JPH0233846B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-valve internal combustion engine, in particular, to a four-valve internal combustion engine, in which the electrode of the spark plug mounted on the cylinder head faces the combustion chamber near the cylinder axis, and The present invention relates to a four-valve internal combustion engine in which a valve and an exhaust valve are arranged to surround the electrode.

The OHC type valve train in a four-valve internal combustion engine includes the SOHC type valve train, which has a single camshaft perpendicular to the axis of the cylinder, and the SOHC type valve train, which has one camshaft arranged perpendicular to the axis of the cylinder, and the SOHC type valve train, which has one camshaft installed in the vicinity of the intake and exhaust valves, respectively. There is a DOHC type valve train that has two camshafts for exhaust.
In the former, two rocker shafts are installed on both sides of the camshaft to support the suction and exhaust rocker arms that connect the camshaft and the intake and exhaust valves, so the camshaft and rocker shaft However, the structure of the timing transmission device that drives the camshaft from the crankshaft is simple, and the structure of the timing transmission device that drives the camshaft from the crankshaft is simple. Since only one shaft is required, it is advantageous for reducing the weight of the engine. On the other hand, in the latter case, the spark plug electrode can be easily placed near the cylinder axis without being interfered with by the two camshafts, which reduces the engine output. Although performance can be improved, the structure of the timing transmission becomes more complicated and the weight of the engine increases, so each has its advantages and disadvantages.

Therefore, the present invention makes it possible to arrange the electrode of the spark plug near the cylinder axis even though there is only one camshaft, and in addition, only one rocker shaft is required. It is an object of the present invention to provide a four-valve internal combustion engine that is simple in structure, lightweight, and easy to assemble and maintain by making it possible to construct a valve train assembly as described above.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, in FIG. Polymerized and bonded. A piston 5 is slidably fitted into each cylinder 1, and a combustion chamber 6 is recessed in the bottom surface of the cylinder head 3 facing the piston 5. The spark plug 16 has an electrode 16a facing the combustion chamber 6 in the vicinity of the cylinder axis A.
It is screwed onto the cylinder head 3.

The ceiling surface of each combustion chamber 6 is constituted by two roof-shaped slopes 7a and 7b that intersect at a ridge line L (see FIG. 1A) extending in the direction in which the plurality of cylinders 1 are arranged. A pair of intake ports 8, 8 are opened on one slope 7a, and a pair of exhaust ports 9, 9 are opened in parallel along the ridge line L, respectively, on the other slope 7b. Each pair of intake valves 10, 10 and exhaust valves 11, 11 are connected to valve guides 12, 12 provided in the cylinder head 3 so as to open and close the intake valves 10, 10 and the exhaust ports 9, 9, respectively.
and 13, 13, respectively, so as to be slidable. Thus the four valves 10, 10; 11, 11
are arranged so as to surround the electrode 16a. These valves 10, 10; 11, 11 are urged in the valve closing direction by valve springs 14, 14; 15, 15, respectively.

A roof-shaped head cover 17 is superimposed on the upper surface of the cylinder head 3 via a seal ring 18.
They are connected by a plurality of bolts 19, 19, . . . . Inside the head cover 17, a valve operating device 20 is provided which opens the intake and exhaust valves 10, 10; 11, 11, and has the following configuration.

The head cover 17 is integrally formed with a plurality of support walls 21, 21, . . . arranged in the direction of the ridge line L and extending in the vertical direction on its inner surface. Bearing holes 22, 22... and shaft hole 2 parallel to the ridge line L, respectively
3, 23... are drilled. At that time, bearing hole 2
2, 22... and the shaft holes 23, 23... are arranged so that their respective axes are substantially orthogonal to the axis A, and the shaft holes 23, 23...
22... is arranged below.

A cam shaft 24 is fitted into the bearing holes 22, 22, . . . from one end side of the head cover 17 so that a plurality of journals 24j, 24j, . The camshaft 24 is driven by a crankshaft (not shown) via a well-known timing transmission 25 at an end projecting outward from one end surface of the head cover 17.

As shown in FIG. 2, the camshaft 24 has a pair of adjacent exhaust cams 24 corresponding to each cylinder 1.
e, 24e, and these exhaust cams 24e, 24e
A pair of intake cams 24i, 2 arranged on both outer sides of
4i is formed between adjacent journals 24j, 24j.

A rocker shaft 26 is fitted into the shaft holes 23, 23, . In order to prevent this rotation and axial movement of the rocker shaft 26, the tip of a bolt 29 screwed onto a portion of the support wall 21 is fitted into the side wall of the rocker shaft 26.

The rocker shaft 26 is a pair of bell crank-shaped intake valves that connect the intake valves 10, 10 and the intake cams 24i, 24i, and the exhaust valves 11, 11 and the exhaust cams 24e, 24e, respectively, corresponding to each cylinder 1. Rocker arms 30, 30 and exhaust rocker arms 31, 31
Each is supported so that it can swing freely.

A pair of intake rocker arms 30, 30 that engage with intake cams 24i, 24i at both outer positions are located on both outer sides of a pair of exhaust rocker arms 31, 31 that engage with exhaust cams 24e, 24e at inner positions, so that the rocker arm spacing is maintained. are widened on the camshaft 24 side. A cylindrical socket 50 is disposed between the two rocker arms 30, 30 at a wide space between them to guide the attachment and detachment of the spark plug 16. The lower part of the socket 50 is fitted into the cylinder head 3, and the upper end thereof is It is fitted into the head cover 17 via the seal member 51.

Bolts 32, 33 for adjusting the valve head gap are threaded onto the ends of the locker arms 30, 31 on the valve 10, 11 side, and lock nuts 34, 35 are threaded into these bolts 32, 33.

When adjusting the valve head clearance of each intake and exhaust valve 10, 11, a thickness gauge of a predetermined thickness is inserted between the lower parts of the opposing cams 24i, 24e and the slipper surfaces of the rocker arms 30, 31. Then screw the adjusting bolts 32, 33 of the locker arms 30, 31 forward or backward to bring them into contact with the heads of the intake and exhaust valves 10, 11, and tighten the lock nuts 34, 35 to adjust the adjusting bolts 32, 33. Fix the position.
Then, by pulling out the thickness gauge, a predetermined valve head clearance can be obtained.

In order to insert a tool into the head cover 17 for such adjustment work, the head cover is provided with:
Each set of intake and exhaust cams 24i, 24i; 24e, 2
4e, and a second window 36 opposite the adjustment bolt 32 of each intake rocker arm 30.
Further, a third window 38 is bored opposite the adjustment bolt 33 of the exhaust rocker arm 31. During normal times, these windows 36, 37, 38 are connected to the cap 39,
40 and 41, respectively, are closed.

The rocker shaft 26 is formed hollow, and a hollow portion 26a thereof is connected as an oil path to a lubricating oil supply source (not shown).

A portion of the rocker shaft 26 that supports each rocker arm 30, 31 has an outer circumferential groove 42 and an outer circumferential groove 42.
2 is provided with a horizontal hole 43 that communicates with the hollow portion 26a, and the boss of each rocker arm 30, 31 is provided with a cam 24i,
24e and adjustment bolts 32, 33
First oil injection holes 44, 45 and second oil injection holes 46, 47, which respectively face the abutting portions of the intake and exhaust valves 10, 11, are provided so as to communicate with the outer circumferential groove 42, respectively.

Therefore, when lubricating oil is pumped into the hollow part 26a of the camshaft 24, the oil moves from the horizontal hole 43 to the outer circumferential groove 42, lubricates the inner surface of the boss of each rocker arm 30, 31, and also lubricates the inner surface of the boss of each rocker arm 30, 31. 2 oil injection holes 44, 4
5; Spouting from 46, 47, Rotsuka arm 3
0, 31 and the cams 24i, 24e, as well as the adjustment bolts 32, 33 and the intake and exhaust valves 10, 1.
1 and lubricates them.

An oil trap 48 is integrally provided on the inner surface of the head cover 17 and extends directly above the camshaft 24 side end of the exhaust rocker arm 31.
The direction of rotation of the oil trap 48 is determined such that the upper side thereof faces the oil trap 48, as indicated by an arrow R. Therefore, while the camshaft 24 is rotating, each cam 24i, 24
When the lubricating oil adhering to the oil trap 48 is scattered by centrifugal force and adheres to the oil trap 48, the oil flows down along the vertical surface of the oil trap 48 and hits the rocker arms 31, 31 and the exhaust cam 24e below.
24e to lubricate them.

Next, the operation of this embodiment will be explained.

When the camshaft 24 is rotated by the timing transmission 25, each time the peaks of the intake cams 24i, 24i push the intake rocker arms 30, 30, the rocker arms 30, 30 move around the rocker shaft 26 as a fulcrum. In FIG. 1, the intake valve 10,
10 is pushed down against the valve closing force of the valve springs 14, 14 to open these valves, and the exhaust cams 24e, 2
Every time the peaks 4e push the exhaust rocker arms 31, 31, the rocker arms 31, 31 similarly swing clockwise in FIG. , 15 to open them.

At the end of the compression stroke of the engine, when the air-fuel mixture in the combustion chamber 6 is ignited by the spark discharge from the ignition plug 16, the flame spreads from near the electrode 16a of the ignition plug 16 to its surroundings. electrode 16
Since a is arranged approximately on the axis A of the cylinder 1, the distances from the electrode 16a to each peripheral part of the combustion chamber 6 are approximately equal, and therefore the flame propagates to each part in a short time, so there is no knocking. Good combustion can be obtained.

In this way, the camshaft 24 and rocker shaft 26 are
Since they are commonly used to operate the intake and exhaust rocker arms 30 and 31, only one rocker arm is required for each, which contributes to simplifying the structure and reducing the weight of the valve train 20.

Moreover, since the cam shaft 24 and the rocker shaft 26 are arranged so as to be perpendicular to the axis A of the cylinder 1, the rocker arms 30 and 31 have approximately the same arm length, and therefore have approximately the same weight. Therefore, it is possible to avoid the occurrence of a valve jumping phenomenon during high-speed operation due to the weight being biased toward one rocker arm.

Furthermore, since the camshaft 24 and the rocker shaft 26 are supported by the head cover 17, when assembling the engine, the camshaft 24, the rocker shaft 26, and the rocker arms 30, 31 are attached to the head cover 17 in advance, and the valve train 20 is assembled. If a three-dimensional body is made and the head cover 17 is attached to the cylinder head 3 on the engine assembly line, the valve train 20 will be connected to the intake and exhaust valves 1.
0, 11 can be connected all at once, thus improving the efficiency of engine assembly work. Further, when the head cover 17 is removed, the valve train 20 is also separated from the cylinder head 3 side, so that inspection, repair, etc. thereof can be easily performed.

When attaching and detaching the spark plug 16, a tool for attaching and detaching the spark plug 16 is inserted into the socket 50. Since the socket 50 is disposed at a location with a wide distance between the rocker arms 30, 30, the rocker arms 30, 3
The large diameter socket 50 can be placed between them without being obstructed by the camshaft 24, rocker shaft 26, rocker arms 30, 31, intake and exhaust valves 10, 11, etc. No spark plug 1
6 can be easily attached and detached, thus making it possible to arrange the electrode 16a near the cylinder axis A. Furthermore, the ignition plug 16 is arranged with its axis closer to the cylinder axis A than the intake and exhaust valves 10 and 11, and can exhibit good ignition performance.

Furthermore, since the intake valves 10 are not interfered with by the sockets 50, the spacing between the pair of valves can be freely selected. For example, it is possible to select a valve spacing that maximizes the opening area of the intake port 8 on the combustion chamber 6 side, and it is possible to improve the engine output.

Furthermore, the intake and exhaust ports 8 and 9 are connected to the intake and exhaust valve 1.
Since they extend outward from the cylinder 1 from 0 and 11, they are not interfered with by the socket 50 at all and can therefore have any shape suitable for improving the engine output.

In the above embodiment, the intake and exhaust cams 24
The positions of i and 24e may be exchanged to arrange the exhaust valve 11 on the spark plug 16 side and the intake valve 10 on the opposite side.

As described above, according to the present invention, the head cover adhered to the upper surface of the cylinder head has a bearing hole extending substantially orthogonally to the axis of the cylinder in the direction in which the intake and exhaust valves are arranged, and a bearing hole extending below the bearing hole. A shaft hole extending in parallel is drilled, and a single camshaft connected to the intake and exhaust valves via a rocker arm is rotatably fitted into the bearing hole, and the rocker arm can be freely swung into the shaft hole. Attach a single rocker shaft to support the suction,
The distance between the pair of rocker arms on one side of the exhaust valve is widened on the camshaft side so that the pair of rocker arms on one side of the exhaust valve are connected to the camshaft on both outsides of the rocker arms on the other side. A socket that guides the installation and removal of the ignition plug is placed between both rocker arms at a wide space between the two, making it possible to place the ignition plug electrode close to the cylinder axis, even though only one camshaft is required. Moreover, since only one rocker shaft is required, the structure is simple and lightweight, and there is no risk of the occurrence of the jumping phenomenon of the intake and exhaust valves. Furthermore, the assembly of the valve train can be constructed on the head cover before it is attached to the cylinder head, which significantly improves the ease of assembly and maintenance.

Furthermore, a large diameter socket can be placed between the rocker arms without being obstructed by the rocker arms, and the ignition plug can be easily attached and detached. Moreover, since the ignition plug is disposed with its axis closer to the cylinder axis than the intake and exhaust valves, good ignition performance can be achieved.

Furthermore, since the intake and exhaust valves are not obstructed by sockets in any way, the spacing between the pairs of valves can be freely selected.For example, the valves that maximize the opening area of the intake and exhaust ports on the combustion chamber side can be It is also possible to select the interval, and it is possible to improve the engine output.

Furthermore, since the suction and exhaust ports extend outward from the cylinder from the suction and exhaust valves, they are not interfered with by the socket at all, so they can be shaped freely to improve engine output. can be held in

[Brief explanation of drawings]

FIG. 1 is a vertical sectional side view of the main parts of an internal combustion engine equipped with a device according to an embodiment of the present invention, FIG. 1A is a bottom view of the cylinder head in FIG. 1, and FIG.
3 is a partially cross-sectional bottom view of the head cover in FIG. 1. A...Cylinder axis, 1...Cylinder, 2...
...Cylinder block, 3...Cylinder head, 6
... Combustion chamber, 10 ... Intake valve, 11 ... Exhaust valve,
16... Spark plug, 16a... Electrode, 17... Head cover, 20... Valve gear, 21... Support wall,
22...Bearing hole, 23...Shaft hole, 24...Camshaft, 24e...Exhaust cam, 24i...Intake cam,
24j... Journal, 25... Timing transmission device,
26...Rotsuka shaft, 30...Intake rocker arm,
31...Exhaust rocker arm, 50...Socket.

Claims (1)

[Claims] 1. The electrode 16a of the spark plug 16 attached to the cylinder head 3 is connected to the combustion chamber 16 near the cylinder axis A.
In a four-valve internal combustion engine, each pair of intake valves 10, 10 and exhaust valves 11, 11 mounted on the cylinder head 3 are arranged so as to surround the electrode 16a. A bearing hole 22 extending in the direction in which the intake and exhaust valves 10, 10; 11, 11 are arranged substantially perpendicular to the cylinder axis A, and a shaft extending parallel to the bearing hole 22 below the bearing hole 22 are attached to the head cover 17 to be connected. A hole 23 is bored in the bearing hole 22, and rocker arms 30, 30;
Intake and exhaust valves 10, 10; 11,
A single cam shaft 24 connected to the shaft hole 23 is rotatably fitted, and a rocker arm 30, 3 is fitted into the shaft hole 23.
A single rocker shaft 26 that swingably supports the intake and exhaust valves 10, 10; 1 is installed.
A pair of rocker arms 30 on one side of 1 and 11,
The distance between the pair of rocker arms 30, 30 on one side is adjusted so that the distance between the pair of rocker arms 30, 30 on the other side is adjusted to the camshaft 24 so that
4 side, both rocker arms 30 on one side,
30. A four-valve internal combustion engine characterized in that a socket 50 for guiding the attachment and detachment of the spark plug 16 is disposed at a widely spaced location between the two.