JPH1182158A - Ohc engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily regulate a rocker shaft to the specified position by installing a rib which is projected to the specified height from the inside surface of a rocker cover fixed to a cylinder main body so as to cover the rocker shaft mounting side, and regulates the move in the shaft direction of the rocker shaft. SOLUTION: A cylinder head of an OHC engine has a cylinder head main body 20 and a rocker cover 50, and almost plane-shaped ribs 54 which hang down and face through the specified interval in the direction of the outside surface 38a of a supporting part 38 and a rocker shaft 34 are projected from the inside surface 50b of the rocker cover 50. The lower end of the rocker rib 54 is formed in almost semi-circular arc shape, and the tip 54a hangs down to the position facing part of the end surface 34a of the rocker shaft 34. When the rocker shaft moves in the shaft direction, the move exceeding the specified distance is regulated by coming in contact with the rib 54, and coming-off of the rocker shaft from a through hole 40 of the supporting part 38 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OHC engine. , An OHC engine comprising:

[0002]

2. Description of the Related Art An engine having an intake / exhaust valve in a cylinder head is provided with a rocker arm for opening and closing the intake / exhaust valve by swinging in accordance with the rotation of a cam. , Supported by a rocker shaft.

Japanese Patent Application Laid-Open No. 7-102933 discloses a cylinder head of an overhead cam (OHC) type engine, in which a rocker shaft that supports a rocker arm is fixed to a cylinder body by mounting bolts. It is shown.

[0004] As shown in the publication, conventionally, a rocker shaft is fixed to a cylinder head by fastening means such as mounting bolts.

[0005]

However, when machining the cylinder head, the rocker shaft must be fixed.
A step of drilling holes for the mounting bolts and cutting the screws must be provided, resulting in an increase in the number of processing steps and an increase in cost.

Also, when assembling the engine, a mounting step of mounting bolts is required, which is complicated and costly due to an increase in the number of assembly steps. Further, since a separate mounting bolt is required for mounting the rocker shaft, the number of parts is increased, and the cost is high.

In addition, since the head of the mounting bolt projects a predetermined height above the rocker shaft, the height of the rocker cover must be increased, thereby increasing the overall height of the engine. , Which hindered miniaturization of the entire engine.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to easily regulate a rocker shaft to a predetermined position, and to reduce the number of parts with a small number of rocker shafts. An object of the present invention is to provide an OHC engine capable of eliminating a processing step for fixing the OHC.

[0009]

In order to solve the above-mentioned problems, an OHC engine according to a first aspect of the present invention comprises a cylinder head body having a rocker shaft rotatably supported on an upper portion thereof, and a rocker shaft mounting side. A rocker cover attached to the cylinder body so as to cover the locker cover, and a rib protruding from the inner surface of the rocker cover by a predetermined height and restricting the axial movement of the rocker shaft is provided.

Therefore, only by attaching the rocker cover to the cylinder body, the rocker shaft is restricted from moving in the axial direction, and can be easily positioned. Thereby, the mounting bolt for fixing the rocker shaft can be eliminated, and the number of parts can be reduced. Further, the processing steps for mounting bolts can be omitted, and the number of manufacturing and assembling steps can be reduced.

In the OHC engine according to the second aspect, the ribs are formed so as to protrude at positions opposed to both axial end surfaces of the rocker shaft. Thus, the rocker shaft can be prevented from coming off in the axial direction, and the same effect as that of the first aspect can be obtained.

According to a third aspect of the present invention, in the OHC engine, the rib is formed so as to face only a part of both axial end surfaces of the rocker shaft. Therefore, claim 1
Alternatively, the same effect as the operation described in 2 can be obtained, and the shape of the rib can be reduced. Thereby, the sliding contact area between the rib and the axial end face of the rocker shaft can be reduced, and free rotation of the rocker shaft can be easily secured. Further, by reducing the size of the rib, the weight of the rocker cover can be reduced.

In the OHC engine according to a fourth aspect, the rib is opposed to both end surfaces of the rocker shaft with a predetermined gap therebetween, and regulates a range of movement of the rocker shaft in the axial direction. Here, the predetermined gap refers to a gap such that even when the rocker shaft extends in the axial direction due to thermal expansion, both end faces in the axial direction do not contact at the same time with the ribs facing each other.

Thus, the rocker shaft is rotatably supported on the upper portion of the cylinder head and can freely move in the axial direction by a predetermined gap. Therefore, it is not necessary to strictly set the positions of the ribs facing the both end faces in the axial direction of the rocker shaft, and it is possible to eliminate a processing step for adjusting the position between the both end faces in the axial direction and the rib.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory front view of the present embodiment, and FIG. 2 is an explanatory sectional view of FIG. 1 as viewed from the side. In this embodiment, the cylinder head is applied to an air-cooled overhead cam (OHC) type engine.

The cylinder head according to the present embodiment includes a cylinder head main body 20 and a rocker cover 50 as shown. As shown in FIG. 2, the cylinder head body 20 includes a ceiling portion 24 that forms a pent roof type combustion chamber 22 at a lower portion, and is mounted on an upper surface of a cylinder portion (not shown) into which a piston is inserted. Is placed.

On the one inclined surface 24a of the ceiling portion 24, the other end of the intake port 26 opened on one side wall surface side (hereinafter referred to as IN side) of the cylinder head main body 20 is connected to the intake valve seat 2.
It is open through 6a. In addition, the other inclined surface 24b is provided on the other side wall surface side of the cylinder head main body 20 (hereinafter, referred to as the cylinder head main body 20).
The other end of the exhaust port 28 that opens to the EX side) opens through an exhaust valve seat 28a.

The intake port 26 and the exhaust port 28
An intake valve and an exhaust valve (not shown) are provided on the combustion chamber 22 side. The valve is closed by sitting on the intake valve seat 26a and the exhaust valve seat 28a, and protrudes toward the combustion chamber 22. To open. The intake valve and the exhaust valve are always biased by the intake valve seat 26a.
And is urged in a direction of sitting on the exhaust valve seat 28a.

A camshaft 3 provided coaxially with an intake cam 30a and an exhaust cam 30b for opening and closing an intake valve and an exhaust valve is provided above the combustion chamber 22.
0 is provided. As shown in FIG. 1, the camshaft 30 is inserted into a through hole 32 formed in the cylinder head body 20 in the left-right direction, and both ends thereof are rotatably supported.

A rocker shaft 3 having a predetermined length coaxially with the cam shaft 30 is provided at an upper position of the cam shaft 30.
4 are provided. The rocker shaft 34 is formed of a round bar member having a constant diameter, and has both ends 35 formed by bearings 38 formed at positions above the camshaft 30.
Is supported.

As shown in FIG. 1, the support portion 38 is provided with a through hole 40 passing through the center thereof on the same axis in the left-right direction with a constant diameter. The diameter of the through hole 40 is slightly larger than the diameter of the rocker shaft 34, and has a size to support a loose fit state having a predetermined clear balancer with both ends 35 of the rocker shaft 34.

The length of the rocker shaft 34 in the axial direction is set so that the rocker shaft 3 is supported by the support portion 38.
4 is an outer side surface 38a in the left-right direction of the support portion 38.
In the present embodiment, it is formed to have a length that is recessed by a predetermined distance from the outer side surface 38a. Therefore, the rocker shaft 34
Is rotatably and axially movably supported by a support portion 38.

As shown in FIG. 1, the rocker shaft 34 supports a rocker arm 36 composed of an intake arm 36a and an exhaust arm 36b. One end of the intake arm 36a extends toward the IN side and contacts the top of the intake valve, and the other end contacts the intake cam 30a.
One end of the exhaust arm 36b extends to the EX side and contacts the top of the exhaust valve, and the other end contacts the exhaust cam 30b (both not shown). Therefore, the rocker arm 36 swings by the rotation of the camshaft 30, and the swing causes the other end of the rocker arm 36 to push the intake valve and the exhaust valve.

As shown in FIG. 1, the rocker cover 50 has a basic shape of a U-shaped cross section which forms a predetermined space on the cylinder head main body 20 side, and
4 is mounted on the upper part of the cylinder head body 20 so as to cover the upper side of the cylinder head 4. Further, a plurality of cooling fins 52 extending in the left-right direction and standing upright are provided on the outer surface 50a.

The inner surface 5 of the rocker cover 50
0b, the support portion 3 hangs downward from the inner surface 50b.
A substantially plate-shaped rib 54 is provided to face the outer surface 38a of the lock member 8 in the axial direction of the rocker shaft 34 with a predetermined gap therebetween. As shown in FIG. 2, the lower end of the rib 54 is formed in a substantially semicircular arc shape, and the tip 54 a of the rib 54 hangs down to a position facing a part of the end face 34 a of the rocker shaft 34.

The rocker cover 50 having the above configuration
1 is mounted on the cylinder head main body 20, as shown in FIG. 1, the rib 54 faces the end face 34 a of the rocker shaft 34 at a predetermined gap on the outer surface 38 side of the support part 38. It will be.

Therefore, when the rocker shaft 34 moves in the axial direction, the moved end face 34 a contacts the rib 54. Accordingly, the range of movement of the rocker shaft 34 in the axial direction can be restricted, and the rocker shaft 34 can be prevented from falling out of the through hole 40 of the support 38. That is, the rib 5
4 has a function of preventing the rocker shaft 34 from coming off.

Thus, without using the mounting bolt conventionally used for fixing the rocker shaft,
The position of the rocker shaft 34 can be regulated at a predetermined position, and the number of processing steps and the number of assembly steps can be reduced. Further, the number of parts such as mounting bolts can be eliminated, and cost can be reduced. Further, the inner surface 50b of the support portion 38 and the rocker cover portion 50
The height of the rocker cover can be reduced by minimizing the gap between the locker and the engine, so that the overall height of the engine can be reduced and the entire engine can be downsized.

The end surface 34 of the rocker shaft 34
By providing a predetermined gap between a and the rib 54, the step of cutting the rib 54 for adjusting the positional relationship between the end face 34a and the rib 54 after the rocker cover 50 is manufactured by casting can be eliminated. it can.

It should be noted that the present invention is not limited to the above embodiment, and various changes can be made within the gist of the present invention. For example, in the present embodiment, the position where the tip end 54a of the rib 54 extends over the end face 34a, that is, the rib 54
Is set so as to face a part of the end face 34a of the rocker shaft 34. However, the present invention is not limited to this, as long as the movement range of the rocker shaft 34 in the axial direction can be regulated. It may be a size that does.

In this embodiment, the case where the two ribs 54 are provided at the positions facing the end face 34a of the rocker shaft 34 has been described. However, the present invention is not limited to this. If the through hole 40 provided in one of the portions 38 is not a through hole but a blind hole, only one rib 54 is provided only on the outer surface 38 a side of the other support portion 38, and the rocker shaft comes off. A stop function can be provided.

[0032]

As described above, the OH according to the present invention is used.
According to the C engine, it is possible to restrict the movement of the rocker shaft in the axial direction by simply attaching the rocker cover to the upper portion of the cylinder head main body, thereby preventing the rocker shaft from coming off, and making positioning easy. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory front view in the present embodiment.

FIG. 2 is an explanatory cross-sectional view of FIG. 1 as viewed from the side.

[Explanation of symbols]

 Reference Signs List 20 Cylinder head main body (cylinder head main body) 34 Rocker shaft 34a End face (axial end face) 38 Bearing 50 Rocker cover 50b Inner side face 54 Rib

Claims (4)

[Claims] 1. An OHC engine comprising: a cylinder head body having a rocker shaft rotatably supported on an upper portion thereof; and a rocker cover attached to the cylinder body so as to cover the rocker shaft mounting side. An OHC engine having a rib protruding from an inner surface of the cover at a predetermined height and restricting axial movement of the rocker shaft. 2. The OHC engine according to claim 1, wherein the ribs are formed so as to protrude at positions opposed to both axial end surfaces of the rocker shaft. 3. The OHC engine according to claim 2, wherein the rib faces only a part of both axial end surfaces of the rocker shaft. 4. The rocker shaft according to claim 2, wherein the ribs oppose end faces of both ends of the rocker shaft via a predetermined gap, and regulate an axial movement range of the rocker shaft. OHC engine according to any one of the above.