JP2000297655A - Four-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a four-cycle engine provided with an OHV type valve train capable of being driven at high speed. SOLUTION: A four-cycle engine has a crank shaft 10 provided lengthwise in an engine 3, such that the rotation of a cam shaft 31 driven by this crank shaft 10 is transmitted to a rocker arm 36 within a cylinder head 18 via a bush rod 38, thereby opening and closing supply and exhaust valves 28, 29. An idler gear 34 is provided between the crank shaft 10 and the cam shaft 31. Both the crank shaft 10 and the cam shaft 31 are operated in communication by this idler gear 34, which is disposed on the cylinder head 18 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a four-stroke engine.

[0002]

2. Description of the Related Art In a small four-stroke engine mounted on a general-purpose or outboard motor, a method of driving a rocker arm for opening and closing an intake / exhaust valve includes rotating a camshaft driven by a crankshaft. An OHV-type valve operating structure that transmits to the rocker arm via a push rod is adopted.

On the other hand, as a lubrication method for the small four-cycle engine, a splash type is generally used. The splash-type lubrication method is, for example, to provide an oil splash member such as a slinger (wing) at the large end of a connecting rod, and to fly the oil to each part of the engine while scooping up the oil in an oil pan with the slinger. The cost is low because the structure is simpler than the oil pump lubrication method used for engines.

[0004] On the other hand, the engine is liable to generate primary vibration based on the reciprocating motion of the piston. Therefore, some engines include a balancer device for removing the primary vibration. The balancer device is configured such that a balancer weight corresponding to the total mass of, for example, a piston and a connecting rod is fixed to a balancer shaft, and the balancer shaft is rotated in conjunction with a crankshaft to eliminate vibration during engine operation.

[0005] As an example of the arrangement of the balancer device, for example, there is one in which a balancer shaft is arranged on the opposite side of a camshaft with respect to a crankshaft.

[0006]

SUMMARY OF THE INVENTION However, OHV
The valve operating system of the type has a problem that as the push rod becomes longer, the equivalent weight increases, which is disadvantageous for high-speed rotation of the engine.

On the other hand, the splash type lubrication method is effective only when the crankshaft is in a horizontal state. In the case of a vertical engine having a vertically arranged crankshaft such as an outboard motor, a rotating body having a splash member is provided. Must be provided as a separate part, which leads to an increase in cost and weight. Further, lubricating oil does not easily reach a high position such as the upper part of the camshaft.

On the other hand, since the outboard motor has a vertically arranged crankshaft, providing a balancer shaft on the opposite side of the camshaft increases the engine length and width.
The outboard motor becomes large. Further, although both the camshaft and the balancer shaft use the crankshaft as a drive shaft, they are not functional because they use drive systems independent of each other.

The present invention has been made in consideration of the above circumstances, and has as its object to provide a four-stroke engine having an OHV type valve operating structure capable of high-speed operation.

Another object of the present invention is to provide a four-stroke engine which has a simple structure and can improve lubrication performance.

It is still another object of the present invention to provide a four-stroke engine with a functional balancer device.

[0012]

According to the present invention, there is provided a four-stroke engine for solving the above-mentioned problems.
As described in the above, the crankshaft is vertically arranged in the engine, and the rotation of the camshaft driven by the crankshaft is transmitted to the rocker arm in the cylinder head via the push rod, and the intake / exhaust valve is controlled. In a four-cycle engine that performs opening and closing operations, an idler gear is disposed between the crankshaft and the camshaft, the crankshaft and the camshaft are operatively connected by the idler gear, and the idler gear is disposed on the cylinder head side. is there.

According to another aspect of the present invention, an oil pan is disposed below the engine, and an oil splash member extending toward the inside of the oil pan is provided on the idler gear. It is a thing.

Further, in order to solve the above-mentioned problems,
As described in claim 3, the crankshaft is vertically arranged in the engine, and the rotation of the camshaft driven by the crankshaft is transmitted to the rocker arm in the cylinder head via the push rod to absorb and rotate the crankshaft. In a four-stroke engine for opening and closing an exhaust valve, a balancer shaft having a balancer weight is disposed between the crankshaft and the camshaft, and the crankshaft and the camshaft are operatively connected with the balancer shaft. A shaft is arranged on the cylinder head side.

Still further, in order to solve the above-mentioned problem, an oil pan is disposed below the engine, and the oil splash member extending toward the inside of the oil pan is connected to the balancer weight. It is provided in.

Then, in order to solve the above-mentioned problem,
As described in claim 5, a breather chamber is formed on the side of the engine, the breather chamber is disposed above the camshaft, and an oil passage communicating the upper end of the camshaft and the breather chamber is formed. It was done.

[0017]

Embodiments 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 provided with a four-stroke engine according to the present invention. As shown in FIG. 1, the outboard motor 1 has a box-shaped engine cover 2 at the top, and a vertical (vertical) engine 3 is housed therein. A steering handle 4 extends forward from the front of the engine cover 2 (the right side in FIG. 1), and a throttle grip 5 for adjusting the engine output is provided at its tip.

A shaft housing 6 is provided below the engine cover 2.
The gear case 7 is provided at the lower part of the vehicle. A propeller shaft 8 is rotatably supported inside the gear case 7, and a propeller 9 is provided at a rear end thereof.

In the engine 3, a crankshaft 10 is provided vertically (vertically) so as to face a substantially vertical direction. A drive shaft 11 connected to the lower end of the crankshaft 10 extends downward in the shaft housing 6, and the lower end of the drive shaft 11 is connected to the propeller shaft 8 via a bevel gear 12. The output of the engine 3 is transmitted to the propeller shaft 8 via the drive shaft 11 and the bevel gear 12, and rotates the propeller 9.

The upper portion of the shaft housing 6 is rotatably supported by a rotation support portion 13a of a clamp bracket 13, and the clamp bracket 13 is fixed to a transom of a ship (not shown). That is, the outboard motor 1 is rotatable about 360 ° with respect to the boat, and the steering of the boat can be performed by swinging the steering handle 4 in the horizontal direction to change the direction of the entire outboard motor 1. It is configured as follows.

The engine cover 2 is, for example, vertically splittable, and comprises a lower cover 2a fixed to the lower part of the engine, and an upper cover 2b detachably mounted on the lower cover 2a. The steering handle 4 is provided integrally with the lower cover 2a.

FIG. 2 is a sectional view taken along the line II-II of FIG. 1 and shows a first embodiment of the present invention. FIG. 3 is a sectional view taken along line III-III in FIG.
FIG. 4 is a sectional view taken along line IV-IV in FIG. As shown in FIGS. 2 and 3, the engine 3 used in the present embodiment
Is, for example, a single-cylinder engine having a 4-cycle OHV type valve operating structure, and an engine housing 14 thereof includes a front (right side in the figure) crankcase 15 and a rear (left side in the figure) cylinder block 16. You.

The cylinder block 16 has a cylindrical cylinder 17 extending rearward (leftward in the figure) in a direction perpendicular to the crankshaft 10, and a cylinder head 18 is provided at the rear end of the cylinder 17. An oil pan 19 in which lubricating oil is stored is provided in a lower portion of the engine housing 14 composed of the crankcase 15 and the cylinder block 16 so as to bridge all of them. The tank 20 is arranged.

The cylinder bore 17 is provided inside the cylinder 17.
a, a combustion chamber 21 is formed in the cylinder head 18 so as to match the cylinder bore 17a, and a spark plug 22 is connected to the combustion chamber 21 from outside.

In the crankshaft 10, a pair of webs 10a are formed substantially at an intermediate portion thereof so as to be separated from each other in the axial direction, and a crankpin 10b is formed eccentrically therebetween. On the other hand, a piston 23 is slidably inserted into the cylinder bore 17a. The piston pin 23a of the piston 23 and the crankpin 10 of the crankshaft 10
b is connected by a connecting rod 24, whereby the reciprocating motion of the piston 23 in the cylinder bore 17a is converted into the rotational motion of the crankshaft 10. In addition,
At the upper end of the crankshaft 10, a flywheel magneto device 25 for power generation and a rope recoil type engine starting device 26 are provided.

An intake port 27 and an exhaust port 28 connected to the combustion chamber 21 are formed in the cylinder head 18.
An intake valve 29 and an exhaust valve 30 for opening and closing both ports 27 and 28 are arranged in the cylinder head 18.

On the other hand, as shown in FIGS. 2 to 4, a camshaft 31 is disposed obliquely rearward of the crankshaft 10, that is, on the side of the cylinder head 18 (left side in the figure) in parallel with the crankshaft 10. Crankshaft 10
A timing drive gear 32 is provided integrally or integrally with the crankshaft 10 at a lower portion. Further, a timing driven gear 33 is provided below or below the camshaft 31 integrally or integrally with the camshaft 31. Further, an idler gear 34 is disposed between the timing gears 32 and 33 below the cylinder 17.
The rotational force of the crankshaft 10 is transmitted to the camshaft 31 by operatively connecting the two timing gears 32 and 33 with the camshaft 31. The idler gear 34 is provided with an oil dipper 35 which is an oil splash member extending toward the inside of the oil pan 19, and the idler gear 34 rotates to scoop up the lubricating oil in the oil pan 19.

A cam 30a is provided on the camshaft 31, and a rocker arm 36 is swingably supported in the cylinder head 18. And the camshaft 3
By the rotation of 1, the profile of the cam 30 a causes the push rod 38 arranged on the side of the cylinder 17 to advance and retreat in the axial direction thereof, thereby causing the rocker arm 36 to swing. The rocking arm 36 swings the intake valve 29 and the exhaust valve 30 in the cylinder head 18 to open and close.

FIG. 5 is a view taken in the direction of the arrow V in FIG. 3, and FIG. 6 is a sectional view taken along the line VI-VI in FIG. As shown in FIGS. 5 and 6, the engine 3 of the outboard motor 1 is provided with a breather device. Breather chamber 3 that constitutes the breather device
Numeral 9 is formed integrally on the side of the cylinder block 16 so as to straddle both the cylinder 17 and the cylinder head 18.

The breather chamber 3 formed on the cylinder 17 side
9 is disposed above the camshaft 31 and is connected to the breather chamber 3.
Oil passage 4 which communicates the inside of 9 with the upper end of camshaft 31
0 is formed, and a reed valve 41 is provided in an opening formed on the mating surface of the breather chamber 39 with the cylinder head 18. The reed valve 41 supplies blower gas to the breather chamber 39 on the cylinder head 18 side. It is set so that it can pass only from the breather chamber 39 on the cylinder 17 side (not shown).

FIG. 7 is a plan sectional view showing a second embodiment of the four-stroke engine 3 according to the present invention, and FIG. 8 is a sectional view taken along the line VIII-VIII of FIG. Since the basic structure of the engine shown in the second embodiment is the same as that of the engine shown in the first embodiment, the description of the same components will be omitted, and the same components will be denoted by the same reference numerals.

As shown in FIGS. 7 and 8, a camshaft 31 is disposed obliquely rearward of the crankshaft 10, that is, on the side of the cylinder head 18 (left side in the figure) in parallel with the crankshaft 10. A balancer shaft 51 is arranged between the crankshaft 10 and the camshaft 31 in parallel with the crankshaft 10. In the present embodiment, the balancer shaft 51 also serves as the final output shaft, and the lower end of the balancer shaft 51 is formed with a connecting portion 52 of the drive shaft 11.

A balancer drive gear 53 is provided integrally or integrally with the crankshaft 10 below the crankshaft 10. Further, a timing driven gear 54 is provided integrally or integrally with the camshaft 31 below the camshaft 31. Furthermore, the balancer shaft 5
1 is provided with a balancer driven gear 55 and a timing drive gear 56 integrally or integrally with the balancer shaft 51. In this embodiment, the balancer driven gear 55 also functions as the timing drive gear 56.

Then, the balancer drive gear 53 of the crankshaft 10 and the balancer driven gear 55 of the balancer shaft 51 are operatively connected, and the timing driven gear 54 of the camshaft 31 and the timing drive gear of the balancer shaft 51 are operatively connected. The rotational force of the crankshaft 10 is transmitted to the balancer shaft 51 and the camshaft 31.

The balancer shaft 51 is provided with a balancer weight 51a, and the rotation of the balancer shaft 51 cancels the primary vibration of the engine 3 based on the reciprocating motion of the piston 23. In addition, balancer weight 51
a, an oil dipper 57, which is an oil splash member, is provided toward the inside of the oil pan 19;
By rotating 1a, the lubricating oil in the oil pan 19 is scooped up.

Next, the operation of the first embodiment of the present invention will be described.

When the crankshaft 10 rotates, the rotational force is transmitted to the timing drive gear 32 and the idler gear 34.
And transmitted to the camshaft 31 via the timing driven gear 33 to open and close the intake / exhaust valves 29 and 30.

The crankshaft 10 and the camshaft 31
Between the crankshaft 10 and the cylinder head 1.
The camshaft 31 can be arranged on the 8 side. as a result,
Cam 31a on camshaft 31 and cylinder head 18
Push rod 38 for connecting to a rocker arm 36 inside
Can be shortened, the equivalent weight can be reduced, and the rotation speed of the engine 3 can be increased.

The idler gear 34 is connected to the oil pan 19.
By providing the oil splash member 35 (oil dipper) extending inward, even if the crankshaft 10 is vertically arranged, it is not necessary to provide a rotating body having the splash member as a separate component, and the timing drive gear 56 and the idler gear Since the lubricating oil scooped up by the splash member 35 is rotated by the rotation of the timing driven gear 33 and the timing driven gear 33, the lubricating performance is improved.

Further, a breather chamber 39 is formed on the side of the cylinder block 16 over both the cylinder 17 and the cylinder head 18, and a breather chamber 39 formed on the cylinder 17 side is formed above the camshaft 31. By arranging and forming the oil passage 40 that communicates the inside of the breather chamber 39 with the upper end of the camshaft 31, the camshaft 31 can be lubricated by the oil component in the blow-by gas flowing into the breather chamber 39.

Next, the operation of the second embodiment of the present invention will be described.

When the crankshaft 10 rotates, its rotational force is transmitted to the balancer shaft 51 via the balancer drive gear 53 and the balancer driven gear 55,
The primary vibration of the engine 3 is canceled.

When the balancer shaft 51 rotates, its rotational force is transmitted to the camshaft 31 via the timing drive gear 56 and the timing driven gear 54 to open and close the intake and exhaust valves 29, 30.

Crankshaft 10 and camshaft 31
And the camshaft 31 can be arranged obliquely rearward of the crankshaft 10, that is, on the cylinder head 18 side. As a result, the length and width of the engine 3 can be reduced, and the size of the outboard motor 1 can be reduced.
The push rod 38 connecting the a to the rocker arm 36 in the cylinder head 18 can be shortened, the equivalent weight can be reduced, the engine 3 can be rotated at a higher speed, and the camshaft 31 and the balancer shaft 51 can be connected to the crankshaft 10. To use a common drive system with
The balancer device becomes functional.

Further, since the oil splash member 57 (oil dipper) extending toward the inside of the oil pan 19 is provided on the balancer weight 51a on the balancer shaft 51, even if the crankshaft 10 is arranged vertically, the rotating body having the splash member is provided. Need not be provided as separate parts,
Balancer drive gear 53, balancer driven gear 5
5. Since the lubricating oil scooped up by the splashing member 57 due to the rotation of the timing drive gear 56 and the timing driven gear 54 is blown to each part of the engine 3, the lubrication performance is improved.

Although the present invention is applied to the four-stroke engine 3 of the outboard motor 1 in any of the embodiments, the present invention can be applied to a four-stroke engine used for other equipment, for example, a general-purpose engine. Yes, the same effect can be obtained.

[0048]

As described above, according to the four-stroke engine of the present invention, the crankshaft is vertically arranged in the engine, and the rotation of the camshaft driven by the crankshaft is controlled by the push rod. To the rocker arm in the cylinder head via
In a four-stroke engine that opens and closes an exhaust valve, an idler gear is disposed between the crankshaft and the camshaft, the idler gear operatively connects the crankshaft and the camshaft, and the idler gear is disposed on the cylinder head side. As a result, the push rod can be shortened and the equivalent weight is reduced, so that the engine can be operated at a high speed.

Further, since an oil pan is arranged below the engine and an oil splash member extending toward the inside of the oil pan is provided on the idler gear, lubrication performance is improved.

The crankshaft is arranged vertically in the engine, and the rotation of the camshaft driven by the crankshaft is transmitted to the rocker arm in the cylinder head via the push rod to open and close the intake / exhaust valve. In a four-cycle engine that operates,
A balancer shaft provided with a balancer weight is arranged between the crankshaft and the camshaft, the crankshaft and the camshaft are operatively connected by the balancer shaft, and the balancer shaft is arranged on the cylinder head side. Since the size can be reduced and the push rod can be shortened to reduce the equivalent weight, the engine can be operated at a high rotation speed, and the balancer device becomes functional.

Further, since an oil pan is arranged below the engine and an oil splash member extending toward the inside of the oil pan is provided on the balancer weight, lubrication performance is improved.

Further, a breather chamber is formed on the side of the engine, and the breather chamber is disposed above the camshaft. An oil passage communicating the upper end of the camshaft and the breather chamber is formed. The camshaft can be lubricated by the oil in the blow-by gas flowing into the camshaft.

[Brief description of the drawings]

FIG. 1 is a right side view of an outboard motor showing one embodiment of a four-stroke engine according to the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG. 1 (first embodiment).

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

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is a view taken in the direction of the arrow V in FIG. 3;

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5;

FIG. 7 is a plan sectional view of a four-stroke engine according to the present invention (second embodiment).

FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 7;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 outboard motor 3 4 cycle engine 10 crankshaft 18 cylinder head 19 oil pan 29 intake valve 30 exhaust valve 31 camshaft 34 idler gear 35, 57 oil dipper (oil splashing member) 36 rocker arm 38 push rod 39 breather chamber 40 oil passage 51 balancer Shaft 51a Balancer weight

Claims (5)

[Claims] A crankshaft is vertically arranged in an engine, and rotation of a camshaft driven by the crankshaft is transmitted to a rocker arm in a cylinder head via a push rod to open and close an intake / exhaust valve. In the four-cycle engine for operation, an idler gear 34 is arranged between the crankshaft 10 and the camshaft 31 to operatively connect the crankshaft 10 and the camshaft 31 with the idler gear 34 and to connect the idler gear 34 to the cylinder head. A four-stroke engine, which is arranged on the 18 side. 2. An oil pan 19 is provided below the engine 3.
The four-stroke engine according to claim 1, wherein an oil splash member (35) extending toward the inside of the oil pan (19) is provided on the idler gear (34). 3. A crankshaft is vertically arranged in an engine, and rotation of a camshaft driven by the crankshaft is transmitted to a rocker arm in a cylinder head via a push rod to open and close an intake / exhaust valve. In the four-cycle engine for operation, a balancer shaft 51 having a balancer weight 51a is arranged between the crankshaft 10 and the camshaft 31, and the crankshaft 10 and the camshaft 31 are operatively connected by the balancer shaft 51. ,
A four-stroke engine, wherein the balancer shaft 51 is disposed on the cylinder head 18 side. 4. An oil pan 19 is provided below the engine 3.
The four-stroke engine according to claim 3, wherein an oil splash member 57 extending toward the inside of the oil pan 19 is provided on the balancer weight 51a. 5. A breather chamber 39 is formed on the side of the engine 3, and the breather chamber 39 is disposed above the camshaft 31. An oil that communicates the upper end of the camshaft 31 with the inside of the breather chamber 39 is provided. The four-stroke engine according to claim 1, wherein the passage (40) is formed.