JP4216992B2 - Engine valve gear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a rocker arm that is swingably supported by a cylinder head via a rocker shaft and is rocked by a cam shaft, and the rocking end of the rocker arm is slidably supported by the cylinder head. The present invention relates to a valve operating device for an engine which is brought into contact with an end portion of a valve stem.
[0002]
[Prior art]
As shown in FIG. 3, a conventional valve operating apparatus for an engine includes a rocker arm 013 that is swingably supported by a rocker shaft 012 and a cam shaft 014 that is slidably in contact with one end of the rocker arm 013. A convex spherical surface 08 is formed at the tip of the adjusting bolt 20 screwed to the other end portion of the rocker arm 013. This spherical surface 08 is brought into contact with a flat surface 017 formed at the end portion of the stem 04b of the valve 04. An opening / closing operation is given to the valve 04 through the contact portion (see, for example, Japanese Patent No. 2757318). According to such a configuration, it is possible to smoothly open and close the valve by reducing friction between the rocker arm and the contact portion of the valve stem.
[0003]
[Problems to be solved by the invention]
By the way, in the configuration of the conventional device, even if the distance S between the rocker shaft 012 and the valve 04 is constant, there is an error in the distance L between the rocker shaft 012 and the center O of the convex spherical surface 08. The effective arm length of the rocker arm 013 changes, and such a change has some influence on the opening / closing stroke of the valve 04 and is not preferable. Accordingly, the portion having the rocker arm 013, particularly the convex spherical surface 08, must be processed with high accuracy in order to minimize the above-described error, but this is disadvantageous in terms of cost.
[0004]
The present invention has been made in view of such circumstances. If the distance between the rocker shaft and the valve is made constant, the distance between the axis of the rocker shaft and the center of the convex spherical surface is also determined. Thus, an object of the present invention is to provide a valve operating device for the engine that can contribute to a reduction in manufacturing cost.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention includes a rocker arm that is supported by a cylinder head via a rocker shaft so as to be swingable, and is rocked by a camshaft. In the valve operating apparatus of the engine, which is in contact with the end of the valve stem slidably supported on the cylinder head, the rocker shaft is attached to the cylinder head so that its axis is perpendicular to the axis of the valve, The rocker arm is made of a single steel plate, and is composed of a pair of opposing side wall portions and a bottom wall portion integrally connecting the side wall portions. A shaft hole for swingably fitting and rocking the rocker arm is formed, and a concave and arc-shaped slipper surface on which the cam of the cam shaft is slidably contacted is formed on the upper edge of the other end of each side wall. Slippers Located immediately below to form a flat surface on the bottom wall portion, especially that the convex spherical surface in contact with the flat surface, the spherical center is formed on the end portion of the stem of the valve to come on the axis of the valve It is a sign.
[0006]
According to features of this, the center of the convex spherical surface formed at the end of the stem of the valve, so positioned on the axis of the stem, the rocker shaft and a valve mounted to axes perpendicular to each other If the distance between the axes is made constant, the distance between the axis of the rocker shaft and the center of the spherical surface is uniquely determined. Therefore, it is not necessary to manage the accuracy of the distance between the axis of the rocker shaft and the center of the spherical surface, and the manufacturing cost can be reduced.
[0007]
Also, the rocker arm with a single steel plate, a pair of side wall portions facing each, between these side wall constituted by a bottom wall portion connected integrally to both side wall portions, said rocker shaft By forming a shaft hole that fits rotatably and forming the flat surface on the bottom wall, a rocker arm with a large section modulus and high bending rigidity can be formed on both side walls and the bottom wall. In addition, it can be easily manufactured by press working, and since it is not necessary to form a spherical surface on the rocker arm, the press mold can be easily manufactured, and the manufacturing cost can be further reduced.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described based on an embodiment of the present invention shown in the accompanying drawings.
[0009]
FIG. 1 is a partially longitudinal side view of an engine provided with a valve gear of the present invention, and FIG. 2 is a sectional view taken along line 2-2 of FIG.
[0010]
In these drawings, the cylinder head 1 of the engine has a combustion chamber 2 and an intake or exhaust port 3 opened to the combustion chamber 2, and the port 3 is opened and closed by a valve 4. This valve 4 is a stem that is slidably supported by an umbrella portion 4a seated on a valve seat 5 embedded in an opening to the combustion chamber 2 of the port 3 and a valve guide 6 fixed to the cylinder head 1. 4b, and the umbrella portion 4a and the stem 4b are welded to each other at the opposed end surface 7. The upper end surface of the stem 4 b is formed as a convex spherical surface 8. At that time, the spherical surface 8 is formed such that its center O is on the axis A of the bulb 4. Such spherical surface 8 can be easily formed by cutting or forging.
[0011]
A retainer 9 is attached to the outer periphery of the upper end portion of the stem 4b, and a valve spring 10 that biases the valve 4 in the closing direction is contracted between the retainer 9 and the cylinder head 1.
[0012]
A valve operating device 11 of the present invention that opens and closes the valve 4 in cooperation with the valve spring 10 is disposed in the cylinder head 1. This valve operating apparatus 11 has a rocker shaft 12 fixedly attached to the cylinder head 1 so that the axis B is orthogonal to the axis A of the valve 4, and a base end portion rotatably supported by the rocker shaft 12. A rocker arm 13 having a rocking end abutted against the upper end of the stem 4b, and a cam shaft 14 rotatably supported by the cylinder head 1 and having a cam 14a slidably contacting the upper surface of the rocker arm 13. The camshaft 14 is driven from a crankshaft (not shown).
[0013]
The rocker arm 13 is formed by pressing a single steel plate, and includes a pair of opposite side wall portions 13a and 13a and a bottom wall portion 13b that integrally connects the side wall portions 13a and 13a. It has become. Shaft holes 15 and 15 that are rotatably fitted to the rocker shaft 12 are formed in one end portions of the both side wall portions 13a and 13a, and the cam 14a is slid on the upper edges of the both side wall portions 13a and 13a. A concave and arcuate slipper surface 16 is formed. Further, a flat surface 17 is formed on the bottom wall portion 13b located immediately below the slipper surface 16 , and this abuts against the convex spherical surface 8 of the stem 4b.
[0014]
Next, the operation of this embodiment will be described.
[0015]
When the cam shaft 14 rotates, the rocker arm 13 is rocked by the rocker shaft 12 around the rotation of the sliding contact cam 14a on the sliding surface 16, the swinging force through the flat surface 17 and a convex spherical surface 8 abut each other The valve 4 can be opened and closed while being transmitted to the valve 4 and cooperating with the return force of the valve spring 10.
[0016]
Incidentally, since the center O of the convex spherical surface 8 formed at the upper end of the stem 4 b of the valve 4 is located on the axis A of the valve 4, it is between the axis B of the rocker shaft 12 and the axis A of the valve 4. As long as the distance S is made constant, the distance L between the axis B of the rocker shaft 12 and the center O of the spherical surface 8 is uniquely determined. Therefore, it is not necessary to manage the accuracy of the distance L between the axis B of the rocker shaft 12 and the center O of the spherical surface 8, and the manufacturing cost can be reduced.
[0017]
Thus, the variation in the distance L between the axis B of the rocker shaft 12 and the center O of the spherical surface 8 is eliminated, and the effective length of the rocker arm 13 can always be constant, so that the opening / closing stroke of the valve 4 is stabilized. be able to.
[0018]
Further, the rocker arm 13 made of a single steel plate is composed of a pair of side wall portions 13a, 13a facing each other and a bottom wall portion 13b integrally connecting them to each other. Flexural rigidity is strengthened and weight is reduced. In addition, the rocker arm 13 can be easily manufactured by pressing, and since it is not necessary to form a spherical surface on the bottom wall portion 13b, the press mold can be easily manufactured, contributing to further reduction in manufacturing cost. obtain.
[0019]
The present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the scope of the gist thereof.
[0020]
【The invention's effect】
According to features of the present invention as described above, is swingably supported via a rocker shaft in a cylinder head, comprising a rocker arm which is swung by a cam shaft, a swinging end portion of the rocker arm, the cylinder In a valve operating system of an engine that is in contact with an end of a valve stem that is slidably supported by a head, the rocker shaft is attached to the cylinder head so that its axis is perpendicular to the axis of the valve. The rocker arm is made of a single steel plate, and is composed of a pair of opposing side wall portions and a bottom wall portion integrally connecting the side wall portions, and the rocker shaft is attached to one end portion of both side wall portions. A shaft hole for swinging the rocker arm is formed by being rotatably fitted to the upper surface, and a concave and arc-shaped slipper surface on which the cam of the cam shaft is slidably contacted is formed on the upper edge of the other end of both side walls. Directly on this slipper surface Forming a flat surface on the bottom wall portion located on the convex spherical surface in contact with this flat surface, because the spherical center is formed on the end portion of the stem of the valve to come on the axis of the valve, rocker shaft Even if the accuracy control of the distance between the axis of the sphere and the center of the spherical surface is not performed, the variation in the distance between them can be eliminated, and the manufacturing cost can be reduced.
[0021]
Also, the rocker arm with a single steel plate, a pair of side wall portions facing each, between these side wall constituted by a bottom wall portion connected integrally to both side wall portions, said rocker shaft the shaft hole for rotatably fitted to form, by the fact that to form a flat surface on the bottom wall portion, the section modulus at the both side wall and the bottom wall portion is large, constitute the flexural rigidity is high and light weight rocker arms In addition, it can be easily manufactured by press working, and since it is not necessary to form a spherical surface on the rocker arm, it is easy to manufacture the press mold, and the manufacturing cost can be further reduced. it can.
[Brief description of the drawings]
FIG. 1 is a partially longitudinal side view of an engine provided with a valve gear of the present invention.
2 is a sectional view taken along line 2-2 of FIG.
FIG. 3 is a side view of a conventional valve gear.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cylinder head 4 ... Valve 4b ... Valve stem 8 ... Convex spherical surface 12 ... Rocker shaft 13 ... Rocker arm 13a ... Side wall Part 13b ... Bottom wall part 14 ... Cam shaft
14a ... cam 15 ... shaft hole
16 .... Slipper surface 17 .... Flat surface
A: Valve axis
B: Rocker shaft axis

Claims (1)

A rocker arm (13) is supported by the cylinder head (1) through a rocker shaft (12) so as to be swingable, and is rocked by a cam shaft (14). A rocking end of the rocker arm (13) is provided. In the valve operating device of the engine, which is brought into contact with the end of the stem (4b) of the valve (4) slidably supported by the cylinder head (1),
The rocker shaft (12) is attached to the cylinder head (1) so that its axis (B) is orthogonal to the axis (A) of the valve (4),
The rocker arm (13) is made of a single steel plate, and is composed of a pair of opposing side wall portions (13a) and a bottom wall portion (13b) integrally connecting the side wall portions (13a). A shaft hole (15) is formed at one end of both side wall portions (13a) so as to be rotatably fitted to the rocker shaft (12) to swing the rocker arm (13). A concave and arc-shaped slipper surface (16) with which the cam (14a) of the cam shaft (14) is slidably contacted is formed on the upper edge of the other end portion, and the bottom wall portion located directly below the slipper surface (16) A flat surface (17) is formed on (13b), and the convex spherical surface (8) in contact with the flat surface (17) is arranged such that the center (O) of the spherical surface is on the axis (A) of the valve (4). It is formed at the end of the stem (4b) of the valve (4). Valve operating device.

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