JPH0941910A - Structure of doch-type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent a lubricating oil from leaking through a bearing hole of a cam shaft on another side among bearing devices without causing the structural complication of the bearing device. SOLUTION: The ends on one side of two cam shafts 5, 7 arranged on the upper face of a cylinder head 2 are borne by a bearing device 3 provided on the one end part of the cylinder head, and a power transmitting timing belt 11 is wound on the end part protruding from the bearing device of the cam shaft 7 on one side. A blind cap 20 for shunting a bearing hole 3a is fittedly inserted in the said hole 3a, and moreover a cover for covering the timing belt is provided with a projection 21 which protrudes toward the blind cap to prevent its falling-off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a so-called DOHC type internal combustion engine in which a cam shaft for an intake valve and a cam shaft for an exhaust valve are arranged on an upper surface of a cylinder head.

[0002]

2. Description of the Related Art Conventionally, in this type of DOHC type internal combustion engine, as disclosed in, for example, Japanese Patent Application No. 3-33408, it is arranged on the upper surface of a cylinder head fastened to a cylinder block. One end of each of the intake valve cam shaft and the exhaust valve cam shaft is a bearing portion provided at one end portion in the longitudinal direction of the cylinder head, and one of the cam shafts projects outward from the bearing portion. So that the timing belt or chain for power transmission from the crankshaft to the one cam shaft is wrapped around the protruding end portion of the one cam shaft from the bearing portion, while the cylinder block and The cylinder belt has a structure in which a cover for the timing belt or the chain is attached to one end face in the longitudinal direction. The other cam shaft of the two cam shafts receives power from one of the cam shafts by a gear mechanism provided inside the bearing portion.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the OHC type internal combustion engine, the bearing hole for the other cam shaft of the bearing parts for the one end of both cam shafts is
Since the outer side is opened, a part of the lubricating oil supplied to the bearing portion leaks from the bearing hole opened on the outer side as described above.

Therefore, conventionally, it is necessary to provide a means for preventing the leakage of the lubricating oil at the opening to the outside of the bearing hole, which increases the number of processing steps and the number of parts for this. However, there is a problem that not only the cost is considerably increased, but also this part is enlarged. The present invention has a technical problem to solve this problem with an extremely simple structure.

[0005]

In order to achieve this technical object, the present invention discloses that "one end portion of an intake valve cam shaft and an exhaust valve cam shaft provided on an upper surface of a cylinder head fastened to a cylinder block is provided. A bearing device provided at one end portion in the longitudinal direction of the cylinder head, wherein one of the cam shafts is rotatably supported so as to project outward from the bearing device, and the bearing of the one cam shaft is provided. A timing belt or chain for power transmission from the crankshaft to the one camshaft is wound around the end protruding from the device, while the timing belt or chain is attached to one end face in the longitudinal direction of the cylinder block and the cylinder head. In a DOCH type internal combustion engine in which a cover for each of the camshafts is mounted on the other camshaft In, fitted blind lid for closing the opening portion of the bearing hole, further, on the cover, and the configuration called the blind toward the cover is provided a protrusion for falling prevention protruding. ".

[0006]

[Operation] With this structure, it is ensured that the lubricating oil leaks from the bearing hole for the other cam shaft of the bearing devices for one end of both cam shafts by the blind lid inserted into this bearing hole. While it can be prevented, the blind lid
The protrusion provided on the cover can reliably prevent the cover from falling off from the bearing hole.

[0007]

Therefore, according to the present invention, a blind lid for preventing the leakage of the lubricating oil from the one bearing hole in the bearing device with respect to one end of both cam shafts is provided in the bearing hole.
Using a timing belt or a cover that covers the chain,
It can be fixed so that it does not fall off from the bearing hole, and no separate parts are required for this fixing, so the leakage of lubricating oil from the bearing hole is prevented and the number of parts and the number of processing steps are increased. Without doing so, it is possible to surely achieve it, and it is possible to avoid an increase in the size of that portion.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.
The drawing of FIG. 4 will be described. In FIG.
Indicates a cylinder block, and reference numeral 2 indicates a cylinder head fastened to the upper surface of the cylinder block 1 by a plurality of head bolts (not shown).

Reference numeral 5 indicates a cam shaft for the intake valve 6, and reference numeral 7 indicates a cam shaft for the exhaust valve 8. Both cam shafts 5, 7 are a valve mechanism chamber 2a on the upper surface of the cylinder head 2. The intermediate bearing devices 4a and 4b, which are arranged in parallel with each other inside the cylinders, and the bearing device 3 at one longitudinal end of the cylinder head 2.
It is supported by and.

That is, one end of the exhaust valve cam shaft 7 of the cam shafts 5 and 7 is supported by a bearing hole 3b provided in the bearing device 3 so as to project outward from the bearing hole 3b. Further, one end of the intake valve camshaft 5 is provided with a bearing hole 3a provided in the bearing device 3 so that the bearing hole 3a
It is pivoted so that it does not project further. The two cam shafts 5 and 7 are configured to rotate in conjunction with each other by gears 8 and 9 which are arranged inside the bearing device 3 so as to mesh with each other. One of the shafts 5, 7 has a cam shaft 7 fitted to a shaft end portion projecting outward from the bearing device 3 and a timing pulley 10 is fitted to the timing pulley 10 from a crank shaft (not shown). By winding 11 around, the rotation of the crankshaft is transmitted to the one camshaft 7, and the rotation is transmitted from the one camshaft 7 to the other camshaft 5.

Further, a cover 17 for covering the timing belt 11 is detachably attached to one end face in the longitudinal direction of the cylinder block 1 and the cylinder head 2 by a bolt or the like not shown. The bearing device 3 includes a bearing portion 12 formed integrally with the cylinder head 2 and a common bearing cap 1 disposed on the upper surface side thereof.
3 and the common bearing cap body 13 is fastened to the bearing portion 12 on the cylinder head 2 side with three bolts 14, 15 and 16.

The lubricating oil from the lubricating oil pump is supplied to both bearing holes 3a and 3b in the bearing device 3 through the oil passage 18, and the lubricating oil supplied to one bearing hole 3a is the same as the bearing. After lubricating the inside of the hole 3a, the oil is supplied to one of the gears 8 and 9 through the oil passage 19. A bearing hole 3 of the bearing device 3 into which the intake valve camshaft 5 is fitted.
The blind lid 20 for closing the opening is inserted into the opening to the outside of a, while the inner surface of the cover 17 covering the timing belt 11 has a portion corresponding to the blind lid 20. A protrusion 21 that projects toward the blind lid 20 is integrally provided.

In this structure, the leakage of the lubricating oil from the bearing hole 3a for the intake valve cam shaft 5 of the bearing device 3 for one end of the cam shafts 5, 7 is prevented by the blind lid 20 inserted into the bearing hole 3a. Can be reliably prevented by
It is possible to reliably prevent the blind lid 20 from coming off from the bearing hole 3a by means of the projection 21 provided integrally with the cover 17.

[Brief description of drawings]

FIG. 1 is a plan view of a cylinder head showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG.

[Explanation of symbols]

 1 Cylinder Block 2 Cylinder Head 3 Bearing Device 5 Intake Valve Cam Shaft 7 Exhaust Valve Cam Shaft 8, 9 Gear 10 Timing Pulley 11 Timing Belt 3a, 3b Bearing Hole 17 Cover 20 Blind Cover 21 Projection

Claims (1)

[Claims] 1. A bearing device in which one ends of an intake valve cam shaft and an exhaust valve cam shaft arranged on an upper surface of a cylinder head fastened to a cylinder block are provided at one longitudinal end of the cylinder head. , One of the cam shafts is supported so as to project outward from the bearing device,
At the protruding end of the one cam shaft from the bearing device,
A DOHC in which a timing belt or a chain for power transmission from the crankshaft to the one camshaft is wound, while a cover for the timing belt or the chain is attached to one end face in the longitudinal direction of the cylinder block and the cylinder head. Type internal combustion engine, a blind lid that closes an opening of the bearing hole is fitted into a bearing hole for the other cam shaft of the bearing devices for the one end portions of the cam shafts, and further, the cover and the blind lid. DOH characterized in that it is provided with a projection portion for preventing the drop-out which projects toward
Structure of C-type internal combustion engine.