JPH09242523A - Shaft lubricating structure of valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the lubricating property of a cam shaft. SOLUTION: An oil lubricating route for supplying the lubricating oil from an oil discharge port 32 of a cam shaft journal to a cylinder head bearing part through an oil passage inside of a cam shaft is provided. A notch part 34 is formed in the inner circumferential surface 17 of the cylinder head bearing part so that each central position CP of cross dimension between both edges 17a crossing a rotary axis of the cam shaft CL is positioned at a different position in the circumferential direction crossing the rotary axis CL. The cam shaft is displaced to the center of rotation so that the oil discharge hole 32 is separated from the notch part 34 at the time of angle of rotation of the cam shaft that the oil discharge hole 32 passes near the notch part 34. Consequently, reduction of the seal width S between the notch part 34 and the oil discharge hole 32 is restricted so as to lower the oil leakage from the notch part 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft lubrication structure for preventing leakage of lubricating oil due to a change in shape of a cylinder head bearing portion that supports a camshaft journal in a valve train of an internal combustion engine.

[0002]

2. Description of the Related Art In a conventional camshaft lubrication structure (for example, see Japanese Utility Model Laid-Open No. 2-40909), a camshaft journal is rotatably supported between a lower bearing portion and an upper bearing portion of a cylinder head bearing portion. As the camshaft rotates, the outer peripheral surface of the camshaft journal slides on the inner peripheral surfaces of the lower bearing part and the upper bearing part, and the oil discharge holes on the outer peripheral surface periodically correspond to the oil grooves of the lower bearing part. To do. Then, the lubricating oil supplied from the hydraulic pressure source is supplied to the oil groove of the cylinder head bearing portion from the oil discharge hole of the camshaft journal through the oil passage in the camshaft and is discharged to the valve lifter hole.

By the way, when a head bolt counterbore hole, a valve lifter hole, etc. are formed in a cylinder head, as shown in FIG. 6 (c), the notch 34 which becomes a part of these holes is provided with the lower bearing. It is formed on the inner peripheral surface 17 of the section to reduce the size of the engine.

[0004]

As shown in FIG. 6 (c), the center of the width dimension between both end edges 17a on the inner peripheral surface 17 of the lower bearing portion where the rotational axis CL of the camshaft intersects. Assuming the position CP, the oil discharge hole 32 of the camshaft journal passes along the linear movement locus A connecting the central positions CP with the rotation of the camshaft. Therefore, except for the cutout portion 34, it is possible to maintain the seal width S between the both end edges 17a of the inner peripheral surface 17 and the outer peripheral edge of the oil discharge hole 32 which are formed to have the same width.

However, since the inner end edge 34a of the cutout portion 34 is closer to the linear movement locus A side than the one end edge 17a of the inner peripheral surface 17 formed to have the same width except the cutout portion 34,
At a camshaft rotation angle when the oil discharge hole 32 passes near the cutout portion 34, the seal width S between the inner end edge 34a of the cutout portion 34 and the outer peripheral edge of the oil discharge hole 32 decreases. To do. Therefore, even when the oil discharge hole 32 does not correspond to the oil groove of the cylinder head bearing portion, the lubricating oil leaks from the inner end edge 34a of the cutout portion 34, and the oil shortage occurs between the cylinder head bearing portion and the camshaft journal. Occurs. Therefore, there is a possibility that the lubricity is reduced and baking occurs.

It is an object of the present invention to improve the locus of movement of the oil discharge hole to reduce oil leakage from the notch and improve lubricity.

[0007]

In the valve operating system for an internal combustion engine according to the present invention, the lubrication structure for the camshaft is constructed as follows.

There is an oil lubrication path for introducing the lubricating oil supplied from the hydraulic pressure source into the oil passage in the camshaft and supplying the lubricating oil in the oil passage from the oil discharge hole of the camshaft journal to the cylinder head bearing portion. are doing. On the inner peripheral surface of the cylinder head bearing portion that supports the outer peripheral surface of the camshaft journal, each center position of the width dimension between both end edges where the rotation axis of the camshaft intersects is orthogonal to the rotation axis of the camshaft. Notches for arranging other members are formed on the inner peripheral surface of the cylinder head bearing so as to be present at different positions in the width direction in the circumferential direction.

At the time of the camshaft rotation angle where the oil discharge hole of the camshaft journal passes near the notch for arranging another member on the inner peripheral surface of the cylinder head bearing portion, the oil discharge hole is separated from the notch. Thus, the camshaft is provided with means for displacing the camshaft in the direction of its rotation axis.

Therefore, the reduction of the seal width between the notch and the oil discharge hole is suppressed, and the oil leakage from the notch is reduced.

[0011]

DETAILED DESCRIPTION OF THE INVENTION A camshaft lubricating structure according to a first embodiment of the present invention will be described below with reference to FIGS.

[Outline of Valve Operating Device for Internal Combustion Engine Shown in FIGS. 1 to 3] In a DOHC engine having two intake valves and two exhaust valves per cylinder, the valve operating device is a cylinder head 1. It is installed in the space between the cylinder head cover (not shown).

(Valve Drive Mechanism) Intake side and exhaust side camshafts 2 are arranged side by side, and are rotatably supported by a plurality of cylinder head bearing portions 3 corresponding to each cylinder. Further, one ends of the camshafts 2 are rotatably supported by a cylinder head bearing portion 4. The rotation of the crankshaft (not shown) is transmitted to the camshafts 2 by the timing belt 5, the timing pulley 6, and the gears 7 and 8.

Corresponding to the two cams 9 supported so as to be integrally rotatable with respect to the intake side camshaft 2 and the two cams 9 supported so as to be integrally rotatable with respect to the exhaust side camshaft 2, respectively. Each cylinder lifter has 10 valve lifter holes 10
Are formed. A retainer 12 is attached to the stem 11 of each valve.
The valve lifter 13 is attached via the valve lifter 13, and the valve lifter 13 is slidably fitted in each valve lifter hole 10. The retainer 12 is biased by the valve spring 14 so that the valve lifter 13 is pressed against the cam 9.

(Cylinder head bearing portion 3, 4) The cylinder head bearing portion 3 includes a lower bearing portion 15 projecting from the cylinder head 1 and an upper bearing portion 16 fixed on the lower bearing portion 15. Consists of. Both bearings 15,
Inner peripheral surface 1 of the cylinder head bearing portion 3 formed between 16
The outer peripheral surface 20 of the camshaft journal 19 is rotatably supported by the shafts 7 and 18.

The cylinder head bearing portion 4 is shown in FIG.
As shown in (a), it comprises a lower bearing portion 21 projecting from the cylinder head 1 and an upper bearing portion 22 fixed on the lower bearing portion 21. Inner peripheral surfaces 23, 2 of the cylinder head bearing portion 4 formed between the both bearing portions 21, 22
4, the outer peripheral surface 26 of the camshaft journal 25 is rotatably supported. On both sides of the camshaft journal 25, a flange-shaped thrust receiving portion 27 is provided on the entire outer periphery thereof.
Also, the pressure receiving portion 28 is formed.

(Oil Lubrication Path) In the cylinder head bearing portion 4, an oil passage 29 is formed in the lower bearing portion 21 and penetrates the inner peripheral surface 23, and the camshaft journal 25 has a cross shape. The oil supply hole 30 is formed so as to extend in the radial direction and penetrate the outer peripheral surface 26, and the oil supply hole 30 periodically communicates with the oil passage 29 as the camshaft 2 rotates. An oil passage 31 is formed in the camshaft 2 so as to extend in the rotation axis direction C. In the cylinder head bearing portion 3, the camshaft journal 19
An oil discharge hole 32 is formed so as to extend from the oil passage 31 in the radial direction and penetrate the outer peripheral surface 20, and an oil groove 33 is formed in the inner peripheral surface 17 of the lower bearing portion 15. The oil discharge hole 32 is communicated with the oil groove 33 periodically as the camshaft 2 rotates.

In the cylinder head bearing portion 4, lubricating oil is supplied from a hydraulic source (not shown) to the lower bearing portion 21.
When it is supplied to the oil passage 29 inside, it is introduced into the oil passage 31 inside the camshaft 2 through the oil supply hole 30 inside the camshaft journal 25. The lubricating oil in this oil passage 31 is
In the cylinder head bearing portion 3, from the oil discharge hole 32 of the camshaft journal 19 to the oil groove 3 of the lower bearing portion 15.
3 is supplied and released.

[Camshaft Displacement Means Shown in FIG. 4] In the cylinder head bearing portion 3, a head bolt counterbore hole (not shown) is formed on the inner peripheral surface 17 of the lower bearing portion 15 as shown in FIG. 6A. Notch 34 that forms a part of
(A notch for arranging another member) is formed. Because of the notch 34, each center position CP of the width dimension between the both end edges 17a of the inner peripheral surface 17 where the rotation axis CL of the camshaft 2 intersects in the circumferential direction orthogonal to the rotation axis CL. It exists at different positions in the width direction (rotation axis direction C).

In the cylinder head bearing portion 4,
As shown in FIG. 4A, with the thrust bearing portion 27 of the camshaft journal 25 supported by one end surface of the upper bearing portion 22, the other end surface of the upper bearing portion 22 and the pressure receiving portion 28 of the camshaft journal 25 are supported. A gap 35 is formed between and in the range of a predetermined circumferential angle. An oil communication hole 36 is formed in the inner peripheral surface 24 of the upper bearing portion 22,
As the camshaft 2 rotates, the camshaft journal 2
The oil supply holes 30 of No. 5 periodically communicate with the oil communication holes 36. Then, the lubricating oil introduced into the oil supply hole 30 in the camshaft journal 25 flows out to the gap 35 through the oil communication hole 36 of the upper bearing portion 22, becomes a film in the gap 35, and is then discharged. It Therefore, the film-like lubricating oil in the gap 35 functions as the oil damper D. The camshaft 2 is attached to the pressure receiving portion 28 of the camshaft journal 25.
The oil control hole 37 that can communicate with the gap 35 of the oil damper D is formed by the rotation of the.

In the cylinder head bearing portion 3, the inner peripheral surface 17 of the lower bearing portion 15 is attached to the camshaft journal 19.
The outer peripheral surface 20 of the sliding member slides and the notch 34 shown in FIG.
When the camshaft rotation angle where the oil discharge hole 32 of the outer peripheral surface 20 passes in the vicinity of, the oil control hole of the pressure receiving portion 28 of the camshaft journal 25 in the cylinder head bearing portion 4 as shown in FIG. 4B. 37 is the upper bearing portion 22
Is located in the extension direction of the oil communication hole 36 (direction parallel to the rotation axis direction C of the cam shaft 2). In the released state of the oil damper D, the film-shaped lubricating oil in the gap 35 flows out from the oil control hole 37 of the pressure receiving portion 28, so that the oil discharge hole 32 of the outer peripheral surface 20 is separated from the cutout portion 34. The camshaft 2 is displaced in the rotational axis direction C (rear direction R side) by the width dimension of the gap 35, the thrust receiving portion 27 of the camshaft journal 25 is separated from the one end surface of the upper bearing portion 22, and the upper bearing portion 22 is also moved.
And the pressure receiving portion 28 of the camshaft journal 25 makes sliding contact.

From the vicinity of the notch 34, the oil discharge hole 32
Is gradually separated, the gap 35 is generated again, and the film-like lubricating oil in the gap 35 functions as an oil damper D, and the state shown in FIG. 4B returns to the state shown in FIG. 4A.

Therefore, the oil discharge hole 32 on the outer peripheral surface 20 of the inner peripheral surface 17 of the lower bearing portion 15 moves along the locus A shown in FIG. 6 (a).
The movement locus A passes through the widthwise center position CP of the inner peripheral surface 17.

The first embodiment has the following characteristics (a) (other than other technical ideas described later). (A) As shown in FIG. 6 (a), the width dimension between both end edges 17a on the inner peripheral surface 17 of the lower bearing portion 15 of the cylinder head bearing portion 3 at which the rotation axis CL of the camshaft 2 intersects Assuming each central position CP, the oil discharge hole 32 of the camshaft journal 19 is
As the camshaft 2 rotates, the camshaft 2 passes along a linear movement locus A ₁ (a part of A) connecting the central positions CP. Therefore, except for the cutout portion 34, it is possible to maintain the seal width S between the both end edges 17a of the inner peripheral surface 17 and the outer peripheral edge of the oil discharge hole 32 which are formed to have the same width.

On the other hand, the inner end edge 34a of the cutout portion 34 is closer to the linear movement locus A ₁ side than the one end edge 17a of the inner peripheral surface 17 formed to have the same width except the cutout portion 34. However, at the camshaft rotation angle when the oil discharge hole 32 passes near the cutout portion 34, the camshaft 2 is displaced and the oil discharge hole 32 moves around the avoidance movement locus A ₂ (A Since it partially passes above, the seal width S between the inner end edge 34a of the cutout portion 34 and the outer peripheral edge of the oil discharge hole 32
The oil leakage from the inner end edge 34a of the cutout portion 34 can be reduced. Therefore, it is possible to prevent oil shortage between the cylinder head bearing portion 3 and the camshaft journal 19, improve lubricity, and prevent seizure.

In addition to the first embodiment, the following configuration (a) may be adopted. (A) The second embodiment shown in FIG. 5 is a modification of the camshaft displacement means of the first embodiment shown in FIG. 4, and differs from the first embodiment in the following points.

In the cylinder head bearing portion 3, a notch portion 34 forming a part of the valve lifter hole 10 is formed on the inner peripheral surface 17 of the lower bearing portion 15 as shown in FIG. 6 (b). In the cylinder head bearing portion 4, as shown in FIG. 5A, the thrust receiving portion 2 of the camshaft journal 25 corresponding to both end surfaces of the upper bearing portion 22.
7 and the pressure receiving portion 28 are reversed as compared with the case of the first embodiment shown in FIG. As shown in FIG. 5B, the oil control hole 37 of the pressure receiving portion 28 is located at the upper bearing portion 22 at the camshaft rotation angle when the oil discharge hole 32 passes near the cutout portion 34 shown in FIG. 6B. When the oil damper D positioned on the extension direction of the oil communication hole 36 of the
Since the film-like lubricating oil in 5 flows out from the oil control hole 37, the camshaft 2 has a gap 35 in the rotation axis direction C (front direction F side) so that the oil discharge hole 32 is separated from the notch 34. It is displaced by the width dimension of. Therefore, in the inner peripheral surface 17 of the lower bearing portion 15, the oil discharge hole 32 of the outer peripheral surface 20 is formed in
A movement locus A (a linear movement locus A ₁ and an avoidance movement locus A ₂ ) shown in (b) is drawn, and the movement locus A is the inner peripheral surface 17
It passes through the center position CP of the width dimension. Therefore, as in the case of the first embodiment, the reduction of the seal width S between the inner end edge 34a of the cutout portion 34 and the outer peripheral edge of the oil discharge hole 32 is suppressed, and the inner end edge 34a of the cutout portion 34 is suppressed. Oil leakage from the cylinder head bearing portion 3 and the camshaft journal 19 can be prevented from being insufficient, and lubricity can be improved to prevent seizure.

[Other Technical Ideas] The technical ideas (other than claims) that can be understood from each embodiment will be described together with the effects. (A) In claim 1, the means for displacing the camshaft 2 in the rotational axis direction C includes a bearing portion 4 that supports the camshaft 2 and an inside of the bearing portion 4 that communicates with an oil passage 31 in the camshaft 2. Of the camshaft journal 19 and the oil communication hole 36 of the camshaft journal 19 and the oil communication hole 36 of the camshaft 2. When the oil discharge hole 32 passes near the other member locating notch 34 of the inner peripheral surface 17 of the cylinder head bearing portion 3 when the camshaft is rotated, the inside of the bearing portion 22 is passed through the gap 35 of the oil damper D. The camshaft 2 is provided with an oil control hole 37 corresponding to the oil communication hole 36.
The pressure receiving portion 28 of Therefore, the existing oil lubrication path and the oil damper D can be used as the camshaft displacement means with a simple structure.

[0029]

According to the camshaft lubrication structure for the valve operating system of the internal combustion engine according to the present invention, the movement locus of the oil discharge hole of the camshaft journal is improved, so that the oil leakage from the notch for arranging other members is achieved. Can be reduced and the lubricity between the cylinder head bearing portion and the camshaft journal can be improved.

[Brief description of drawings]

FIG. 1 is a partial plan view showing a camshaft and the like in a valve operating system for an internal combustion engine according to a first embodiment.

FIG. 2 is an enlarged sectional view taken along line XX of FIG.

3 is a partially enlarged cross-sectional view taken along the line YY of FIG.

4A is an enlarged sectional view taken along line ZZ of FIG. 1 showing an oil damper function state, and FIG. 4B is an enlarged sectional view taken along line ZZ of FIG. 1 showing an oil damper released state. is there.

5A is a view corresponding to FIG. 4A showing an oil damper function state in the second embodiment, and FIG. 5B is a view corresponding to FIG. 4B similarly showing an oil damper released state.

FIG. 6A is an operation explanatory diagram showing a movement locus of an oil discharge hole of a camshaft journal in the first embodiment, and FIG. 6B is an operation explanatory diagram showing a similar movement locus in the second embodiment. Yes, (c) is an operation explanatory view showing a similar movement locus in the valve train of the conventional internal combustion engine.

[Explanation of symbols]

2 ... Cam shaft, 3 ... Cylinder head bearing, 15 ...
Lower bearing part, 17 ... Lower bearing part inner peripheral surface, 19 ... Camshaft journal, 20 ... Camshaft journal outer peripheral surface, 31 ... Oil passage, 32 ... Oil discharge hole, 34 ... Notch part (notch part for arranging other members) ), C ... Camshaft rotation axis direction, CL ... Camshaft rotation axis, CP ... Center position of inner peripheral surface width dimension of lower bearing portion, A, A ₁ , A ₂ ... Movement locus, S
… Seal width.

Claims (1)

[Claims] 1. An oil lubrication path for introducing lubricating oil supplied from a hydraulic pressure source into an oil passage in a camshaft and supplying the lubricating oil in the oil passage from an oil discharge hole of a camshaft journal to a cylinder head bearing portion. The inner peripheral surface of the cylinder head bearing portion that supports the outer peripheral surface of the camshaft journal, and the central position of the width dimension between both edges where the rotation axis of the camshaft intersects is the rotation of the camshaft. A valve operating device for an internal combustion engine, wherein a notch portion for disposing another member is formed on an inner peripheral surface of a cylinder head bearing portion so as to exist at different positions in a width direction in a circumferential direction orthogonal to an axis. When the camshaft rotation angle where the oil discharge hole of the journal passes near the notch for disposing another member on the inner peripheral surface of the cylinder head bearing, the oil discharge hole is separated from the notch. Camshaft lubrication structure in a valve gear of an internal combustion engine, characterized in that it comprises means for displacing the cam shaft to the rotational axis direction.