JP2001355425A - Breather device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a breather device of an engine capable of improving the lubricating performance of a valve system and preventing the leakage of lubricant caused by storage attitude. SOLUTION: In this breather device 42 of the engine 3 for guiding the blowby gas in a crank case 15 to the external of the crank case 15 in the engine formed by successively connecting the crank case 15, a cylinder block 16 and a cylinder head 17, breather passages 43 and 44 are formed on the cylinder block 16 and the cylinder head 17 for communicating the crank case 15 and a valve system chamber 20 formed in the cylinder head 17, a breather outlet 46 for communicating the inside and outside of the valve system chamber 20 is formed on an outer wall of the cylinder head 17, and the breather outlet 46 is located at a side opposite to the breather passages 43 and 44 through a center line 45 connecting front and rear parts of the engine 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a breather device for an engine.

[0002]

2. Description of the Related Art In an engine, a small amount of gas with pressure generated in a combustion chamber leaks into a crankcase through a gap between a piston and a cylinder bore. Also, the pressure of the gas in the crankcase constantly fluctuates with the sliding of the piston, so when the crankcase is in a sealed state, the pressure of the gas in the crankcase, so-called blow-by gas, hinders the movement of the piston. . This allows blow-by gas in the crankcase to escape to the outside,
It is necessary to provide a means for separating oil mixed in the blow-by gas, that is, a breather device.

[0003] In some cases, the oil content in the blow-by gas, ie, oil mist, is positively introduced into the valve operating chamber of the cylinder head to lubricate the valve operating device.

An example of a breather device used for a small four-stroke engine such as a lawnmower, a generator, and an outboard motor includes:
For example, a breather chamber is formed above the cylinder block of the engine, a breather chamber is formed between the cylinder head and the cylinder head cover, or a breather chamber is formed separately in the cylinder head cover of the engine to form a breather device. There are those configured.

[0005]

However, when the breather chamber is formed above the cylinder block of the engine, the oil mist is not guided into the valve operating chamber, and the valve operating system is not sufficiently lubricated. Therefore, an oil pump is required separately, complicating the structure and assemblability, increasing the cost, and is not preferable for a small engine.

Further, when the engine such as an outboard motor is portable,
If there is a breather chamber above the cylinder block, depending on the storage posture of the outboard motor, lubricating oil may leak from the breather chamber and spill into the cover.

Further, when a breather chamber is formed between the cylinder head and the cylinder head cover, or when the breather chamber is formed separately from the cylinder head cover of the engine, the engine becomes larger.

The present invention has been made in consideration of the above circumstances, and has as its object to provide an engine breather device which improves the lubrication performance of a valve train and prevents leakage of lubricating oil due to a storage position. And

Another object of the present invention is to provide a breather device for an engine which is reduced in size.

[0010]

According to a first aspect of the present invention, there is provided a breather device for an engine in which a crankcase, a cylinder block, and a cylinder head are connected in this order. An engine breather apparatus for guiding blow-by gas in the crankcase out of the crankcase, wherein the cylinder block and the cylinder head include the inside of the crankcase and the valve chamber formed in the cylinder head. While forming a breather passage communicating with
A breather outlet is formed on the outer wall of the cylinder head for communicating the inside and outside of the valve operating chamber, and the breather outlet is disposed on the opposite side of the breather passage with respect to a center line connecting the front and rear of the engine.

In order to solve the above-mentioned problem, the breather outlet is covered with a breather cover and a breather chamber is formed inside the breather outlet.

Further, in order to solve the above-mentioned problems,
As described in claim 3, the breather chamber is provided on a side of the cylinder head.

Still further, in order to solve the above-described problem, an intake device is disposed on a side of the engine, and the intake device is connected to the cylinder head via an inlet pipe. On the other hand, the breather outlet is formed on the same side as the intake device while being connected, and the breather cover covering the breather outlet is formed integrally with the inlet pipe.

Then, in order to solve the above-mentioned problem,
As described in claim 5, a valve device is provided at the breather outlet, and the valve device is set so that blow-by gas can pass only from the valve operating chamber to the outside of the valve operating chamber.

[0015]

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 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 inside. A steering handle 4 extends forward from a lower front part of the engine 3 (right side in FIG. 1), and a throttle grip 5 for adjusting an engine output is provided at a tip end thereof.

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.

FIG. 2 is a longitudinal sectional view of the engine 3 of the outboard motor 1, and FIG. 3 is a sectional view taken along the line III-III of FIG. As shown in FIGS. 1 and 2, a crankshaft 10 is provided vertically (vertically) in the engine 3 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, that is, the rotation of the crankshaft 10, 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 14a of the boat 14. That is, the outboard motor 1 is provided so as to be rotatable about 360 ° with respect to the boat 14, and the steering of the boat 14 is performed by changing the direction of the entire outboard motor 1 by swinging the steering handle 4 in the horizontal direction. It is configured to be able to.

On the other hand, the engine 3 used in this embodiment
Is a single-cylinder engine of, for example, a four-cycle OHC type. As shown in FIGS. 2 and 3, the engine 3 includes a front (right side in the figure) crankcase 15 and a rear side (left side in the figure) of the crankcase 15. And a cylinder head 17 on the rear side (left side in the figure) of the cylinder block 16.
The engine 3 is fixed on an extension case 18 provided at the upper end of the shaft housing 6 (see FIG. 1).

The cylinder block 16 includes a cylindrical cylinder 19 extending rearward (to the left in the drawing) in a direction perpendicular to the crankshaft 10, and a rear portion of the cylinder head 17 is opened and a valve valve is provided therein. A chamber 20 is formed and closed by a cylinder head cover 21.

A cylinder bore 22 is provided inside the cylinder 19.
Is formed, and a combustion chamber 23 is formed in the cylinder head 17 so as to match the cylinder bore 22. The ignition plug 24 is connected to the combustion chamber 23 from outside.

A piston 25 is slidably inserted into the cylinder bore 22. The piston 25 and the crankshaft 10 are connected by a connecting rod 26, whereby a reciprocating motion of the piston 25 in the cylinder bore 22 is converted into a rotational motion of the crankshaft 10. At the upper end of the crankshaft 10, a flywheel magneto device 27 for power generation and a rope recoil type engine starting device 28 are provided.

An exhaust port 29 (see FIG. 2) and an intake port 30 (see FIG. 3) connected to the combustion chamber 23 are formed in the cylinder head 17. In the cylinder head 17, an exhaust valve 31 and an intake valve 32 for opening and closing both ports 29, 30 are arranged.

The exhaust port 29 extends downward in the cylinder head 17 toward the extension case 18, and although not shown in detail, exhaust gas is discharged from the extension case 18 through the shaft housing 6 to the outside of the machine. Is done. Further, an intake device 33 is provided on a side portion of the cylinder block 16, that is, on a right side portion in this embodiment.
And a downstream side thereof is connected to an intake port 30 of the cylinder head 17 through an inlet pipe 35 formed of an aluminum alloy or a synthetic resin, and a silencer 36 is provided upstream of the carburetor 34. Is connected.

Valve train chamber 2 formed in cylinder head 17
A valve operating device 37 is provided in 0. The valve gear 37 is a camshaft 3 arranged in parallel with the crankshaft 10.
The rotation of the crankshaft 10 is transmitted to the camshaft 38 via a timing chain (not shown) or the like.

A cam 39 is provided on the camshaft 38. When the camshaft 38 rotates, the profile of the cam 39 swings a rocker arm 41 which is swingably supported by a rocker shaft 40 in the cylinder head 17. Let it. The swinging movement of the rocker arm 41 opens and closes the exhaust valve 31 and the intake valve 32 in the cylinder head 17.

FIG. 4 is a view taken in the direction of the arrow IV in FIG. 3, and is a view of the cylinder block 16 alone viewed from the cylinder head 17 side. 5 is a view taken in the direction of the arrow V in FIG. 3, and is a view of the cylinder head 17 alone viewed from the cylinder block 16 side. 6 is a view taken in the direction of the arrow VI in FIG. 3, and is a view of the cylinder head 17 alone viewed from the cylinder head cover 21 side.

FIG. 7 is a side view of the inlet pipe 35 alone. FIGS. 8 and 9 show V in FIG.
FIG. 3 is a view taken along arrows III and IX, and is a view of a cylinder head 17 alone viewed from a mounting surface side of an inlet pipe 35. FIG. 9 shows a state in which the inlet pipe 35 is attached to the cylinder head 17.

As shown in FIGS. 3 to 9, the engine 3 of the outboard motor 1 is provided with a breather device 42. The breather device 42 escapes gas with pressure leaking into the crankcase 15 by a small amount through the gap between the piston 25 and the cylinder bore 22, that is, blow-by gas, and mixes the blow-by gas into the blow-by gas. This is a means for separating oil.

In the cylinder block 16 and the cylinder head 17, breather passages 43 and 44 for communicating the inside of the crankcase 15 and the inside of the valve train chamber 20 are integrally formed. The breather passages 43 and 44 are formed on the opposite side of the intake device 33 with respect to a center line 45 connecting the front and rear of the engine 3, and on the left side of the engine 3 in the present embodiment.

On the other hand, a breather outlet 46 is formed on the outer wall of the cylinder head 17 to communicate the inside and outside of the valve chamber 20. The breather outlet 46 is formed on the opposite side of the breather passages 43 and 44 with respect to a center line 45 connecting the front and rear of the engine 3, in the present embodiment, on the right side of the engine 3. Further, a reed valve 47 as a valve device is provided outside the breather outlet 46.
7 is set so that the blow-by gas can pass only from the inside of the valve operating chamber 20 to the outside of the valve operating chamber 20.

The breather outlet 46 is covered by a breather cover 48, and forms a breather chamber 49 therein. The breather chamber 49 separates oil mixed in the blow-by gas inside the breather chamber 49,
As shown in FIG. 7, the breather cover 48 is formed integrally with the inlet pipe 35, and is fixed to a seating surface 17a (see FIG. 8) formed on the right side surface of the cylinder head 17 with, for example, bolts 50 (see FIG. 9). ).

A breather oil discharge port 51 communicating with the valve operating chamber 20 is formed on the outer wall of the cylinder head 17 facing the bottom surface of the breather chamber 49, and an oil component in the blow-by gas separated in the breather chamber 49 is formed. That is, it has a role of returning the lubricating oil into the valve operating chamber 20.

On the other hand, a blow-by gas discharge union 52 is formed on the upper surface of the breather cover 48, and one end of a breather hose (not shown) is connected to the blow-by gas discharge union 52. Although not shown in detail, the other end of the breather hose is connected to the intake device 33, and the blow-by gas is reburned in the combustion chamber 23.

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

The breather passages 43 and 44 and the breather chamber 49
Are arranged opposite to each other with a center line 45 connecting the front and rear of the engine 3 therebetween, so that the blow-by gas containing oil flowing from the crankcase 15 into the valve operating chamber 20 is discharged to the outside. The valve gear 3 with this oil
7 can be sufficiently lubricated. As a result, an oil pump or the like becomes unnecessary, and advantageous effects for a small engine such as simplification of structure and assemblability and reduction of cost can be obtained.

Further, since the breather cover 48 forming the breather chamber 49 is formed on the side surface of the cylinder head 17, there is no increase in the length and height of the engine 3 so that the engine 3 can be made compact and the breather outlet can be formed. By providing the reed valve 47 as a valve device in the 46, the lubricating oil does not leak from the breather chamber 49 even when the outboard motor 1 is placed sideways.

Further, the breather cover 48 is connected to the intake device 3.
3 and formed integrally with the inlet pipe 35, it is possible to reduce the number of parts and to improve the assemblability, and to reduce the cost.

[0041]

As described above, according to the breather apparatus for an engine according to the present invention, an engine in which a crankcase, a cylinder block, and a cylinder head are connected in this order, and blow-by gas in the crankcase is removed. In the breather device for an engine that is guided outside the crankcase, a breather passage communicating between the inside of the crankcase and a valve chamber formed in the cylinder head is formed in the cylinder block and the cylinder head. A breather outlet communicating the inside and outside of the valve train chamber is formed on the outer wall, and the breather outlet is disposed on the opposite side of the breather passage with respect to a center line connecting the front and rear of the engine. Can be sufficiently lubricated.

Further, since the breather outlet is covered with a breather cover and a breather chamber is formed in the inside thereof, it is possible to separate the oil mixed in the blow-by gas.

Further, since the breather chamber is provided on the side of the cylinder head, the engine can be made more compact.

Further, an intake device is arranged on a side of the engine, and the intake device is connected to the cylinder head via an inlet pipe, while the breather outlet is formed on the same side as the intake device. Since the breather cover covering the breather outlet is formed integrally with the inlet pipe, the number of parts can be reduced,
The ease of assembly is also improved.

A valve device is provided at the breather outlet, and the valve device is set so that blow-by gas can pass only from the valve operating chamber to the outside of the valve operating chamber. Therefore, lubricating oil is discharged from the breather chamber depending on the storage posture of the engine. Do not leak.

[Brief description of the drawings]

FIG. 1 is a right side view of an outboard motor showing an embodiment of an engine breather device according to the present invention.

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

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

FIG. 4 is a view taken in the direction of an arrow IV in FIG. 3, and is a view of a cylinder block alone viewed from a cylinder head side.

5 is a view taken in the direction of the arrow V in FIG. 3, and is a view of a cylinder head alone viewed from a cylinder block side.

6 is a view taken in the direction of an arrow VI in FIG. 3 and is a view of a cylinder head alone viewed from a cylinder head cover side.

FIG. 7 is a side view of the inlet pipe alone.

FIG. 8 is a view taken in the direction of the arrow VIII in FIG. 3, and is a view of the cylinder head alone viewed from the side where the inlet pipe is attached;

9 is a view taken in the direction of the arrow IX in FIG. 3, and is a view of a cylinder head alone having an inlet pipe attached to the cylinder head as viewed from the inlet pipe mounting surface side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outboard motor 3 Engine 15 Crankcase 16 Cylinder block 17 Cylinder head 20 Valve train room 33 Intake device 35 Inlet pipe 37 Valve train device 42 Breather device 43,44 Breather passage 45 Center line connecting the front and rear of engine 46 Breather outlet 47 Lead Valve (valve device) 48 Breather cover 49 Breather chamber

Claims (5)

[Claims] An engine in which a crankcase, a cylinder block, and a cylinder head are connected in this order,
In a breather device for an engine that guides blow-by gas in the crankcase out of the crankcase, a breather passage that communicates the cylinder block and the cylinder head with the inside of the crankcase and the valve chamber formed in the cylinder head is provided. On the other hand, a breather outlet communicating the inside and outside of the valve operating chamber is formed on the outer wall of the cylinder head, and the breather outlet is disposed on the opposite side of the breather passage with respect to a center line connecting the front and rear of the engine. A breather device for an engine. 2. A breather device for an engine according to claim 1, wherein said breather outlet is covered with a breather cover to form a breather chamber therein. 3. A breather device for an engine according to claim 2, wherein said breather chamber is provided on a side portion of said cylinder head. 4. An intake device is disposed on a side of the engine, and the intake device is connected to the cylinder head via an inlet pipe, while the breather outlet is formed on the same side as the intake device. 5. The breather device for an engine according to claim 4, wherein said breather cover for covering a breather outlet is formed integrally with said inlet pipe. 5. The engine according to claim 1, wherein a valve device is provided at the breather outlet, and the valve device is set so that blow-by gas can pass only from the valve operating chamber to the outside of the valve operating chamber. Breather device.