JPS6324136B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a V-type internal combustion engine, in particular, a V-type internal combustion engine, in which first and second engine blocks are arranged at a certain angle with respect to a crankshaft that they share, and a head portion of each engine block is provided with a first and a second engine block. A pair of intake and exhaust valve drive camshafts are disposed parallel to the crankshaft, and the intake and exhaust valve drive camshafts of the first engine block are arranged between the intake and exhaust valve drive camshafts and the crankshaft, and between the intake and exhaust valve drive camshafts of the first engine block. A timing chain is suspended between the exhaust valve camshaft and the crankshaft, and a tensioner is provided on the slack side of each timing chain to apply tension to the chain, and a tensioner is provided between the two engine blocks. , in which first and second carburetors are arranged to separately supply air-fuel mixture to the cylinders.

In general, in order to improve the filling efficiency of an engine by utilizing the inertia effect of intake air, the intake passage from the intake cylinder inlet of the carburetor to the intake valve port of the cylinder is formed to a predetermined length, and as much as possible, the intake path is formed with bends. However, it is not possible to dispose the first and second carburetors in a narrow space between the first and second engine blocks of the engine while satisfying such requirements. It was extremely difficult.

The present invention has been proposed in view of the above, and includes a crankshaft in which the rotational direction of the crankshaft is set from the first engine block to the second engine block, and the cylinders are connected between the first and second engine blocks. When viewed from the axial direction of the crankshaft, the center lines of the intake cylinders of these carburetors are approximately equal to the angle formed by the center lines of both engine blocks. The above requirements are satisfied by arranging the two carburetors so as to intersect on the dividing line, and by arranging the throttle valve operating devices for both carburetors between the bisecting line and the first engine block. An object of the present invention is to provide the V-type internal combustion engine.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. The shaft 2 is arranged in the left-right direction of the vehicle, and the first and second engine blocks E ₁ and E ₂ that share the crankshaft 2 are arranged in a V-shape at a constant angle θ (in the illustrated example).
90°) opened and placed front to back. These engine blocks E ₁ and E ₂ each have two cylinders 3 ₁ and 3 ₂ .

In the space S between _both engine blocks _E1 and _E2 , _the first
and second carburetors C ₁ and C ₂ are mounted adjacent to each other on the first and second engine blocks E ₁ and E ₂ , respectively. At this time, the center lines D ₁ and D ₂ of the respective intake cylinders 4 ₁ and 4 ₂ of both carburetors C 1 _and C ₂ intersect at a point P when viewed from the side of the engine E, and the point P is Angle θ between center lines A ₁ and A ₂ of both engine blocks E ₁ and E ₂
It is arranged so as to be approximately on the bisector B of .

In Figure 2, each engine block E ₁ , E ₂
The cylinder head 6 is constructed by polymerizing and fixing cylinder heads 6, 6 on cylinder blocks 5, 5 in the usual manner, and head covers 7, 7 are attached to the cylinder heads 6, 6.

Each cylinder head 6, 6 has a pair of valve drive camshafts 8, 9 for intake and exhaust parallel to the crankshaft 2;
9 is rotatably supported, and these valve drive camshafts 8, 9; 8, 9 have intake and exhaust valves 10, 11;
Opening/closing cams 12, 13; 12, 13 of numbers 0 and 11 are integrally provided.

There are two drive sprockets 1 on the crankshaft 2.
4, 14 are fixed in parallel, and driven sprockets 16, 17; 16, 17 are fixed to each pair of camshafts 8, 9; 8, 9, respectively.
6, 17; Endless timing chains 18, 18 are suspended between 16, 17, and the rotation of the crankshaft 2 is controlled by a valve drive cam from each drive sprocket 14 via the timing chain 18 and driven sprockets 16, 17. Transmitted to shafts 8 and 9, intake and exhaust valves 1
0 and 11 can be driven to open and close. In this case, the rotational direction of the crankshaft 2 is set from the first engine block _E1 to the second engine block _E2 .

A tensioner 19 curved in an arcuate shape is disposed on the outer side of the slack side of each timing chain 18,
A fixed end 20 of the tensioner 19 is rotatably supported on the internal combustion engine body by a support shaft 22, and a movable end 21 is rotatably supported by a pivot pin 23 at the free end of a swing arm 24, which will be described later. is connected to. A guide member 25 having a U-shaped cross section is fixed to the back side of the middle part of the tensioner 19, and this guide member 25 surrounds both sides of the timing chain 18 to guide it so that it does not swing left and right.

Inside the timing chain 18, between the crankshaft 2 and the pair of valve drive camshafts 8 and 9, the tensioner 19 is urged toward the timing chain 18 to apply a constant tension to the chain 18. Further, a tension applying device T is provided which automatically adjusts the tension to keep the tension constant even if the chain 15 stretches.
Next, to explain the configuration of this device T, the cylinder heads 6, 6 have driven sprockets 16, 6, respectively.
17, four lower support columns 27, 27... are integrally erected at each vertex of the rectangle, and a support frame 26 formed long in the vertical direction is attached to the fixing bolts 28, 27... on these support columns 27, 27... 28... is rigidly fixed. The support frame 26 is connected to the driven sprocket 1 from the lower supports 27, 27...
It is constructed by integrally joining together an upper support frame 29 extending upward toward the gap G between the lower columns 27, 17, and a lower support frame 30 extending below the tops of the lower columns 27, 27... At the upper end of the support frame 29,
Further, an auxiliary frame 31 having a channel-shaped cross section is fitted from above, and this auxiliary frame 31 has two upper supports 32 extending integrally from the cylinder head 6,
32 by fixing bolts 33, 33. At the upper end of the upper support frame 29, the base end of the swing arm 24, which is curved in a dogleg shape so as to surround the driven sprocket 17, is pivotally supported with a pivot 34 so as to be swingable. The movable end 21 of the tensioner 19 is connected to the free end of the arm 24 with the pivot pin 23, as described above. The swing arm 24 has a U-shaped cross section with the side facing one of the driven sprockets 16 or 17 open, and a part of the driven sprocket 16 or 17 enters into the U-shaped groove 24a. There is. The lower support frame 30 is clearly shown in FIG. 2A.
A rocking piece 35 is pivotally supported at the lower end with a pivot 36, and a locking hole 37 is bored in the bottom surface 35a of the rocking piece 35. The free end of a rod 39, which is pivotally supported at the intermediate portion of the swing arm 24 with a pivot 38, is loosely passed through the stop hole 37. A tension spring 40 is stretched between the intermediate portion of the swing arm 24 and the swing piece 35, and the tensile force of the tension spring 40 causes the swing arm 24 to rotate around the pivot 34 in FIG. Further, the swinging pieces 35 are biased to swing counterclockwise around the pivots 36, the tensioner 19 is pressed against the slack side of the timing chain 18 via the swinging arm 24, and the swinging pieces 35 are biased so as to swing counterclockwise. The clockwise rotation causes the diagonal edges e ₁ and e ₂ of the locking hole 37 to
9 engages with the free end of the rod 39 to prevent the rod 39 from moving with respect to the swinging piece 35 in the pulling direction, that is, in the direction of arrow A in FIG. 2A.

A bow-shaped slider 41 is provided on the tension side of each timing chain 18, and a boss 42 is provided at the base of the slider 41 near the crankshaft 2.
is fixed, and this boss 42 is swingably supported by a support pin 45 supported by the engine body. Further, a restraining piece 43 made of an elastic material is fixed to the back surface of the intermediate portion of the slider 41 near the driven sprocket 17, and the slider 41 is engaged with the engine body via this restraining piece 43. The slider 41 has a support pin 45
The tension side of the timing chain 18 is guided to move along a predetermined trajectory. A guide piece 44 having a U-shaped cross section is provided in the middle of the engine body, and this guide piece 44 surrounds the timing chain 18 and guides it to prevent it from wobbling laterally.

Now, when the internal combustion engine is operated, the crankshaft 2
is rotated clockwise in FIG.
18 and driven sprockets 16, 17; 16,
The signal is transmitted to the camshafts 8, 9 through 17 to drive the valve mechanism. At this time, the tensile force of the tension spring 40 is applied to the tensioner 19 via the swing arm 24.
A predetermined tension is applied to the timing chain 18 by pressing the slack side of the timing chain 18 inward.
By the way, when the timing chain 18 stretches to some extent, the tensile force of the tension spring 40 swings the swing arm 24 clockwise in FIG. A thrust is generated in the direction of arrow B in the figure, and the rod 39 moves in the same direction, and the tensioner 19 moves through the swing arm 24.
is moved to the timing chain 18 side so as to follow the elongation of the timing chain 18, and its tension is automatically adjusted to be constant.

Due to the arrangement of the tensioner 19, the outer wall 6a of the cylinder head 6 located outside its movable end 21 is formed to bulge outward. Due to this bulging outer wall 6a, the space _S2 between the second engine block _E2 and the bisector B is narrower than the space _S1 between the first engine block _E2 and the bisector B.
Therefore, there was a large space on the side of the first engine block _E1.
A throttle valve operating device 46 for the first and second carburetors C ₁ and C ₂ is disposed at S ₁ . This device 46 will now be described.

Each intake cylinder 4 ₁ , 4 ₂ supports the throttle valve 48 ₁ , 48 ₂ in each intake cylinder 4 ₁ , 4 ₂ on its downstream side, and rotates valve shafts 49 ₁ , 49 ₂ that extend parallel to each other. It is freely supported and the first engine block
A driving drum 50 is fixed to the valve shaft 49 ₁ on the E ₁ side, and a driven lever 51 is fixed to the other valve shaft 49 ₂ , and the driving drum 50 and the driven lever 51 are interlocked and connected via a link 52. . A valve opening wire 53 and a valve closing wire 5 are alternately pulled by the driving drum 50 by opening and closing operations of a throttle grip (not shown) provided on the steering handle of the vehicle.
4 is connected. In the above, the main drive drum 50
The opening and closing wires 53 and 54 constitute the throttle valve operating device 46.

When the valve opening wire 53 is pulled, the driving drum ₅₀ rotates to the _left in FIG. , this causes the throttle valve 48 ₁ ,
When the throttle valves 48 ₂ are opened synchronously and the valve closing wire 54 is pulled, the driving drum 50 rotates clockwise to close the throttle valves 48 ₁ and 48 ₂ synchronously.

As described above, according to the present invention, the first and second engine blocks are arranged in a V-shape with the crankshaft that they share as the center, and the head of each engine block is provided with a shaft parallel to the crankshaft. A pair of intake and exhaust valve drive camshafts are arranged between the intake and exhaust valve drive camshafts of the first engine block and the crankshaft, and between the intake and exhaust valve drive camshafts of the second engine block. In a V-type internal combustion engine, a timing chain is suspended between a cam and the crankshaft, and a tensioner is provided on the outside of the slack side of each timing chain to apply tension to the chain. 1st between engine blocks
and the second carburetor are arranged so that the center lines of their intake shells intersect on approximately the bisector of the angle formed by the central axes of both engine blocks when viewed from the axial direction of the crankshaft. In the narrow space between the two carburetors, each intake cylinder of both carburetors can be arranged at a predetermined length without bending, thereby making full use of the inertia effect of the intake air to improve the engine's output performance. Furthermore, since the intake shells of both carburetors intersect, the inlets of those intake shells open in opposite directions, so even if both intake shells are arranged adjacent to each other, there is almost no intake interference, and each carburetor It is possible to stably supply the air-fuel mixture to each cylinder.

Further, the rotational direction of the crankshaft is set from the first engine block to the second engine block, and the throttle valve operating devices for both the carburetors are arranged between the bisector and the first engine block. So,
Although the outer wall of the second engine block bulges due to the presence of the second tensioner and narrows the space between the two engine blocks, the throttle valve operating device can be easily arranged without being obstructed by this. ,
This has the effect of making the engine more compact and improving the maintainability of the carburetor at the same time.

Note that the timing chain in the present invention also includes a toothed timing chain.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a side view of an internal combustion engine mounted on a motorcycle, FIG. 2 is an enlarged cross-sectional side view of the main parts of the engine, and FIG. FIG. 3 is an enlarged view of a part of FIG. 2, and FIG. 3 is an enlarged view of FIG. A ₁ , A ₂ ... Center line of the first and second engine blocks, B ... Bisector line, C ₁ , C ₂ ... First and second engine blocks
Carburetor, E ₁ , E ₂ ... First and second engine blocks, θ ... Angle formed by center lines A ₁ and A ₂ , E ... Internal combustion engine, 2 ... Crankshaft, 8 ... Intake drive Valve camshaft, 9... Exhaust valve drive camshaft, 18... Timing chain, 19... Tensioner, 46... Throttle valve operating device, 48 ₁ , 48 ₂ ... Throttle valve.

Claims (1)

[Claims] 1 The first and second engine blocks are arranged in a V-shape with the crankshaft that they share as the center, and a pair of intake and exhaust valves are provided at the head of each engine block parallel to the crankshaft. A camshaft is provided between the intake and exhaust valve drive camshafts of the first engine block and the crankshaft, and between the intake and exhaust valve drive camshafts of the second engine block and the crankshaft. In a V-type internal combustion engine, in which a timing chain is suspended in between, and a tensioner is provided on the outside of the slack side of each timing chain to apply tension to the chain, the direction of rotation of the crankshaft is determined from the first engine block. set in the direction toward the second engine block, and the first and second
Between the engine blocks, there are first and second carburetors that separately supply air-fuel mixture to the respective cylinders, and when viewed from the axial direction of the crankshaft, the center line of the intake cylinders of these carburetors is located at the center of both engine blocks. The two carburetors are arranged so as to intersect on a substantially bisector of the angle formed by the lines, and the throttle valve operating devices for both carburetors are arranged between the bisector and the first engine block. A V-type internal combustion engine.