JPH0352966Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is a camshaft bearing for an engine. Specifically, a cam cap is fastened with bolts to the upper surface of a bearing base formed in a cylinder head, and the camshaft is rotatably supported. This invention relates to a camshaft bearing for an engine.

(Prior art) This type of camshaft bearing was
As an example is shown in No. 90406, the journal portion of the camshaft is rotatably supported between the bearing base and the bearing surface of the cam cap, and its vertical and horizontal movements are restrained. In order to reliably restrain and support the vertical and horizontal movements of the journal portion of the camshaft and prevent the cam cap from tilting in the axial direction of the camshaft or vibrating in the same direction (hereinafter referred to as cam cap falling), bolts are required. It is necessary to have a sufficiently strong fastening force and to provide a sufficient contact area in the axial direction between the cam cap and the bearing base. In particular, when the camshaft rotates at high speed, such as in a DOHC engine (double overhead camshaft type engine), the problem of the cam cap falling becomes serious. Therefore, conventionally, the thickness of the cam cap in the axial direction is increased over the entire cam cap to solve the above problem.

(Problem to be solved by the invention) However, in the conventional example described above, the thickness of the cam cap in the axial direction is increased over the entire axial direction just to prevent the cam cap from falling down, and the journal part of the camshaft is As a result, the contact surface width of the bearing increases beyond the range necessary for normal bearing function, resulting in increased friction loss. Also, since the cam cap has increased thickness in the axial direction over its entire length, it becomes heavier.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention has been developed for engines in which a cam cap is fastened with bolts to the upper surface of a bearing base formed in a cylinder head to rotatably support a camshaft. In a camshaft bearing, each of the cam cap and the bearing base is provided with a protrusion that protrudes in the axial direction of the camshaft, and the protrusion of the cam cap and the protrusion of the bearing base are provided at corresponding positions so as to be in contact with each other. Features.

(Function) The protrusion in the camshaft axial direction provided on the cam cap is in contact with the protrusion in the bearing base, increasing the dimension between both ends of the contact surface in the axial direction between the cam cap and the bearing base, thereby increasing the diameter of the camshaft. Strengthen the restraint support for the parts to prevent them from falling. In addition, the axial thickness of the portion of the cam cap and bearing base that supports the journal portion can be set to the minimum dimension necessary for normal bearing function, thereby reducing friction loss and improving the thickness of the cam cap and bearing base. The weight can be reduced.

(Example) FIGS. 1 to 3 show an example in which the present invention is applied to a DOHC engine, in which a camshaft 1 equipped with a cam 1a is mounted on a cylinder head 2 at a journal portion 8 thereof. It is rotatably supported between an integrally formed bearing base 3 and a cam cap 5 fastened to its upper surface 3a with bolts 4. The cam cap 5 has protrusions 6 that protrude in the axial direction of the camshaft 1 integrally formed on both side surfaces of each end. The bearing base 3 is integrally formed with a protrusion 7 on both sides of each end, which faces the protrusion 6 of the cam cap 5, and the protrusion 6 is in contact with the protrusion 7. .

As a result, the cam cap has a substantial width (thickness in the axial direction) A, as shown in FIG. The fixed width is increased, and both ends are prevented from falling over. Therefore, the cam cap 5 has a stable contact surface width B in the axial direction of the camshaft 1 that does not fall down due to the local protrusion 6, and most of the cam cap 5 can have the minimum width A necessary to bear the journal portion 8 of the camshaft 1. , the overall weight is reduced compared to the conventional example. Furthermore, since the cam cap 5 contacts the journal portion 8 of the camshaft 1 only with the minimum width necessary to properly perform the bearing function, an increase in friction loss due to unnecessary widening does not occur. This is particularly effective when the present invention is applied to a DOHC engine, which has good valve followability and can rotate at high speeds, as in this embodiment.

The bearing base 3 also has local protrusions called protrusions 7 that satisfy the upper surface width necessary to prevent the cam cap 5 from collapsing, so as with the cam cap 5, weight reduction and efficient high-speed rotation of the camshaft 1 are achieved. achieve the goal of

The protrusions 6 and ridges 7 provided on one side of the bearing base 3 and cam cap 5 and the protrusions 6 and ridges 7 provided on the other side are shifted in position from each other, as seen in FIG. It is provided. As a result, when the cam cap 5 is installed in the opposite direction from the one shown in the drawings, the protrusion 6 of the cam cap 5 and the protrusion 7 of the bearing base 3 face each other in a different manner, so that it is possible to distinguish between the different installation orientations. This can be easily confirmed by workers.

During use, the bearing surface of the cam cap 5 is worn out due to contact with the journal portion 8 of the camshaft 1, and the cam cap 5 conforms to the bearing surface. This wear condition differs not only for each bearing part, but also for each contact point even in the same bearing part, and if the cam cap 5 that has been removed for repair etc. is reinstalled in the opposite direction,
The mutual surfaces of the cam cap 5 and the camshaft 1, which had become familiar due to wear due to use, now come into contact with each other under conditions different from before, resulting in abnormal contact and the generation of abnormal noises. This may cause premature wear and rattling.

However, such a situation can be prevented because the mounting direction of the cam cap 5 can be easily confirmed as described above, and erroneous mounting of the cam cap 5 can be reliably avoided.

In addition, the present invention can be implemented in various ways other than the above-mentioned embodiments, for example, a cam cap 5
In order to receive the protrusion 6 provided on the bearing base 3, the protrusion 7 may be shaped to protrude only from the upper end of the bearing base 3.

(Effects of the invention) Since the present invention has the above-mentioned structure and function, it is possible to reliably prevent the cam cap from falling down, and
It is possible to provide a camshaft bearing for an engine that can reduce friction loss and reduce the weight of the cam cap and the bearing base.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing one embodiment of the present invention;
The figure is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a perspective view of the camshaft bearing. 1...Camshaft, 2...Cylinder head,
3...Bearing base, 4...Bolt, 5...Cam cap, 6...Protrusion, 7...Protrusion.

Claims (1)

[Scope of utility model registration request] In an engine camshaft bearing in which a cam cap is fastened with bolts to the upper surface of a bearing base formed in a cylinder head to rotatably support a camshaft, each of the cam cap and the bearing base is provided with a protrusion that protrudes in the axial direction of the camshaft, A camshaft bearing for an engine, characterized in that a protruding part of a cam cap and a protruding part of a bearing base are provided at corresponding positions so as to be in contact with each other.