JP4609225B2 - Valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to a valve operating apparatus for an internal combustion engine such as an automobile, and more particularly, to an improvement of a retainer (spring retainer) and a coil spring (valve spring) assembled to an intake valve or an exhaust valve (hereinafter referred to as intake / exhaust valve). .

As described in Patent Document 1, a valve system of an internal combustion engine generally includes a coil spring that biases the intake / exhaust valve of the internal combustion engine in a closing direction, and a valve stem of the intake / exhaust valve. And a retainer assembled through a cotter. The retainer is provided with a guide portion fitted into one end of the coil spring and a flange portion projecting radially outward from one end of the guide portion, and a seating surface for receiving one end of the coil spring is formed on the flange portion. Is done.
JP-A-9-250317

  If the first winding portion of the coil spring on the retainer side contacts and interferes with the corner portion between the guide portion and the flange portion of the retainer, local wear and stress concentration may occur. For this reason, conventionally, it has been necessary to form a chamfered part or a notch part to avoid interference with the corner part of the retainer inside the first turn part of the retainer side of the coil spring. Further, since the radius of curvature of the corner portion of the retainer is limited to a small value so as not to interfere with the coil spring, stress is easily concentrated on the corner portion. In addition, if a predetermined clearance is secured between the outer periphery of the guide portion of the retainer and the inner periphery of the coil spring, the retainer and the coil spring rotate relatively to promote wear. In particular, when the retainer is formed of a light alloy such as an aluminum alloy, although it is lightweight, since its strength and durability are relatively low, it is an important problem to suppress wear.

The present invention has been made in view of such problems, a coil spring for biasing the intake / exhaust valve of the internal combustion engine in a closing direction, a retainer assembled to the valve stem of the intake / exhaust valve, The retainer includes a cylindrical guide portion and a flange portion projecting radially outward from one end of the guide portion, and the flange portion receives one axial end of the coil spring. A large-diameter portion that is formed with a seating surface and in which one end in the axial direction in which the guide portion is inserted in the coil spring is opposed to the flange portion so as to be able to contact the flange portion, and a small-diameter portion excluding the large-diameter portion And the inner diameter of the large diameter portion is set larger than the outer diameter of the guide portion and larger than the inner diameter of the small diameter portion, and the large diameter portion extends from the outer periphery of the guide portion. While separated Diameter is characterized by being press-fitted into the outer periphery of the guide portion.

In the present invention, the large-diameter portion that can be in contact with the flange portion is locally expanded in one axial end portion of the coil spring into which the guide portion of the retainer is inserted. Without causing an increase, it is possible to effectively suppress the occurrence of local wear and stress concentration due to the interference between the large diameter portion and the retainer. Furthermore, since the small diameter portion is press-fitted into the outer periphery of the guide portion, relative rotation between the retainer and the coil spring can be prevented, and acceleration of wear can be suppressed / avoided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a main part of a valve operating apparatus for an internal combustion engine for an automobile according to a first embodiment of the present invention. This valve operating apparatus includes a coil spring 10 that urges an intake / exhaust valve of an internal combustion engine in a closing direction, and a retainer 20 that is assembled to an upper end portion of a valve stem 1 of the intake / exhaust valve via a cotter 2 having a half structure. And have.

  The retainer 20 is cast from a lightweight aluminum alloy. The retainer 20 is disposed on the same axis as the valve stem 1 and is fitted to the outer periphery of the cotter 2. And a flange portion 22 projecting outward in the direction. A seating surface 23 that receives the upper end of the coil spring 10 is formed on the flange portion 22. The corner portion 24 between the guide portion 21 and the flange portion 22 is smoothly curved with a predetermined curvature.

  FIG. 3 shows a valve gear according to a comparative example. In this comparative example, the radial dimension of the coil spring 110 is constant, and a predetermined gap ΔD is secured between the coil spring 110 and the guide portion 120. Compared with this comparative example, the characteristic configuration of this embodiment and the function and effect thereof will be described.

  The upper end in the axial direction in which the guide portion 21 is inserted in the coil spring 10 is constituted by a large-diameter portion 11 that faces the flange portion so as to come into contact with the flange portion, and a small-diameter portion 12 excluding the large-diameter portion 11. Yes. The large diameter portion 11 is a portion of the first turn of the coil spring 10. The small diameter portion 12 includes a second winding portion of the coil spring 10, and in this example, is substantially only the second winding portion.

  The inner diameter R1 of the large diameter portion 11 is set to be larger than the outer diameter R2 of the guide portion 21 and larger than the inner diameter R3 of the small diameter portion 12. That is, the large diameter portion 11 is locally expanded in the axial upper end portion of the coil spring 10 located on the outer periphery of the guide portion 21. Furthermore, the inner diameter R1 of the large diameter portion 11 is set larger than the maximum outer diameter R4 of the corner portion 24, that is, the outer diameter R4 of the portion that smoothly connects to the flange portion 22. Accordingly, the large diameter portion 11 is prevented from interfering with the guide portion 21 and the corner portion 24 without causing an increase in clearance with the guide portion 21, and local wear and stress concentration due to this interference are prevented. can do. Furthermore, since it is not necessary to process the chamfered portion 115 on the inner peripheral side as in the comparative example, the manufacturing cost can be reduced.

  The minimum inner diameter R3 of the small diameter portion 12 is set to be equal to or smaller than the outer diameter R2 of the guide portion 21 in the natural length state. Therefore, the small diameter portion 12 is press-fitted into the outer periphery of the guide portion 21 and is in close contact with the outer periphery of the guide portion 21. In FIG. 1, for the sake of clarity, the minimum inner diameter R3 of the small-diameter portion 12 is drawn larger than the outer diameter R2 of the guide portion 21, but actually R3 is equal to or less than R2. Therefore, relative rotation between the retainer 20 and the coil spring 10 is more reliably prevented, and acceleration of wear is suppressed / avoided. In particular, when the retainer 20 is formed of a lightweight aluminum alloy, it is lightweight, but it is difficult to ensure the strength and durability against wear, and thus it is extremely effective to suppress and avoid the wear.

  In this way, the coil spring 10 is gradually reduced in diameter in the axial direction toward the large-diameter portion (toward the upper side in FIG. 1) so that the small-diameter portion 12 partially becomes smaller in diameter than the outer periphery of the guide portion 21. It has the shape which has the taper part 13 to do.

  Further, by locally increasing the diameter of the large-diameter portion 11 as in this embodiment, the radius of curvature of the corner portion 24 of the retainer 20 facing the large-diameter portion 11 is changed to the corner portion 124 of the comparative example. The radius of curvature can be made larger than that, and the stress concentration on this portion can be relaxed to improve the reliability and durability.

FIG. 2 is a cross-sectional view showing a main part of a valve gear for an internal combustion engine according to a reference example . Note that the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted as appropriate. In this reference example , in the coil spring 10A, the radial dimension of only the large-diameter portion 11 of the first winding is increased, and the radial dimension of the remaining portion including the small-diameter portion 12 is made uniform. Thus, in the reference example , the coil spring 10A has a simple shape without the tapered portion (13) as in the first embodiment, and its manufacture is easy.

  A predetermined clearance ΔD1 is secured between the guide portion 21 and the small diameter portion of the coil spring 10A. Therefore, although the retainer 20 and the coil spring 10 can be rotated relative to each other, it is not necessary to press-fit the both 20 and 10, so that the assembling operation is easy and excessive dimensional accuracy is not required and the manufacture is easy. .

  As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above-described embodiments, and includes various modifications and changes without departing from the spirit of the present invention. . For example, it is good also as a taper shape which diameter-reduces the outer peripheral surface of a cylindrical guide part downward.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the principal part of the valve operating apparatus of the internal combustion engine which concerns on 1st Example of this invention. Sectional drawing which shows the principal part of the valve operating apparatus of the internal combustion engine which concerns on a reference example . Sectional drawing which shows the principal part of the valve operating apparatus of the internal combustion engine which concerns on a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Valve stem 10, 10A ... Coil spring 11 ... Large diameter part 12 ... Small diameter part 13 ... Tapered part 20 ... Retainer 21 ... Guide part 22 ... Flange part 23 ... Seat surface 24 ... Corner part

Claims (5)

A coil spring that urges the intake / exhaust valve of the internal combustion engine to close, and a retainer that is assembled to the valve stem of the intake / exhaust valve.
The retainer has a cylindrical guide portion and a flange portion projecting radially outward from one end of the guide portion, and a seating surface that receives one axial end of the coil spring is formed on the flange portion. Has been
One end portion in the axial direction in which the guide portion is inserted and inserted in the coil spring is configured by a large diameter portion facing the flange portion so as to come into contact with the small diameter portion excluding the large diameter portion,
The inner diameter of the large diameter portion is set to be larger than the outer diameter of the guide portion and larger than the inner diameter of the small diameter portion ,
The valve operating apparatus for an internal combustion engine, wherein the large diameter portion is separated from the outer periphery of the guide portion, and the small diameter portion is press-fitted into the outer periphery of the guide portion . The corner portion of the guide portion and the flange portion is smoothly curved with a predetermined curvature,
2. The valve operating apparatus for an internal combustion engine according to claim 1, wherein an inner diameter of the large diameter portion is set larger than a maximum outer diameter of the corner portion. 3. The valve operating apparatus for an internal combustion engine according to claim 1, wherein the coil spring has a tapered portion that gradually decreases in diameter toward the small diameter portion. The valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3 , wherein the retainer is made of an aluminum alloy. The large diameter portion is an th-turn portion of the coil spring, an internal combustion engine according to any one of claims 1 to 4, characterized in that the small diameter portion contains two th-turn portion of the coil spring Valve gear.

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