JPH0217170Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to the cylinder structure of an engine, and particularly to an improvement in a structure in which a camshaft is disposed on the mating surface of a cylinder head and a cylinder head cover.

(Prior Art) Conventionally, in this type of engine, holes are formed on the camshaft axis in the front and rear walls of the cylinder head, and when machining the camshaft bearing of the cylinder head or installing the cam sprocket, holes are formed from the holes. A jig is inserted into the cylinder head for processing and installation, and when assembling the engine, a cap member is fitted into the hole, and a cylinder head cover is installed over it to ensure blow-by gas sealing. is being carried out. In this case, the hole is formed into a half-moon shape according to the cross-sectional shape of the cylinder head side of the camshaft, and the same half-moon shape as the hole is used as the cap member, and the cylinder head cover is not processed in any way. Generally, the upper end of the cap member that faces the horizontal surface has a corresponding horizontal surface (vehicle manual published by Mazda (formerly known as Toyo Kogyo) Co., Ltd., October 1971). 29 of “Capella Structure and Maintenance”
(See page 31).

(Problem to be solved by the invention) However, in such an engine cylinder structure, since the cap member and the seal flange portion of the cylinder head cover are arranged on the camshaft axis, the thickness of the cap member and the seal flange portion is There is a problem in that the overall length of the engine increases due to the Further, since the upper end of the cap member is formed in a horizontal plane, a gap is likely to be formed between the mating surface of the cylinder head cover and the upper end of the cap member, resulting in insufficient sealing performance for blow-by gas.

By the way, generally, a cam pulley or cam sprocket is attached to one end of the camshaft with a tightening bolt, and a timing belt or timing chain is wound between the cam pulley or cam sprocket and the engine output shaft, and the timing belt is tightened by the engine output shaft. Alternatively, the camshaft is driven via a timing chain.

The present invention was devised in view of these points, and its purpose is to reduce the overall length of the engine by devising the shape of the cap member and the arrangement relationship with the tightening bolts of the cam pulley and cam sprocket. Another object of the present invention is to improve the sealing performance of the blow-by gas by the cap member by devising the shape and structure of the cap member.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention provides a cylinder head and a cylinder on the front and rear walls of the engine, which are composed of a cylinder head and a cylinder head cover attached to the cylinder head. A circular hole centered on the camshaft axis is formed by a semicircular part on the cylinder head side and a semicircular part on the cylinder head cover side at the mating part with the head cover.
Further, a circular cap member is provided which is fitted into the hole and closes the hole. Furthermore, at least the cap member on the side of the cam pulley or cam sprocket has a recessed part whose inner surface is formed in a concave shape, and is integrally formed with a core material forming the recessed part and the outer side of the core material, and is connected to a cylinder head and a cylinder head cover. It has a double structure consisting of the rubber that forms the seal and the rubber that forms the seal. The head of the tightening bolt of the cam pulley or cam sprocket is inserted into the recess of the cap member.

(Function) With the above configuration, the present invention allows the camshaft axis to be aligned between the semicircular part on the cylinder head side and the semicircular part on the cylinder head cover side at the joint part of the cylinder head and cylinder head cover on the front and rear walls of the engine. Since a circular hole is formed at the center and the cap member is inserted into the hole to close the hole, a sufficient tightening margin can be secured compared to a half-moon-shaped cap member. This increases the adhesion between the semicircular portions on the cylinder head side and the cylinder head cover side and the cap member, and improves the sealing performance for blow-by gas.

In this case, a concave portion is formed in the cap member, and the cap member is made of a core material forming the concave portion and a rubber integrally formed on the outside of the core material and forming a sealing portion between the cylinder head and the cylinder head cover. Due to the double structure, the rigid core material prevents the cap member from being pressed and deformed when the cylinder head cover is installed.This allows good blow-by gas sealing performance to be maintained, and the cap member This prevents interference between the cam pulley or the cam sprocket tightening bolt. Furthermore, the rubber on the outside of the core material further improves the sealing performance against blow-by gas.

In addition, since the head of the tightening bolt of the cam pulley or cam sprocket is inserted into the recess of the cap member, interference of the cylinder head or cylinder head cover with the tightening bolt head is avoided, and the overall length of the engine is becomes more compact.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

1 and 2 show an engine equipped with a cylinder structure according to an embodiment of the present invention. 1 is a cylinder block, 2 is a cylinder head disposed on the cylinder block 1, and a plurality of cylinders 3 are formed between the cylinder block 1 and the cylinder head 2. Above cylinder head 2
A cylinder head cover 4 is attached to the upper side of the cylinder head. Thick seal flange portions 2a and 4a are formed at the mating portions of the cylinder head 2 and cylinder head cover 4, respectively, and a gasket 5 is attached to the seal flange portion 4a of the cylinder head cover 4. This prevents blow-by gas from leaking from the space inside the cylinder head cover to the outside space.

Further, a camshaft 6 is pivotally supported on the cylinder head 2 so that its axis coincides with the joint between the cylinder head 2 and the cylinder head cover 4. A cam sprocket 7 is attached to the front end of the camshaft 6.
A boss member 8 having a cam portion 8a for driving a mechanical pump and a gear portion 8b for driving a distributor is attached to the front side of the cam sprocket 7 and the boss member 8 are tightened from the front through a hole 13 which will be described later. It is fixed to the camshaft 6 with a tightening bolt 9. Then, the cam sprocket 7 and the drive shaft sprocket (not shown)
A chain 10 is wound between the cylinders 1 and 1, and a drive shaft rotates a camshaft 6 to operate intake and exhaust valves (not shown) for each cylinder 3. A mechanical pump 11 is disposed in the cylinder head 2 with a drive lever 11a in contact with the cam portion 8a of the boss member 8, and is used to supply fuel to the engine. Further, 12 is a distributor disposed in the cylinder head 2 with a drive gear 12a meshed with a gear portion 8b of the boss member 8.

Furthermore, holes 13 are formed in the front and rear walls of the engine, each of which is comprised of the cylinder head 2 and the cylinder head cover 4, at the joints between the cylinder head 2 and the cylinder head cover 4. The hole portion 13 is formed in a circular shape centered on the camshaft axis, has approximately the same diameter as the bearing portion of the camshaft 6, and consists of a semicircular portion on the cylinder head side and a semicircular portion on the cylinder head cover side. .

A cap member 14 that closes the hole 13 is fitted into each hole 13 with a concave-convex connection.

The cap member 14 is formed in a circular shape centered on the camshaft axis, and has a recess 15 in the center with a concave inner surface. The cap member 14 is made up of a core material 14a that forms the recess 15, and a rubber 14b that is integrally formed on the outside of the core material 14a and forms a seal between the cylinder head 2 and the cylinder head cover 4. It has a double structure.

Furthermore, the head of the tightening bolt 9 is inserted into the recess 15 of the cap member 14 to avoid interference between the head of the tightening bolt 9 and the cap member 14.

Therefore, in the above embodiment, the camshaft axis is formed at the joint between the cylinder head 2 and the cylinder head cover 4 on the front and rear walls of the engine by a semicircular part on the cylinder head side and a semicircular part on the cylinder head cover side. Since a circular hole 13 is formed at the center and the cap member 14 is fitted into the hole 13 to close the hole 13, the tightening allowance is reduced compared to the conventional half-moon-shaped cap member. Cylinder head cover 4 can be secured sufficiently.
When the cylinder head 2 and the cylinder head cover 4 are installed, the sealing flange portions 2a, 4a of the cylinder head cover 4 and the cap member 14 are brought into close contact with each other, so that the blow-by gas inside the cylinder head cover can be sealed well.

In that case, a recess 15 is formed in the cap member 14, and the cap member 14 is
A core material 14a that forms a cylinder head 2 and a rubber 14b that is integrally formed on the outside of the core material 14a and forms a seal between the cylinder head 2 and the cylinder head cover 4.
Since the cap member 14 has a double structure, the rigid core member 14a prevents the cap member 14 from being pressed and deformed when the cylinder head cover 4 is attached, thereby maintaining good blow-by gas sealing performance. Cap member 1
4 and the tightening bolt 9 are prevented from interfering with each other. Moreover, the sealing performance against blow-by gas is further improved by the rubber 14b on the outside of the core material.

Further, the tightening bolt 9 of the camshaft 6 is inserted into the recess 15 of the cap member 14 arranged on the front wall of the engine.
Since the head of the bolt is located, the tightening bolt 9 and cylinder head 2 or cylinder head cover 4
The longitudinal length of the cylinder head 2 and the cylinder head cover 4 can be made as short as possible within the range that can secure the clearance in front of the boss member 8 while avoiding interference with the cylinder head 2 and the cylinder head cover 4, and the overall length of the engine can be made compact. .

Furthermore, FIG. 3 shows a modification of the cap member 14. This is a gasket 5 attached to the seal flange 4a of the cylinder head cover 4.
are arranged in a detour along the upper peripheral edge of the cap member 14 in the hole 13, thereby further improving the blow-by gas sealing performance.

In the above embodiment, an engine in which the camshaft 6 is driven by a chain has been described, but the present invention can be similarly applied to an engine in which the camshaft 6 is driven by a belt.

(Effects of the invention) As explained above, according to the engine cylinder structure of the invention, the semicircular part on the cylinder head side and the cylinder head cover are attached to the joint part of the cylinder head and the cylinder head cover on the front and rear walls of the engine. A circular hole centered on the camshaft axis is formed with the semicircular portion on the side, and a circular cap member that closes the hole is inserted into the hole, and at least the cap member on the cam pulley or cam sprocket side is inserted. ,
A double cylinder having a concave portion with a concave inner surface and consisting of a core material forming the concave portion and a rubber integrally formed on the outside of the core material and forming a seal between the cylinder head and the cylinder head cover. Since the head of the tightening bolt of the cam pulley or cam sprocket is inserted into the recess of the cap member, interference of the cylinder head or cylinder head cover with the tightening bolt head can be avoided and the overall length of the engine can be reduced. While being compact, the adhesion between the semicircular parts on the cylinder head side and the cylinder head cover side and the cap member is increased, deformation of the cap member is prevented, and the rubber on the outside of the core material has a sealing effect. Accordingly, the sealing performance of the blow-by gas by the cap member can be improved.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a longitudinal sectional side view of the main part, FIG. 2 is a front view, and FIG. 3 is a sectional view of the main part showing a modification of the cap member. 2... Cylinder head, 4... Cylinder head cover, 6... Camshaft, 7... Cam sprocket, 9... Bolt, 13... Hole, 4... Cap member, 15... Recess.

Claims (1)

[Scope of Claim for Utility Model Registration] A semicircular portion on the cylinder head side is located at the joint of the cylinder head and cylinder head cover on the front and rear walls of the engine, which is composed of a cylinder head and a cylinder head cover attached to the cylinder head. and a semicircular part on the cylinder head cover side to form a circular hole centered on the camshaft axis, and a circular cap member is provided that is fitted into the hole to close the hole, and at least the cam pulley or The cap member on the cam sprocket side has a recess with a concave inner surface, and is integrally formed with a core material forming the recess and on the outside of the core material, and has a sealing portion between the cylinder head and the cylinder head cover. 1. A cylinder structure for an engine, characterized in that the head of a tightening bolt of a cam pulley or a cam sprocket is inserted into the recess of the cap member.