JPH0119045B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an overhead camshaft type multi-cylinder V-type 4-cycle engine, and more specifically to an overhead camshaft that is compact and quiet while having a breather chamber. This invention relates to a multi-cylinder V-type four-stroke engine.

[Conventional technology]

2. Description of the Related Art A relatively large engine installed in a motorcycle or the like is a so-called overhead camshaft multi-cylinder V-type four-stroke engine. This engine has a plurality of cylinders arranged in a V-shape, and a camshaft for valve operation is arranged above a cylinder head arranged above each cylinder. Because each cylinder has a large head at the top, it is easy to generate vibrations, and because it is arranged in a V shape, it acts like a tuning fork, reducing the noise peculiar to V-type engines. There was a problem that occurred.

In addition, in this type of engine, the crank chamber is repeatedly pressurized and depressurized as the piston reciprocates, and blow-by gas leaking from the combustion chamber side flows in. Therefore, this blow-by gas is transferred to the crank chamber. When pressurized, it is vented to the outside. On the other hand, since the crank chamber is filled with lubricating oil in the form of mist, when the blow-by gas is discharged, this oil is also taken along with it and may pollute the environment. A breather chamber is provided in between, and the blow-by gas and oil are separated in this breather chamber, and only the blow-by gas is discharged.

However, if such a breather chamber is simply installed on the side of the engine, the engine will become larger. This is especially true in vehicles such as motorcycles, where various devices are installed in a limited space. This was not desirable as it would lead to an increase in size.

[Problem to be solved by the invention]

An object of the present invention is to provide an overhead camshaft multi-cylinder V-type 4-cycle engine that prevents the above-mentioned noise peculiar to the V-type engine from being generated and also prevents the breather chamber from increasing the size of the vehicle body. There is a particular thing.

[Means to solve the problem]

To achieve the above object, the present invention is an overhead camshaft type multi-cylinder V-type engine in which a plurality of cylinder parts are arranged in a V-shape, and a camshaft for valve operation is arranged in the upper part of the cylinder head arranged in the upper part of each cylinder part. In a 4-stroke engine, the plurality of cylinder parts are integrally formed in the upper crankcase of the crankcase which is divided into upper and lower parts, and the upper ends and lower ends of the cylinder parts arranged in a V shape are respectively joined together by partition walls. and a V-shaped space inside thereof is formed into a breather chamber surrounded by the upper and lower partition walls and the cylinder part, and this breather chamber is communicated with the crank chamber through a throttle hole. be.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to embodiments shown in the drawings. In FIG. 1, 1 and 2 are front and rear wheels of a motorcycle, respectively, 3 is a handlebar, 4 is a fuel tank, and 5 is a seat. A four-stroke engine 6 is mounted below the fuel tank 4, and has four cylinders arranged in a V-shape. 7 is an air cleaner, front and rear carburetors 8, 8' are connected to this air cleaner 7, and engine 6 is connected to the front and rear carburetors 8, 8'.
The combustion chamber is reached from the front and rear cylinder heads 9a, 9'a. A radiator 11 for cooling cooling water for the engine 6 is provided in front of the down tube 10.

As shown in detail in FIGS. 2 and 3, the cylinder body 9 has cylinder parts 9b and 9'b arranged in a V-shape at the front and rear, and cylinder heads 9a and 9'a are fixed to the upper parts of the cylinder parts 9b and 9'b, respectively. It is configured as follows. The lower part of the cylinder body 9 also serves as the upper crankcase 12.
2 is combined with the lower crankcase 13 to form a crank chamber 14 inside. 15 is a crankshaft, to which the large ends of connecting rods 16, 16' are rotatably connected, and the small ends of these connecting rods 16, 16' are connected to cylinder parts 9b, 9. Piston 17, 1 inserted into 'b
7' and are rotatably connected to each other.

An intermediate shaft 20 is supported via bearings 18, 19 in a V-shaped space formed between the front and rear cylinder parts 9b, 9'b, and the intermediate shaft 20 is By suspending a chain 23 between the sprocket 21 and the sprocket 22 at the end of the crankshaft 15, the power of the crankshaft 15 is transmitted. crankshaft 1
The intermediate shaft 20, which rotates under the power of the cylinder head 5, is connected to camshafts 26, 27, and 26 provided above the cylinder heads 9, 9'a by chains 25, 25' suspended from sprockets 24, 24' on the shaft. ',2
7' are rotated respectively. Camshafts 26, 27, 26', 27' drive intake and exhaust valves, respectively.

The sprockets 21, 22 and the chain 23 are housed in a chain housing 28 that is independently surrounded by a wall on the side of the crank chamber 14, and the chain housing 28 and the crank chamber are relatively small. They are communicated via a restricting hole 29 having a large area. In addition, the front and rear cylinder parts 9
The V-shaped space sandwiched between b and 9b' is located between both cylinder parts 9
b, 9b' are connected at their upper ends by a partition wall 37 and at their lower ends by a partition wall 39, thereby forming a housing surrounded by the surroundings. In this embodiment, the housing is divided into two parts: a housing 30, which is separated by a wall that supports bearings 18, 19 that pivotally support the intermediate shaft 20 on both sides of the sprockets 24, 24', and a housing 33, which is adjacent thereto. formed, the former housing 3
0 is the breather chamber 30. This breather chamber 30 communicates with the aforementioned chain housing 28 through a throttle hole 31 with a relatively small area, and further communicates with the adjacent housing 33 separated by the support wall of the bearing 19 through a throttle hole 32. There is. The housing 33 further communicates with the atmosphere via a conduit 34 and an air cleaner, which is an intake system.

Further, 35 is a generator, 38 is an ignition device, and 36 is a water pump.

According to the above-described device, the blow-by gas pressurized from the crank chamber 14 is accompanied by the throttle hole 29.
The mist-like oil carried into the chain housing 28 through the pores 29 condenses due to the pressure drop in the general hole 29 or adheres to the wall surface, and is returned to the crank chamber 14 again. Further, when the blow-by gas flows from the chain housing 28 through the throttle hole 31 to the breather chamber 30, the remaining oil droplets are mostly aggregated and removed due to the same phenomenon as described above, and then flowed through the throttle holes 31 and 29. The water then flows back to the crank chamber 14.

According to the above-mentioned engine, the upper ends of both the front and rear cylinder parts 9b, 9b' are integrally connected to each other by the partition wall 37, and the lower ends thereof are connected to each other by the partition wall 39.
Furthermore, since the cylinder part is integrally connected to the upper crankcase 12, the rigidity of the cylinder body 9 can be increased without particularly increasing the wall thickness of the cylinder part or the crankcase. This improves the vibration characteristics. That is, in the above configuration, the partition walls 37 and 3
9 suppresses the generation of vibration in the cylinder parts 9b and 9b' by absorbing strain energy caused by vibration, reducing noise caused by tuning fork vibration peculiar to an overhead camshaft type V-type engine, and making it quiet. enables smooth driving.

It has been confirmed by vibration analysis that the strain energy sharing rate by the partition walls 37 and 39 is particularly larger for the partition wall 39 that connects the lower ends of each other than for the partition wall 37 that connects the upper ends of each other. The lower partition wall 39 that performs such an action may be provided with a throttle hole that communicates with the crank chamber 14, but if provided, it is not preferable to make it too large as this will reduce the above effect.

Further, in the above engine, the V-shaped space surrounded by the partition walls 37, 39 and the cylinder parts 9b, 9b' is used as the breather chamber 30, so there is no need to prepare a special space for this breather chamber. , the sides of the engine do not protrude. Therefore, there is no need to increase the size of the vehicle body.
Furthermore, there is no increase in weight due to an increase in the size of the vehicle body.

Further, the breather chamber 30 includes both cylinder portions 9.
Since it utilizes a V-shaped space surrounded by 9b and 9b', it has a larger volume compared to the small breather chamber generally provided in conventional engines, so it is possible to prevent lubrication in blow-by gas. Complete separation of the oil mist can be advantageous.

〔Effect of the invention〕

As described above, the overhead camshaft type multi-cylinder V-type 4-stroke engine of the present invention has the plurality of cylinder parts integrally formed in the upper crankcase of the crankcase which is divided into upper and lower parts, and arranged in a V-shape. Since the upper and lower ends of the cylinder parts are integrally connected by partition walls, the rigidity is increased without increasing the wall thickness of the cylinder parts, etc., and the generation of vibrations is suppressed. It is possible to prevent the generation of noise due to

Furthermore, since the V-shaped space sandwiched between the upper and lower partition walls and the cylinder section is used as a breather chamber, the breather chamber can be installed without providing a special space, and the engine can be made more compact.
Furthermore, since the breather chamber can have a larger volume than the breather chamber of a conventional engine, it is possible to improve the effect of separating lubricant mist in the blow-by gas.

[Brief explanation of drawings]

FIG. 1 is a side view of a motorcycle equipped with a breather device according to the present invention, FIG. 2 is a side view showing a partially cut away engine portion, and FIG. 3 is a cross-sectional view taken from FIG. 2. 6...Engine, 9...Cylinder body, 9
a, 9'a... cylinder head, 9b, 9'b...
Cylinder part, 14... Crank chamber, 15... Crankshaft, 20... Intermediate shaft, 26, 27, 26',
27'...camshaft, 28...chain housing,
29, 31, 32... Throttle hole, 30... Breather chamber, 34... Conduit, 37, 39... Partition wall.

Claims (1)

[Claims] 1 In an overhead camshaft type multi-cylinder V-type 4-cycle engine in which multiple cylinders are arranged in a V shape and a camshaft for valve operation is placed above the cylinder head placed above each cylinder, the engine is divided into upper and lower parts. The plurality of cylinder parts are integrally formed in the upper crankcase of the crankcase arranged in a V-shape, and the upper and lower ends of the cylinder parts arranged in a V-shape are integrally connected by a partition wall, and the inner V An overhead camshaft type multi-cylinder V-type 4-stroke engine in which a shape space is formed in a breather chamber surrounded by the above-mentioned upper and lower partition walls and a cylinder section, and this breather chamber is communicated with a crank chamber through a throttle hole.