JPS58187506A - Valve train of internal-combustion engine - Google Patents

Abstract

PURPOSE:To decrease noise from a rocker arm, by constituting a rocker arm in a valve train mechanism by dividing it into two parts to the valve side and the cam side, with each base part being supported pivotably by a rocker shaft, and by energizing each rocker arm part toward the valve side and the cam side respectively by the tension of a spring. CONSTITUTION:A rocker arm in a valve train mechanism is composed of rocker arms 11 and 12 on the valve side and the cam side respectively. The cylindrical bearing part 13 of the rocker arm 11 is pivotally fitted to a rocker shaft 2. On the other hand, the rocker arm 12 is fitted to the rocker shaft 2 by a pair of annular bearing parts 18 formed in a forked shape. These two rocker arms 11 and 12 are spring-tensioned in such a manner that the abutted surfaces 16 and 22 formed in the upper part of each arm 11 and 12 can be separated from each other by an approximately V-shaped wire spring 25 of which end parts 25a and 25b are connected to each rocker arms 11 and 12. A lubricant fed from an oil hole 17, passing through a lubricant passage 26, lubricates the sliding parts of rocker arms 11 and 12 with the rocker shaft 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a valve train for an internal combustion engine using a rocker arm.

Figure 1 shows an example of a valve train using a rocker arm.
Camshaft 1 is placed at the top of the cylinder head,
The rocker arm 3 rotatably supported by the rocker/yant 2 has one end 3a in contact with the cam 4, and the other end 3b in contact with the valve of the intake and exhaust pulp 5. It comes into contact with the stem end 5a and transmits the lift of the cam 4 to the intake/exhaust pulp 5 at a predetermined rocker ratio.The end of the rocker arm 3 that pushes the intake/exhaust pulp 5: t b Valp stem end 5
Since it is necessary to have an appropriate valve clearance C in advance to cope with the thermal expansion of the intake and exhaust pulp 5, between the
For example, an adjustment screw 6 is provided as a 1441 mechanism for this valve clearance C.

However, in a conventional valve train with such a configuration,
As is well known, due to the above-mentioned valve clearance C during cam lift, severe collision occurs between the rocker arm 3 (adjust screw 6) and the rubber stem 5a, or between the rocker arm 3 and the cam 4. occurs,
It has the disadvantage of producing a harsh rocker sound. Visit,
This also applies to a so-called OHv type valve operating system in which a book rod is interposed between the cam i and the rocker arm 3.

This invention was made in view of the above-mentioned drawbacks of the conventional technology, and it is possible to divide the rocker arm into a rocker arm on the loop side and a rocker arm on the cam side, thereby reducing the clearance between each rocker arm, the valve stem end, and the cam. The object of the present invention is to reduce the rocker noise with a simple configuration that does not use a complicated mechanism such as an oil tappet, by always keeping the rocker noise at zero, and by bringing the two-end hook arms into surface contact via a lubricating oil film.

That is, the valve train for an internal combustion engine according to the present invention is rotatably supported by the shaft of the rocker 7, and the end of which is in contact with the loop stem end of the intake and exhaust valve, and the rocker arm of the rocker 7, A cam-side rocker arm that is rotatably supported by the shaft and whose end is driven directly or indirectly by the cam, and the double-ended hook arm,
A pair of contact surfaces that are formed to face each other so as to be able to approach and separate and that transmit the valve opening/closing force by making surface contact with each other, and a pair of contact surfaces that are arranged between the rocker arm and that extend in the direction of separation of the inner contact surfaces. This device includes a spring member that biases the hook arm, and a lubrication mechanism that supplies lubricating oil between the two contact surfaces.

Hereinafter, a specific embodiment of the present invention will be described in detail based on the drawings.

FIG. 2 shows an embodiment in which the present invention is applied to an OHO type valve train similar to the conventional example, in which 11 is a valve-side rocker arm, 12 is a cam-side rocker arm, and the lift of the cam 4 is controlled by a double-end lever arm. It is transmitted to the intake and exhaust pulp 5 via 11 and 12. As shown in FIGS. 4 and 5, the valve-side rocker arm 11c includes a cylindrical bearing portion 13 that rotatably fits into the shaft 2 of the rocker 7, and an arm portion 14 that has an adjustment screw 6 screwed onto its tip. It is roughly composed of
Further, a contact surface 16 is provided on a protrusion @15 extending from the bearing portion opening so as to be substantially perpendicular to the arm portion 14. Reference numeral 17 denotes an oil hole formed through the bearing 813K, which opens relatively close to the projection ``in order to supply lubricating oil to the contact surface 16'' as described below.

On the other hand, as shown in FIGS. 6 and 7, the cam-side rocker arm 12 has a pair of annular bearing portions 18 formed in a bifurcated shape that rotatably fit into the rocker shaft 72, and a pair of annular bearing portions 18 at the tip thereof. It is roughly composed of an arm part on which a chip part 19 is fixedly attached,
A contact surface 2 is provided on a protrusion 21 extending from the proximal end of the arm.

Further, 1: On both sides of the protrusion 21, side wall portions n are formed continuously with the bearing portion 18 so as to slidably fit with the side surfaces of the protrusion 15 of the valve side rocker arm 11. Furthermore, as shown in FIG.
The lubricating oil is configured to be in sliding contact with the third outer surface at a position in the clockwise direction from the position of the opening 17a of the oil hole 17, so that the lubricating oil mainly flows upward. Contact surfaces 16 of each of the double-ended hook arms 11 and 12. ．． 2f'Fi, which can be moved toward and away from each other by rotation, and as shown in FIG. The linear spring 25 causes the double-ended hook arms 11 and 12 to move in the direction in which the inner contact surfaces ts and 22 are separated, that is, in the direction in which the adjustment screw 6 is pressed against the pulp stem end 5a and the tip portion 19 is pressed against the cam. A lubricating oil passage X communicating with an oil pump (not shown) of the engine is provided in the rocker shaft 2, and an oil hole I thereof is connected to the oil hole 17. It is formed.

The functions of the valve train with this structure are as follows:
In the non-lifting state where the tip portion 19 is in contact with the base circle portion of the optical cam, the biasing force of the linear spring 5 causes the gap between the adjusting screw 6 and the pulp stem end 5a, and the tip portion. 19 and the cam d are maintained in contact with each other, while the contact surfaces 16 and 22 of the double-ended hook arms 11 and 12 are kept in contact with each other, as shown in FIG. A predetermined gap A is maintained. This gap AH1 can be adjusted by the adjustment screw 6, and can be adjusted to, for example, 0.
It is set to a value of about 0.05 to 0.151. This gap is filled with lubricating oil that is about to flow upward from the oil hole 17 through the gap.

When the cam 4 starts to lift from this non-lifting state, the cam-side rocker arm L rotates to compress the above-mentioned gap A and the gap A, and the inner contact surface 16°2 is in surface contact with each other through the oil film. As a result, the pulp-side rocker arm 11 is driven by the cam-side rocker arm 12, and the intake and exhaust valves 5 are pushed open via the adjustment screw 6.

At this time, between the adjusting screw 6 and the pulp stem end 5a, which are in contact with each other from the beginning, and the tip portion 1
Between the inner contact surfaces 16 and 22, AM oil is present between the relatively wide contact surfaces, and this lubricating oil is gradually released from between the two. When moving to the sea, a large effect of the H1 shrine is obtained, so there is no need to make any sudden noises.

Also, when the cam lift is finished, the linear spring 250f
The gap A is formed again by the force j, and the lubricating oil supplied from the gradient oil path d returns to the initial state filled with the lubricating oil.

As described above, according to the above structure, a rocker sound is not generated when the cam lifts, and wear between the adjusting screw 6 and the pulp stem end 5a is also reduced, thereby improving the valve clearance (distance fiA). Less frequent adjustment is required. Furthermore, measures against wear between the tip portion 19 and the cam 4 can be easily taken.

Furthermore, when compared to the conventional rocker arm 3 (see Figure 1), although an increase in inertial mass is unavoidable, the increase in weight is small compared to cases where oil tappets are used, and the configuration is extremely simple. The mouth is the nest, and the protrusions 15, 21 i! are the main part of the weight increase! Since it is located near the center of rotation, the increase in the moment of inertia is small and high-speed operation is possible.

Although an embodiment in which the present invention is applied to an OHO type valve train has been described above, the present invention is not limited to this.
A book block is inserted between the cam and the rocker arm on the cam side. It is also possible to configure it as an NV type valve train f or the like.

As is clear from the above description, the valve train for an internal combustion engine according to the present invention can significantly reduce the rocker noise caused by collision of the valve stem end, etc. during cam lift, thereby reducing the noise of the internal combustion engine.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a conventional valve train, Fig. 2 is a sectional view showing a valve train according to the present invention, Fig. 3 is a sectional view taken along the center line of the rocker arm, and Fig. 4 is a sectional view showing the valve train according to the present invention. FIG. 5 is a top view of only the valve side rocker arm, FIG. 5 is a front view thereof, FIG. 6 is a top view of only the cam side rocker arm, and FIG. 1...Cam 7 shaft, 2...Rocker shaft, 4
・Cam, 5... Intake and exhaust valve, 6... Adjustment screw '7.11 Valve side rocker arm, '2...
Force/mus side rocker arm, 16...contact surface, 17...
・Oil hole, ν...Contact surface, 5...Linear spring, X...
・Warm oil aisle. 17. □. Agent Shigafuji Yat,,',i;,',,
;,,'Cancer Figure 1 Figure 2 Figure 3-

Claims (1)

[Claims] (1) A valve-side rocker arm that is rotatably supported by the rocker shaft and whose end abuts the valve stem end of the intake and exhaust valve, and a valve-side rocker arm that is also rotatably supported by the rocker shaft and whose end abuts against the valve stem end of the intake and exhaust valve. a cam-side rocker arm that is driven directly or indirectly; a pair of abutment surfaces formed on the double-ended lock arm so as to be able to approach and separate from each other, and that transmit the valve opening and closing force by making surface contact with each other; A spring member disposed between the double-ended hook arms and urging the double-ended hook arms in the direction of separation between the two contact surfaces, and a lubrication mechanism that supplies engine #I'll oil between the two contact surfaces. A valve train for an internal combustion engine.