JPH0452406Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an operating mechanism for intake and exhaust valves in an internal combustion engine, that is, a valve operating mechanism.

[Conventional technology]

In general, the valve mechanism of an internal combustion engine has a cylindrical valve lifter that is slidably supported by a cylinder head fitted to the upper end of the valve stem of the intake and exhaust valves, and a valve lifter and a cam are mounted on the top surface of the valve lifter. A shim is placed to adjust the distance between the two, and this shim is brought into contact with the cam surface, and the rotation of the cam opens and closes the intake and exhaust valves via the shim and the valve lifter. There is.

In a valve train with such a configuration, the applicant has devised a new valve train that makes it easier to rotate the shim and reduces friction between the cam and the shim, and between the shim and the valve lifter. Showa 62
-49945).

The valve mechanism of Utility Model Application No. 62-49945 (see Utility Model Application No. 63-158502) has a valve lifter slidably supported by a cylinder head fitted into the upper end of a valve stem. A shim for adjusting the distance is disposed on the top surface, and the shim is brought into contact with a cam surface on a camshaft, and the center line of the cam surface and the center line of the shim are deviated from each other. In the valve mechanism, a convex portion is formed at the center of the top surface of the valve lifter, and a concave portion that fits into the convex portion is provided at the center of the inner surface of the shim, and the depth of the concave portion is greater than the height of the convex portion. The width of the recess is smaller than the width of the cam surface, and the shim is provided with a lubricating oil supply hole that communicates with the recess, and the valve lifter is provided with a sliding hole between the recess, the shim, and the valve lifter. An oil groove is provided that communicates with the contact surface.

[Problem that the invention attempts to solve]

According to the above-mentioned valve train mechanism devised by the present applicant, the friction between the valve lifter and the shim is reduced and the wear resistance is improved. Since there is no complete non-contact with the provided recess, there is a certain limit to the reduction in friction and improvement in wear resistance between the valve lifter and the shim.

The present invention aims to maintain a non-contact state between the valve lifter and the shim, thereby further increasing the effects of reducing friction and improving wear resistance.

[Means for solving problems]

According to the present invention, the above problem is solved by forming a groove in the sliding contact surface between the top surface of the valve lifter and the inner surface of the shim into which lubricating oil is introduced as the shim rotates, and forming an oil film between the valve lifter and the shim. This can be solved by keeping the two out of contact.

That is, the structural features of the present invention include a valve lifter fitted onto the upper end of the valve stem and slidably supported by the cylinder head, and a shim for adjusting the distance disposed on the top surface of the valve lifter. , a cam that comes into contact with the outer surface of the shim to raise and lower the valve lifter, a convex portion is formed at the center of the top surface of the valve lifter, and a recess that fits into the convex portion is formed at the center of the shim and the inner surface. In a valve operating mechanism for an internal combustion engine, the cam is arranged such that its center line is offset from the center line of the shim, and the shim rotates around the axis of the valve lifter as the cam is rotationally driven. , on the sliding surface between the top surface of the valve lifter and the inner surface of the shim, a spiral groove that is inclined at a constant angle with respect to the tangential direction of the sliding surface is formed from the periphery of the sliding surface to the center. The rotation of the shim causes the lubricating oil to flow from the periphery of the sliding surface toward the center, and the width of the spiral groove gradually increases from the periphery of the sliding surface toward the center. This is because it was formed to be narrow.

The spiral groove on the sliding surface may be provided either on the top surface of the valve lifter or on the inner surface of the shim. In the former case, the spiral direction of the spiral groove is the same as the rotation direction of the shim, and in the latter case, the spiral direction of the spiral groove is the opposite to the rotation direction of the shim.

[Effect]

In the present invention having the above configuration, the center of the shim and the center of the cam surface are offset, so that the shim rotates about its central axis with respect to the valve lifter as the cam is driven. As the shim rotates, the lubricating oil filled between the shim and the valve lifter flows along the spiral groove from the periphery of the sliding surface between the shim and the valve lifter toward the center.
Since the width of the spiral groove becomes narrower toward the center, the lubricating oil is squeezed and pressure is generated. The shim levitates due to the hydraulic pressure of this lubricating oil.
The top surface of the valve lifter and the inner surface of the shim are completely out of contact, and the friction between them is significantly reduced, thereby improving the wear resistance of the valve lifter and shim.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

In FIG. 5, reference numeral 1 denotes a valve stem, the lower end of which is integrally formed with intake and exhaust valve bodies (not shown). At the upper end of the valve stem 1 is a kotsuta 2.
The retainer 3 is fixed through the
The upper end of the spring 4 is fixed to the lower surface of the
The exhaust valve is biased upward, that is, in the direction of closing the valve. A valve lifter 5 is fitted onto the top end of the valve stem 1 . The valve lifter 5 has a cylindrical shape with a closed upper end surface, and its outer peripheral surface is supported by a cylinder head 6 so as to be slidable in the vertical direction. A shim 7 is attached to the top surface of the valve lifter 5, and the top surface of the shim 7 is in contact with a cam surface 8 of the camshaft. In order to attach the shim 7 to the valve lifter 5, a convex portion 5a is provided at the center of the top surface of the valve lifter 5.
On the other hand, a recess 7a is formed in the center of the lower surface of the shim 7.
is formed, and the convex portion 5a is fitted into the concave portion 7a. Further, the depth of the recess 7a is made slightly larger than the height of the projection 5a, so that a gap is formed between the recess 7a and the projection 5a. The space between the valve lifter 5 and the shim 7 is filled with lubricating oil by appropriate means.

Cam surface 8 of the camshaft that comes into contact with the top surface of the shim 7
The center line of the shim 8 is offset from the center line of the shim 7 by an eccentric amount m, so that the shim 8 rotates relative to the valve lifter 5 about its center axis as the camshaft rotates.

Further, the diameter of the recess 7a is smaller than the width of the cam surface 8.

Referring to FIGS. 1 and 2, the valve lifter 5
A large number of spiral grooves 51 extending from the periphery toward the center are formed on the top surface 50 of. This spiral groove 5
1 is α with respect to the tangential direction of the valve lifter top surface 50
(Actually, α = 20° to 40°). The direction of the inclination, that is, the spiral direction, is the same direction as the rotation direction of the shim 7 shown by the arrow. Note that the rotation direction of the shim 7 is the second
As shown in the figure, when the center line of the cam 8 is offset to the left with respect to the center line of the shim 7, it rotates in the direction of the arrow in FIG. 1.

As shown in FIG. 1, the spiral groove 51 is formed so that the groove width gradually narrows from the periphery of the valve lifter top surface 50 toward the center. Further, the depth of the groove 51 is several μm. 52 in the diagram
indicates a raised portion left between each spiral groove 51.

Further, the spiral groove 51 is formed to spiral in the same direction as the rotational direction of the shim 7, but as shown in FIG. When the shim 7 rotates in the direction of the arrow in FIG. 3, the spiral groove 51 provided on the top surface 50 of the valve lifter rotates in the direction shown in FIG. becomes a groove in the opposite direction.

The present embodiment having the above configuration operates as follows.

When a camshaft that rotates in synchronization with the engine crankshaft rotates, the rotation of a cam 8 integrated with the camshaft opens and closes intake and exhaust valves via a shim 7 and a valve lifter 5. At this time, the center line of the cam 8 and the center line of the shim 7 are offset, so as the cam 8 rotates, the shim 7 rotates relative to the valve lifter 5 around its center axis. Since the space between the shim 7 and the valve lifter 5 is filled with lubricating oil, when the shim 7 rotates, this lubricating oil follows the shim 7 due to its viscosity and rotates with it.
The lubricating oil given this rotational force is introduced into the spiral groove 51 of the top surface 50 of the valve lifter formed in the same direction as this rotational direction, and flows from the periphery of the top surface 50 of the valve lifter toward the center. Since the spiral groove 51 is formed so that its groove width becomes narrower from the periphery toward the center, the introduced lubricating oil is squeezed toward the center and generates pressure. This hydraulic pressure causes the shim 7 to float,
The inner surface of the shim 7 and the top surface of the valve lifter 5 are completely out of contact, the friction between the shim 7 and the valve lifter 5 is significantly reduced, and the wear resistance of this portion is greatly improved. As a result, the rotational action of the shim is stabilized, and vibration and noise are also reduced.

In the above embodiment, the spiral groove is provided on the top surface of the valve lifter.
It may be provided on the inner surface of the

In this case, the direction of the spiral groove is opposite to the direction of rotation of the shim 7.

In operation, as the shim 7 rotates, the lubricating oil is introduced into the spiral groove provided in the shim itself and flows from the periphery toward the center. After this, hydraulic pressure is generated to levitate the shim in the same manner as in the illustrated embodiment.

[Effect of idea]

As described above, the present invention combines the rotation of the shim and the provision of a groove for introducing lubricating oil on the sliding surface of the shim and valve lifter to generate hydraulic pressure between the shim and the valve lifter. As a result, the shim floats, and the shim and valve lifter are completely out of contact with each other, the friction between them is significantly reduced, and the wear resistance of this part is greatly improved.

Furthermore, the rotational action of the shim is stabilized and is not affected by the surface shape of the shim surface or the top surface of the valve lifter, thereby reducing vibration and noise.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the main part of an embodiment of the present invention, Fig. 2 is a cutaway front view thereof, Fig. 3 is a plan view of the main part of another embodiment of the present invention, and Fig. 4 is a cutaway front view thereof. FIG. 5 is a cutaway front view showing the entire embodiment of the present invention. 1... Valve stem, 5... Valve lifter, 5
a... Convex portion, 6... Cylinder head, 7... Shim, 7a... Concave portion, 8... Cam, 50... Valve lifter top surface, 51... Spiral groove.

Claims (1)

[Claims for Utility Model Registration] 1. A valve lifter fitted onto the upper end of a valve stem and slidably supported by a cylinder head, a shim for adjusting the distance disposed on the top surface of the valve lifter, and a cam that comes into contact with the outer surface of the shim and raises and lowers the valve lifter, a convex portion is formed at the center of the top surface of the valve lifter, and a recess that fits into the convex portion is provided at the center of the inner surface of the shim, In the valve operating mechanism for an internal combustion engine, the cam is arranged such that its center line is offset from the center line of the shim, and the shim rotates around the axis of the valve lifter as the cam is rotationally driven. A spiral groove that is inclined at a certain angle with respect to the tangential direction of the sliding surface is formed on the sliding surface between the top surface of the valve lifter and the inner surface of the shim, from the periphery of the sliding surface toward the center. The rotation of the shim causes lubricating oil to flow from the periphery of the sliding surface toward the center, and the width of the spiral groove gradually narrows from the periphery of the sliding surface toward the center. A valve mechanism for an internal combustion engine characterized by being formed as follows. 2. The internal combustion engine according to claim 1, wherein the spiral groove is formed on the top surface of the valve lifter, and the spiral direction of the spiral groove is oriented in the same direction as the rotational direction of the shim. Engine valve mechanism. 3 forming the spiral groove on the inner surface of the shim;
2. The valve operating mechanism for an internal combustion engine according to claim 1, wherein the spiral direction of the spiral groove is directed in a direction opposite to the rotational direction of the shim.