JPH076370B2 - SOHC internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of the Invention (1) Field of Industrial Application The present invention relates to a SOHC internal combustion engine, and in particular, an intake valve that opens and closes an intake port and an exhaust port that open to a combustion chamber of a cylinder head. And exhaust valves are arranged on both sides of the cylinder axis, and a cam shaft is arranged between the intake and exhaust valves. Above the cam shaft, between the shaft and the intake and exhaust valves. Each intake and exhaust rocker arm that pivotally supports each intake and exhaust rocker arm is arranged in parallel with the cam shaft, and an ignition plug is attached so that the electrode faces the center of the ceiling surface of the combustion chamber. The present invention relates to an improvement of an internal combustion engine in which a cylinder head is provided with a plug mounting hole for doing so.

(2) Prior Art This type of internal combustion engine is disclosed in Japanese Patent Laid-Open No. 60-166715, and in the one disclosed therein, a bearing integrally formed on a cylinder head at a corresponding position between adjacent cylinders. A cam shaft and an intake / exhaust rocker shaft are supported on the wall, and a plug accommodating cylinder for accommodating an ignition plug manufactured separately from this bearing wall is fixed to the cylinder head.

(3) Problems to be Solved by the Invention In the structure as described above, the plug accommodating cylinder for accommodating the ignition plug is indispensable, so that the structure is complicated and the assembly is troublesome. Since it is inserted into the bearing hole from the side, the journal of the camshaft must be formed with a diameter larger than that of the intake and exhaust cams, which causes a problem of increasing the weight of the camshaft.

The present invention has been made in view of the above circumstances, and enables the omission of the plug housing cylinder to simplify the structure and
An object of the present invention is to provide a SOHC type internal combustion machine which can form a journal of a camshaft into a smaller diameter than an exhaust cam and can reduce the weight of the camshaft.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, a joint surface between a bearing wall integrally formed with a cylinder head so as to cross the axis of the cylinder and a holder fixed to the same. A cam shaft is supported by a bearing formed therebetween, and a suction rocker shaft and an exhaust rocker shaft are supported by the holder. The bearing wall and the holder have a series of plug receiving holes that communicate with the plug mounting holes and receive the ignition plug. Is provided.

(2) Action Since the camshaft is supported by the bearing formed between the bearing wall integral with the cylinder head and the joint surface of the holder fixed to this, the bearing is a split type. ,
The journal of the camshaft can support this even if it has a smaller diameter than the intake and exhaust cams.

Since the spark plug is accommodated in the series of plug accommodating holes provided in the bearing wall and the holder, a dedicated plug accommodating cylinder can be omitted.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 to 3, a plurality of cylinders 1,
The cylinder head 3 is attached to the upper surface of the cylinder block 2 having 1 ... A piston 5 is slidably fitted into each cylinder 1, and a combustion chamber 6 is provided in a bottom surface of a cylinder head 3 facing the piston 5.

The ceiling surface 7 of each combustion chamber 6 is formed in a mountain shape from two slopes 7a and 7b that descend toward both sides from a ridge line L (FIG. 3) extending in the arrangement direction of the plurality of cylinders 1, 1. Slope 7
a has one end of a pair of intake ports 8,8 and the other slope 7
Similarly, one ends of a pair of exhaust ports 9 and 9 are opened in b and 7b side by side along the ridge line L, respectively. A pair of intake ports 8,8
The other end of the cylinder head 3 merges into one inside the cylinder head 3 and opens to one outside surface of the cylinder head 3, to which an intake manifold (not shown) is connected. Also a pair of exhaust ports
The other end sides of 9, 9 merge into one in the cylinder head 3 and open to the other outer side surface of the cylinder head 3, to which an exhaust manifold (not shown) is connected.

The pair of intake valves 10, 10 and the exhaust valves 11, 11 for opening and closing the pair of intake ports 8, 8 and the exhaust ports 9, 9 are valve guides 12, 12 and 13 fitted to the cylinder head 3. , 13 are slidably supported respectively. At that time, the intake and exhaust valves 10 and 11 facing each other are arranged in a V shape so that the valve heads thereof are separated from each other on both sides of the axis Y of the cylinder 1.

The intake and exhaust valves 10 and 11 are equipped with valve springs 14 and 15 for biasing them in the valve closing direction.

Between the intake valve 10, 10 group and the exhaust valve 11, 11 group, one cam shaft 16 extending in the arrangement direction of the plurality of cylinders 1, 1 is biased from the cylinder axis Y to the exhaust valve 11 side. It is arranged as a place. Above the cam shaft 16, an intake rocker shaft 17 parallel to the shaft 16 is displaced to the intake valve 10 side from the shaft 16 and also an exhaust rocker shaft parallel to the cam shaft 16. The shaft 18 is arranged so as to be offset from the cam shaft 16 toward the exhaust valve 11 side.

The cam shaft 16 corresponds to each cylinder 1 and has one journal 19 and a pair of exhaust cams 21 and 21 adjacent on both sides thereof.
It has a pair of intake cams 20, 20 adjacent to each other on both sides.

A pair of intake rocker arms 22, 22 are pivotally supported on the intake rocker shaft 17 so as to correspond to each cylinder 1, one end of which is provided with the intake cams 20, 20 and the other end thereof is provided with adjusting bolts 24, 24. The heads of the intake valves 10 and 10 are engaged with each other.

A pair of exhaust rocker arms 23, 23 corresponding to each cylinder 1 are swingably supported on the exhaust rocker shaft 18, one end of which is connected to the exhaust cams 21, 21, and the other end thereof is adjusted bolts 25, 25.
Are engaged with the head portions of the exhaust valves 11 and 11 via the.

The journal 19 includes a bearing wall 26 formed integrally with the cylinder head 3 so as to cross the cylinder axis Y, and a bearing wall 26 formed on the bearing wall 26.
Is rotatably supported by a bearing 31 formed between joint surfaces of a holder 30 (see FIGS. 4 to 6) fixed by bolts 27, 28, 29 of the book, and the rocker shafts 17, 18 are holders. It is supported by bosses 32 and 33 formed integrally with 30. At that time, in particular, the exhaust rocker shaft 18 includes the semicircular cutout 34 on the outer periphery thereof and the bolt.
It is stopped by the engagement with the outer peripheral surface of 27.

The cylinder head 3 is provided with a plug mounting hole 37 that opens in the center of the ceiling surface 7 of each combustion chamber 6 as a screw hole. The plug mounting hole 37 communicates with the intake rocker shaft 18 and the intake valves 10, 1.
A series of plug receiving holes 38 passing between the bearing wall 2 and
An ignition plug 39 is screwed into the plug mounting hole 37 through the plug accommodating hole 38 so as to face the center of the ceiling surface 7.

A seal member 40 is interposed between the joint surfaces of the bearing wall 26 and the holder 30 so as to surround the plug housing hole 38.

As shown in FIG. 2, the cam shaft 16 also has a journal 19 'at its end, which is fixed to both end walls of the cylinder head 3 and two bolts 41, 42. Is rotatably supported by a bearing 44 formed between the joint surface with the holder 43, and the holder 43 sucks and exhausts the rocker shaft.
17,18 ends are supported.

The intake rocker shaft 17 is equipped with a wave washer 45 interposed between the adjacent intake rocker arms 22 and 22, and a wave washer 45 'interposed between the intake rocker arm 22 and the holder 43 at the outer position, By these, each intake rocker arm 22 is elastically held by the adjacent holder 30.

In addition, the exhaust rocker shaft 23 has two adjacent exhaust rocker arms 23, 2
The coil springs 46 interposed between the exhaust rocker arms 23 and the holders 43 are mounted between the coil springs 46, and the exhaust rocker arms 23 and the holder 43 at the outer position. Retained.

As shown in FIG. 1, a head cover 47 that covers the cylinder head 3 is joined to the upper end of the cylinder head 3 via a seal member 48. The head cover 47 is provided with a plug insertion port 49 communicating with the plug accommodating hole 38, and the sealing member 50 surrounds the plug insertion port 49 so that the seal member 50 surrounds the head cover 47 and the bearing wall 26.
And is interposed between the surfaces facing each other.

The plug accommodating hole 38 accommodates a plug cap 52 which is attached to the plug 51 so as to connect a high-voltage cord 51 connected to an ignition coil (not shown) to the ignition plug 39, and the upper end of the cap 52 has a plug insertion port 49. Is fitted airtightly.

Next, the operation of this embodiment will be described. During operation of the engine, the cam shaft 16 is rotationally driven from the crank shaft via a timing transmission device (not shown). When the intake stroke is started in each cylinder 1, the intake cams 20, 20 exert a lift action to swing the intake rocker arms 22, 22 in the opening direction of the intake valves 10, 10, so that the intake valves 10, The valve 10 is opened against the force of the valve springs 14 and 14, and the air-fuel mixture generated by the air-fuel mixture generating device such as a vaporizer (not shown) is sucked into the cylinder 1 through the intake ports 8 and 8.

When the intake cams 20,20 release the intake rocker arms 22,22,
The intake valves 10 and 10 are closed by the force of the valve springs 14 and 14, and the engine shifts to the compression stroke.

At the end of the compression stroke, the spark discharge of the spark plug 39 ignites the compressed gas in the combustion chamber 6 and advances to the expansion stroke. At this time, since the electrode of the ignition plug 39 occupies the central portion of the ceiling surface 7 of the combustion chamber 6, the flame propagation distances from the ignition point to the peripheral edge of the combustion chamber 6 are substantially equal, and therefore the combustion time is minimized. A good combustion state that is advantageous for exhibiting high output can be obtained.

Next, when the exhaust stroke is started, the exhaust cams 21, 21 exert a lift action to swing the exhaust rocker arms 23, 23 in the opening direction of the exhaust valves 11, 11, so that the exhaust valves 11, 11 are Spring 15,15
The exhaust valve exhausts exhaust gas from the combustion chamber 6 by opening the valve against the force of
Discharge to 9,9. Exhaust cams 21,21 are exhaust rocker arms 23,2
When 3 is released, the exhaust valves 11 and 11 are closed by the force of the valve springs 15 and 15.

In such an internal combustion engine, the camshaft 16 journal 1
Reference numerals 9, 19 'denote a bearing wall 26 integral with the cylinder head 3, an end wall of the cylinder head 3, and holders 30, 43 to which these are fixed.
Since they are supported by bearings 31 and 44 formed between the joint surfaces with the
Even if 9'has a smaller diameter than the intake and exhaust cams 20,21, these can be easily supported by the bearings 31,44.

Moreover, since the spark plug 39 is accommodated in the series of plug accommodating holes 38 provided in each bearing wall 26 and the holder 30, a dedicated plug accommodating cylinder is not required.

C. Effects of the Invention As described above, according to the present invention, the cam shaft is formed by the bearing formed between the joint surface of the bearing wall integrally formed with the cylinder head so as to cross the cylinder axis and the holder fixed thereto. In addition to supporting the intake and exhaust rocker shafts in the holder, the bearing wall and the holder are provided with a series of plug accommodating holes that communicate with the plug mounting holes and accommodate the ignition plugs. It is possible to contribute to the simplification of the structure and the improvement of the assemblability by eliminating the need for a housing cylinder, and the cam shaft has a smaller diameter than the intake cam and the exhaust cam.
It is easy to assemble to the cylinder head and can contribute to weight reduction of the cam shaft.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a vertical sectional side view of an SOHC type internal combustion engine, FIG. 2 is a view taken along the line II-II of FIG. 1 with a head cover removed, and FIG. The figure shows II in Figure 1.
FIG. 4, FIG. 5, FIG. 6 and FIG. 6 are a side view, a plan view and a bottom view of the holder in the internal combustion engine. Y ... Cylinder axis line, 3 ... Cylinder head, 6 ... Combustion chamber, 7 ... Ceiling surface,
8 ... intake port, 9 ... exhaust port, 10 ... intake valve,
11 …… Exhaust valve, 16 …… Cam shaft, 17 …… Intake rocker shaft, 18
...... Exhaust rocker shaft, 19 …… Journal, 20 …… Intake cam, 21 …… Exhaust cam, 22 …… Intake rocker arm, 23 ……
Exhaust rocker arm, 26 ... Bearing wall, 30 ... Holder, 31 ...
…bearing

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F02F 1/24 H 8503-3G F02P 13/00 301 B

Claims (1)

[Claims] Claims: 1. An intake valve and an exhaust valve for opening and closing an intake port and an exhaust port opening to a combustion chamber of a cylinder head are arranged on both sides of an axis of a cylinder, and one cam is provided between the intake and exhaust valves. A shaft is provided, and one intake and exhaust rocker shaft that pivotally supports each intake and exhaust rocker arm is provided in parallel with the cam shaft above the cam shaft. In the SOHC type internal combustion engine in which a cylinder head is provided with a plug mounting hole for mounting a spark plug so that the electrode faces the center of the ceiling surface of the combustion chamber.
The cam shaft is supported by the bearing formed between the joint surface of the bearing wall integrally formed on the cylinder head so as to cross the cylinder axis and the holder fixed to it, and the intake and exhaust rocker shafts are supported by the holder. The SOHC internal combustion engine is characterized in that the bearing wall and the holder are provided with a series of plug accommodating holes that communicate with the plug mounting holes and accommodate the ignition plugs.