JPS5891313A - Valve gear in internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce the frictional sound and friction loss of the titled gear by providing a rotatable tappet on one end of a locker arm, in the valve gear in the internal combustion engine using the locker arm. CONSTITUTION:The locker arm 12 rotatably supported by the locker shaft 12 has a tappet 14 at its one end 12a on the side of a cam 13, and another end 12b making contact with an end of a valve stem similarly as the conventional device. The tappet 14 comprises a disc-shaped head, a seat 16 and a shaft 17. When the cam 13 is rotated and driven, the tappet 14 is rotated in accordance with the movement of the cam 13. That is, during the operation, continuance of contact of the same part is prevented, and the contact surfaces are constantly changed so that the contact is performed in the form of rolling contact. Therefore, the friction generated between both surfaces are extremely reduced. By this arrangment, the frictional sound and friction loss can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the valve drive position of an internal combustion engine using a rocker arm.

1 and 2 show an example of a rocker shaft type of the so-called 0, Hlo (wA upper cam 7 shaft) type valve train in which the camshaft 1 is disposed at the upper part of the cylinder head. The rocker arm 3 rotatably supported by the rocker shaft 2 has one end 3a in contact with the cam 4, and the other end 3b in contact with the pulp stem end 5a of the intake/exhaust valve 5.
The lift of the cam 4 is transmitted to the intake and exhaust valves 5 at a predetermined rocker ratio. Conventionally, a separate tip 6 having a semi-cylindrical shape and excellent wear resistance has been fixed to the portion in contact with the cam 4 by means such as brazing or the like.

Therefore, as the cam 4 rotates, the cam surface 4a and the convex contact surface 6a slide, producing a large frictional sound and
The drawback was that friction loss was large. Also,
Due to accelerated wear, the valve opening/closing characteristics tend to change over time, which tends to cause deterioration in engine/engine performance and increase in noise.

This invention was made in view of the above-mentioned drawbacks of the conventional internal combustion engine. The purpose of this device is to reduce friction noise and friction loss generated between a rocker arm and a cam.

That is, in the valve operating system for an internal combustion engine according to the present invention, a tappet having a convex spherical cam contact surface is rotatably disposed at one end of the rocker arm, and a contact point between the cam surface and the tappet is connected to the tappet. Offset from the center!
It is characterized by being set to .

Hereinafter, one example of breeding according to the present invention will be explained in detail based on the drawings.

Figures 3 and 4 show the present invention applied to the 010 type valve train (rocker 7 shaft type) similar to the conventional example, in which the rocker arm is supported so that the rocker shaft can rotate freely for one day. is attached to one end 12a on the cam 13 side) 14
The other end 121) is brought into contact with the pulp stem end (path shown) via an adjusting screw for adjusting pulp clearance, as in the conventional case.

The tappet 14, as shown in FIG. The tappet mounting hole 18 is rotatably fitted into the mounting hole ratio, and the opening surface n of the tappet mounting hole 18 is formed on the flat surface of the seat. The seat surfaces of No. 6 are in contact. Further, the cam contact surface 14a of the tappet 14 is formed into a gently convex spherical surface, and the cam brocade facing it is formed as shown in FIG.
The cam surface 13a is formed in a tapered shape slightly inclined (1 to 50 degrees) with respect to the central axis of the camshaft, and as a result, the cam surface 12Ia and the abutting surface 14a
The contact point with the tappet 140 is set at a position offset in the axial direction of the camshaft 19 with respect to the center of rotation of the tappet 140. Furthermore, a lubricating oil passage is formed in the rocker arm 12, and lubricating oil is supplied from the lubricating oil passage in the rocker shaft 11 into the tappet mounting hole 18.

Therefore, in the above configuration, when the cam brocade is driven to rotate, the tappet 14 rotates in accordance with the movement of the five force ribs. That is, during operation, contact between the same parts is avoided, the contact surface is constantly changed, and contact is made in the form of rolling contact, so that the friction generated between the two is extremely small. On the other hand, the tappet 14 comes into sliding contact with the rocker arm U at its seat portion 16 and shaft portion 17, but a warm oil film formed by the lubricating oil supplied from the lubricating oil passageway is well maintained there, so that the tappet 14 is in sliding contact with the rocker arm U at its seat 16 and shaft portion 17. Friction is similarly small. Therefore, the friction noise and friction noise caused by the rotation of the cam 13 are significantly smaller than those of the prior art.

As shown in FIG. 4, it is substantially sufficient to form only the cam lift portion excluding the base circle portion into a tapered shape, but as shown by the line, Of course, the entire circumference of the cam 13 including the base circle portion may be formed into a tapered shape.

Next, Figure 6 shows the brocade bottom of the tappet mounting hole and the tappet) 14
An example is shown in which a steel ball n is disposed between the shaft part 17 of
Tappet without bottom 16) 140 A slight gap is formed between the head 1g and the rocker arm 12. That is, the steel ball n functions as a bearing, and the friction between the tappet 14 and the rocker arm 12 can be further reduced.

However, the present invention is also applicable to other types of O, I, and A type stationary valve operating devices, namely, the so-called pivot type in which the pulp is opened and closed via a four-arm that swings the cam lift of a cam shaft with a pivot as a fulcrum. It goes without saying that it can be done.

As described in detail above, in the valve train for an internal combustion engine according to the present invention, friction noise and flickering loss generated between the rocker arm and the cam can be significantly reduced. Since the wear of various parts due to friction is also reduced, the desired characteristics can be maintained over a long period of time.

[Brief Description of the Drawings] Figure III is a sectional view showing a conventional valve operating system, Figure 2 is a sectional view taken along line I-1, Figure 3 is a sectional view showing a valve operating system according to the present invention, FIG. 4 is a sectional view taken along line 1--N, IIES is a perspective view of the tappet, and FIG. 6 is a sectional view of essential parts showing another embodiment of the present invention. 1]...Rocker shaft, 12...Rocker arm,
U... cam, 14... tappet, trout... cam shaft, Shu... lubricating oil passage. Figure 1 Figure 3 L7, 1. j Figure 6 Figure 2a @ Figure 4 □ Figure 5 1m

Claims (1)

[Claims] (1) In a valve operating system for an internal combustion engine in which a rotatably supported rocker arm contacts a cam and pushes a valve stem through the rocker arm, a convex spherical cam contacts one end of the rocker arm. 1. A valve operating device for an internal combustion engine, characterized in that a tappet having a surface is rotatably disposed, and a contact point between the cam surface and the tappet is set at a position offset from the center of the tappet.