JP2000297654A - Four-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a four-cycle engine that enable realization of an inexpensive OHC valve train. SOLUTION: A four-cylinder engine has a crank shaft 10 provided lengthwise in an engine 3, such that the rotation of this crank shaft 10 is transmitted to a cam shaft 30, thereby opening and closing supply and exhaust valves 28, 29. Timing gears 31, 32 are provided on the crank shaft 10 and the cam shaft 30, respectively, and an idler gear 33 is disposed between both the timing gears 31, 32. Both the timing gears 31, 32 are then operated in connection by this idler gear 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-stroke engine, and more particularly to a four-stroke engine characterized by a valve operating structure and a lubricating structure.

[0002]

2. Description of the Related Art In a small four-stroke engine mounted on a general-purpose machine or an outboard motor, as a method of driving a camshaft for opening and closing an intake / exhaust valve, a crankshaft using a timing chain or a timing belt is used. An OHC type valve train structure that transmits rotation to a camshaft 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 flying member such as a slinger (wing) at the large end of the connecting rod, and to fly the oil to each part of the engine while scraping up the oil in the oil pan with this slinger. Because it is simple, it does not cost much compared to the oil pump lubrication method used for large engines.

[0004]

However, a camshaft drive system using a timing chain or a timing belt has disadvantages such as a large number of parts, a complicated structure, and a high cost.
It is disadvantageous to apply it to a small four-stroke engine on the premise of low cost.

For this reason, these small engines conventionally employ an OHV type valve operating structure in which the rotation of a crankshaft is transmitted to a rocker arm by using a push rod, but the OHV type is disadvantageous for high-speed rotation of the engine. There is.

On the other hand, the droplet lubrication method is effective only when the crankshaft is in a horizontal state. In the case of a vertical engine in which the crankshaft is arranged vertically such as an outboard motor, a rotating body provided with a slinger is used. It must be provided as a separate part, which leads to an increase in cost and weight.

[0007] The above-mentioned splash type lubrication method is affected by the inclination of the engine, and the lubricating performance is inferior to that of the oil pump pressure feeding type lubrication method, for example, the oil circulation is not performed smoothly during acceleration / deceleration.

The present invention has been made in view of the above circumstances, and has as its object to provide a four-stroke engine which has a simple structure and enables a cost-effective OHC type valve operating structure.

Another object of the present invention is to provide a four-stroke engine capable of improving lubrication performance with a simple structure.

[0010]

According to the present invention, there is provided a four-stroke engine for solving the above-mentioned problems.
As described above, the crankshaft is vertically arranged in the engine, and the rotation of the crankshaft is transmitted to the camshaft to open and close the intake and exhaust valves.
In a cycle engine, a timing gear is provided on each of the crankshaft and the camshaft, an idler gear is disposed between the two timing gears, and the two timing gears are operatively connected by the idler gear.

According to another aspect of the present invention, an oil pan is disposed below the engine, and the two timing gears and the idler gear are disposed in the oil pan. is there.

Further, in order to solve the above-mentioned problems,
4. A four-stroke engine according to claim 3, wherein the crankshaft is vertically arranged in the engine, and the rotation of the crankshaft is transmitted to the camshaft to open and close the intake and exhaust valves. A timing gear is provided on the camshaft, and an idler gear is disposed between the two timing gears to operatively connect the two timing gears with the idler gear. On the other hand, a liquid-tight gear chamber is disposed below the engine. The two timing gears and the idler gear are housed in the chamber, and the lubricating oil introduction port and the discharge port are formed in the gear chamber, so that a gear train including the two timing gears and the idler gear functions as a gear pump.

[0013]

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.

The engine cover 2 is, for example, vertically splittable, and comprises a lower cover 2a fixed to a lower portion of the engine 3, and an upper cover 2b removably mounted on the lower cover 2a. . In addition,
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. FIG. 3 is a sectional view taken along the line III-III in FIG. 2 and shows a first embodiment of the present invention. 1 to 3
As shown in FIG.
Are provided vertically (vertically) so that they face almost vertically.

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.

On the other hand, the engine 3 used in this embodiment
Is a single cylinder engine having, for example, a four-cycle OHC type valve operating structure. As shown in FIGS. 2 and 3, the engine housing 14 has a front (right side in the figure) crankcase 15 and a rear side (in the figure). (Left side).

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 containing lubricating oil therein is provided below the engine 3 including the crankcase 15, the cylinder block 16, and the cylinder head 18 so as to extend over all of them. Is provided with a fuel tank 20.

A 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 in the middle of the crankshaft 10 so as to be separated from each other in the axial direction, and the 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,
A flywheel magneto device 25 for power generation is provided at the upper end of the crankshaft 10.

An intake port 26 and an exhaust port 27 connected to the combustion chamber 21 are formed in the cylinder head 18.
An intake valve 28 and an exhaust valve 29 for opening and closing both ports 26 and 27 are arranged in the cylinder head 18.

On the other hand, a camshaft 30 is arranged in the cylinder head 18 in parallel with the crankshaft 10.
A timing drive gear 31 is provided integrally or integrally with the crankshaft 10 below the crankshaft 10 in the oil pan 19. A timing driven gear 32 is provided below the camshaft 30 in the oil pan 19.
Are provided integrally or integrally with the camshaft 30.
Further, an idler gear 33 is disposed below the cylinder 17 in the oil pan 19 and between the timing gears 31 and 32, and the timing gears 31 and 32 are operatively connected to each other by the idler gear 33. Is transmitted to the camshaft 30. At the upper end of the camshaft 30, a rope recoil type engine starting device 34 is provided.

A cam 30a is provided on the camshaft 30, and a rocker arm 35 is swingably supported on the rocker shaft 36 in the cylinder head 18.
When the camshaft 30 rotates, the cam 3
The profile 0a causes the rocker arm 35 to swing, and the swinging movement of the rocker arm 35 causes the intake valve 28 and the exhaust valve 29 in the cylinder head 18 to open and close.

FIG. 4 is a longitudinal sectional view showing a second embodiment of the four-stroke engine 3 according to the present invention, and FIG. 5 is a sectional view taken along line VV 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.

Crankcase 15, cylinder block 1
A gear chamber 42 whose inside is kept liquid-tight by a plate-shaped cover plate 41 is provided below the cylinder head 18 and the cylinder head 18. The two timing gears 31 and 32 and the idler gear 33 are accommodated in the gear chamber 42.

As shown in FIG. 5, the gear chamber 42 has a planar shape along the outer circumferences of both the timing gears 31, 32 and the idler gear 33.
3 is formed. Of the oil chamber 43 formed at the meshing portion between the timing driven gear 32 and the idler gear 33,
An oil inlet 45a is formed in the oil chamber 43a on one side with a line 44 connecting the centers of the gears 32 and 33 therebetween.
An oil discharge port 46a is formed in the oil chamber 43b on the opposite side of the line 44. Similarly, of the oil chamber 43 formed at the meshing portion between the timing drive gear 31 and the idler gear 33, the oil chamber 43c on one side of the oil chamber 43c with the line 47 connecting the centers of both gears 31 and 33 interposed therebetween. Inlet 45b
Is formed, and an oil discharge port 46b is formed in the oil chamber 43d on the opposite side of the line 47.

Although not shown in detail, the oil introduction port 45 is connected to an oil pan or an oil tank for storing lubricating oil, and the oil discharge port 46 is connected to the engine 3.
It is connected to an oil gallery and an oil passage for guiding lubricating oil to each part.

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

When the crankshaft 10 rotates, its rotational force is transmitted to the timing drive gear 31 and the idler gear 33.
And transmitted to the camshaft 30 via the timing driven gear 32. The timing drive gear 31 and the timing driven gear 32
And the camshaft 30 are provided integrally or integrally, respectively, so that only the idler gear 33 is required separately for driving the camshaft 30.

Conventionally, when a timing chain or a timing belt is used for driving the camshaft 30, many components such as a tensioner and a guide are required in addition to a drive driven sprocket (pulley), and the structure is complicated. In the case of the invention, only the idler gear 33 is sufficient, so that the structure is simplified and the number of parts can be reduced, so that the cost can be reduced.

When the timing drive gear 31 and the timing driven gear 32 are operatively connected by the idler gear 33, the friction loss is smaller than when a timing chain or a timing belt is used, so that a decrease in the output of the engine 3 can be prevented.

Further, since the timing drive gear 31, idler gear 33 and timing driven gear 32 are arranged in the oil pan 19 below the engine 3, when these gears 31 to 33 rotate, the oil pan 1
Since the lubricating oil in 9 is blown to each part of the engine 3,
An oil flying member such as a slinger, which has been separately required in the related art, becomes unnecessary, so that the structure can be simplified and the number of parts can be reduced.

Further, the timing drive gear 3
1, idler gear 33 and timing driven gear 3
2 is disposed in the oil pan 19 below the engine 3 so that even if the engine 3 is tilted, one of the gears is immersed in the lubricating oil, so that the lubricating oil can be sufficiently blown off and the oil pump is pumped. The lubrication performance is not inferior to the lubrication method of the formula.

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

When the crankshaft 10 rotates, its rotating force is transmitted to the timing drive gear 31 and the idler gear 33.
And transmitted to the camshaft 30 via the timing driven gear 32. The gear train composed of the timing gears 31, 32 and the idler gear 33 is structurally the same as a well-known gear pump used for a pressure-feeding oil pump. Therefore, the gear chamber 42 in which the timing gears 31, 32 and the idler gear 33 are housed is used as an oil pump chamber, and if the gear chamber 42 is provided with an oil introduction port 45 and an oil discharge port 46, these gear trains 31 to 33 are provided. Also functions as a gear pump.

That is, as shown in FIG. 5, when both the timing gears 31, 32 and the idler gear 33 rotate in the direction of the arrow, the oil inlet 45 is inserted into the oil chambers 43a, 43c.
The lubricating oil is sucked through the oil chambers 43a, 45b, and is guided between the idler gear 33 and the inner wall of the gear chamber 42 to the oil chambers 43b, 43d.
6b (see the arrow in the figure).

Since the timing gears 31 and 32 and the idler gear 33 can function as a gear pump, lubricating oil can be pumped to each part of the engine 3 without increasing the number of parts and costs. The lubrication performance is improved as compared with the lubrication method.

In each embodiment, the present invention is applied to the four-stroke engine 3 of the outboard motor 1. However, 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.

[0042]

As described above, according to the four-stroke engine according to the present invention, the crankshaft is vertically arranged in the engine, and the rotation of the crankshaft is transmitted to the camshaft to intake and exhaust valves. In the four-stroke engine that performs opening and closing operations, a timing gear is provided on each of the crankshaft and the camshaft, and an idler gear is disposed between the two timing gears, and the two timing gears are operatively connected by the idler gear. The valve structure is simplified and the number of parts can be reduced.

Further, since the oil pan is arranged below the engine and the timing gears and the idler gear are arranged in the oil pan, these gears fly the lubricating oil into the engine and have conventionally been required separately. The need for an oil flying member is eliminated.

Further, in a four-cycle engine in which a crankshaft is vertically arranged in an engine and the rotation of the crankshaft is transmitted to a camshaft to open and close an intake / exhaust valve, the crankshaft and the camshaft are connected to each other. Timing gears are provided, idler gears are arranged between the timing gears, and the idler gears operatively connect the timing gears.
A liquid-tight gear chamber is arranged below the engine, the timing chamber and the idler gear are accommodated in the gear chamber, and a lubricating oil introduction port and a discharge port are formed in the gear chamber. Because the gear train consisting of idler gears functioned as a gear pump,
Lubricating oil can be pumped to each part of the engine without increasing the number of parts and cost.

[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 in FIG.

FIG. 3 is a cross-sectional view of the first embodiment of the four-stroke engine according to the present invention, taken along line III-III of FIG. 2;

FIG. 4 is a longitudinal sectional view showing a second embodiment of the four-stroke engine according to the present invention.

FIG. 5 is a sectional view taken along the line VV in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outboard motor 3 4 cycle engine 10 Crankshaft 19 Oil pan 28 Intake valve 29 Exhaust valve 30 Camshaft 31 Timing drive gear 32 Timing driven gear 33 Idler gear 42 Gear chamber 45 Oil introduction port 46 Oil discharge port

Claims (3)

[Claims] 1. A four-stroke engine in which a crankshaft is vertically arranged in an engine and the rotation of the crankshaft is transmitted to a camshaft to open and close an intake / exhaust valve. A four-stroke engine characterized in that timing gears 31 and 32 are provided on the respective 30 and an idler gear 33 is disposed between the timing gears 31 and 32 and the timing gears 31 and 32 are operatively connected by the idler gear 33. 2. An oil pan 19 is provided below the engine 3.
The four-stroke engine according to claim 1, wherein the two timing gears (31, 32) and the idler gear (33) are arranged in the oil pan (19). 3. A four-stroke engine in which a crankshaft is vertically arranged in an engine and the rotation of the crankshaft is transmitted to a camshaft to open and close an intake / exhaust valve. The timing gears 31 and 32 are provided on the timing gear 30, respectively. An idler gear 33 is disposed between the timing gears 31 and 32, and the timing gears 31 and 32 are operatively connected by the idler gear 33. A dense gear chamber 42 is disposed, the timing gears 31, 32 and the idler gear 33 are accommodated in the gear chamber 42, and a lubricating oil inlet 45 and a discharge port 46 are formed in the gear chamber 42. A gear train composed of timing gears 31 and 32 and an idler gear 33 is used as a gear pump. A four-stroke engine characterized by functioning as a.