JPS6319681B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal combustion engine, particularly a V-type internal combustion engine in which two cylinder rows are arranged in a V-shape and a common crankcase is connected to the lower end of the cylinder rows. Regarding a valve device.

Conventionally, in the above-mentioned valve train, a single camshaft that is linked to the crankshaft in the crankcase is arranged in the center between both cylinder rows, and this camshaft connects the cylinder head of each cylinder row via a push rod. There is a known device that opens and closes the intake and exhaust valves by swinging a rotary arm that is supported on a shaft (see Utility Model Application Publication No. 2962 of 1948). This has the advantage that one camshaft can be shared, and the V-shaped space between the cylinder rows can be used as the installation space for the camshaft. However, in the above conventional system, only one follower shaft is disposed directly above the camshaft, and it supports a locking follower that extends toward each cylinder row and engages with the camshaft. Since the push rod is interlocked and connected to the lower end, it is not possible to tilt the push rod greatly with respect to the cylinder axis, and the upper end of the push rod is separated from the upper end of the cylinder row, which affects the overall shape of the valve mechanism and therefore the cylinder head. As the camshaft becomes larger, there are more restrictions on the placement of intake and exhaust valves.If you try to place the camshaft close to the crankshaft, there is a risk that the lower end of the rocker follower and the lower end of the push rod will interfere with the cylinder row, and the camshaft will eventually and was forced to be placed at a distance above it,
Therefore, there are problems such as the fact that the camshaft and the follower shaft above the camshaft cannot be arranged compactly together at the bottom of the V-shaped space between both cylinder rows.

In addition, in order to omit the above-mentioned lock follower, it is already known that the lower end of the push rod is brought into direct sliding contact with the cam surface of the camshaft, as shown in Japanese Patent Publication No. 48-12483. Since the center of rotation of the camshaft is located on the axis of V between cylinder rows
The bottom of the V-shaped space protrudes upward to a large extent, making it easier to interfere with the fuel supply device, etc. above the V-shaped space, and the timing transmission device that interlocks the camshaft and crankshaft becomes larger. This causes problems such as:

An object of the present invention is to provide a valve train for a V-type internal combustion engine that can eliminate all of the above-mentioned problems. In a valve train for a V-type internal combustion engine in which a common crankcase is arranged in series, one camshaft interlocked with the crankshaft in the crankcase via a timing transmission is connected to a central part between the two cylinder rows. and disposed close to the crankshaft, a pair of follower shafts are disposed between each of the camshafts and both cylinder rows so as to sandwich the camshafts, and each of the follower shafts includes: A rocker follower extending from the shaft as a base point toward the cylinder row farther from the shaft and engaging with the camshaft is supported, and an intake valve or The exhaust valve and the rocker arm are connected to each other via a push rod whose axis is offset to the opposite side of the crankshaft with respect to the center of rotation of the camshaft.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The illustrated internal combustion engine has two left and right cylinder rows C ₁ , each having a plurality of cylinders 1 arranged in parallel.
It is configured in a V-shape by arranging C ₂ in a V-shape.
A common crankcase 3 is integrally connected to the lower ends of the cylinder blocks 2 of both cylinder rows C ₁ and C ₂ , and a piston 5 that slides into each cylinder 1 is connected to a crankshaft 4 supported by this crankcase 3 .
are connected via a connecting rod 6.

Each cylinder head 7 of cylinder rows C ₁ and C ₂ has the following:
A main combustion chamber 8 defined by the piston 5, a sub-combustion chamber 9 communicating with the combustion chamber 8 via a torch nozzle 10, a main intake port 11 and an exhaust port 13 opening into the main combustion chamber 8, A sub-intake port 12 that opens into the chamber 9 is formed, and the main intake port 11 is opened and closed by a main intake valve 14, the sub-intake port 12 is opened and closed by a sub-intake valve 15, and the exhaust port 13 is opened and closed by an exhaust valve 16. . These valves 14, 15, 16 are attached with valve closing springs 35, 36, 37 that bias them in the closing direction.

An ignition plug 17 screwed onto the cylinder head 7 has an electrode facing the auxiliary combustion chamber 9.

Cylinder heads 7, 7 of both cylinder rows C ₁ and C ₂
An intake manifold 18 is installed between them, and a carburetor 19 is attached to the upper surface of the intake manifold 18. The carburetor 19 can simultaneously generate a lean mixture and a rich mixture, and the intake manifold 18 supplies the lean mixture to all main intake ports 11 and the rich mixture to all sub-intake ports 12. can be distributed.

A camshaft 20 is disposed as close as possible to the crankshaft 4 in the center between both cylinder rows C ₁ and C ₂ . This camshaft 20 is supported by a cylinder block 2, and a timing transmission device 2 includes a pair of gears 21, 22 and a chain 23 suspended between them.
4, and is connected to the crankshaft 4 via the crankshaft 4, and is then driven at a reduction ratio of 1/2.

Further, a pair of left and right follower shafts 25 are disposed between the camshaft 20 and the cylinder rows C ₁ and C ₂ so as to sandwich the camshaft 20 therebetween. The exhaust follower shaft 27 is connected to each follower shaft 25.
The cylinder row 1 that is farther from the axis 25 based on
The inner surfaces of their swinging ends engage with the intake cam 20a and the exhaust cam 20b of the camshaft 20, respectively, and the intake push rod 30 and the exhaust push rod are provided on their outer surfaces. The inner ends of 31 are each spherically connected.

On the other hand, an intake rocker arm 33 and an exhaust rocker arm 34 are pivotally supported on the rocker shaft 32 supported by each cylinder head 7. Main intake valve 14 and sub-intake valve 1 in the middle part
The upper end of the air intake push rod 30 is in contact with the upper end of the rocker arm 33, and the outer end of the intake push rod 30 is spherically connected to the tip of the outer arm of the rocker arm 33. Also, exhaust Rotsuka arm 3
The upper end of the exhaust valve 16 is in contact with the tip of the outer arm of the rocker arm 34, and the outer end of the exhaust push rod 31 is spherically connected to the tip of the inner arm of the rocker arm 34.

Therefore, the intake and exhaust push rods 30, 31
The axis line is offset from the rotation center of the camshaft 20 to the side opposite to the crankshaft 4.

The intake rocker arm 33 is the push rod 3.
Valve head gap adjustment bolts 38 and 39 are provided at the spherical connection part with 0 and the contact part with the sub-intake valve 15, and the exhaust rocker arm 34 is not provided with such bolts; A hydraulic tappet mechanism 40 is installed in the rocker follower 27 as follows.

As clearly shown in FIG. 4, the exhaust rocker follower 27 has at its tip a hydraulic cylinder 41 whose axis is in the swinging direction, and tappets 42 and 43, which are divided into upper and lower halves, are slid onto the cylinder 41, and the upper tappet 42
The inner end of the push rod 31 is connected to the spherical surface.
A first oil chamber 44 is provided between the tappets 42 and 43, and a second oil chamber 45 is provided between the lower tappet 43 and the bottom of the hydraulic cylinder 41 and communicates with the first oil chamber 44 through a valve port 46. The second oil chamber 45 accommodates a spring 47 that urges the lower tappet 43 upward, and a check valve 48 that closes the valve port 46 with the biasing force of the spring 47. lubricating oil for the engine is supplied through an oil passage 49 from an oil pump (not shown).

Therefore, the exhaust roller lower 27 is connected to the cam 20.
When touching b on the base circle, tappet 42,
43 is pushed up by the elastic force of the spring 47 to make the valve head gap of the exhaust valve 16 zero, and accordingly, the check valve 48 opens and the oil in the first oil chamber 44 fills the second oil chamber 45. When the lift action of the cam 20b starts, the check valve 48 closes and the oil pressure in the second oil chamber 45 increases, and the tappets 42 and 43 move toward the lock follower 27.
The push rod 31 can be pushed up.

In the figure, 50 is a head cover, and 51 is an exhaust manifold connected to the exhaust port 13.

Next, to explain the operation of this embodiment, the camshaft 20 is rotated from the crankshaft 4 via the timing transmission 24, and the intake and exhaust cams 20a and 20b of the camshaft 20 are rotated from the crankshaft 4 via the timing transmission 24.
When the lift action starts, the suction and exhaust rocker followers 26 and 27 are respectively swung upward and push up the suction and exhaust push rods 30 and 31. According to this pushing up of the intake push rod 30, the intake rocker arm 33 swings and the main
When the auxiliary intake valves 14 and 15 are opened against the valve closing springs 35 and 36, and when the exhaust push rod 31 is pushed up, the exhaust rocker arm 34 swings to open the exhaust valve 16 against the valve closing spring 37. Open it. Then, when the lifting action of the cams 20a, 20b is finished, each valve 14, 15, 16 is released by its respective valve closing spring 35,
It can be closed by the elastic force of 36 and 37.

When the main and auxiliary intake valves 14 and 15 are opened, this corresponds to the intake stroke of the piston 5 in the corresponding cylinder 1, so that the lean mixture passes through the main intake port 11 and enters the main combustion chamber 8, and the rich mixture Air is supplied to the sub-combustion chambers 9 through the sub-intake ports 12, respectively. Then, in the next compression stroke, the rich mixture in the auxiliary combustion chamber 9 is ignited by the discharge of the spark plug 17, and the flame is injected into the main combustion chamber 8 through the torch nozzle 10, igniting the lean mixture in the chamber 8. Ignite and burn. As a result, combustion of a mixture with a lean overall air-fuel ratio becomes possible. In response, the piston 5 moves to the expansion stroke, and in the next exhaust stroke, the exhaust valve 16 is opened as described above, so that the burned gas flows into the exhaust port 13.
is discharged to.

As described above, according to the present invention, in the valve operating system for a V-type internal combustion engine in which two cylinder rows are arranged in a V-shape and a common crankcase is connected to the lower end of the cylinder rows, A camshaft interlocked with the crankshaft in the crankcase via a timing transmission is disposed in the center between the two cylinder rows and close to the crankshaft, and this camshaft and the two cylinders A pair of follower shafts are disposed between each row and the cam shaft so as to sandwich the cam shaft therebetween, and each of the follower shafts has a cam shaft extending from the shaft as a base point toward the cylinder row farther from the shaft. A rocker follower that engages with the shaft is supported, and an axis is aligned with the center of rotation of the camshaft between the rocker follower and a rocker arm that is pivotally supported by each cylinder head of both cylinder rows and is linked to an intake valve or an exhaust valve. On the other hand, since the camshaft is connected via a push rod that is offset to the opposite side of the crankshaft, even though the camshaft is placed close to the crankshaft, the axis of the pushrod is largely offset to the opposite side of the crankshaft with respect to the center of the camshaft. Therefore, it is possible to properly arrange the push rod, that is, to have a large inclination angle with respect to the cylinder axis so that the upper end of the rod can be close to the upper end of the cylinder row, and the valve mechanism and the cylinder The overall shape of the head section can be made smaller, and there are fewer restrictions on the arrangement of intake and exhaust valves. Moreover, even if the camshaft is placed close to the crankshaft, there is no risk that the rocker follower or the lower end of the push rod will interfere with the cylinder row, so the camshaft can be placed as close to the crankshaft as possible, and the camshaft The camshaft and follower shafts can be compactly arranged at the bottom of the V-shaped space between both cylinder rows, and the upper part of the V-shaped space can be effectively used as an installation space for intake and exhaust manifolds, carburetors, etc. The timing transmission device between the crankshaft and the crankshaft can be downsized.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional front view of a V-type multi-cylinder internal combustion engine equipped with the valve train of the present invention, and Fig. 2 is a longitudinal cross-sectional side view thereof.
FIG. 3 is an enlarged plan view of one cylinder row with the head cover removed, and FIG. 4 is an enlarged vertical sectional view of the exhaust rocker follower having a hydraulic tappet mechanism. C ₁ , C ₂ ... Cylinder row, 1 ... Cylinder, 4
...Crankshaft, 7...Cylinder head, 14...
... Main intake valve, 15 ... Sub-intake valve, 16 ... Exhaust valve, 20 ... Camshaft, 24 ... Timing transmission, 2
5... Follower shaft, 26... Locker follower for intake, 27... Locker follower for exhaust, 30... Push rod for intake, 31... Push rod for exhaust, 33... Locker arm for intake, 34... Locker arm for exhaust, 40... ...Hydraulic tappet mechanism.

Claims (1)

[Scope of Claims] 1. In a valve train for a V-type internal combustion engine in which two cylinder rows are arranged in a V-shape and a common crankcase is connected to the lower end of these cylinder rows, A camshaft interlocked with the crankshaft of the cylinder via a timing transmission is disposed in the center between the two cylinder rows and close to the crankshaft, and the camshaft and the cylinder rows are connected to each other. A pair of follower shafts are disposed in the middle of each of them so as to sandwich the cam shaft therebetween, and each of the follower shafts has a pair of follower shafts extending from the shaft as a base point toward the row of cylinders farther from the shaft and engaged with the cam shaft. We support the Lotsukafuoroa that matches,
The axis between this rocker follower and a rocker arm that is pivotally supported by each cylinder head of both cylinder rows and interlocks with an intake valve or an exhaust valve is deviated to the opposite side of the crankshaft with respect to the center of rotation of the camshaft. A valve train for a V-type internal combustion engine that is connected via a push rod. 2. In what is stated in claim 1,
The rocker arm is linked to at least two intake valves provided on the same cylinder head.
A valve train for a V-type internal combustion engine. 3 In what is stated in claim 1,
A valve train for a V-type internal combustion engine, wherein the lock follower is provided with a hydraulic tappet mechanism connected to the push rod.