JPS6324135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a V-type internal combustion engine, in particular, two cylinder blocks arranged in a V-shape with a bank angle of approximately 90 degrees centered on the crankshaft, and these cylinder blocks The present invention relates to a casing that is integrally formed with a casing that supports the crankshaft and the transmission shaft.

Such a V-type internal combustion engine can eliminate primary inertia force simply by adding balance wear to the crankshaft, so it has the advantage of less vibration, but in conventional engines, the crankshaft and transmission shaft are arranged in series. Because of this relationship, the casing extends long in the axial direction of the crankshaft, which has the disadvantage of increasing the size of the entire engine.In machines where the installation space for the engine is narrow, such as motorcycles, there are various ways to mount the engine. accompanied by great difficulties.

Therefore, in order to reduce the size of the engine, the cylinders in each cylinder block were formed into an overscale type to lower the height of the cylinder block.
It is conceivable to arrange the transmission shaft in parallel behind the crankshaft so that the casing extends in the direction of the dead space behind the rear cylinder. In this case, from the perspective of processing and assembly, it is convenient to divide the casing into upper and lower parts along a plane that includes the axes of the crankshaft and transmission shaft. Required when equipped with a cylinder.

However, there are the following problems here.
In other words, if the height of each cylinder block is made sufficiently low by adopting an overscale type cylinder, the upper and lower dividing plane of the casing crosses the front cylinder, and the rear upper surface of the casing crosses the rear cylinder block and cylinder head. It may protrude above the joint surface, making it difficult to manufacture the engine.

The present invention was proposed in view of the above, and an object of the present invention is to provide a V-type internal combustion engine that is small, has little vibration, and is easy to manufacture. part cylinder block and rear cylinder block,
These cylinder blocks are arranged in a V-shape with a bank angle of approximately 90° centered on the crankshaft.
The crankshaft is integrally formed with a casing that supports a speed change input shaft and a speed change output shaft disposed in parallel thereto, and the crankshaft and speed change input shaft are formed so as to include their axes and have a bank angle of 2. The casing is arranged on a plane perpendicular to the dividing line, and the casing is divided into an upper casing and a lower casing by the plane, and the straight line extends within a range of 20° from the bisector of the bank angle to the rear cylinder block side. It is located in the place where it is set to pass through.

Below, _{an embodiment} in which the present invention is applied to a motorcycle will be described with reference to the drawings. They are arranged in a V-shape with a bank angle α of approximately 90°. Inside each cylinder block 1 ₁ , 1 ₂ there are 2
Overscale type cylinders 3 ₁ , 3 ₂ are formed, and cylinder heads 4 ₁ , 4 ₂ are joined to their upper end surfaces, and these joining surfaces are A ₁ , 3 2 .
Indicated by A ₂ . A casing 5 extending to the rear of the rear cylinder block ₁ 2 is integrally connected to the lower part of both cylinder blocks 1 1 and _{1 2 ,} and the casing 5 connects the crankshaft 2 and the transmission shaft arranged in parallel behind it. That is, the speed change input shaft 6 and the speed change output shaft 7 are supported.

The connecting rod ₉₁ connected to the piston ₈₁ in the front cylinder ₃₁ and the connecting rod ₉₂ connected to the piston ₈₂ in the rear _cylinder 32 are adjacent to each other, and are connected to the common crank pin 2a of the crankshaft 2. A balance weight 10 is attached to the crankshaft 2 on the opposite side of the crank pin 2a with respect to the axis of the crankshaft 2, and the centrifugal force of this weight 10 is balanced with the primary inertia force of both pistons 8 ₁ and 8 ₂ . It's starting to fit. The allowable range of the bank angle α that satisfies this balance in practice is approximately 90°±10°.

When the crankshaft 2 and the transmission shaft are arranged in parallel, in particular, the crankshaft 2 and the transmission input shaft 6 are arranged on a plane C that is perpendicular to the straight line B that bisects the bank angle α; Said casing 5
is divided into an upper casing 5a and a lower casing 5b. Therefore, the crankshaft 2 and the speed change input shaft 6 are supported between the divided surfaces of the upper and lower casings 5a and 5b. On the other hand, the speed change output shaft 7 is arranged behind and below the speed change input shaft 6, and therefore,
It is supported by the lower casing 5b. A multi-stage speed change gear train 11 is provided within the casing 5 between the speed change input and output shafts 6 and 7.

The plane C, which is the plane where the crankshaft 2 and the speed change input shaft 6 are arranged, and which is the dividing plane of the upper and lower casings 5a and 5b, must not cross the cylinder ₃₁ of the front cylinder block ₁₁ at the front. In addition, if the position of the speed change input shaft 6 rises excessively at the rear, the casing 5
The rear upper surface of the cylinder must not protrude above the joint surface _A2 between the rear cylinder block ₁₂ and the cylinder head ₄₂ . If the upper surface of the casing 5 protrudes and occupies a position above the joint surface _A2 , the joint surface of the rear cylinder block ₁₂
When grinding _A2 , the casing 5 gets in the way and the machining becomes extremely difficult.

For this reason, the plane C should be avoided to approach the axis of the front cylinder block 1 ₁ within β = 20°, and the plane C should be avoided from approaching the axis of the rear cylinder block 1 ₂ by δ = 50° or less should be avoided. In order to satisfy such conditions, if the position of the plane C is defined from the position of the straight line B perpendicular thereto, then γ=0 from the bisector D of the bank angle α toward the rear cylinder block ₁₂ side. The straight line B may be set within an angular range of ~20 degrees, but γ=10 degrees is particularly optimal.

In the illustrated example, a clutch 1 is connected to one end of the speed change input shaft 6.
2 is attached, and a clutch housing 13 accommodating the clutch housing 13 is connected to one end of the casing 5 at an appropriate distance outwardly from the rear cylinder block ₁₂ . Therefore, even if the clutch 12 has a large diameter and the upper surface of its housing 13 protrudes above the joint surface A ₂ between the rear cylinder block 1 ₂ and the cylinder head 4 ₂ , the housing 13 will not fit into the rear cylinder block 1 ₂ . It does not interfere with grinding of joint surface _A2 .

In the figure, reference numeral 14 denotes an oil pan joined to the lower casing 5b, and its joining surface F is parallel to the plane C.

When the internal combustion engine E is mounted on the motorcycle M, the internal combustion engine E is held in such a position that the front cylinder block ₁₁ is largely tilted forward and the rear cylinder block ₁₂ is substantially upright. In this position, the engine E can be compactly accommodated in the narrow space directly below the fuel tank Mt, and both cylinder blocks 1
Cooling by the running wind of both Nos. ₁ and 1 ₂ can be performed satisfactorily.

As described above, according to the present invention, the front cylinder block 1 1 and the rear cylinder block _{1 2} each include overscale type cylinders 3 ₁ and 3 ₂ .
are arranged in a V-shape with a bank angle α of approximately 90° centered on the crankshaft 2, and these cylinder blocks 1 ₁ and 1 ₂ are arranged behind the crankshaft 2 and in parallel therewith. Since the shaft 6 and the variable speed output shaft 7 are integrally formed in the casing 5 that supports the shaft 6 and the variable speed output shaft 7, it is possible to extend the casing 5 to the rear of the rear cylinder block ₁₂ , which is generally regarded as a dead _space .
_1. Together with the reduction in height, the V-type engine E can be made smaller.

Further, the crankshaft 2 and the speed change input shaft 6 are
The casing 5 is arranged on a plane C that includes these axes and is orthogonal to a straight line B that bisects the bank angle α, and divides the casing 5 into an upper casing 5a and a lower casing 5b on the plane C. Since it is set to pass through the range from the bisector D of the bank angle α to 20° on the rear cylinder block ₁₂ side, the dividing plane of the casing 5 is aligned with the front cylinder 3.
₁ or the casing 5 obstructing the grinding of the joint surface A 2 of the rear cylinder block 1 ₂ with the cylinder head 4 ₂ can be avoided, making _it easier to process and assemble each part. It can be done.

[Brief explanation of the drawing]

The drawing is a side view of an embodiment of the engine of the present invention. α...bank angle, B...straight line, C...plane, D
... Bisector, E ... Internal combustion engine, 1 ₁ , 1 ₂ ...
Front and rear cylinder blocks, 2...crankshaft,
3 ₁ , 3 ₂ ... cylinder, 4 ₁ , 4 ₂ ... cylinder head, 5 ... casing, 5a, 5b ... upper and lower casings, 6 ... speed change input shaft, 7 ... speed change output shaft.

Claims (1)

[Claims] 1 each overscale type cylinder 3 ₁ ,
A front cylinder block ₁₁ and a rear cylinder block ₁₂ each having a cylinder block 11 and a rear cylinder block ₁₂ are arranged in a V-shape with a bank angle α of approximately 90° centered on the crankshaft 2,
These cylinder blocks 1 ₁ , 1 ₂ are integrally formed in a casing 5 that supports the crankshaft 2 and a speed change input shaft 6 and a speed change output shaft 7 arranged behind and in parallel thereto. The input shaft 6 is arranged on a plane C that includes these axes and is orthogonal to a straight line B that bisects the bank angle α, and the casing 5 is divided into an upper casing 5a and a lower casing 5b on the plane C. , a V-type internal combustion engine in which the straight line B is set to pass through a range from the bisector D of the bank angle α to 20° on the rear cylinder block ₁₂ side.