JPH1037757A - Engine for outboard motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize an oil pump and an engine itself by enabling driving of the oil pump with the same driving speed as a crankshaft. SOLUTION: An engine 3 is so mounted on an outboard motor that a crankshaft 6 is perpendicularly arranged. A balancer shaft 40 is journalled inside an engine case 23 parallely to the crankshaft 6. Rotation of the crankshaft 6 is constant-speed transmitted to the balancer shaft 40. A fuel pump 50 is arranged on the engine case 23, while an eccentric cam 40 is formed on the balancer shaft 40. The fuel pump 50 is driven by the eccentric cam 40c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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 performed via a drive shaft that extends long downward. The power is transmitted to a propeller for propulsion provided at the bottom of the outboard motor.

[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 outboard motor engine according to the present invention has been invented in order to solve such a problem. The first object of the present invention is to operate the fuel pump at a driving rotational speed equal to that of the crankshaft. It is an object of the present invention to enable high-speed driving and to downsize the fuel pump and the engine itself.

A second object of the present invention is to facilitate attachment and detachment of a fuel pump to and from an engine case and to improve the assembling and maintenance of the engine.

A third object of the present invention is to enable the fuel pump to be driven by the balancer shaft without impairing the vibration isolating effect of the balancer shaft.

A fourth object of the present invention is to improve the space efficiency in the engine room of the outboard motor.

[0010]

According to a first aspect of the present invention, an engine for an outboard motor according to the present invention is provided with an outboard motor mounted vertically so that a crankshaft is oriented vertically. A balancer shaft is supported in the engine case in parallel with the crankshaft in the engine case, and the outboard motor engine is configured to transmit the rotation of the crankshaft to the balancer shaft at a constant speed. An eccentric cam is formed on the balancer shaft while the fuel pump is provided in the case, and the fuel pump is driven by the eccentric cam.

As described above, if the fuel pump is driven by the balancer shaft to which the rotation of the crankshaft is transmitted at a constant speed, the fuel pump can be driven quickly at the same driving rotation speed as the crankshaft. The fuel pump and the engine itself can be downsized by reducing the capacity of the fuel pump accordingly.

Further, the engine of the outboard motor according to the present invention includes:
As described in claim 2, the installation height of the fuel pump is adjusted to the height of the horizontal center line of the cylinder bore. For this reason,
The fuel pump can be easily attached to and detached from the engine case, and the assembling and maintenance of the engine can be improved.

Furthermore, in the engine for an outboard motor according to the present invention, the balance weight of the balancer shaft is arranged uniformly in the vertical direction with the horizontal center line of the cylinder bore interposed therebetween, and the balance between the upper and lower parts is adjusted. An eccentric cam was formed between the weights. As a result, the balance weight of the balancer shaft does not generate a couple, and the fuel pump can be driven by the balancer shaft without impairing the vibration isolation effect of the balancer shaft.

In the outboard motor engine according to the present invention, the eccentric direction of the balance weight of the balancer shaft and the eccentric direction of the eccentric cam are the same. For this reason, the centrifugal force of the eccentric cam does not cancel the centrifugal force of the balance weight. In this respect, the fuel pump can be driven by the balancer shaft without impairing the vibration-proof effect of the balancer shaft.

Further, the engine of the outboard motor according to the present invention comprises:
As described in claim 5, the outboard motor is mounted vertically on the outboard motor so that the crankshaft is oriented vertically, and a balancer shaft and a camshaft for driving the valve train are arranged in the engine case in parallel with the crankshaft. In an outboard motor engine configured so that rotation of the crankshaft is transmitted to the balancer shaft and the camshaft, the balancer shaft is arranged on one side of the crankshaft and the camshaft is arranged on the other side. .

With this arrangement, the cam shaft protrudes from one side of the engine case in plan view and the balancer shaft protrudes from the other side, so that the space on both sides of the engine is effectively used, and the space efficiency in the engine room of the outboard motor is improved. Can be improved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to 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, and FIG.
FIG. 3 is a cross-sectional view along the line III. Fig. 4 shows the IV-
One embodiment of the present invention is shown in a longitudinal sectional view along the IV line.

The outboard motor 1 has a box-shaped engine cover 2 at the uppermost part, and an engine 3 is housed in the 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 supported inside the gear housing 8, and a propeller 11 is provided at a rear end of the propeller shaft 10.

On the other hand, a drive shaft extending vertically downward from the lower end of the crankshaft 6 of the engine 3 is provided in the drive housing 7.
A lower end of the drive shaft 12 is supported by a forward / reverse switching device 13 composed of a bevel gear or the like.
Works with 10.

The output of the engine 3 is transmitted to a propeller shaft 10 via a drive shaft 12 and a forward / reverse switching device 13, and the switching operation of the forward / reverse switching device 13 switches the rotation direction of the propeller shaft 10 and the propeller 11 or shifts the rotation to neutral. can do.

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 fixed to a transom (stern portion) 18 of a boat 17. Therefore, the outboard motor 1 is provided so as to be able to rotate 360 ° with respect to the hull 17, and the steering of the hull 17 can be performed by turning the steering handle 4 to change the direction of the entire outboard motor 1.

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. Engine 3 on
Has been fixed. In addition, the steering handle 4 is provided integrally with the lower cover 2a, and a waterproof cover 21 which 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 cylinder bore 27 is formed in the cylinder head 25.
Is formed. In addition, an intake port 29 and an exhaust port 30 connected to the combustion chamber 28 are formed in the cylinder head 25, and these two ports 29, 3
An intake valve 31 and an exhaust valve 32 for opening and closing the valve 0 are set, and a valve train 33 for opening and closing the valves 31 and 32 is further incorporated. Note that an ignition plug 34 is provided in the combustion chamber 28.

On the other hand, the crankshaft 6 is
The metal bearing 35 provided on the a side and the cylinder block 23
It is rotatably supported by a bearing 36 provided on the b side. 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, and a piston rod 37a provided on the piston 37 and a crankpin 6c of the crankshaft 6 are connected by a connecting rod 38. Cylinder bore
The reciprocating motion of the piston 37 in the shaft 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. These two shafts 40,4
1 has its lower end pivotally supported by the crankcase 23a and its upper end pivotally supported by the cylinder block 23b.

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 rotary 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 cam shaft 41 is disposed on the opposite side of the balancer shaft 40, that is, on the right side of the crankshaft 6.

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

The number of teeth of the balancer drive gear 42 and the balancer driven gear 43 is the same, and the number of teeth of the cam drive gear 44 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 is also driven to rotate in the reverse direction at half the speed. The balancer shaft 40
An oil pump 46 for lubricating the engine 3 is provided at a lower end of the oil pump, and the oil pump 46 is driven by the rotation of the balancer shaft 40.

The camshaft 41 has an intake cam 41a and an exhaust cam 41b.
Are formed, and the intake cam 41a accompanying the rotation of the camshaft 41 is formed.
And the movement of the exhaust cam 41b is two tappets 48 and 2
Transmitted to the valve train 33 via a push rod 49,
The valve train 33 is driven.

On the other hand, the balancer shaft 40 is formed integrally with two upper and lower balance weights 40a and 40b. These balance weights 40a, 40b are arranged uniformly above and below the horizontal center line C (shown in FIG. 4) of the cylinder bore 27, and an eccentric cam 40c is formed between the upper and lower balance weights 40a, 40b. ing. 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. The fuel pump 50 is of a plunger type, for example, and has a driven rod 50a extending horizontally.
The fuel is discharged by advancing and retreating the fuel cell.

The fuel pump 50 is installed 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 center line C of the cylinder bore 27. Therefore, the height of the driven rod 50a of the fuel pump 50 and the eccentric cam provided on the balancer shaft 40
The height of 40c matches.

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). Connected to the discharge side union 50
The other end of the fuel hose connected to c is connected to a fuel supply device (not shown) such as a carburetor.

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

When the engine 3 starts, the balancer shaft 40 is driven to rotate by the rotation of the crankshaft 6, and two balance weights 40a, 40b provided on the balancer shaft 40 are provided.
Centrifugal force cancels engine vibrations 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, when the eccentric cam 40c of the balancer shaft 40 rotates, the driven rod 50a of the fuel pump 50 is periodically pressed to discharge the fuel, and the fuel is supplied to a fuel supply device such as a carburetor. .

As in the engine 3, an eccentric cam 40c is formed on a balancer shaft 40 rotating at the same speed as the crankshaft 6,
If the fuel pump 50 is driven by the eccentric cam 40c, the fuel pump 50 can be driven at a high speed at the same drive rotation speed as the crankshaft 6.

Therefore, compared to 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. The size of the fuel pump 50 and the engine 3 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 facilitating the assembly and maintenance of the engine 3. Can be greatly improved.

Further, the balance weight of the balancer shaft 40
The upper and lower balance weights 40a, 40b are evenly arranged with the horizontal center line C of the cylinder bore 27 interposed therebetween.
Since the eccentric cam 40c is formed between 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. it can.

Moreover, the balance weight of the balancer shaft 40
Since the eccentric direction of the eccentric cams 40c and the eccentric direction of the eccentric cam 40c are the same, the centrifugal force of the eccentric cam 40c does not cancel out the centrifugal force of the balance weights 40a and 40b. The fuel pump 50 can be driven by the balancer shaft 40 without impairment.

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

In the present embodiment, the engine 3 is a single-cylinder engine of the four-cycle OHV type. However, if the engine 3 has a balancer shaft that rotates at a constant speed with respect to the crankshaft, for example, a multi-cylinder four-cycle engine 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, it is also possible to form an eccentric cam on a rotating shaft other than the balancer shaft and to which the rotation of the crankshaft is transmitted at a constant speed, and drive the fuel pump with this rotating shaft. Conceivable.

[0049]

As described above, the engine of the outboard motor according to the present invention is mounted vertically on the outboard motor so that the crankshaft is oriented vertically, and is parallel to the crankshaft in the engine case. A balancer shaft is pivotally supported, and in an outboard motor engine configured so that rotation of a crankshaft is transmitted to the balancer shaft at a constant speed, a fuel pump is provided in an engine case, while an eccentric cam is mounted on the balancer shaft. And the fuel pump is driven by the eccentric cam.

As described above, if the fuel pump is driven by the balancer shaft to which the rotation of the crankshaft is transmitted at a constant speed, the fuel pump can be driven quickly at the same drive rotation speed as the crankshaft. A sufficient fuel discharge amount can be obtained even with a small capacity fuel pump. Therefore,
By reducing the capacity of the fuel pump, the size of the fuel pump and the engine itself can be reduced.

The engine of the outboard motor according to the present invention
Since the installation height of the fuel pump is adjusted to the height of the horizontal center line of the cylinder bore, the fuel pump can be easily attached to and detached from the engine case. Therefore, it is possible to improve the assemblability and maintainability of the engine.

Further, in the engine of the outboard motor according to the present invention, the balance weights of the balancer shafts are evenly arranged vertically so as to sandwich the horizontal center line of the cylinder bore, and an eccentric cam is formed between the upper and lower balance weights. Therefore, the balance weight of the balancer shaft does not generate a couple, and the fuel pump can be driven by the balancer shaft without impairing the vibration isolation effect of the balancer shaft.

In the engine of the outboard motor according to the present invention, since the eccentric direction of the balance weight of the balancer shaft and the eccentric direction of the eccentric cam are the same, the centrifugal force of the eccentric cam cancels the centrifugal force of the balance weight. Also in this respect, the fuel pump can be driven by the balancer shaft without impairing the vibration isolating effect of the balancer shaft.

Further, the engine of the outboard motor according to the present invention
The outboard motor is mounted vertically so that the crankshaft is oriented vertically, and a balancer shaft and a camshaft for driving the valve gear are supported in the engine case in parallel with the crankshaft, and the rotation of the crankshaft is performed. Is transmitted to the balancer shaft and the camshaft, wherein the balancer shaft is arranged on one side of the crankshaft and the camshaft is arranged on the other side of the crankshaft.

With this configuration, the camshaft protrudes from one side of the engine case in plan view and the balancer shaft protrudes from the other side, so that the space on both sides of the engine is effectively utilized.
The space efficiency in the engine room of the outboard motor 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 an 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 3 Engine 6 Crankshaft 23 Engine case 27 Cylinder bore 33 Valve train 40 Balancer shaft 40a, 40b Balance weight 40c Eccentric cam 41 Camshaft 42,43,44,45 Gear 50 Fuel pump C Horizontal center line of cylinder bore

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F16F 15/26 B63H 21/26 K

Claims (5)

[Claims] An outboard motor 1 is mounted vertically on the outboard motor 1 so that the crankshaft 6 is oriented vertically, and a balancer shaft 40 is supported in the engine case 23 in parallel with the crankshaft 6. In an outboard motor engine configured to transmit the rotation of the crankshaft 6 to the engine 40 at a constant speed, a fuel pump 50 is provided in the engine case 23, and an eccentric cam 40c is formed on the balancer shaft 40. An engine 3 for an outboard motor, wherein the fuel pump 50 is driven by 40c. 2. The installation height of the fuel pump 50 is controlled by a cylinder bore.
The engine 3 of the outboard motor according to claim 1, wherein the engine 3 is adjusted to a height of a horizontal center line C of 27. 3. The balance weight 40a of the balancer shaft 40,
2. The outboard motor engine 3 according to claim 1, wherein the upper and lower balance weights 40a and 40b are formed with eccentric cams 40c. 4. The balance weight 40a of the balancer shaft 40,
4. The engine 3 for an outboard motor according to claim 3, wherein the eccentric direction of the eccentric cam 40c and the eccentric direction of the eccentric cam 40c are the same. 5. The outboard motor 1 is mounted vertically on the outboard motor 1 so that the crankshaft 6 is oriented vertically, and a balancer shaft 40 and a valve driving device 33 are driven in the engine case 23 in parallel with the crankshaft 6. In the engine of the outboard motor configured so that the camshaft 41 is supported and the rotation of the crankshaft 6 is transmitted to the balancer shaft 40 and the camshaft 41, the balancer shaft 40 is provided on one side of the crankshaft 6. An engine 3 for an outboard motor, wherein a camshaft 41 is disposed on the other side.