JPH0710003Y2 - Rocker arm adjustment mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a rocker arm for driving an intake / exhaust valve and the like, and more particularly to a rocker arm adjustment mechanism for finely adjusting the drive amount of the rocker arm.

[Prior Art] As a proposal for appropriately transmitting the driving force of the rocker arm to the intake / exhaust valve, there is a "rocker arm" (Japanese Utility Model Laid-Open No. 59-67502) proposed by the present applicant as shown in FIG.

In this "rocker arm", a cap d that is in contact with a stem end c of an intake / exhaust valve is swingably fitted to the tip of an adjustment screw b for fine adjustment attached to the rocker arm a. An elastic member e for urging the cap c toward the stem end d side between the rocker arms a.
Is provided and configured. Therefore, the elastic member e appropriately regulates the swing of the cap c, and the driving force of the rocker arm a is favorably transmitted in the driving direction of the intake / exhaust valve.

[Problems to be Solved by the Invention] However, since the movement of the cap d, which swings relative to the tip of the adjusting screw a, is a sliding movement with respect to the tip of the adjusting screw b, the supply of lubricating oil does not occur. It has been pointed out that there is a problem that wear tends to progress remarkably at the time of starting the engine or at low speed rotation, which tends to be insufficient.

[Means for Solving the Problems] The present invention is intended to solve the above problems, and a spherical surface in which a cap that is brought into contact with a rear end of a valve rod is swingably fitted to a tip of an adjusting screw of a rocker arm. A rocker arm adjusting mechanism is formed by forming a head portion, the inner bottom of the cap with which the tip of the spherical head portion is in contact is a smooth surface, and the circumferential spherical portion of the cap and the spherical head portion is a curved surface formed of a trochoidal curve. Is configured.

[Operation] When the inner bottom of the cap is formed into a smooth surface, the swinging fulcrum between the spherical head and the cap when the rocker arm is driven is located on the upper side of the cap. As a result, the tip of the spherical head moves in a trochoidal curve relative to the smooth surface. On the other hand, since the inner bottom of the cap is formed as a smooth surface and the cap and the spherical surface on the circumferential side of the spherical head are formed as a curved surface formed of a trochoid curve, the trochoid curve movement becomes smoother. As a result, wear of the spherical head (fretting wear) is suppressed.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

Reference numeral 1 shown in FIG. 1 is a rocker arm that is driven by a cam or tappet or the like, and an adjusting screw 5 having a spherical head 4 integrally at the tip is screwed into an arm 2 that is the point of action of the rocker arm 1. A cap 8 which is brought into contact with a rear end 7 of a valve rod 6 such as an intake or exhaust valve is swingably fitted to the spherical head portion 4. In the embodiment, as shown in FIG. 2, the cap 8 has a peripheral side surface 10 having a predetermined curvature that is slidably fitted to the tip side of the peripheral spherical surface portion 9 of the spherical head 4. The cylindrical insert member 11 and the insert member 11 are integrally fitted, and the smooth surface 14 with which the spherical surface portion 13 at the tip of the spherical head portion 4 is in contact.
And a cup-shaped cap body 15 that forms a
The spherical portion 13 at the tip is formed to have a large curvature with respect to the peripheral spherical portion 9.

The cap 8 has a circumferential side surface 10 formed by a curved surface formed by a continuous trochoidal curve in the Z-axis direction in the circumferential direction with respect to the three X-, Y-, and Z-axis directions. The spherical portion 9 on the peripheral side of the spherical head is also formed by a curved surface formed by continuous trochoidal curves in the Z-axis direction.

By the way, the fixing of the insert member 11 is performed by the cap body 15
After the insert member 11 is fitted to, the upper end of the cap body 15 is bent inward in the radial direction and downward (caulking process). Further, the hardness (surface hardness) of the insert member 11 is formed of a material that is higher than that of the peripheral spherical surface portion 9 or is surface-treated.
Reference numeral 17 denotes a lip portion formed on the upper portion of the peripheral spherical surface portion 9 of the insert member 11, and reference numeral 18 denotes a notch portion that engages with the lip portion 17 and determines the swing limit of the cap 8. FIG. 3 is an analysis diagram showing the relative movement of the adjusting screw 5 with respect to the cap 8.

As shown in the figure, it can be confirmed that when the adjusting screw 5 is relatively swung, the spherical portion 13 at the tip end makes a trochoidal curve movement so as to roll on the smooth surface 14. At this time, it can also be confirmed that the peripheral spherical surface portion 9 moves (slides) along the peripheral side surface 10 of the insert member 11 with the notch portion 18 as a fulcrum.

[Effects of the Invention] As is apparent from the above description, according to the present invention, a spherical head having a cap that abuts the rear end of the valve rod is swingably fitted to the tip of the adjusting screw of the rocker arm. Since the inner bottom of the cap with which the tip of the spherical head is in contact is a smooth surface and the peripheral spherical parts of the cap and the spherical head are curved surfaces composed of trochoidal curves, a spherical head that moves trochoidally is formed. On the other hand, the cap can be smoothly moved in a trochoid manner, wear of the spherical head portion in contact with the smooth surface can be prevented, and the clearance adjustment value of the adjusting screw can be kept constant.

[Brief description of drawings]

FIG. 1 is a schematic view showing a preferred embodiment of the present invention, FIG. 2 is a detailed view of essential parts of FIG. 1, FIG. 3 is an analysis view showing relative movement between an adjusting screw and a cap, and FIG. It is the schematic which shows the rocker arm as a prior art example. In the figure, 1 is a rocker arm, 5 is an adjusting screw,
Reference numeral 8 is a cap, 11 is an insert member, and 15 is a cap body.

Claims (1)

[Scope of utility model registration request] 1. A spherical head having a cap that abuts against a rear end of a valve rod is swingably fitted at the tip of an adjusting screw of a rocker arm, and the tip of the head is in contact with the inside of the cap. An adjusting mechanism for a rocker arm, wherein the bottom is a smooth surface, and the cap and the spherical surface on the peripheral side of the spherical head are formed by a curved surface composed of a trochoidal curve.