JPH04232321A - Valve system of engine - Google Patents

Abstract

PURPOSE:To rapidly perform oil supply to a variable valve timing mechanism at the time of starting an engine, and secure decrease in sliding friction of oil seal. CONSTITUTION:A variable valve timing mechanism 1 is provided between a cam pulley 3 and a cam shaft 5. A boss part 22 is provided on the engine main body side of the cam pulley 3 which receives rotation of a crank shaft in the variable valve timing mechanism 1, and an oil sump part 21 is formed inside the boss part 22, so as to supply necessary oil for the frictional sliding-contact face from the oil sump part 21 at the time of starting an engine. An oil seal 23 is provided around the boss part 22, and an oil returning passage 24 is provided inside the seal radius of the oil seal 23.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating mechanism for an engine equipped with a variable valve timing mechanism.

0002

BACKGROUND OF THE INVENTION It has been known to variably control the phase of a camshaft with respect to a crankshaft in order to obtain optimum valve timing according to the rotational speed of an engine. This type of variable valve timing mechanism is described in, for example, Japanese Unexamined Patent Publication No. 185914/1983, and the mechanism in this publication includes:
A relative rotation mechanism consisting of an inner sleeve and an outer sleeve in which intersecting slits are formed is provided between the cam pulley, which receives rotation of the crankshaft, and the camshaft, which is rotatably supported by the cylinder head. The valve timing is adjusted by relatively rotating both sleeves by linear movement, thereby relatively rotating the cam pulley and the camshaft.

0003

[Problems to be Solved by the Invention] However, the variable valve timing mechanism as described above is overhanging the front side of the upper cylinder head, where the mechanism itself is heavy, and is pulled downward by the timing belt or chain, causing it to bend. Since the structure must bear loads, it is especially important to keep the friction sliding surfaces constantly lubricated. Therefore, as described in the above-mentioned publication, various structures have been proposed to prevent the oil from running out in the mechanism.

However, oil for lubricating the inside of the variable valve timing mechanism is normally sucked up by an oil pump from an oil pan at the bottom of the cylinder block and supplied through a long oil passage. With the structure of conventional variable valve timing mechanisms, it takes a considerable amount of time for oil to be supplied to the mechanism immediately after the engine starts, resulting in the problem that the mechanism operates without oil during that time. . In addition, in the above conventional structure, the oil seal on the engine body side is usually formed with a large diameter, so when the cam pulley is driven to rotate, the circumferential speed of the oil seal's sliding surface increases, causing the oil seal to slide. There was also the problem of increased wear and generation of cracks.

The present invention has been made in view of the above-mentioned problems, and provides an engine that can quickly supply oil to a variable valve timing mechanism when starting an engine and reduce sliding wear of oil seals. The purpose is to obtain a valve train.

[0006]

[Means for Solving the Problems] An engine valve train according to the present invention is an engine valve train equipped with a variable valve timing mechanism that makes the phase of a camshaft variable with respect to a crankshaft. An oil reservoir is provided within the timing mechanism, and a boss portion having a smaller diameter than the oil reservoir portion is provided on the engine body side of the variable valve timing mechanism, and an oil seal is provided around the boss portion, This configuration solved the above problem.

[0007] It is preferable that an oil return passage is provided inside the seal diameter of the oil seal.

[0008]

[Operation] In the present invention, since the oil reservoir is provided in the variable valve timing mechanism, the oil necessary for lubrication of the friction sliding contact surface is supplied from this oil reservoir when the engine is started. driving is prevented. Additionally, since the oil seal is provided around the boss portion, which is formed to have a smaller diameter than the oil reservoir, the diameter of the oil seal becomes smaller, thereby making it possible to reduce the sliding contact area of the oil seal. , reducing sliding wear.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIG. 1 is a longitudinal sectional view of a variable valve timing mechanism according to an embodiment of the present invention. In this embodiment, the variable valve timing mechanism 1 controls the rotation of a crankshaft (not shown) disposed below by a timing belt 2.
The cam pulley 3 is provided between the cam pulley 3 and the cam shaft 5, which is rotatably supported by the cylinder head 4.The rotation of the cam pulley 3 is transmitted to the cam shaft 5, so that The intake and exhaust valves are opened and closed by a cam formed at 5.

An engagement groove 3a is formed on the inner periphery of the cam pulley 3 and extends spirally in the axial direction. On the other hand, an advancing plate 6 is disposed on the inner circumference of the cam pulley 3, and a spiral engagement protrusion 6a is formed on the outer circumference of the advancing plate 6. And the above-mentioned engagement groove 3a
By engaging with the engagement protrusion 6a, the advancing plate 6 can be rotated together with the cam pulley 3 and relatively movable in the axial direction.

A generally cylindrical drum 7 having a boss portion 7a at its outer end is screwed onto the inner periphery of the advancing plate 6. That is, the advancing plate 6
A male thread 6b is formed on the inner periphery of the drum 7.
A female thread 7b is formed on the outer periphery of the advancing plate 6 and the drum 7. By screwing the male thread 6b and the female thread 7b together, the advancing plate 6 and the drum 7 can be relatively moved in the axial direction by relative rotation. .

A camshaft 5 is fitted into the inner periphery of the boss portion 7a of the drum 7. Further, on the outer periphery of the boss portion 7a, there is a bent portion 8a that is bent toward the axial end side at the outer periphery.
A locking plate 8 is provided, and a spring 9 is provided on the end side of the locking plate 8. One end of this spring 9 is locked to the drum 7, and the other end is locked to the cam pulley 3, thereby biasing the drum 7 in a certain direction of rotation. Further, a stop plate 11 is inserted between the end of the boss portion 7a of the drum 7 and an annular support member 10 provided at the end of the camshaft 5. This stop plate 11 has a circumferential engagement hole 11a that engages with the bent portion 8a of the locking plate 8.
By being locked, rotation of the locking plate 8 is prevented, thereby restricting the rotation of the drum 7 to a predetermined angle or less.

The support member 10 is fixed to the end of the camshaft 5 by a bolt 12. A bearing 14 is inserted between the outer periphery of the support member 10 and the inner periphery of a case 13 bolted to the end of the cam pulley 3, so that the cam pulley 3 and the camshaft 5 are prevented from rotating relative to each other. It is considered possible. Note that an end cover 15 is provided on the end side of the case 13.

One end of the inner circumference of the drum 7 has a lead wire 1.
An annular electromagnetic coil 17 connected to 6 is fitted. This electromagnetic coil 17 is fixed to the cylinder head 4 side and rotatably supported by the drum 7, and an electromagnetic clutch is configured between the electromagnetic coil 17 and the drum 7.

In the variable valve timing mechanism 1 having such a configuration, under normal conditions, the rotation of the cam pulley 3 is transmitted to the advancing plate 6, and furthermore, the rotation of the advancing plate 6 is transmitted from the drum 7 to the camshaft 5. They are rotated as one by the transmission. That is, the rotation of the cam pulley 3 is directly transmitted to the camshaft 5.

When a voltage is applied to the electromagnetic coil 17 to generate magnetic force in such a state, a braking torque is generated in the drum 7, so that the drum 7 lags in rotation with respect to the advancing plate 6, and the drum 7 and the advancing plate 6 are rotated relative to each other against the urging force of the spring 9. Therefore, the advancing plate 6 is moved relative to the cam pulley 3 in the axial direction, and the helical engagement protrusion 6a of the advancing plate 6
is moved along the spiral engagement groove 3a of the cam pulley 3, so the cam pulley 3 is rotated by a predetermined angle relative to the camshaft 5. Therefore, valve timing can be changed.

By the way, oil for lubricating the inside of the variable valve timing mechanism 1 is supplied as follows. That is, oil sucked up by an oil pump from an oil pan at the bottom of the cylinder block passes through an oil passage formed in the cylinder block, reaches a passage 18 formed in the vertical direction in the cylinder head 4, and reaches the passage 18. From there, it is supplied into a central hole 19a formed in the journal portion 19 of the camshaft 5. The oil supplied into this central hole 19a is then transferred to the camshaft 5.
An oil hole 20 formed in the radial direction of the camshaft 5 passes through a gap around the shaft of the bolt 12 attached to the end of the camshaft 5.
is supplied into the mechanism 1 from above. In addition, when the engine is stopped, the oil in the mechanism 1 flows through the oil return passage 24.
is returned to the oil pan through the

The interior of the variable valve timing mechanism 1 is structured such that an oil reservoir 21 is formed therein. That is, a boss portion 22 is provided on the engine body side of the cam pulley 3, an oil seal 23 is provided on the outer periphery of the boss portion 22, and the inner portion of the boss portion 22 serves as an oil reservoir portion 21. This structure prevents the variable valve timing mechanism 1 from operating without oil immediately after the engine starts, and also reduces the total circumferential area of the oil seal 23 to reduce sliding wear. can be achieved.

Further, the oil return passage 24 is provided so as to be located inside the seal diameter of the oil seal 23. The oil overflowing from the oil reservoir 21 inside the boss 22 is collected from the oil return passage 24.

[0021]

[Effects of the Invention] Since the present invention is constructed as described above, it is possible to quickly supply oil to the variable valve timing mechanism when starting the engine, and it is also possible to reduce the sliding wear of the oil seal. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a variable valve timing mechanism according to an embodiment of the present invention.

[Explanation of symbols]

1 Variable valve timing mechanism 5 Camshaft 21 Oil reservoir 22 Boss part 23 Oil seal 24 Oil return passage

Claims (2)

[Claims] 1. A valve operating mechanism for an engine equipped with a variable valve timing mechanism that varies the phase of a camshaft with respect to a crankshaft, wherein an oil reservoir is provided within the variable valve timing mechanism, and the variable valve timing mechanism A valve mechanism for an engine, characterized in that a boss portion having a smaller diameter than the oil reservoir portion is provided on the side of the engine body, and an oil seal is further provided around the boss portion. 2. The engine valve mechanism according to claim 1, further comprising an oil return passage provided inside the seal diameter of the oil seal.