JPS63239303A - Bearing for cam shaft - Google Patents

Abstract

PURPOSE:To prevent lubricating oil from spraying outwards by means of extruding members so as to improve the lubricating ability by forming semi-cylindrical extruding members extruding over the cam circumferential surface above the cam shaft of an OHC type engine integrally on the side surface of a bearing. CONSTITUTION:The cam shaft 7 of an OHC type engine is formed by providing a plurality of pair of cams 8 corresponding respectively to plural pistons arranged in a row within a cylinder block, and supported rotatably on the upper portion of a cylinder head 2 by means of plural beings 15. Each bearing 15 has a cap 17 adapted to cover the upper portion of the bearing formed between a pair of cams 8 of the cam shaft 7, and the cap 17 is fixed to a base 16 through bolts B. In this case, each semi-cylindrical extruding member 26 is integrally formed coaxially with the bearing surface 22 of the cap 17 on the both side surfaces 17a of the cap 17. The extruding member 26 has sufficient width to reach the upper portion of the cam 8 when the cap is attached and is formed in order that it covers the circumferential/surface 8a of the cam 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a camshaft bearing mainly used in an internal combustion engine.

[Prior Art] Among the four-stroke internal combustion engines installed in motorcycles, etc., there is a type called OHC type in which a camshaft is arranged above the cylinder (for example, the type shown in Japanese Utility Model Application Laid-open No. 59-68165). There is something like that.

In this case, the camshaft is rotatably mounted on a bearing at the top of the cylinder head, and is covered by a cylinder head canopy.

Lubricating oil is supplied to the sliding surfaces of the bearing and the camshaft from oil holes on the bearing side or the camshaft side.

As this oil is supplied, it flies out from the sliding surfaces of the camshaft and bearing and also lubricates the cam.

[Problems to be Solved by the Invention] However, after the lubricating oil seeps out from the sliding part of the camshaft and bearing, it flies in the radial direction of the camshaft due to centrifugal force. A lot of it adhered, and it did not reach the point where it was concentrated on the circumferential surface of the cam, which should be lubricated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a camshaft bearing that can supply lubricating oil to the cam in a concentrated manner.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention integrates a semi-cylindrical extension piece that extends to cover the circumferential surface of the cam on the camshaft into the side surface. It is characterized by having

[Function] The lubricating oil seeping out from the sliding surfaces of the camshaft and the bearing flies outward in the radial direction of the camshaft due to centrifugal force, but is blocked by the semi-cylindrical extension piece and does not scatter any further.

Furthermore, the lubricating oil that bounces off the inner surface of the extension piece adheres to the circumferential surface of the cam.

[Example] Hereinafter, an example in which a camshaft bearing of the present invention is applied to a four-stroke internal combustion engine mounted on a motorcycle will be described with reference to FIGS. 1 to 7.

FIG. 1 shows a sectional view of the internal combustion engine.

This internal combustion engine is a so-called 4-valve DO, HC type, which has two valves on the intake side and two on the exhaust side per cylinder, and has two camshafts to operate the valves on each side independently. be.

In the figure, reference numeral 1 denotes a cylinder block, 2 a cylinder head fixed on the cylinder block 1 integrated with the crankcase, 3 a cylinder head cover that extends over the upper surface of the cylinder head 2, and 4 a side cover.

Inside the cylinder block 1, there are multiple (four in this case)
Pistons 5 are provided in a row, and a crankshaft 6 is also provided.

Inside the cylinder rad cover 3, there are figures 2 and 3.
As shown in the figure, two camshafts 7 (only one is visible in FIG. 1) are arranged parallel to the crankshaft 6. A pair of cams 8 are provided for one piston 5 on the camshaft 7, and a cam gear 9 is also attached. The camshaft 7 is rotated by the rotation of the crankshaft 6 via the crank gear lO, the idle gear ll, and the cam gear 9.

Further, by rotating the camshaft 7 in this manner, the cam 8 is rotated toward the valve 12 provided inside the cylinder head 2.
is pressed through a tappet 13 to open and close the valve 12. Note that the tappet 13 is inserted into a guide hole '14 formed in the cylinder head 2.

As shown in FIGS. 1 and 5, bearing portions 7a are formed between the pair of cams 8 of the camshaft 7, and these bearing portions 7a are connected to each bearing provided on the upper part of the cylinder head 2. 15, the camshaft 7 is rotatably supported.

The bearing 15 in this case is divided into two halves vertically, and as shown in FIG.
It consists of.

As shown in FIG.
．． 14, and a semi-circular bearing surface 18 at the center of the upper surface.
, Also, there are screw holes on the mating surfaces on both sides! It has 9. Furthermore, arc-shaped notches 20 are formed on both side surfaces 16a facing the guide hole 14, along the wall surface of the guide hole 14. Incidentally, the one indicated by 21 in Fig. 5 is the spark plug P (
(see Figure 1). This hole 21
has an elliptical shape and is formed on a convex portion 21a provided between the two stands 16.

On the other hand, the cap I7 has the same length and width as the base 16, and has a semi-circular bearing surface 22 at the center of its lower surface, similar to the base 16 side. As shown in FIGS. 6 and 7, an oil retaining groove (hereinafter referred to as an oil groove) 22a is formed at the center of the bearing surface 22 in the width direction.

A protrusion 23 is formed at the center of the upper part, and a protrusion 24 with a screw hole 24a is formed on the upper surface of the protrusion 23. Further, as shown in FIG. 5, the cap 17 is provided with a bolt through hole 25 at a position corresponding to the screw hole 19 on the side of the base 16.

Further, on both sides 17a of the cap 17, the cap 1
Semi-cylindrical extending pieces 26 coaxially with the bearing surface 22 of No. 7 are formed integrally with the cap 17, respectively. These extending pieces 26 connect the bearing portion 7a of the camshaft 7 to the bearing portion 1 of the base 16.
8, and has a width that reaches above the cam 8 when the bearing surface 22 is aligned with the bearing part 7a of the camshaft 7 and the cap 17 is placed on the cap 17, and is formed so as to cover the circumferential surface 8a of the cam 8. ing. Both ends of the extending piece 26 are located slightly above the lower surface of the cap 17, and a rib 26a is formed at the top of the extending piece 26, as shown in FIGS. 2 and 3.

In addition, in FIG. 1, the extension piece 26A formed on the cap 17A of the third bearing 15A from the right side extends downward at the left end in the figure to position the camshaft 7 in the axial direction. ing.

In order to support the camshaft 7 by the bearing 15 having the above configuration, as shown in FIG. The bolts B can be fastened together using the bolt holes 25 of the cap 17 and the screw holes 19 of the base 16. Also, by using the screw hole 24a provided on the cap 17, a third
As shown in the figure, attach the cylinder head cover 3 with bolts B.

can be fixed to the cylinder head 2.

Next, the lubrication mechanism for the camshaft 7, bearing 15, and cam 8 will be explained.
As shown in the figure, the main oil passage 2 that sends lubricating oil to each bearing part 7a
7 and a branch oil passage 28 are formed. Branch oil path 28
are open on the outer circumferential surface of each bearing portion 7a of the camshaft 7 and communicate with the oil groove 22a on the cap 17 side, and the main oil passage 27 is
It communicates with an oil path (the illustrated path) from the main gear rally via one set of the branch oil path 28 and the oil groove 22a.

Next, the action will be explained. When the internal combustion engine operates and the camshaft 7 rotates, lubricating oil is supplied to the oil grooves 22a of the bearing surface 22 of each cap 17. Then, it enters the sliding surfaces of the bearing I5 and the bearing portion 7a of the camshaft 7 to lubricate these surfaces.

Subsequently, as the oil is supplied, it seeps out from the sliding surface between the bearing portion 7a of the camshaft 7 and the bearing 15. This seeped oil is blown away by the centrifugal force caused by the rotation of the camshaft 7, and is removed from the extending piece 2 provided on the side surface of the cap 17.
It bounces off the inner surface of cam 6 and attaches to the circumferential surface of cam 8. Further, when a certain amount remains on the inner surface of the extension piece 26, it falls onto the circumferential surface 8a of the cam 8. With this, cam 8
Lubricating oil is intensively supplied to the sliding surface of the tappet 13.

In this way, the lubricating oil that seeps out from the sliding surface between the bearing portion 7a of the camshaft 7 and the bearing 15 and is blown away by the rotation of the camshaft 7 is blocked by the extending piece 26 provided on the cap 17 and flows into the cylinder. It is effectively supplied to the cam 8 with almost no adhesion to the inner surface of the rad cover 3.

Further, by providing the extending piece 26, the rigidity of the cap 17 is increased, which improves durability and further stabilizes the supporting force of the camshaft 7.

Note that the extending piece 26 does not necessarily have to be formed continuously all around the circumference. Further, in the above embodiment, the extension piece is located above the cam because it is an OHC type internal combustion engine, but it may be arranged on the side or below depending on the arrangement of the camshaft. In that case, there is no supply effect due to oil falling, but there is a rebound adhesion effect.

[Effects of the Invention] As explained above, according to the camshaft bearing of the present invention,
Since it has an integrally extending piece on the side surface that extends to cover the circumferential surface of the cam on the camshaft, it seeps out from the sliding surface of the camshaft and the bearing, causing centrifugal force to cause the camshaft to move outward in the radial direction. The lubricating oil that flies out in the opposite direction is blocked by the extending piece and does not scatter any further, but hits the inner surface of the extending piece, bounces back, and adheres to the circumferential surface of the cam. Therefore, most of the lubricating oil is supplied to the cam peripheral surface and is effectively used for cam lubrication.

Further, by having the extending piece, the rigidity of the bearing itself is increased, thereby improving durability and supporting force of the camshaft.

[Brief explanation of the drawing]

1 to 7 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view of an internal combustion engine to which this embodiment is applied, and FIG. 2 is a part of the upper part of the cylinder head. Figure 3 is a partial side sectional view of the upper part of the internal combustion engine, Figure 4 is a partial top view of the cylinder head, Figure 5 is an exploded perspective view of the bearing and camshaft, and Figure 6 is a vertical cross-section of the cap. The top view and FIG. 7 are the same bottom views. 7...Cam shaft, 8...Cam, 88 town.
・Cam circumferential surface, 17a...Side surface, 26...
・Extending piece.

Claims (1)

[Claims] 1. A camshaft bearing, characterized in that a half-cylindrical extension piece is integrally formed on a side surface of the camshaft and extends to cover the circumferential surface of a cam on the camshaft.