JP2002155821A - Outboard engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an outboard engine that facilitates attachment and detachment of a fuel pump to and from an engine case and improves the assembly performance and maintenance performance of an engine. SOLUTION: A crankshaft 6 is vertically arranged, and a piston 37 is horizontally reciprocated in a cylinder bore 27, so that the crankshaft 6 converts the reciprocation of the piston 37 into rotation and transmits it to a propeller via a driveshaft to drive the propeller rotatively. The fuel pump 50 for supplying fuel to a fuel supply device is fixed to the engine case 23 at a height crossed by the horizontal centerline C of the cylinder bore 27. The lower end and upper end of a shaft 40 disposed parallel to the crankshaft 6 of the engine 3 are journaled respectively to a crankcase 23a and a cylinder block 23b. An eccentric cam 40c formed on the shaft 40 drives the fuel pump to deliver fuel from a fuel tank to the fuel supply device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outboard motor used for ship propulsion.

[0002]

2. Description of the Related Art Many outboard motor engines are mounted vertically on an outboard motor such that its crankshaft is oriented vertically, and the rotation of the crankshaft is carried out via a drive shaft extending long downward. The power is transmitted to a propeller for propulsion provided at the bottom of the outer unit.

[0003] When the engine is a four-stroke engine, a camshaft for driving a valve train is supported inside the engine. In many cases, pumps such as a fuel pump and an oil pump are driven by the camshaft. For example, in the outboard motor described in Japanese Patent Publication No. 3-3904, the fuel pump is driven by an eccentric cam provided near the lower end of the camshaft.

[0004]

However, since the rotation speed of the camshaft is set to half of the rotation speed of the crankshaft, driving the fuel pump with the camshaft rotating so slowly requires the capacity of the fuel pump. Need to be larger,
This leads to an increase in the size of the fuel pump and, consequently, the size of the engine.

On the other hand, if the fuel pump is directly driven by the crankshaft, the driving rotation speed of the fuel pump is increased and the size of the fuel pump can be reduced. However, the drive shaft is connected to the lower end of the crankshaft. Since a flywheel magneto device and starting device are provided at the upper end, it is necessary to provide a special gear device etc. in the middle of the crankshaft to extract the rotation of the crankshaft. This leads to shape and structural complexity.

The present invention has been made in view of the above-mentioned circumstances, and provides an outboard motor in which a fuel pump can be easily attached to and detached from an engine case, and the assembling and maintenance of the engine can be improved. The purpose is to:

It is another object of the present invention to provide an outboard motor which improves the space efficiency of the arrangement of the outboard motor in an engine room.

[0008]

An outboard motor according to the present invention comprises:
In order to solve the above-mentioned problem, as described in claim 1, the piston is reciprocated horizontally in the cylinder bore with the crankshaft being oriented vertically so that the crankshaft is oriented vertically, and the reciprocating motion of the piston is performed by the crankshaft. Is transmitted to a propeller via a drive shaft and transmitted to a propeller to rotate the propeller. The outboard motor covers the engine with an engine cover and has an air intake port in the engine cover. And a four-stroke engine in which a fuel supply device that mixes outside air taken in from the air intake with fuel and supplies the fuel and a fuel pump that supplies fuel to the fuel supply device is disposed in the engine cover. In the mounted outboard motor, the fuel pump is fixed to the engine case at a height at which the horizontal center line C of the cylinder bore crosses. Furthermore the lower end crank case side of the axis being arranged parallel to the crankshaft of the engine and its upper end is respectively pivotally supported on the cylinder block side, by driving the fuel pump with an eccentric cam formed on the shaft,
The fuel from the fuel tank is discharged to the fuel supply device.

According to another aspect of the present invention, there is provided an outboard motor parallel to a crankshaft when the outboard motor is viewed from above in a vertical direction. Is arranged near the center of the engine cover and on one side of the crankshaft.

[0010]

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

FIG. 1 is a right side view showing an example of an outboard motor according to the present invention. FIG. 2 is a longitudinal sectional view of an engine portion of the outboard motor, and FIG. 3 is a transverse sectional view taken along the line III-III of FIG. FIG. 4 shows an embodiment of the present invention in a longitudinal sectional view along the line IV-IV in FIG.

The outboard motor 1 has a box-shaped engine cover 2 at the top, and an engine 3 is housed inside. A steering handle 4 extends forward from the front of the engine cover 2 and has an engine 3
The throttle grip 5 for adjusting the output is provided. The engine 3 is mounted vertically so that its crankshaft 6 is oriented vertically.

A drive housing 7 is connected to a lower portion of the engine cover 2, and a gear housing 8 is provided below the drive housing 7. A propeller shaft 10 is rotatably supported inside the gear housing 8.
A propeller 11 is provided at the rear end.

On the other hand, a drive shaft 12 extending vertically downward from the lower end of the crankshaft 6 of the engine 3 is supported in the drive housing 7, and the lower end of the drive shaft 12 is constituted by a bevel gear or the like. It is operatively connected to the propeller shaft 10 via 13 and is linked.

The output of the engine 3 is transmitted to the propeller shaft 10 via the drive shaft 12 and the forward / reverse switching device 13,
The switching operation of the forward / reverse switching device 13 causes the propeller shaft 10
In addition, the direction of rotation of the propeller 11 can be switched or shifted to neutral.

The upper portion of the drive housing 7 is rotatably supported by a rotation support portion 16 of a clamp bracket 15, and the clamp bracket 15 is attached to a ship (hull) 17.
Is fixed to a transom (stern portion) 18 of the stern. Therefore, the outboard motor 1 is provided so as to be rotatable 360 ° with respect to the hull 17, and by turning the steering handle 4, it is possible to change the direction of the entire outboard motor 1 and steer the hull 17.

The engine cover 2 has a structure in which a synthetic resin upper cover 2b is detachably mounted on a metal lower cover 2a with a sealing member 19 interposed therebetween. The engine 3 is fixed on the top. Note that the steering handle 4 is provided integrally with the lower cover 2a, and a waterproof cover 21 which also serves as an air intake 20 and also serves as a handle is provided at the rear upper portion of the upper cover 2b.

The engine 3 is a single-cylinder engine of, for example, a four-cycle OHV type, and is configured as follows.

First, the lower cover 2 of the engine cover 2
The engine case 23 is fixed on a. The engine case 23 is configured by joining a lower crankcase 23a and an upper cylinder block 23b. A cylindrical cylinder sleeve 24 extending horizontally rearward is formed integrally with the cylinder block 23b, and a cylinder head 25 and a head cover 26 are fixed to the rear end of the cylinder sleeve 24.

A cylinder bore 27 is formed inside the cylinder sleeve 24, and a combustion chamber 28 that matches the cylinder bore 27 is formed in the cylinder head 25. Further, an intake port 29 and an exhaust port 30 connected to the combustion chamber 28 are formed in the cylinder head 25, and an intake valve 31 for opening and closing these two ports 29, 30 is provided.
And an exhaust valve 32 are set.
A valve train 33 for opening and closing the valves 1 and 32 is incorporated. Note that a spark plug 34 is provided in the combustion chamber 28.

On the other hand, the crankshaft 6 is
The metal bearing 35 provided on the 3a side and the bearing 36 provided on the cylinder block 23b side rotatably support the shaft. A pair of upper and lower crank webs 6a and 6b are formed at an intermediate portion of the crankshaft 6, and a crank pin 6c is eccentrically provided therebetween.

A piston 37 is slidably inserted into the cylinder bore 27. A piston pin 37a provided in the piston 37 and a crank pin 6 of the crank shaft 6 are provided.
is connected by a connecting rod 38, whereby the reciprocating motion of the piston 37 in the cylinder bore 27 is converted into the rotational motion of the crankshaft 6. Since the upper end of the drive shaft 12 is integrally connected to the lower end of the crankshaft 6 by spline fitting or the like, the rotation of the crankshaft 6 is transmitted to the drive shaft 12 as it is.

By the way, as shown in FIGS. 3 and 4,
A balancer shaft 40 and a camshaft 41 are supported in the engine case 23 in parallel with the crankshaft 6. The lower ends of the two shafts 40 and 41 are supported on the crankcase 23a side, and the upper ends are supported on the cylinder block 23b side.

The balancer shaft 40 is a rotating shaft for reducing engine vibration generated due to inertial force caused by reciprocating motion of the piston 37 and centrifugal force caused by rotating motion of the crank webs 6a and 6b. On the other hand, the cam shaft 41 is a rotating shaft for driving the valve train 33 incorporated in the cylinder head 25. For example, the balancer shaft 40 is disposed on the left side of the crankshaft 6, and the camshaft 41 is disposed on the balancer shaft 40.
, That is, on the right side of the crankshaft 6.

The upper crank web 6a of the crankshaft 6
A balancer drive gear 42 is fixed above the balancer drive gear 42, and the balancer drive gear 42 meshes with a balancer driven gear 43 provided on the balancer shaft 40. Further, a cam drive gear 44 is fixed below the crank web 6 b on the lower side of the crank shaft 6, and the cam drive gear 44 meshes with a cam driven gear 45 provided on the cam shaft 41.

The balancer drive gear 42 and the balancer driven gear 43 have the same number of teeth.
The number of teeth of 4 is one half of the number of teeth of the cam driven gear 45. Therefore, when the crankshaft 6 rotates, the balancer shaft 40 is driven to rotate in the opposite direction at a constant speed, and the camshaft 41
It is also rotationally driven in the opposite direction at a speed of 1 /. In addition,
An oil pump 46 for lubricating the engine 3 is provided at a lower end of the balancer shaft 40, and the oil pump 46 is driven by rotation of the balancer shaft 40.

An intake cam 41a and an exhaust cam 41b are formed on the camshaft 41. The movement of the intake cam 41a and the exhaust cam 41b caused by the rotation of the camshaft 41 causes two tappets 48 and two push rods 49 to move. Is transmitted to the valve operating device 33, and the valve operating device 33 is driven.

On the other hand, the balancer shaft 40 is integrally formed with two upper and lower balance weights 40a and 40b.
The balance weights 40a and 40b are arranged vertically evenly across the horizontal center line C (shown in FIG. 4) of the cylinder bore 27.
An eccentric cam 40c is formed between a and 40b. The eccentric directions of the two balance weights 40a and 40b and the eccentric direction of the eccentric cam 40c are the same.

The fuel pump 50 provided in the engine case 23 is driven by the eccentric cam 40c of the balancer shaft 40. This fuel pump 50
Is, for example, of a plunger type, and is configured such that fuel is discharged by moving a driven rod 50a extending horizontally thereof forward and backward.

The fuel pump 50 is installed from the outside on the front surface of the engine case 23 (cylinder block 23b) near the balancer shaft 40, and its installation height is adjusted to the height of the horizontal center line C of the cylinder bore 27. . Therefore, the fuel pump 50 can be easily attached to and detached from the engine case 23, so that the assemblability and maintenance of the engine 3 can be improved. The driven rod 50 of the fuel pump 50
a and the eccentric cam 40c provided on the balancer shaft 40
Heights match.

As shown in FIG. 4, the fuel pump 50 is provided with a suction-side union 50b and a discharge-side union 50c, and the other end of a fuel hose connected to the suction-side union 50b has a fuel tank (not shown). The other end of the fuel hose connected to the discharge-side union 50c is connected to a fuel supply device (not shown) such as a carburetor that mixes with the outside air to vaporize the fuel.

The engine 3 is configured as described above. In addition, as shown in FIG.
A flywheel magneto device 51 for power generation and a low pre-coil type starting device 52 are provided.

When the engine 3 starts, the balancer shaft 40 is driven to rotate by the rotation of the crankshaft 6, and two balance weights 40 provided on the balancer shaft 40 are provided.
The centrifugal forces a and 40b cancel the engine vibration caused by the inertial force of the piston 37 and the centrifugal force of the crank webs 6a and 6b. Therefore, the quietness of the engine 3 is greatly improved.

At the same time, the eccentric cam 40c of the balancer shaft 40
The rotation of the driven rod 50 of the fuel pump 50
a is pressed periodically to discharge the fuel, and the fuel is supplied to a fuel supply device such as a carburetor.

If the eccentric cam 40c is formed on the balancer shaft 40 rotating at the same speed as the crankshaft 6 like the engine 3, and the fuel pump 50 is driven by the eccentric cam 40c, the fuel pump 50 Can be driven faster at the same drive rotation speed as the crankshaft 6.

Therefore, as compared with the case where the fuel pump 50 is driven by the camshaft 41 rotating at half the rotation speed of the crankshaft 6, a sufficient fuel discharge amount can be obtained even when the capacity of the fuel pump 50 is small. As a result, the capacity of the fuel pump 50 can be reduced, and the size of the fuel pump 50 and the engine 3 itself can be reduced.

Also, since the installation height of the fuel pump 50 is adjusted to the height of the horizontal center line C of the cylinder bore 27, the fuel pump 50 can be easily attached to and detached from the engine case 23, thereby making the engine 3 easy to assemble and maintain. Can be greatly improved.

Further, since the balance weights 40a, 40b of the balancer shaft 40 are vertically arranged uniformly with the horizontal center line C of the cylinder bore 27 interposed therebetween, and the eccentric cam 40c is formed between the upper and lower balance weights 40a, 40b. The balance weights 40a and 40b do not generate a couple, and the fuel pump 50 can be driven by the balancer shaft 40 without impairing the vibration-proof effect of the balancer shaft 40.

Further, since the eccentric directions of the balance weights 40a and 40b of the balancer shaft 40 and the eccentric direction of the eccentric cam 40c are the same, the centrifugal force of the eccentric cam 40c does not cancel the centrifugal force of the balance weights 40a and 40b. In this respect, the fuel pump 50 can be driven by the balancer shaft 40 without impairing the vibration-proof effect of the balancer shaft 40.

In the engine 3, the balancer shaft 40 is arranged on one side of the crankshaft 6 and the camshaft 41 is arranged on the other side, so that the cam 3 is arranged on one side (the right side in the present embodiment) of the engine case 23 in plan view. Since the shaft 41 protrudes and the balancer shaft 40 protrudes to the other side (left side), the space on both sides of the engine 3 is effectively used, and the space efficiency in the engine room of the outboard motor 1 (the internal space of the engine cover 2) is reduced. Can be improved.

Further, in plan view of the outboard motor 1, FIG.
As clearly shown, a balancer shaft 40 and a camshaft 41 arranged in parallel with the crankshaft 6 are arranged near the center of the engine cover 2 and on one side and the other side of the crankshaft 6, respectively.

In this embodiment, the engine 3 is a four-cycle OHV single-cylinder engine. However, if the engine 3 has a balancer shaft that rotates at the same speed as the crankshaft, for example, a multi-cylinder four-cycle OHV engine is used. Engine and OHC
The configuration according to the present invention can be applied to an engine of a type or a two-cycle engine. Further, the configuration according to the present invention can be applied to an engine used other than the outboard motor.

Further, as an application example of the present invention, an eccentric cam may be formed on a rotating shaft other than the balancer shaft to which rotation of the crankshaft is transmitted at a constant speed, and the fuel pump may be driven by this rotating shaft. Conceivable.

[0044]

As described above, in the engine of the outboard motor according to the present invention, the fuel pump is fixed to the engine case in accordance with the height of the horizontal center line of the cylinder bore. It is easy to put on and take off. Therefore, it is possible to improve the assemblability and maintainability of the engine.

Further, in the outboard motor according to the present invention, the shaft arranged parallel to the crankshaft is arranged near the center of the engine cover and on one side of the crankshaft. The space provided on the side of the engine can be effectively utilized by being provided on the side of the engine case when viewed, and the space efficiency of disposing the outboard motor in the engine room can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a right side view showing an example of an outboard motor according to the present invention.

FIG. 2 is a longitudinal sectional view of an engine portion of the outboard motor.

FIG. 3 is a transverse sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a view showing one embodiment of the present invention by a longitudinal sectional view taken along the line IV-IV in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outboard motor 2 Engine cover 3 Engine 6 Crankshaft 11 Propeller 20 Air intake 23 Engine case 23a Crankcase 23b Cylinder block 27 Cylinder bore 33 Valve train 37 Piston 40 Balancer shaft (axis parallel to crankshaft) 40a, 40b Balance Weight 40c Eccentric cam 41 Camshaft (axis parallel to crankshaft) 42, 43, 44, 45 Gear 50 Fuel pump C Horizontal center line of cylinder bore

Claims (2)

[Claims] A piston is reciprocated horizontally in a cylinder bore so that a crankshaft is oriented vertically and a reciprocating motion of the piston is converted into a rotary motion by the crankshaft, and the propeller is driven via a drive shaft. And the propeller is rotated to drive the propeller. The outboard motor covers the engine with an engine cover, has an air intake port in the engine cover, and is taken in from the air intake port. In an outboard motor equipped with a fuel supply device that mixes outside air with fuel to supply the fuel and a fuel pump that supplies fuel to the fuel supply device within the engine cover, a four-cycle engine is mounted. The cylinder case 27 is fixed to the engine case 23 at a height that the horizontal center line C of the cylinder bore 27 crosses. The lower end of the shaft within the crank case side is disposed parallel to the axis 6 and its upper end is respectively pivotally supported on the cylinder block side, the shaft 40
An outboard motor characterized in that the fuel pump is driven by an eccentric cam 40c formed in the fuel tank and fuel from a fuel tank is discharged to the fuel supply device. 2. When the outboard motor 1 is viewed from above in the vertical direction, a shaft 40 disposed in parallel with the crankshaft 6 is moved toward the center of the engine cover 2 and to one side of the crankshaft 6. The outboard motor according to claim 1, wherein the outboard motor is arranged at a position where the outboard motor is located.