JPH07166831A - Cam shaft lubricating device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent seizure or the like by surely lubricating each cam shaft bearing surface formed into a shape divided into two parts by a peripheral groove formed in a cam journal. CONSTITUTION:In order to supply a pressure of oil to a variable valve timing mechanism actuator 9 in the front,end of a cam shaft 7, a pressure oil supply hole 14 is opened to a cam shaft bearing part 3, and a peripheral groove 15 is formed in a cam journal 7a corresponding to this supply hole. Separately from this controlling pressure oil supply route, a lubricating oil supply hole 22 for lubricating the cam journal 7a is opened to connecting surfaces of the cam shaft bearing part 3 and bracket 4, and a branch passage 23 is formed in almost U shape from this connecting surface, to open the point end of this passage respectively to a bearing surface 6 in both sides by interposing the peripheral groove 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft lubricating device for supplying lubricating oil to a camshaft bearing surface of an internal combustion engine,
In particular, the present invention relates to a lubricating device in which a circumferential groove is formed in a cam journal for supplying hydraulic pressure to the variable valve timing mechanism actuator at the front end of the camshaft.

[0002]

2. Description of the Related Art In a valve train of an internal combustion engine, a cam pulley or a cam sprocket around which a timing belt or a cam chain is wound is rotatably attached to a cam shaft, and both are predetermined by a hydraulic actuator using a helical gear or the like. Conventionally, various variable valve timing mechanisms have been proposed and put into practical use in which the phase of the camshaft with respect to the crank angle can be changed in two ways by relative rotation.

In this case, the hydraulic actuator is arranged at the end of the camshaft, and the lubricating oil pumped from the engine oil pump passes through the camshaft bearing of the cylinder head to the hydraulic passage inside the camshaft. It is introduced and supplied to the actuator. For this hydraulic pressure supply, for example, a hydraulic pressure supply hole is formed in the camshaft bearing portion closest to the actuator, and correspondingly, a circumferential groove is formed in the cam journal. The switching of the valve timing, that is, the switching of whether or not to operate the actuator is performed by turning on the hydraulic pressure by the solenoid valve arranged on the cylinder head side.
This is done by controlling N and OFF.

In an internal combustion engine having such a variable valve timing mechanism, for the control hydraulic pressure to be supplied to the actuator, the camshaft bearing surface having the hydraulic pressure supply hole is not provided with another lubricating oil supply passage. Lubrication oil is used to provide lubrication at the same time.However, if the solenoid valve is used to control the hydraulic pressure upstream of the hydraulic pressure supply hole, the lubricating oil is supplied to the camshaft bearing surface when the hydraulic pressure is stopped. Therefore, poor lubrication is likely to occur.

Further, in Japanese Utility Model Laid-Open No. 4-6708, in order to lubricate the camshaft bearing surface regardless of the operating state of the actuator, a lubricating oil passage for lubricating the bearing surface is formed separately from the hydraulic pressure supply path. A configuration is disclosed.

[0006]

As described above, since the circumferential groove is formed in the cam journal in order to form the hydraulic pressure supply path for controlling the actuator, the lubrication for the bearing surface lubrication as described in the above publication. Even if the oil passage is formed separately, it is difficult for the lubricating oil to spread over the entire bearing surface. In other words, the camshaft bearing surface that receives this cam journal is substantially divided into two with the circumferential groove sandwiched, and one of the two bearing surfaces where the lubricating oil passage is open is satisfactorily lubricated. However, on the other hand, since the oil pressure in the circumferential groove is reduced, lubrication is likely to be insufficient, and problems such as seizure and wear are likely to occur.

[0007]

Therefore, a camshaft lubricating device of the present invention is provided with an actuator for a variable valve timing mechanism arranged at an end of a camshaft and a hydraulic pressure supply hole opened in a camshaft bearing of a cylinder head. And a control hydraulic pressure supply path that includes a circumferential groove formed in the cam journal corresponding to the hydraulic pressure supply hole, and that supplies lubricating oil from the oil pump to the actuator, and the hydraulic pressure supply hole of the control hydraulic supply path. In an internal combustion engine including an electromagnetic valve disposed in an upstream side portion and opening and closing the lubricating oil supply path, the internal combustion engine communicates with a main oil gallery in a cylinder head, and the camshaft bearing portion and the cam bracket are provided. Lubricating oil supply hole that opens on the joint surface of
The tip is bifurcated so as to be formed along the joint surface between the cam bearing portion and the cam bracket and to open on the camshaft bearing surfaces on both sides with the circumferential groove sandwiched therebetween,
A branch passage communicating with the lubricating oil supply hole is provided.

[0008]

In addition to the control hydraulic pressure supply path, the lubricating oil is supplied to the camshaft bearing surface via the lubricating oil supply hole and the branch passage. That is, the lubrication of the camshaft bearing surface is always performed regardless of the operation of the actuator. In particular, the lubricating oil sent from the main gallery to the lubricating oil supply hole is divided into two by the branch passage and is supplied to the camshaft bearing surfaces on both sides with the circumferential groove sandwiched therebetween, so that both sides are reliably lubricated. It

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a front end portion of a cylinder head 1 having a variable valve timing mechanism. The cylinder head 1 is cast from an aluminum alloy or the like, has a side wall 2 formed so as to surround the periphery, and has cam shaft bearing portions 3 at a plurality of positions so as to connect the side walls 2 to each other. Has been formed. A cam bracket 4 is fixed to each of the camshaft bearing portions 3 with a pair of bolts 5 (see FIGS. 2 and 3), and a camshaft 7 is rotatably supported by a camshaft bearing surface 6 formed by both. Has been done. In the illustrated example, the DOHC type valve operating mechanism is provided, and the camshaft 7 is provided on each of the intake side and the exhaust side, but the variable valve timing mechanism is provided only on the intake side camshaft 7. (The camshaft on the exhaust side is not shown).

A chain chamber 8 covered with a cover (not shown) is formed at the front end of the cylinder head 1.
A timing chain (not shown) that drives the camshaft 7 is housed in the chain chamber 8.

The front end of the intake side camshaft 7 supported by the camshaft bearing portion 3 projects into the chain chamber 8 and
In addition, a variable valve timing mechanism actuator 9 having a cylindrical shape is arranged therein. The actuator 9 relatively rotates an inner cylinder 10 fixed to a flange portion 7a of the camshaft 7 and an outer cylinder 11 having a sprocket portion 11a around it by a predetermined angle (for example, about 10 °) by hydraulic pressure. The hydraulic pressure is introduced through the hydraulic passage 12 (see FIGS. 2 and 3) inside the camshaft 7.

As shown in FIG. 2, the control hydraulic pressure supply path for the actuator 9 has a hydraulic pressure at the tip of the hydraulic passage 13 on the camshaft bearing surface 6 on the inner circumference of the camshaft bearing 3 at the front end of the cylinder head 1. The supply hole 14 is formed, and a circumferential groove 15 is formed in the cam journal 7a of the cam shaft 7 corresponding to the hydraulic pressure supply hole 14 over the entire circumference. A communication hole 16 is formed through the hydraulic passage 12 in the shaft 7. As shown in FIG. 2, the hydraulic passage 13 formed inside the cylinder head 1 is used for the hydraulic control solenoid valve 1.
It is possible to communicate with the main oil gallery 18 inside the cylinder head 1 via the valve portion 17a of No. 7. still,
The upstream portion of the main oil gallery 18 communicates with the discharge side of an oil pump (not shown). Further, the hydraulic pressure supply hole 14 and the circumferential groove 15 are located substantially at the center in the axial direction of the corresponding cam journal 7a, as shown in FIG.

The solenoid valve 17 is attached to the side of the cylinder head 1 with the solenoid portion 17b protruding outward, and the valve portion 17a at the tip is arranged so as to cross the main oil gallery 18, and the hydraulic passage 13 outlet port 19 and the main oil gallery 18
The space between and is opened and closed via an internal passage (not shown). When the outlet port 19 and the main oil gallery 18 are closed, the outlet port 19 is simultaneously connected to the drain port 20 and the hydraulic pressure in the actuator 9 is released. That is, the solenoid valve 17 controls the hydraulic pressure upstream of the hydraulic pressure supply hole 14 in the control hydraulic pressure supply path, and the lubricating oil is supplied to the hydraulic pressure supply hole 14 only when the actuator 9 is hydraulically switched. It is configured to.

On the other hand, inside the cylinder head 1, as shown in FIG. 3, in addition to the above-mentioned control hydraulic pressure supply path, the main oil gallery 1 is provided for lubrication of the camshaft 7.
8 to the camshaft bearing 3 toward the lubricating oil supply passage 2
1 is formed. The lubricating oil supply hole 22 at the tip of the lubricating oil supply passage 21 does not directly communicate with the camshaft bearing surface 6, but opens at the joint surface between the camshaft bearing portion 3 and the cam bracket 4. Correspondingly, a branch passage 23 having a substantially U shape is formed on the bottom surface of the cam bracket 4 along the joint surface with the camshaft bearing portion 3. The middle portion of the branch passage 23 is the lubricating oil supply hole 2
The tip end extending toward the inner peripheral side of the cam bracket 4 is bifurcated so as to sandwich the peripheral groove 15 of the cam journal 7a, and is opened to the camshaft bearing surface 6 on the inner peripheral side. In this embodiment, the branch passage 23 is formed on the cam bracket 4 side, but it may be formed on the cam shaft bearing portion 3 side.

In the camshaft bearings 3 other than the foremost camshaft bearing 3 that supplies hydraulic pressure for control, the tip of the lubricating oil supply passage communicating with the main oil gallery 18 is the cam of each bearing 3. Lubricating oil is supplied by directly opening the shaft bearing surface 6.

In the above-mentioned structure, a part of the lubricating oil pressure-fed to the main oil gallery 18 by an oil pump (not shown) is fed to the valve portion 17a of the hydraulic control solenoid valve 17. If the solenoid valve 17 is in the ON state,
Since the lubricating oil flows to the outlet port 19, the hydraulic passage 1
The hydraulic pressure is introduced through the route of 3 → hydraulic pressure supply hole 14 → circumferential groove 15 → hydraulic passage 12 → actuator 9 to switch the valve timing. When the solenoid valve 17 is OFF, the hydraulic pressure is cut off and the hydraulic pressure in the actuator 9 is released to the drain port 20, so that the valve timing is maintained in the initial state.

A part of the lubricating oil pressure-fed to the main oil gallery 18 is separated from the control hydraulic pressure by way of the lubricating oil supply passage 21 and the branch passage 23, and the camshaft bearing portion 3 and the cam bracket. It is supplied to the camshaft bearing surface 6 on the inner circumference of the shaft 4. At this time, the cam journal 7a
The substantial contact surface that is in sliding contact with is divided into two parts, front and rear, by the circumferential groove 15. Since the lubricating oil is supplied to each of them through the branch passage 23, the circumferential groove 15 divides the oil film. Good lubrication is performed on each. By distributing the lubricating oil through the branch passage 23 in this manner, the number of processing steps of the lubricating oil supply passage 21 in the cylinder head 1 is reduced. In particular, in this embodiment, since the branch passage 23 is formed on the cam placket 4 side, the machining is easier.

[0019]

As is apparent from the above description, according to the camshaft lubricating device for an internal combustion engine of the present invention, the lubricating oil for lubricating the cam journal is provided separately from the hydraulic pressure supply to the actuator for the variable valve timing mechanism. Is supplied and the lubricating oil is supplied to each of the camshaft bearing surfaces that are substantially divided into two by the circumferential groove through the branch passages, so that good lubrication can be performed at each part, and seizure and wear can be prevented. It can be prevented.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 3 ... Camshaft bearing part 4 ... Cam bracket 7 ... Camshaft 9 ... Actuator 14 ... Hydraulic pressure supply hole 15 ... Circumferential groove 17 ... Electromagnetic valve 22 ... Lubricating oil supply hole 23 ... Branch passage

Claims (1)

[Claims] 1. A variable valve timing mechanism actuator disposed at an end of a camshaft, a hydraulic pressure supply hole opened in a camshaft bearing portion of a cylinder head, and a circumference formed in a cam journal corresponding to the hydraulic pressure supply hole. A control hydraulic pressure supply path that includes a groove and that supplies lubricating oil from an oil pump to the actuator, and a control hydraulic pressure supply path that is disposed upstream of the hydraulic pressure supply hole and that includes the lubricating oil supply path. In an internal combustion engine including an electromagnetic valve that opens and closes, a lubricating oil supply hole that communicates with a main oil gallery in a cylinder head and opens at a joint surface between the camshaft bearing portion and the cam bracket, and the cam bearing. Is formed along the joint surface between the cam portion and the cam bracket, and the tip is formed so as to open on both sides of the cam shaft bearing surface with the circumferential groove sandwiched therebetween. With branches in the crotch like,
A camshaft lubricating device for an internal combustion engine, comprising: a branch passage communicating with the lubricating oil supply hole.