JP2001164909A - Coupling structure of valve spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the coupling structure of a valve spring that it is desirable that a valve spring assembled to the valve of an internal combustion engine is coupled to a valve stem with structure that is simplified as much as possible and simultaneously, the coupling part maintains a stable coupling state through simple structure. SOLUTION: To satisfy a problem described above, structure is formed such that a spiral groove 12 is formed in the end part of a valve stem 7, the small part 10 of a valve spring 8 is caused to coincide with the spiral groove 12 and a cylinder member 13 is fitted in the outside of the small part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A valve spring of an internal combustion engine is known in which one end is seated on a cylinder head side and the other end is connected to an end of a valve stem. The invention belongs to the technical field relating to such coupling of valve springs.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open Publication No. Sho 58-144008 discloses a valve spring in which an end portion has a small diameter and is connected to a valve stem. In this device, a split cotter is attached to an end of a valve stem, and the cotter is wound around a small diameter portion of a valve spring. Therefore, since the cotter is held from the outer peripheral side, it does not come off from the valve stem and compresses the valve spring.

[0003]

With the above structure, if the spring wire wound around the cotter is broken for some reason, the cotter may come off the valve stem and the valve may fall into the combustion chamber. . Alternatively, if the valve clearance goes wrong or the piston pushes up the valve, the cotter may come off the valve stem, causing a similar problem. Furthermore, since the cotter method is used, the number of parts increases, which is disadvantageous in terms of the number of assembly steps and cost.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems.
The basic idea is to wind the end of the valve spring directly around the valve stem and maintain that state.

According to a first aspect of the present invention, there is provided a valve spring in which one end of a valve spring is seated on a cylinder head side and the other end is connected to an end of a valve stem. A helical groove is provided at the end of the valve stem, the small-diameter portion is matched with the helical groove, and a cylindrical member for preventing detachment is fitted to the outside of the small-diameter portion.

Therefore, since the small diameter portion matches the spiral groove and this state is maintained by the cylindrical member, the small diameter portion is surely prevented from expanding and coming off the spiral groove. And since the small diameter part which is a part of the valve spring has a structure which directly matches the valve stem, only the cylindrical member needs to be added to the joint part, which is effective for reducing the number of parts.

A second aspect of the present invention is characterized in that, in the first aspect, the groove bottom diameter of the spiral groove is set slightly larger than the inner diameter of the small diameter portion in the free state. Therefore, when assembled, the small diameter portion elastically tightens the concave surface of the spiral groove. In addition, the groove bottom diameter of the spiral groove is a dimension having a meaning corresponding to the root diameter of the male screw.
Therefore, since there is no gap in the connecting portion, there is no so-called "rattle", which is advantageous for stable connection and prevention of noise.

A third aspect of the present invention is characterized in that, in the first or second aspect, the cylindrical member is formed in a cup shape, and a valve opening force of the valve is applied to a top surface thereof. I have. Therefore, since the valve receives the driving force of the valve while performing the coupling function as described above, it is effective for reducing the number of parts. The valve driving force acts in a direction that prevents the cylindrical member from coming off the small-diameter portion, so that the cylindrical member is securely installed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cylinder head 1 has an intake or exhaust port 2 and communicates with a combustion chamber 4 through an opening 3. The valve 5 is a normal one and comprises a valve 6 and a valve stem 7.

The valve spring 8 is provided on the cylinder head 1.
The diameter of the spring wire is gradually reduced toward the opposite side, and the thickness of the spring wire is also gradually reduced. A small diameter portion 10 is formed by winding the spring wire 9 at the end portion small. The valve spring 8 is seated on a spring sheet 11 fixed on the cylinder head 1.

The spiral groove 12 will be described with reference to FIG. This is formed at the end of the valve stem 7. The four central grooves are complete four-turn spiral grooves, and the upper and lower ones are gradually changing portions. The spring wire 9 of the small diameter portion 10 is wound around the spiral groove 12, and the small diameter portion 10 matches the complete groove portion of the spiral groove 12. In this embodiment, as is apparent from FIG. 1, the small-diameter portion 10 is formed by winding the spring wire 9 twice, so that the portion fits perfectly with the second and third spiral grooves 12. I have.

In order to maintain the above-mentioned match, the cylindrical member 1
3 are fitted as shown in FIG. To prevent the small diameter portion 10 from coming off the spiral groove 12, the cylindrical member 13
The member 13 is a cup-shaped component comprising a cylindrical portion 14 and a flat top surface portion 15. The groove of the spiral groove 12 has an arc-shaped cross section, and is shown as a concave surface 16 in the figure. The dimensional relationship between the spiral groove 12 and the small diameter portion 10 will be described. The groove bottom diameter of the spiral groove 12 is slightly larger than the inner diameter of the small diameter portion 10 in the free state (state before assembly). Therefore, when assembled, the small diameter portion 10 elastically tightens the concave surface 16 of the spiral groove 12. When such a dimensional relationship is established, the small-diameter portion 12 is in a tightened state.
A slight gap is provided between the inner surface of the cylindrical portion 14 and the spring wire 9 of the small diameter portion. The groove bottom diameter of the spiral groove 12 is
This is a dimension equivalent to the root diameter of the external thread.

[0013] Instead of the above dimensional relationship of the tightening,
There is also a method of joining without tightening. That is, the small diameter portion 1
In a state where 0 is matched with the spiral groove 12, the dimensional relationship between the groove bottom diameter of the spiral groove 12 and the small diameter portion 10 is set so that a slight gap is formed between the spring wire 9 and the concave surface 16 of the spiral groove. I do. When the cylindrical portion 14 is fitted in this state,
The diameter of the small diameter portion 10 is reduced, so that the spring wire 9 comes into close contact with the concave surface 16. That is, the inner diameter of the cylindrical portion 14 is selected so as to obtain such close contact.

A valve opening force is applied to the top surface portion 15. In the case of FIG. 1, the valve is opened and closed by swinging of the rocker arm 17.

FIG. 3 shows another embodiment. Members that perform the same functions as in the previous embodiment are denoted by the same reference numerals in the drawings, and detailed description is omitted. Here, the valve opening force is applied by the cam 18. Therefore, the diameter of the top surface portion 15 is increased and the large-diameter cylinder 19 is arranged outside the cylindrical member 13, and is called “bucket type”. Conversely, in bucket type,
That is, the cylindrical member 13 is integrally installed in the central part of the inside.

FIG. 4 shows a cylindrical member having no top surface, in which a large number of slit grooves 20 are cut in the upper part of the cylindrical portion 14. The upper end of the cylindrical portion 14 is bent toward the center, and the fitting portion 21 is bent.
Is formed. A circumferential groove 22 is formed near the end of the valve stem 7, into which the fitting portion 21 fits. Although not shown, when viewed in plan, the slit groove 2
0 is cut radially from the center, for example, eight lines. When fitting the cylindrical portion 14, the fitting portion 21 is elastically fitted into the groove 22 after the fitting portion 21 is pushed out at the upper end corner of the valve stem 7. By doing so, the positioning of the cylindrical portion 14 is performed. In this case, the valve is opened by the rocker arm 17 pressing the top surface of the valve stem.

[0017]

According to the present invention, in a type in which one end of a valve spring is seated on the cylinder head side and the other end is connected to an end of a valve stem, a small diameter portion is formed at the end of the valve spring. At the same time, a spiral groove is provided at the end of the valve stem, the small-diameter portion is matched with the spiral groove, and a cylindrical member for preventing detachment is fitted outside the small-diameter portion, so that the small-diameter portion matches the spiral groove, This state is maintained by the cylindrical member. Therefore, the small diameter portion is reliably prevented from expanding and coming off the spiral groove. And since the small diameter part which is a part of the valve spring has a structure which directly matches the valve stem, only the cylindrical member needs to be added to the joint part, which is effective for reducing the number of parts. Furthermore, since the cylindrical member is a component having a simple structure,
It is easy to reduce the weight, so that the mass of the valve operating mechanism can be reduced, which is advantageous in high-speed operation and the like.

Since the groove bottom diameter of the spiral groove is set slightly larger than the inner diameter of the small diameter portion in the free state, the small diameter portion elastically tightens the concave surface of the spiral groove when assembled. ing. This is a state in which the small-diameter part is gripping the spiral groove, so that the connection between the valve spring and the valve stem is firm, and even if the small-diameter part may be loosened, the cylindrical member may be loosened. Since the loosening is regulated, the valve spring does not come off. Further, since there is no gap in the joint portion, there is no so-called "rattle", which is advantageous for stable jointability and prevention of noise. Since the cross-section of the spring wire is circular, when pushing in the tube, the inner end of the tube comes into contact with the rounded part of the spring wire, so work can be done easily without excessive frictional resistance. Can be.

Since the cylindrical member is formed in a cup shape and the valve opening force of the valve is applied to the top surface thereof,
The valve receives the driving force of the valve while performing the coupling function as described above. Therefore, the cylindrical member fulfills two functions of preventing the expansion of the small diameter portion and transmitting the valve opening force, and is effective in reducing the number of parts. The valve driving force acts in a direction that prevents the cylindrical member from coming off the small-diameter portion, so that the cylindrical member is securely installed.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the present invention.

FIG. 2 is a side view showing a spiral groove of a valve stem.

FIG. 3 is a longitudinal sectional front view showing another embodiment.

FIG. 4 is a cross-sectional view showing another embodiment.

[Explanation of symbols]

 Reference Signs List 8 valve spring 1 cylinder head 7 valve stem 10 small diameter portion 12 spiral groove 13 cylindrical member 16 concave surface 15 top surface

Claims (3)

[Claims] 1. A valve spring in which one end of a valve spring is seated on a cylinder head side and the other end is connected to an end of a valve stem, wherein a small diameter portion is formed at an end of the valve spring and an end of the valve stem is formed. With a spiral groove on
A coupling structure for a valve spring, wherein a small-diameter portion is aligned with a spiral groove, and a cylindrical member for preventing detachment is fitted to the outside of the small-diameter portion. 2. The method according to claim 1, wherein the groove bottom diameter of the spiral groove is
A coupling structure for a valve spring, wherein the inner diameter of the small-diameter portion in the free state is slightly larger than the inner diameter. 3. The coupling of a valve spring according to claim 1, wherein the cylindrical member has a cup-like shape, and a valve opening force of the valve is applied to a top surface thereof. Construction.