JPH086566B2 - Valve spring mounting structure for internal combustion engine - Google Patents

Description

The present invention relates to a valve spring mounting structure for an internal combustion engine.

[Prior Art] Conventionally, in a valve mechanism of an internal combustion engine, a lift of a cam driven by the internal combustion engine is transmitted to an intake valve or an exhaust valve via a rocker arm to open and close these valves. This will be specifically described with reference to FIGS. 4 and 5. As shown in FIGS. 4 and 5, the intake valve 11 and the exhaust valve 22 are slidably fitted in the stem guide 5 fixed to the cylinder head 15, respectively.
The retainer 7 is fitted into the groove 4 formed at the end of the valve stem 2 through the split collet 21, and the valve is provided between the retainer 7 and the spring seat portion 25 provided on the cylinder head 15. The spring 9 is interposed in a compressed state. That is, the intake / exhaust valves 11, 22 are constantly urged in the valve closing direction via the retainer 7 by the spring force of the valve spring 9. On the other hand, above the cylinder head 15, a rocker arm 13 provided with a rocker shaft 17 is swingably attached to the rocker shaft 17. One end of the rocker arm 13 is in contact with a cam 19 as an arm swinging means, and the other end is in contact with the stem head 3 as the rocker arm 13 swings, and the stem head 3 is valved against the spring of the valve spring 9. It is configured to push in the opening direction to open the valve. Therefore, as shown in FIG. 5, by rotating the cam 19 at a speed half that of a crankshaft (not shown), the intake valve 11 is used in the intake stroke of the internal combustion engine, and the exhaust valve 11 is used in the exhaust stroke.
It is possible to open each 22.

[Problems to be solved by the invention]

By the way, as shown in FIG. 3, the valve spring 9 in the above-described conventional valve mechanism may fall to the opposite side of the auxiliary winding portion 91 (that is, the X direction) in a compressed state under load even if it is upright when there is no load. Had the property of This is because the spring is deformed with the auxiliary winding portion 91 as a fulcrum, and the spring center axis line Y moves to Y ′ to generate a component force Wx for tilting the spring. Therefore, as shown in FIG. 4, the valve spring 9 is inserted between the spring seat portion 25 of the valve mechanism and the retainer 7 in a compressed state, and the valve body is pressed in the valve closing direction via the retainer 7. When the caulking port opening is closed, the component force Wx has already been generated in the valve spring 9. When the valve head 1 is seated on the valve seat 27 when the component force Wx is generated when the valve is closed, the valve head 1 and the valve seat 27 are partially abutted against each other, and the valve seat 27 is unevenly worn. Valve stem 2
There was a problem that was broken. In addition, there was a problem that impact noise was generated when seated and the S / N ratio was adversely affected in knocking control by detecting acceleration of the cylinder block.

[Means for solving problems]

In view of the above, the present invention is a valve spring mounting structure for an internal combustion engine for preventing eccentric seating of a valve, the valve stem slidably inserted in a stem guide fixed to the internal combustion engine body. And a valve head that is connected to one end of the valve stem and is detachably attached to the port opening of the combustion chamber, a retainer mounted near the other end of the valve stem, and the above inside The valve stem is inserted and is interposed between a spring seat portion provided on the stem guide or the internal combustion engine body and the retainer, and urges the retainer in a direction away from the spring seat portion. A coiled valve spring that urges the main body in the closing direction and the other end of the valve stem are pressed according to the output rotation of the internal combustion engine. A valve opening means for sliding the valve stem against the urging force of the valve spring in the stem guide to separate the valve head from the port opening and open the opening. In the mechanism, the valve spring is formed such that, in a free state, a central axis of the valve spring is inclined toward a winding portion side of the valve spring lower end with respect to a lower end surface of the valve spring, and the valve spring connects the spring seat portion and the retainer. When the port opening is closed, the central axis line is substantially perpendicular to the lower end surface of the valve spring when interposed between them in a compressed state.

[Work]

In the valve spring mounting structure of the internal combustion engine of the present invention,
When the valve body is urged through the retainer in the valve closing direction to close the port opening of the combustion chamber, the central axis of the valve spring becomes perpendicular to the lower end surface of the valve spring, and the eccentricity of the valve head and valve seat Prevent straight seating.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a valve operating mechanism of an internal combustion engine using a valve spring of the present invention.

In FIG. 1, a valve stem 2 of an intake valve 11 (or an exhaust valve 22) is slidably fitted in a stem guide 5 fixed to a cylinder head 15. A retainer 7 is fitted in the groove 4 formed at the end of the valve stem 2 via a split collet 21. A valve spring 8 composed of a coil spring is interposed in a compressed state between the spring seat portion 25 formed on the cylinder head 15 and the retainer 7, and the valve spring 8 is interposed via the retainer 7. The intake valve 11 (exhaust valve 22) is always biased in the valve closing direction. On the other hand, at a position near the retainer 7 and off the axis of the valve stem 2, the rocker shaft 17
The rocker shaft 17 supports the rocker arm 13 swingably. One end of the rocker arm 13 is in contact with the cam 19, and the other end is in contact with the end of the valve stem 2 (that is, the stem head 3) along with the swing of the arm due to the rotation of the cam 19 and the valve stem. 2 is pressed in the valve opening direction. That is, the rocker arm 13, the rocker shaft 17, and the cam 19 constitute valve opening means.

In the valve spring 8, as shown in FIG. 2, the center axis Y of the spring is inclined toward the auxiliary winding portion 81 side of the spring seat portion 25 side when there is no load, and when the load W acts, the auxiliary winding portion 81 is used as a fulcrum. The spring is deformed so that the central axis Y of the spring moves to Y'and the spring stands upright. That is, the spring center axis Y is preliminarily inclined toward the auxiliary winding portion 81 so that a lateral force is not generated with respect to the spring center axis Y'when the spring is compressed.

Therefore, as shown in FIG. 1, the valve spring is assembled to the valve operating mechanism described above, and the intake valve 11 (exhaust valve 22) is biased in the valve closing direction via the retainer 7 to move the valve head 1 and the valve seat 27. When the abutted valve is closed, the valve spring 8 stands upright with respect to the valve spring lower end surface 83 (that is, the spring seat portion 25), and the central axis of the valve stem 2 and the valve seat 27.
The central axes of are also in agreement. That is, when the valve is closed, no lateral force is generated with respect to the central axis Y'of the spring, the swing of the valve head 1 is eliminated, and the valve head 1 is centered. Therefore, eccentric seating of the valve is prevented, seating noise is reduced, and the problem of uneven wear of the valve seat 27 is solved.

As in the conventional method for processing the valve spring 8, the spring end surface is ground so that it stands upright when there is no load, and the opposite side of the auxiliary winding portion 81 (arrow θ is shown in FIG. 2).
Part) to be opened, or the lower end surface of the valve spring so that it falls toward the auxiliary winding 81 side when no load is applied.
83 may be polished.

Further, the rocker arm 13 as a valve opening means has a swing arm whose end opposite to the abutting end with the valve stem 2 is swingably supported by a pivot, and a cam is engaged with substantially the center of both ends. A direct acting type in which the valve stem 2 is directly pressed by a cam via a tappet without using an arm member may be used.

〔The invention's effect〕

The valve spring of the internal combustion engine of the present invention urges the valve body in the valve closing direction via the retainer, and when the valve is closed by bringing the valve head and the valve seat into contact with each other, a lateral force that tends to fall the valve spring is applied. Does not occur,
Therefore, the valve head is centered when the valve is seated, eccentric seating of the valve is prevented, seating noise is reduced, and problems such as uneven wear of the valve seat are eliminated.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a valve mechanism using a valve spring of the present invention, FIG. 2 is a sectional view of a valve spring according to the present invention, FIG. 3 is a sectional view of a conventional valve spring, and FIG. FIG. 5 is a sectional view of a conventional valve mechanism, and FIG. 5 is a sectional view of a main part of the conventional valve mechanism. 1: Valve head, 2: Valve stem 3: Stem head, 4: Groove 5: Stem guide, 7: Retainer 8: Valve spring, 9: Valve spring 11: Intake valve, 13: Rocker arm 15: Cylinder head, 17: Rocker Shaft 19: Cam, 22: Exhaust valve 25: Spring seat part, 27: Valve seat

Claims (1)

[Claims] 1. A valve stem slidably fitted in a stem guide fixed to the body of an internal combustion engine, and a valve stem connected to one end of the valve stem so as to be detachable from a port opening of a combustion chamber. A valve body having a valve head, a retainer mounted near the other end of the valve stem, the valve stem inserted inside, and a spring seat portion provided on the stem guide or the internal combustion engine body and the retainer. A coil-shaped valve spring that is interposed between the valve seat and the valve seat to urge the retainer in a direction away from the spring seat portion, and the other end of the valve stem. The valve stem is pressed according to the rotation of the output shaft, and the valve stem is slid in the stem guide against the biasing force of the valve spring. In a valve operating mechanism of an internal combustion engine equipped with a valve opening means for separating a valve head from the port opening and opening the port opening, in a free state, the central axis of the valve spring is lower than the lower end surface of the valve spring. The valve spring is formed so as to incline toward the side of the auxiliary winding portion, and when the valve spring is interposed between the spring seat portion and the retainer in a compressed state, the central axis is below the valve spring when the port opening is closed. A valve spring mounting structure for an internal combustion engine, characterized in that it is configured so as to be substantially perpendicular to an end face.