JP2910539B2 - Camshaft lubrication system for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft lubricating apparatus for supplying lubricating oil to a camshaft bearing surface of an internal combustion engine.
In particular, the present invention relates to a lubrication device in which a circumferential groove is formed in a cam journal for supplying hydraulic pressure to an actuator for a variable valve timing mechanism at a front end of a 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 and a cam chain are wound are rotatably mounted on a camshaft, and both are fixed by a hydraulic actuator using a helical gear or the like. Various variable valve timing mechanisms capable of changing the phase of a camshaft with respect to the crank angle in two ways by relative rotation by an angle have heretofore been proposed and put to practical use.

In this case, the hydraulic actuator is disposed 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. And is supplied to the actuator. In order to supply the hydraulic pressure, for example, a hydraulic pressure supply hole is formed in a cam shaft bearing portion closest to the actuator, and a peripheral groove is formed in the cam journal corresponding to the hydraulic pressure supply hole. Switching of the valve timing, that is, switching of whether to operate the actuator or not is performed by turning off the hydraulic pressure supply by an electromagnetic valve disposed on the cylinder head side.
The control is performed in the N, OFF manner.

In an internal combustion engine equipped with such a variable valve timing mechanism, the control oil pressure supplied to the actuator is provided on the camshaft bearing surface where the oil pressure supply hole is opened without providing another lubrication oil supply passage. The lubricating oil is also provided at the same time, but if the hydraulic control by the solenoid valve is performed on the upstream side of the hydraulic supply hole, the lubricating oil is supplied to the camshaft bearing surface when the hydraulic pressure stops. Since lubrication is not performed, poor lubrication is likely to occur.

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

[0006]

As described above, the circumferential groove is formed in the cam journal to form the hydraulic pressure supply path for controlling the actuator. Even if the oil passage is formed separately, it is difficult for the lubricating oil to spread over the entire bearing surface. That is, the camshaft bearing surface for receiving the cam journal is substantially divided into two with the circumferential groove interposed therebetween, and one of the two bearing surfaces where the lubricating oil passage is opened is lubricated well. On the other hand, on the other hand, since the hydraulic pressure is reduced in the circumferential groove, lubrication tends to be insufficient, and problems such as seizure and wear are likely to occur.

[0007]

Accordingly, a camshaft lubricating apparatus according to the present invention comprises an actuator for a variable valve timing mechanism provided at an end of a camshaft and a hydraulic supply hole opened in a camshaft bearing of a cylinder head. And a control hydraulic supply path including a circumferential groove formed in the cam journal corresponding to the hydraulic supply hole, and supplying lubricating oil from the oil pump to the actuator, and a hydraulic supply hole in the control hydraulic supply path. An electromagnetic valve disposed on the upstream side and opening and closing the lubricating oil supply path, wherein the internal combustion engine communicates with a main oil gallery in a cylinder head, and the camshaft bearing portion and the cam bracket A lubricating oil supply hole opening at 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 open to the camshaft bearing surfaces on both sides of the circumferential groove,
And a branch passage communicating with the lubricating oil supply hole.

[0008]

The lubricating oil is supplied to the camshaft bearing surface via the lubricating oil supply hole and the branch passage separately from the control hydraulic pressure supply path. That is, the lubrication of the camshaft bearing surface is constantly 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 supplied to the camshaft bearing surfaces on both sides with the circumferential groove interposed therebetween, so that both are reliably lubricated. You.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One 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 provided with a variable valve timing mechanism. The cylinder head 1 is cast from an aluminum alloy or the like, has side walls 2 formed so as to surround the periphery, and has camshaft bearings 3 at a plurality of locations so as to connect between the side walls 2. Is 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. Have been. In the illustrated example, a DOHC type valve operating mechanism is provided, and the camshaft 7 is provided on each of the intake side and the exhaust side. However, only the intake side camshaft 7 is provided with a variable valve timing mechanism. (The exhaust-side camshaft is not shown).

At the front end of the cylinder head 1, there is formed a chain chamber 8 which is covered by a cover (not shown).
The chain chamber 8 accommodates a timing chain (not shown) for driving the camshaft 7.

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

As shown in FIG. 2, the control hydraulic pressure supply path for the actuator 9 includes a camshaft bearing surface 6 inside the camshaft bearing portion 3 at the front end of the cylinder head 1 and a hydraulic pressure supply passage at the tip of the hydraulic passage 13. A supply hole 14 is formed, and a circumferential groove 15 is formed in the cam journal 7a of the camshaft 7 so as to correspond to the hydraulic pressure supply hole 14. The circumferential groove 15 extends 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
7 can communicate with a main oil gallery 18 inside the cylinder head 1 via a valve portion 17a. still,
An upstream portion of the main oil gallery 18 communicates with a discharge side of an oil pump (not shown). Further, as shown in FIG. 1, the hydraulic pressure supply hole 14 and the circumferential groove 15 are located substantially at the center of the corresponding cam journal 7a in the axial direction.

The solenoid valve 17 is mounted on the side of the cylinder head 1 with a solenoid portion 17b protruding to the outside. A valve portion 17a at the tip is disposed so as to cross the main oil gallery 18, and the hydraulic passage 17 is provided. 13 and the main oil gallery 18
Is opened and closed via an internal passage (not shown). When the space between the outlet port 19 and the main oil gallery 18 is closed, the outlet port 19 is connected to the drain port 20 at the same time, 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 lubricating oil is supplied to the hydraulic pressure supply hole 14 only when the actuator 9 is switched by hydraulic pressure. Configuration.

On the other hand, as shown in FIG. 3, the main oil gallery 1 is provided inside the cylinder head 1 to lubricate the camshaft 7 separately from the above-described control hydraulic supply path.
8 toward the camshaft bearing 3
1 is formed. The lubricating oil supply hole 22 at the end 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 3 and the cam bracket 4. Correspondingly, a substantially U-shaped branch passage 23 is formed on the bottom surface of the cam bracket 4 along the joint surface with the camshaft bearing 3. The branch passage 23 has an intermediate portion in which the lubricating oil supply hole 2 is provided.
2, and a tip extending toward the inner peripheral side of the cam bracket 4 branches into a forked shape so as to sandwich the peripheral groove 15 of the cam journal 7a, and each of the bifurcated ends 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 may be formed on the cam shaft bearing 3 side.

In each of the camshaft bearings 3 other than the foremost camshaft bearing 3 for supplying hydraulic pressure for control, the tip of the lubricating oil supply passage communicating with the main oil gallery 18 is connected to the cam of each bearing 3. It opens directly on the shaft bearing surface 6 to supply lubricating oil.

In the above configuration, a part of the lubricating oil, which is fed to the main oil gallery 18 by an oil pump (not shown), is sent to the valve portion 17a of the hydraulic control solenoid valve 17. And if the solenoid valve 17 is ON,
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 supply hole 14 → circumferential groove 15 → hydraulic passage 12 → actuator 9, and the valve timing is switched. If the solenoid valve 17 is OFF, the supply of 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 kept in the initial state.

A part of the lubricating oil fed to the main oil gallery 18 is separated from the camshaft bearing 3 and the cam bracket via a lubricating oil supply passage 21 and a branch passage 23 separately from the control oil pressure. 4 is supplied to a camshaft bearing surface 6 on the inner periphery of the camshaft 4. At this time, the cam journal 7a
The contact surface which is in sliding contact with the cylinder is divided into two front and rear portions by a circumferential groove 15, but lubricating oil is supplied to each of the two through a branch passage 23, so that the oil film is divided by the circumferential groove 15. , And good lubrication is performed in each case. By distributing the lubricating oil through the branch passage 23 in this way, 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 processing is further facilitated.

[0019]

As is apparent from the above description, according to the camshaft lubricating apparatus for an internal combustion engine according to 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 lubricating oil is supplied to each of the camshaft bearing surfaces, which are substantially divided into two by a circumferential groove, through a branch passage, so that good lubrication can be performed in each part, and seizure and wear are reduced. Can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along the line AA in FIG. 1;

FIG. 3 is a sectional view taken along the line BB of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 ... Cam shaft bearing part 4 ... Cam bracket 7 ... Cam shaft 9 ... Actuator 14 ... Hydraulic supply hole 15 ... Peripheral groove 17 ... Solenoid valve 22 ... Lubricating oil supply hole 23 ... Branch passage

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01M 1/06 F01L 1/34 F01M 9/10

Claims (1)

(57) [Claims] 1. An actuator for a variable valve timing mechanism disposed at an end of a camshaft, a hydraulic supply hole opened in a camshaft bearing of a cylinder head, and a periphery formed in a cam journal corresponding to the hydraulic supply hole. A control hydraulic supply path for supplying lubricating oil from the oil pump to the actuator, the control hydraulic supply path being disposed upstream of the hydraulic supply hole of the control hydraulic supply path, and including the groove; and An internal combustion engine comprising: a solenoid valve that opens and closes; a lubricating oil supply hole that communicates with a main oil gallery in a cylinder head and that opens at a joint surface between the camshaft bearing and the cam bracket; The tip is formed along the joint surface between the part and the cam bracket, and opens to the camshaft bearing surfaces on both sides of the circumferential groove. With branches in the crotch like,
A camshaft lubrication device for an internal combustion engine, comprising: a branch passage communicating with the lubricating oil supply hole.