JPS6318105A - Sohc type internal combustion engine - Google Patents

Abstract

PURPOSE:To make fixing work for a rocker shaft easy by forming a cylindrical part having an ignition plug inserting hole extending obliquely in a body with a cam holder, and fixedly holding a rocker shaft on the side of the formed cylindrical part between the cam holder and a rocker shaft holder. CONSTITUTION:An intake and an exhaust valve are opened and closed by the rotation of a cam shaft 14 through an intake and an exhaust rocker arm whose middle parts are rotatably supported on an intake and an exhaust rocker shaft 15, 16 borne in parallel with a cylinder axis, and each of the rocker shafts 15, 16 is borne. A cylindrical part 45 having an inserting hole 44 extending obliquely toward the center of the ceiling of a combustion chamber 6 is formed in a body with a cam holder 31 comprising a lower and an upper holder 27, 28. The rocker shaft 15 on the side where the cylindrical part 45 is formed is fixedly held between the upper holder 28 and a rocker shaft holder 41 coupled with said upper holder 28 through bolts 40, and a notch 48 for accommodating the cylindrical part 45 is formed over the rocker shaft 15 and the rocker shaft holder 41.

Description

Detailed Description of the Invention A4 Purpose of the Invention (1) Industrial Application Field The present invention provides a spark plug facing the center of the ceiling of a combustion chamber, and a cam holder provided at the top of the cylinder head. A single camshaft is rotatably supported at a position substantially above the spark plug, rocker arm shafts are fixed and arranged on both sides of the camshaft, and one rocker arm shaft has an intake valve and a shaft that interlocks between the camshafts. The present invention relates to an SOHC internal combustion engine in which an intake side rocker arm that connects is swingably supported on the other rocker arm shaft, and an exhaust side rocker arm that interlocks and connects an exhaust valve and a camshaft is supported on the other rocker arm shaft.

(2) Conventional technology Conventionally, the rocker arm shaft was
As disclosed in Japanese Utility Model Publication No. 5 and Japanese Utility Model Application Publication No. 60-58804, it is generally fixed to the cylinder head with bolts.

(3) Problems to be Solved by the Invention However, if the rocker arm shaft is fixed with bolts as in the above-mentioned conventional method, the position of the rocker arm shaft must be determined in accordance with the bolt, making assembly work cumbersome. It is.

The present invention has been made in view of the above circumstances, and aims to simplify the assembly work by making it possible to easily fix the rocker arm shaft, and to increase the degree of freedom in the arrangement of the components of the valve train. The purpose is to provide a larger SOHC type internal combustion engine.

B4 Structure of the Invention (Means for Solving Problems 11) According to the present invention, the cam holder has a cylindrical portion that forms an insertion hole for inserting a spark plug in the center of the ceiling surface of the combustion chamber, and faces upward. The one rocker arm shaft is sandwiched between a cam holder and a rocker shaft holder detachably coupled to the cam holder, and the one rocker arm shaft and Each rocker shaft holder is provided with a cutout portion for accommodating the cylinder portion.

(2) Since the cylindrical portion integrated with the working cam holder is housed in the rocker arm shaft and the notch of the rocker shaft holder, rotation of the rocker arm shaft is prevented by the cylindrical portion, and the insertion hole is located close to the cam shaft side. This increases the degree of freedom in arrangement.

(3) Example Below, an example in which the present invention is applied to an SOHC type four-valve internal combustion engine will be explained with reference to the drawings.
2, and 3, the engine body E includes a cylinder block 1 and a cylinder head 2 which is superimposed and bonded to the upper part of the cylinder block 1 via a gasket 3. A piston 5 is slid into the bored cylinder 4. A combustion chamber 6 is defined by the cylinder block 1, cylinder head 2, and piston 5, and the ceiling surface of the combustion chamber 6 is formed in the shape of a roof that slopes toward each other.

Two intake valve lowers a and 7b with the same diameter are opened in parallel on one side of the ceiling surface of the combustion chamber 6, and two exhaust valves with a slightly smaller diameter than the intake valve lowers a and 7b are opened on the other side of the ceiling surface. Valve port 8a,
8b are opened in parallel and opposite to the intake valve lowers a and 7b.

Two intake valves? an intake port 9a communicating with a, 7b;
9b is bored in the cylinder head 2, and these intake boats 9a, 9b are assembled into one in the cylinder head 2,
It is connected to a fuel supply device, such as a carburetor, via an intake manifold (not shown). In addition, two exhaust valve ports 8a, 8
Exhaust ports 10a and 10b are bored in the cylinder head 2, and these exhaust ports 10a and 10b are collected into one in the cylinder head 2 and connected to the exhaust system via an exhaust manifold (not shown). be done.

A pair of intake valves 11a and 11b that open and close intake valve lowers a and 7b, and a pair of exhaust valves 12a and 12b that open and close exhaust valve ports 8a and 8b are supported in the cylinder head 2 so as to be able to freely slide up and down, respectively. Ru. Moreover, the intake valves 11a, llb and the exhaust valve 12a.

12b is the central axis of cylinder 4! 130 are arranged with their upper ends slanted away from each other on both sides.

Both intake valves 11a, llb and re-exhaust valve 12a.

12b, above the combustion chamber 6, the central axis &? 1
A single camshaft 14 is rotatably arranged near the camshaft 13 . At a position above the camshaft 14 between this camshaft 14 and the two intake valves 11a and llb, there is a camshaft 1 = 1.
An intake side rocker arm shaft 15 parallel to the camshaft 14 is fixedly arranged, and an exhaust side rocker arm shaft 16 parallel to the camshaft 14 is located above the camshaft 14 between the camshaft 14 and the two exhaust valves 12a and 12b. Fixed location.

Two intake rocker arms 17a and 17b per cylinder are swingably supported on the intake rocker arm shaft 15, and the outer ends of these rocker arms 17a and 17b are connected to the intake valves 11a and 11a through adjusters 19, respectively. llb
The slipper surfaces 20 provided at each inner end are in sliding contact with the intake side valve operating cams 21 of the camshaft 14, respectively. In addition, the exhaust side rocker arm shaft 16 has a
Two exhaust-side rocker arms 182.18b are pivotally supported per cylinder, and these rocker arms 18
The outer ends of a and 18b are brought into contact with the upper ends of the exhaust valves 12a and 12b via adjusters 22, respectively, and slipper surfaces 23 provided at each inner end slide into contact with the exhaust side valve operating cam 24 of the camshaft 14. has been done. Therefore, as the camshaft 14 rotates, the intake side and exhaust side rocker arms 1
7a, 17b; 18a, 18b are rocker arm shafts 15.
The intake and exhaust valves 11a and 11 each swing around 16, respectively.
b; 12a and 12b can be opened and closed in cooperation with valve springs 25 and 26.

Referring also to FIGS. 4, 5, 6, and 7, the camshaft 14 includes a lower holder 27 that is integrally provided in the upper part of the cylinder head 2, and a bolt 29, 30 attached to the lower holder 27. The lower holder 2°7 is rotatably supported by a cam holder 31 composed of an upper holder 28 and an upper holder 28 to which the lower holder 28 is connected. It is provided integrally at the upper part of the cylinder head 2.

The upper holder 28 has an insertion hole 65 parallel to the camshaft 14.
is bored, and the exhaust side rocker arm shaft 16 is inserted through this insertion hole 65. Moreover, a holder 34 is attached to the end of the cylinder head 2 along the axial direction of the camshaft 14, and the end of the exhaust side rocker arm shaft 16 is supported by the holder 34. Further, the bolt 30 is arranged to penetrate a part of the exhaust side rocker arm 16 and connect the lower holder 27 and the upper holder 28 to each other, and the exhaust side rocker arm shaft 16 is prevented from rotating by this bolt 30. .

The exhaust side rocker arms 18a, 18b are arranged adjacent to both sides of the cam holder 31 along the axis of the exhaust side rocker arm shaft 16, and are located between the holder 34 and the exhaust side opening arm 18b, and between the cam holder 31 and the cam holder 31 along the axis of the exhaust side rocker arm shaft 16.
A coil spring 35 that surrounds the exhaust-side rocker arm shaft 16 is interposed between the exhaust-side rocker arm shaft 16 and the exhaust-side rocker arm shaft 16 . These coil springs 35 elastically bias each exhaust side rocker arm 18a, 18b toward the cam holder 31, thereby fixing the axial position of each rocker arm 18a, 18b.

The upper holder 28 is integrally provided with a support portion 38 having an upwardly open semicircular support surface 37 for supporting the intake rocker arm shaft 15.
The rocker shaft holder 41, which is connected to the rocker shaft holder 41 with bolts 39 and 40, is provided with a semicircular pressing surface 42 that corresponds to the support surface 37 and is open downward. The intake rocker arm shaft 15 is held between the support surface 37 and the pressing surface 42 , and the end of the intake rocker arm shaft 15 is supported by the holder 34 . Support part 38
is formed thicker in the axial direction than the portion of the upper holder 28 that supports the camshaft 14.

The intake rocker arms 17a, 17b are pivotally supported by the intake rocker arm shaft 15 so as to be in sliding contact with the camshaft 14 at positions further away from the cam holder 31 than the exhaust rocker arms 18a, 18b.

In order to prevent the axial movement of both intake side rocker arms 17a, 17b, between the intake side rocker arm 17a and the holder 34, and both the intake side rocker arms 17a, 17b.
A web washer 43 is interposed between them.

The lower holder 27 and the upper holder 28 that constitute the cam holder 31 are formed with an insertion hole 44 that is coaxially connected via a seal member 66 and extends obliquely from the outer side of the support portion 38 toward the center of the ceiling surface of the combustion chamber 6. A cylindrical portion 45 is integrally provided, and a screw hole 46 communicating with the center of the ceiling surface of the combustion chamber 6 is provided at the tip of this insertion hole 44 .

A spark plug P is inserted into the insertion hole 44, and the spark plug P is screwed into the screw hole 46 with its tip facing the center of the ceiling surface of the combustion chamber 6.

The cylindrical portion 45 is formed to bite into the axial center of the support surface 37, and the rocker shaft holter 41 is provided with a semicircular notch 47 that accommodates the cylindrical portion 45. Moreover, the notch 4 that accommodates the cylindrical portion 45 is also located on the intake side rocker arm shaft 15.
8 is provided.

The intake side rocker arm shaft 15 is formed in a solid shape,
A portion corresponding to the support surface 37 and the intake side rocker arm 17
Oil supply holes 49 and 50 are drilled between the portions corresponding to a and 17b.

In addition, the intake side rocker arm shaft 15 of the tapped hole 51.52 provided in the support portion 38 for screwing the POL) 39.40.
The part facing the intake side rocker arm shaft 15 has a relief groove 53.5 corresponding to Pole l-39, 40.
4 is provided.

The bolt 29 connects to the oil supply passage 67 provided in the lower holder 27.
An insertion hole 67 provided in the upper holder 28 to insert the bolt 29 across the middle of the oil supply hole 4
Oil supply passages 68 are provided between the portions corresponding to 9.50 and the support surface 37, respectively. This allows lubricating oil to flow from between the support surface 37 and the intake rocker arm shaft 15 to the oil supply hole 4.
It is supplied between the intake side rocker arms 17a, 17b and the intake side rocker arm shaft 15 via the intake side rocker arms 9 and 50.

A head cover 56 that covers the valve train and is coupled to the cylinder head 2 via a seal member 55 is integrally provided with a pressing portion 58 that contacts the upper end of the cylindrical portion 45 via a seal member 57.

A hole 59 connected to the cylindrical portion 45 is bored in the pressing portion 58, and this hole 59 has a cord 60 connected to the spark plug P.
It is closed by a cap 61 that can be opened and closed.

Next, to explain the operation of this embodiment, the camshaft 14 is rotationally driven in accordance with the operation of the engine, so that the rocker arms 17a, 17b;
18b is the intake side and exhaust side rocker arm shaft 15.16
Swinging around and cooperating with valve springs 25, 26, the two intake valves 11a.

Ilb and the two exhaust valves 12a and 12b are opened and closed at predetermined timing. Moreover, since the ignition plug P is placed facing the center of the ceiling surface of the combustion chamber 6, the flame propagation distance from the ignition point to each peripheral edge of the combustion chamber 6 is almost equal, so the combustion time is shortened to the minimum and high output is achieved. is demonstrated.

At this time, the intake side rocker arm shaft 15 has its notch 48
Since the cylindrical portion 45 is housed in the cylindrical portion 45, rotation is prevented, and the exhaust side rocker arm shaft 16 is prevented from rotating by the bolt 30.

With this structure, the intake rocker arm shaft 15 can be fixed simply by attaching the four-shaft holder 41 to the cam holder 31, making the assembly process easier. Further, the cylindrical portion 45 can be arranged as close as possible to the camshaft 14 side, and the degree of freedom in arrangement of the parts constituting the valve train can be increased.

C4 Effects of the Invention As described above, according to the present invention, the cam holder has a cylindrical portion that forms an insertion hole for inserting a spark plug in the center of the ceiling surface of the combustion chamber. The one rocker arm shaft is integrally provided with an inclination toward the shaft side, and the one rocker arm shaft is held between a cam holder and a rocker shaft holder that is detachably coupled to the cam holder, and the one rocker arm shaft and the rocker shaft holder have the above-mentioned rocker arm shaft. Since the notches for accommodating the cylindrical portions are provided, the work for fixing the rocker arm shaft is simplified, and the insertion hole can be brought closer to the camshaft side to increase the degree of freedom in arrangement.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and Fig. 1 is a vertical sectional side view, Fig. 2 is a side view, and Fig.
-■ line view, Fig. 3 is a -■ line view of Fig. 1, Fig. 4 is a vertical sectional view of the cam holder, Fig. 5 is a side view of the upper holder, and Fig. 6 is a plan view of Fig. 5. , FIG. 7 is a bottom view of FIG. 5. . 2... Cylinder block, 6... Combustion chamber, 11a. 1 l b...Intake valve, 12 a, 12' b
- Exhaust valve, 14... Camshaft, 15.16... Rocker arm shaft, 17a.

Claims (1)

[Claims] The spark plug is placed facing the center of the ceiling of the combustion chamber.
A single camshaft is rotatably supported in the cam holder provided at the top of the cylinder head at a position almost above the spark plug, and rocker arm shafts are fixed and arranged on both sides of the camshaft, and one rocker arm shaft The SOHC type has an intake-side rocker arm that interlocks and connects the intake valve and camshaft, and the other rocker arm shaft supports an exhaust-side rocker arm that interlocks and connects the exhaust valve and camshaft so that they can swing freely. In an internal combustion engine, the cam holder is integrally provided with a cylindrical part that forms an insertion hole for inserting a spark plug into the center of the ceiling surface of the combustion chamber, and is inclined toward one of the rocker arm shafts as it goes upward;
The one rocker arm shaft is held between a cam holder and a rocker shaft holder that is removably coupled to the cam holder, and the one rocker arm shaft and the rocker shaft holder are each provided with a notch for accommodating the cylindrical portion. An SOHC internal combustion engine characterized by: