereby driving the high-pressure pump 21, so that the high-pressure pump 21 can be driven without complicating its driving mechanism. The vapor separator tank 25 can be placed in a low place.
And a head difference can be secured.

Since the height relationship between the vapor separator tank 25 and the high-pressure pump 21 can be set as described above, the fuel in the vapor separator tank 25 can be supplied to the high-pressure pump 21 by gravity.
Therefore, a relay pump for sending fuel to the high-pressure pump 21 is not required, so that the fuel supply system can be simplified and the cost can be reduced.

Further, since the relay pump, which is conventionally disposed in the vapor separator tank, is not required, the vapor separator tank 25 can be reduced in size, and the entire outboard motor can be reduced in size accordingly.

In the present embodiment, the fuel injection valve 14 and the fuel supply rail 1
5, the arrangement of these parts does not increase the engine width, and the direct fuel injection system can be realized with almost no increase in the engine mounting space.

That is, the fuel injection valve 14 is connected between the adjacent front bent portions 13a of the intake passage 13, more specifically, between the branch portions 10a, 10a of each cylinder.
4h, and the fuel inlet 14b is positioned outside the bent portion 13a.
b, the supply port 15a of the fuel supply rail 15 disposed outside the bent portion 13a was fitted and connected.
The fuel supply rail 15 is connected to the front bent portion 13 of the intake passage 13.
a and the cylinder head side wall can be positioned in the recess D, so that an increase in the engine width can be avoided.

In addition, a gas-liquid separation chamber is provided at the upper end of the intake side cam chamber 5a of the right bank (high-side bank) B in which the cylinder is deviated to the high side, and the cylinder is deviated to the low side. Since the fuel injection high-pressure pump 21 is driven by the intake camshaft 19 of the left bank (lower bank) A, a space for disposing the high-pressure pump 21 can be easily secured while providing a gas-liquid separation chamber.

Further, since the high-pressure pump 21 is attached to the intake-side head cover 5a so as to be driven by the intake camshaft 19 disposed outside the bank, and is inclined toward the bank center (right bank side), The pump 21 does not protrude in the width direction of the engine, and it is possible to prevent the pump 21 from protruding rearward of the engine.

In the above embodiment, the case of a V-type engine has been described, but the present invention can be applied to an in-line engine.

[Brief description of the drawings]

FIG. 1 is a side view of a fuel supply device for an outboard V-type engine according to an embodiment of the present invention.

FIG. 2 is a sectional plan view of the engine of the embodiment.

FIG. 3 is a bottom view of a cylinder head of the engine of the embodiment.

FIG. 4 is a view of the cylinder head of the engine of the embodiment as viewed from a cylinder block side.

FIG. 5 is a view of the cylinder head of the engine of the embodiment as viewed from a head cover side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outboard engine 8 Crankshaft 19 Intake camshaft 21 High-pressure pump 21d for fuel injection 21d Suction port 22 Fuel supply system (fuel supply device) 25 Vapor separator tank 25a Fuel outlet 27 Fuel hose (fuel supply passage)

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Claims (2)

[Claims] 1. A fuel supply system for an outboard motor with a four-stroke engine mounted on a hull with a crankshaft oriented vertically, wherein a vapor separator tank and a high-pressure fuel injection pump are connected to each other in the fuel tank. A fuel supply device for an outboard motor, comprising: 2. The fuel pump according to claim 1, wherein the high-pressure fuel pump is disposed so as to be driven by a lower portion of a camshaft disposed in parallel with the crankshaft. An outboard motor, which is disposed so as to be located higher than the suction port of the high-pressure pump, and wherein the bottom of the vapor separator tank and the suction port of the high-pressure pump are connected by a fuel supply passage. 4 cycle engine.