JPH0636241Y2 - Bearing structure of engine camshaft - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a bearing structure of a camshaft for driving intake and exhaust valves in an engine.

[Conventional technology]

In an engine, a cam shaft that drives an intake / exhaust valve is rotatably supported by a cylinder head by a cam cap.

As a prior art document disclosing such a bearing structure for an engine camshaft, for example, Japanese Utility Model Laid-Open No. 60-118016
No., actual development 60-183206, actual development 59-116623, actual development 58
-16426 or the applicant of the present application filed on Sep. 25, 1986, Japanese Utility Model Application No. 61-146833 (refer to the bearing structure of the engine camshaft bearing, Japanese Utility Model Application No. Sho 63-52901).

FIG. 6 is a longitudinal sectional view (unknown) of the bearing structure of the camshaft of the engine reproduced from the application No. 61-146833 filed by the applicant on September 25, 1986.

In FIG. 6, 1 is a cam shaft, 2 is a cam, 3 is an intake / exhaust valve, 5 is a valve lifter, 6 is an adjusting system, and 7 is a valve spring.

The cam shaft 1 is rotatably supported by the cylinder head 12 by a cam cap 11 at its journal portion 13.

When the cam shaft 1 rotates as shown by arrow C, the cam 2 drives the intake / exhaust valve 3 via the valve lifter 5. An oil passage 14 and an oil hole 15 through which oil for lubricating the journal portion 13 flows are bored in the camshaft 1. Arrow B represents the flow of oil.

In FIG. 6, a resin coating layer 23 is formed on the sliding surface 22 of the cam cap 11. This is for the following reason.

That is, in FIG. 6, since the camshaft 1 receives the force in the direction of arrow A by the valve spring 7,
13 is pressed against the cam cap 11. For this reason,
Especially when the engine runs at low speed, the journal section 13
The oil film between the cam cap 11 and the cam cap 11 may break, causing the stick-slip phenomenon and noise. Therefore, by forming the resin coating layer 23 on the sliding surface 22 of the cam cap 11, the familiarity between the journal portion 13 and the cam cap 11 is improved and such noise is prevented.

[Problems to be solved by the device]

However, in the conventional camshaft bearing structure as shown in FIG. 6, the oil supplied from the oil passage 14 and the oil hole 15 to the journal portion 13 is decreased due to the decrease of the oil viscosity due to the increase of the oil temperature. However, there is a problem in that a large amount of oil flows out in the axial direction as shown by arrow F, the oil film of the journal portion 13 is cut off, and as a result, the resin coating layer 23 is worn away.

The present invention solves the above-mentioned problems of the conventional technology. The technical problem of the present invention is to provide a camshaft of an engine in which a resin coating layer is formed on the sliding surface of the cam cap. This is to prevent wear of the resin coating layer due to running out of the oil film in the bearing structure.

[Means for Solving the Problems]

In order to achieve this technical problem, the following measures are taken in the present invention.

That is, the bearing structure of the camshaft of the engine according to the present invention is such that the camshaft that drives the intake and exhaust valves of the engine is rotatably supported by the cylinder head by the cam cap in the journal part. Has an oil passage, and an oil hole communicating with the oil passage and opening on the surface of the journal portion is formed in the cam shaft. A resin coating layer is formed on the sliding surface of the cam cap. In the formed camshaft bearing structure of the engine, a circumferentially extending concave portion is provided on the sliding surface of the cam cap on the front and rear sides of the oil hole, and the concave portion of the resin coating layer is formed by the concave portion. It is characterized in that the thickness of the concave portion is thick and the other portion is thin.

[Action]

When the temperature of the oil rises, the resin thermally expands and the thickness of the resin coating layer tends to become thicker. However, according to the above-mentioned means, a recess is provided at the position where the oil hole is sandwiched in the front and rear on the sliding surface of the cam cap. Since the resin of the resin coating layer is also filled in the recesses, the thickness of such a portion is large, and therefore when the temperature of the oil rises, the thermal expansion amount of such a portion is larger than that of other portions. Is also big. Therefore,
When the temperature rises, only the resin in the recesses rises more than other parts.

Since this bulge can be located at a position sandwiching the oil hole in the front and rear, the clearance with respect to the journal part becomes small only at that part, and as a result, oil is accumulated in the vicinity of the oil hole and the outflow of oil is suppressed.

In addition, the adhesive area between the resin coating layer and the cam cap is larger in the portion where the concave portion is present than in the other portion, so that the adhesive force is increased, and the concave portion is one of the forces acting in the cam shaft direction on the resin coating layer. Since the part receives the pressing force or the tensile force, the ratio of the force acting on the coating layer acting as the shearing force becomes small, and the shearing force on the coating layer is relaxed.

〔Example〕

FIG. 1 is a vertical sectional view of a bearing structure for a camshaft of an engine according to a first embodiment of the present invention.

In FIG. 1, 1 is a cam shaft, 2 is a cam, 3 is an intake / exhaust valve, 5 is a valve lifter, 6 is an adjusting shim, and 7 is a valve spring.

The cam shaft 1 is rotatably supported by the cylinder head 12 by a cam cap 11 at its journal portion 13. The cam cap 11 is made of aluminum, while the cam shaft 1 is made of iron.

When the cam shaft 1 rotates as shown by arrow C, the cam 2 drives the intake / exhaust valve 3 via the valve lifter 5.

An oil passage 14 and an oil hole 15 for flowing oil for lubricating the journal portion 13 are formed in the camshaft 1. The oil hole 15 opens on the surface of the journal portion 13. Arrow B represents the flow of oil.

In this embodiment, the resin coating layer 23 is formed on the sliding surface 22 of the cam cap 11 to prevent the generation of noise due to the stick-slip phenomenon. That is, since the metal and the resin are in contact with each other, the stick-slip phenomenon does not occur.

A circumferentially extending recess 31 is provided at a position where the oil hole 15 is sandwiched forward and backward on the sliding surface 22 of the cam cap 11 (both ends of the cam cap 11 in FIG. 1). The resin is also present in the recess 31. This is a feature of this embodiment.

The thickness of the resin coating layer 23 other than the recess 31 is 10
It is said to be between ~ 1000 μm for the following reason.

That is, it is experimentally confirmed that if the thickness is 10 μm or less, the resin coating layer 23 is immediately worn, and if the thickness is 1000 μm or more, heat is accumulated in the resin coating layer 23 and the resin is decomposed. Because. In addition, 1000μ
This is because when the diameter is not less than m, the roundness of the cam hole cannot be obtained due to the difference in the specific cutting resistance between the resin and aluminum when the cam hole is processed.

As the resin, a heat-resistant resin such as tetrafluoroethylene / ethylene or polyimide, which can withstand a continuous use temperature of about 150 ° C, is used. This is because the sliding surface 22 of the cam cap 11 may normally rise up to about 150 ° C. Further, in order to improve wear resistance, fine particles of molybdenum disulfide, carbon, Teflon, etc. are mixed in the resin. In addition, carbon fibers are also filled to improve heat resistance.

Well-known lining method, insert molding, powder coating method or spray coating method is used as the method of resin coating. According to these methods, the resin coating layer 23 can be very easily formed on the surface of the aluminum cam cap 11.

FIG. 2 is a perspective view of a cam cap used in the bearing structure of the camshaft of the engine of FIG.

In FIG. 2, 11 indicates the entire cam cap.
Reference numeral 9 is a bolt hole through which a bolt (not shown) for fixing the cam cap 11 to a cylinder head (not shown) of the engine is inserted.

In the cam cap 11 shown in FIG. 2, the journal portion of the cam shaft (not shown) is attached to the portion indicated by reference numeral 21.
Is located. What is denoted by reference numeral 23 is the resin coating layer described above.

Returning to FIG. 1, in this embodiment, a resin-coated cam cap 11 is attached to the cylinder head 12, and a hole through which the cam shaft 1 passes (indicated by reference numeral 21 in FIG. 2) is formed in that state. Co-processing.

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

As shown in FIG. 3, recesses 31 are provided at both ends of the cam cap 11 which sandwiches an oil hole (not shown) in the front and rear on the sliding surface 22 of the cam cap 11, and the resin of the resin coating layer 23 is formed in the recess 31. You can see well that it is filled inside.

The operation of this embodiment will be described.

When the temperature of the oil rises, the resin thermally expands and the thickness of the resin coating layer 23 tends to increase, but in the present embodiment, as can be seen from FIG. Recesses 31 are provided at both ends of the cam cap 11 that sandwiches the oil hole 15 in the front and rear, and the resin coating layer
Since the resin of No. 3 is also filled in the recess 31, the thickness of such a portion is large, and therefore when the temperature of the oil rises, the thermal expansion amount of such a portion is larger than that of the other portions. Therefore, when the temperature rises, as shown in FIG. 4 (FIG. 4 is a diagram for explaining the operation of the bearing structure of the camshaft of the engine of FIG. 1), only the resin 32 in the recess 31 is designated by the reference numeral 33. It gets excited as it is done.

These swells 33 can be formed at both ends of the cam cap 11 that sandwiches the oil hole 15 in the front and back, and only that part is especially the journal part.
The clearance with 13 becomes smaller. In other words, an oil pool will be formed near the oil hole 15.

Therefore, even if the oil temperature rises and the viscosity of the oil decreases, a large amount of the oil supplied to the journal portion 13 from the oil passage 14 and the oil hole 15 is suppressed from flowing out in the axial direction, and the journal portion is suppressed. No oil film breakage occurs at 13.

Thus, according to this embodiment, it is possible to prevent the abrasion of the resin coating layer 23 due to the oil film running out.

In the present embodiment, the height of the raised portion 33 when the oil temperature rises (the thickness when the pressing force is not applied by the camshaft 1) is about 5 to 50 μm in advance so that the recess 31 is formed.
Depth is decided.

Further, since the cam cap 11 of this embodiment has the recess 31, the recess 31 serves as an anchor of the resin coating layer 23. That is, in the portion where the concave portion 31 is present, the adhesive area between the resin coating layer 23 and the cam cap 11 is larger than in other portions, so the adhesive force is increased, and the concave portion 31 acts on the resin coating layer 23. Since a part of the force in the direction of the camshaft 1 is received as a pressing force or a tensile force, the ratio of the force acting on the coating layer 23 acting as a shearing force is reduced, and the shearing force on the coating layer 23 is relaxed.

As described above, in this embodiment, since the concave portion 31 strengthens the adhesive force and relaxes the shearing force, there is an advantage that the resin coating layer 23 is less likely to peel off.

In a normal engine, it is general that the camshaft 11 is not coated with the resin coating layer 23, but the camshaft 1 is plated with lead or the like. The occurrence of the stick-slip phenomenon is prevented by applying resin coating to the sliding surface 22 of the cam cap 11 instead of plating 1 with lead or the like.

Since there is no need to plate the camshaft 1, oil holes
The work of plugging 15 (necessary when plating) is not necessary, and the cam profile is not changed by the plating layer.

Further, in this embodiment, since the resin-coated cam cap 11 is attached to the cylinder head 12 and the hole through which the cam shaft 1 passes (see reference numeral 21 in FIG. 2) is co-machined in that state, the resin coating is performed. The great advantage is that the thickness of the layer 23 is very easy to control.

It should be noted that coating the aluminum cam cap 11 with a resin is significantly easier than plating by using a lining method, insert molding, powder coating method or spray coating method.

Further, since the frictional resistance between the metal and the resin is much smaller than the frictional resistance between the metal and the metal, there is an advantage that the rotational resistance of the camshaft 1 is reduced and the output of the engine is improved.

Further, since minute foreign matter mixed in the engine oil is buried in the resin coating layer 23, there is an advantage that abnormal wear of the journal portion 13 of the camshaft 1 can be reduced.

FIG. 5 is a vertical cross-sectional view of a camshaft bearing structure according to a second embodiment of the present invention.

In FIG. 5, 11 indicates the entire cam cap.
What is denoted by reference numeral 23 is the resin coating layer described above.

Also in FIG. 5, a concave portion 31 is provided on the sliding surface 22 of the cam cap 11 with the oil hole 15 sandwiched in the front and rear, and the resin of the resin coating layer 23 is also filled in the concave portion 31. However, the recess 31 is not at both ends of the cam cap 11,
It is provided somewhere in the middle from both ends. Therefore, the adhesive area of the concave portion 31 is further increased and the adhesive force is increased as compared with that of FIG. Since it increases, the shearing force on the coating layer 23 is further alleviated, and the coating layer 23 becomes more difficult to peel off.

This point is the only difference from the one in FIG. 1 and other matters are exactly the same as those in the first embodiment, so only the reference numerals are given and no more for the one in FIG. Is omitted.

Although the specific embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various embodiments are included within the scope of the utility model registration claim.

[Effect of device]

As described above, according to the present invention, when the oil viscosity is low and the oil tends to flow out, at the time of high temperature, oil is accumulated in the vicinity of the oil hole, so it is possible to prevent abrasion of the resin coating layer due to oil film breakage at high temperature. become.

Further, the presence of the recess enhances the adhesive force between the resin coating layer and the cam cap, and also reduces the shearing force to the coating layer, so that the resin coating layer is less likely to peel off.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a bearing structure for an engine camshaft according to a first embodiment of the present invention, and FIG. 2 is a perspective view of a cam cap used in the bearing structure for an engine camshaft of FIG. Fig. 3, Fig. 3 is a sectional view taken along the line III-III of Fig. 2, Fig. 4 is an explanatory view of the action of the bearing structure of the camshaft of the engine of Fig. 1, and Fig. 5 is a second embodiment of the present invention. FIG. 6 is a longitudinal sectional view of a bearing structure of a camshaft of an engine according to an example, and FIG. 6 is a longitudinal sectional view of a bearing structure of a conventional camshaft of an engine (however, not known). 1 …… Cam shaft 3 …… Intake / exhaust valve 11 …… Cam cap 12 …… Cylinder head 13 …… Journal part 14 …… Oil passage 15 …… Oil hole 22 …… Cam cap sliding surface 23 …… Resin coating Layer 31 …… Recess 32 …… Resin in the recess

 ─────────────────────────────────────────────────── ───Continued from the front page (56) References Microfilm (JP, U) of the detailed description and drawings attached to the application for Japanese Patent Application No. 58-9034 (No. ) A microfilm (JP, U) obtained by photographing the contents and drawings attached to the application of Japanese Utility Model Application No. 51-128410 (Japanese Utility Model Application No. 53-46448).

Claims (1)

[Scope of utility model registration request] 1. A camshaft for driving an intake / exhaust valve of an engine is rotatably supported by a cylinder head in a journal portion by a cam cap, and an oil passage is provided in the camshaft. In a bearing structure of an engine camshaft, an oil hole communicating with a passage and opening on a surface of the journal portion is formed in the camshaft, and a resin coating layer is formed on a sliding surface of the camcap. A concave portion extending in the circumferential direction is provided on the sliding surface of the cam cap on both front and rear sides of the oil hole, and the thickness of the resin coating layer is large in the concave portion due to the concave portion. The bearing structure of the camshaft of the engine, which is characterized in that it is made thinner in parts.