JPH10184750A - Compression coil spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the increase of plus side stress and to prevent the permanent deformation of a spring by setting a deflection to load spring characteristic set from an attaching point to a transfer point provided in a section lower than a specified percentage of a deflection amount between the attaching point and a maximum compression point to be linear and a characteristic exceeding the above range to be downward projecting non-linear. SOLUTION: The spring characteristic of a compression coil spring is set to be linear from an attaching point to a transfer point set lower than first 30% in the range of a deflection amount between the attaching point and a maximum compression point. With respect to the increase of a deflection amount exceeding the above range and in the flexible range up to the maximum compression point, a downward projecting non-linear characteristic is provided where a spring load is gradually or suddenly increased. For example, if this compression coil spring is used for the valve spring of an internal combustion engine, the valve is rotated without using any valve retainers, the engine is miniaturized and reduced in weight and an engine performance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression coil spring, and more particularly to a compression spring, such as a valve spring of an internal combustion engine or a fuel injection pump, between a mounting point to which a pre-compression load is applied and a maximum compression point. The present invention relates to a compression coil spring used for applications that repeatedly deform.

[0002]

2. Description of the Related Art A valve spring of an internal combustion engine is generally mounted with a certain initial load, and when the valve is fully opened, the spring is in a maximum bending state. It will be repeatedly deformed. However, in a high-speed engine, surging due to resonance of a valve spring becomes a problem, and it is necessary to avoid it. That is, the surging due to the resonance of the valve spring increases the maximum load applied to the valve spring by applying a dynamic load in addition to the static load applied to the valve spring as the engine valve opens and closes. It may cause breakage or permanent deformation. As a countermeasure, various methods have been proposed to avoid the resonance phenomenon by making the coil pitch of the spring unequal and changing the spring constant within the operating range of the spring.

[0003] For example, Japanese Patent Publication No. 47-22363 (Prior Art 1) discloses a compression coil spring having two equally-pitched portions consisting of a densely wound portion and a coarsely wound portion. Then, a method of mounting so that the spring constant changes is disclosed. According to this, only the coarse winding becomes an effective winding in the operating range, the inertial mass becomes relatively small, and the natural frequency becomes relatively high, but the effective number of windings does not change near the maximum compression point, thus preventing resonance. There is a problem that the effect is not always sufficient.

Japanese Utility Model Publication No. Sho 62-8445 (Prior Art 2) provides a densely wound portion having an unequal pitch and a coarsely wound portion having an equal pitch. A technique is disclosed in which some strands are brought into close contact with each other so that a relatively stable resonance prevention effect can be obtained even if there is a slight variation in attachment points. However, since the unequal-pitch portions are used, it is necessary to reduce the initial spring constant in order to obtain predetermined spring loads at the attachment point and the maximum compression point, respectively, and try to fit them in the same space. Therefore, the wire diameter must be reduced, the design stress increases, and practical use becomes difficult. Otherwise, the advantages and disadvantages of this prior art are almost the same as those of the prior art 1 described above.

In Japanese Patent Application Laid-Open No. 54-91656 (prior art 3), two equally-pitch portions including a densely wound portion and a coarsely wound portion are provided, and the densely wound portion is first formed near the maximum compression point. A configuration is shown in which the spring constant changes closely at the same portion. According to this, the entire coil spring functions as an effective winding portion over substantially the entire range of the mounting point and the maximum compression point, and since the mass is large and the spring constant is small, there are many regions where the natural frequency is large, and the resonance preventing effect is obtained. Relatively small.

Japanese Unexamined Patent Application Publication No. 7-332040 (prior art 4) uses a vertically symmetrical coil spring having a large pitch at the center and small pitches at both ends. The changing position is 60 to 8 in the entire deflection range.
It has been proposed to be 0 percent. According to this, the spring constant is changed in the middle part of the entire deflection range, but again, almost all of the coils act as effective windings in a large part within the range from the attachment point to the maximum compression point. And the mass is large and the spring constant is small,
Again, there are many regions where the natural frequency is low, and the resonance prevention effect is relatively small.

FIGS. 1 and 2 show the relationship between deflection versus load and deflection versus natural frequency in these prior arts. In general, as shown in FIG. 3, two peaks of the stress due to the resonance phenomenon are at the mounting point and the maximum compression point. Here, the permanent deformation of the spring is mainly caused by the peak of the maximum compression point when the temperature condition is constant. Further, the breakage of the spring is affected by the magnitude of the dynamic maximum stress amplitude and the dynamic average stress.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, a main object of the present invention is to reduce the increase in the positive side stress due to resonance at the maximum compression point. It is another object of the present invention to provide a compression coil spring that reduces a dynamic average stress without increasing a dynamic maximum amplitude, thereby preventing permanent deformation and breakage of a spring and enabling reduction in size and weight.

A second object of the present invention is to provide a compression coil spring which has a high surging preventing effect and is easy to manufacture and suitable as a valve spring of an engine.

[0010]

According to the present invention, there is provided a compression coil spring which repeatedly deforms between an attachment point under a predetermined pre-compression load and a maximum compression point. The deflection-load spring characteristic from the attachment point to a transition point set in a section of 30% or less of the deflection amount between the attachment point and the maximum compression point is linear, and exceeds the transition point. In the section of the deflection amount up to the maximum compression point, this is achieved by providing a compression coil spring characterized in that the deflection-load spring characteristic has a downwardly convex non-linear characteristic. According to another aspect of the present invention, the natural frequency of the spring from the attachment point to a transition point set in a section of 30% or less of the amount of deflection between the attachment point and the maximum compression point is determined. The natural frequency of the spring is set to be constant, and the natural frequency of the spring is sharply increased in accordance with the increase in the deflection in the section of the deflection amount up to the maximum compression point exceeding the transition point.

As described above, according to the present invention, as the amount of deflection increases toward the maximum compression point, the spring constant or the natural frequency sharply increases, and the + side dynamic near the maximum compression point is increased. Since the amplitude of the stress can be reduced effectively, the maximum stress amplitude can be reduced and the dynamic average stress can be reduced, which is very effective in preventing breakage and settling of the spring. I can do it. Also, since it is not necessary to increase the number of turns of the spring or to increase the torsional rigidity of the element wire of the spring, a conventional valve spring or the like can be applied as it is, and the size and weight of the spring can be reduced. It can also contribute to cost reduction and cost reduction. Also,
By applying such a compression coil spring to a valve spring of an internal combustion engine, the dynamic stress amplitude of the compression coil spring near the attachment point becomes relatively large, so that the compression spring near the attachment point is relatively large. The rotation of the compression coil spring about the axis may be encouraged to cause rotation of a valve coupled thereto.

Such a spring characteristic can be realized in various modes. For example, the compression coil spring has a close-wound portion of unequal pitch and a coarse-wound portion of equal pitch,
At the attachment point, the element wires of the spring do not adhere to each other, and the element wires can gradually adhere from the transition point to the minimum pitch portion of the unequally-wound portion. Conversely, the compression coil spring has a close-wound portion of equal pitch and a coarse-wound portion of unequal pitch, and at the attachment point, the wires of the spring do not adhere to each other, and from the transition point, After the element wire comes into close contact with the close-wound uniform-pitch portion, the element wire may be gradually brought into close contact with the unequal-pitch coarsely-wound portion before reaching the maximum compression point. . Alternatively, the compression coil spring has an uneven pitch as a whole,
At the attachment point, the wires of the spring may not be in close contact with each other, and the wires may gradually contact from the transition point from the minimum pitch portion.

When the compression coil spring is configured as a valve spring of an internal combustion engine, it is preferable to reduce the inertial mass on the moving end side. Are preferably arranged to correspond to the valve stems, respectively. In addition, since it is common to provide an end winding portion at each end of the compression coil spring, in order to utilize smooth continuity from the end winding portion, the close winding portion and the coarse winding portion are vertically symmetrical. The distribution simplifies the manufacturing process of the coil spring.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to specific examples shown in the accompanying drawings.

FIGS. 4 and 5 show the relationship between deflection versus spring load and deflection versus natural frequency for a compression coil spring according to the present invention. That is, from the attachment point to the transition point set within the first 30% or less within the range of the amount of deflection between the attachment point and the maximum compression point, the spring characteristic of the compression coil spring is linear. Thus, in the range of the deflection larger than that, a non-linear spring characteristic such that the spring load increases gradually or rapidly with an increase in the amount of deflection is obtained (FIG. 4). Looking at this in terms of the natural frequency, the natural frequency of the compression coil spring should be constant from the attachment point to the transition point, and in the range of deflection beyond that, the natural frequency increases with the amount of deflection. A non-linear spring characteristic such as a gradual increase or a sudden increase is obtained (FIG. 5). FIGS. 6 and 7 show various modes of distributing the coil pitch of the coil spring in order to realize such spring characteristics.

The compression coil spring shown in FIG. 6A has a densely wound portion having an unequal pitch and a coarsely wound portion having an equal pitch, and is provided between the attachment point and the maximum compression point near the attachment point, that is, from the attachment point. Up to the transition point where the deflection amount is set to a range of 30% or less with respect to the total change amount of the deflection in the range of
At the transition point, the wires of the coil do not come into close contact with each other, and the wires gradually come into close contact with each other from the minimum pitch portion of the densely wound portion.

FIG. 6B shows that the wires have an irregular pitch as a whole, the wires do not adhere to each other from the attachment point to the transition point, and the wires are gradually advanced from the small pitch side between the transition point and the maximum compression point. It is to make close contact.

FIG. 6C shows an arrangement in which a close-wound portion having a uniform pitch and a coarsely-wound portion having an unequal pitch are provided. The wires do not adhere to each other from the attachment point to the transition point. The wires of the tightly wound portion gradually come into close contact with each other from the small pitch side of the sparsely wound portion of irregular pitch until the wires start to come into close contact with each other and reach the maximum compression point.

FIGS. 7A to 7C show an embodiment in which the pitch distribution is distributed vertically symmetrically so that the upper and lower ends are relatively densely wound and the middle portion is roughly wound.

FIG. 8 shows a general valve operating mechanism. The stem 3a of the valve 3 which engages with the valve seat 2 provided on the cylinder head 1 is guided by the valve guide 4 with respect to the cylinder head. A valve retainer 6 is fixed to the outermost end of the stem 3a via a cotter 5. A compression coil spring 7 is disposed between the valve retainer 6 and the opposing surface of the cylinder head 1.
The outermost end of the valve stem 3a is
The valve 3 is driven to open and close by the driving force of the cam 9 against the spring force of the compression coil spring 7 in a known manner.

In such an application, it is desirable to reduce the mass on the moving end side of the compression coil spring.
In the posture as shown in FIGS. 6A to 6C, it is preferable to provide the coarsely wound portion side on the upper end side which engages with the valve stem 3 a. FIG. 6A-
The symmetrical compression coil spring shown by C can eliminate the possibility of incorrectly mounting in the up-down direction.

FIG. 9 shows the relationship between the rotational speed of the cam and the dynamic stress at the mounting point and the maximum compression point when the compression coil spring according to the present invention is used. FIGS. 10 to 12 show the relationship between the rotational speed of the cam and the dynamic stress at the attachment point and the maximum compression point, which are obtained for the prior arts 1, 3, and 4. FIG. According to the present invention, it is understood that the amplitude on the positive side of the dynamic stress particularly at the maximum compression point can be effectively suppressed as compared with the related art.

On the other hand, when the compression coil spring of this embodiment is used for a valve spring of an internal combustion engine,
Since the negative amplitude of the dynamic stress is relatively large and resonance is likely to occur, the chance of the mounting load instantaneously decreasing increases. Further, the vibration amplitude of the compression coil spring near the attachment point is relatively large. Therefore, the rotation around the axis of the spring is promoted by the winding direction of the spring and the rotational moment due to compression. As a result, during operation, rotation tends to occur between the spring seat surface and the valve retainer, and further, the valve connected to the valve retainer via the wedge-shaped cotter can be rotated. Such rotation of the valve has an effect of scraping off deposits on the valve and the valve seat, and is known to be effective in improving the airtightness of the valve seat. Therefore, conventionally, there was a case where a valve rotator using a bearing was actively used to rotate the valve.However, when a compression coil spring based on the present invention was used, the valve was rotated without using the valve rotator. It is possible to reduce the size and weight of the engine, reduce the cost, and improve the performance of the engine.

[0024]

As described above, according to the present invention, it is possible to effectively reduce an increase in the positive side stress due to resonance at the maximum compression point of the compression coil spring, to prevent permanent deformation and breakage of the spring, Moreover, the compression coil spring has been made smaller and lighter,
Its manufacture can be facilitated.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between deflection and spring load in a compression coil spring based on the prior art.

FIG. 2 is a graph showing the relationship between deflection and natural frequency in a compression coil spring based on the prior art.

FIG. 3 is a graph showing a time change of a static stress and a dynamic stress generated in a compression coil spring used as a valve spring.

FIG. 4 is a graph showing the relationship between deflection and spring load in a compression coil spring according to the present invention.

FIG. 5 is a graph showing the relationship between deflection and natural frequency in a compression coil spring according to the present invention.

FIG. 6 is an elevation view of three embodiments of a compression coil spring according to the present invention, consisting of A, B and C.

FIG. 7 is an elevation view of A, B and C showing three further symmetrical embodiments of the compression coil spring according to the invention.

FIG. 8 is a simplified sectional view showing a general valve train for an internal combustion engine.

FIG. 9 is a graph showing the amount of increase in stress on the plus side and the minus side with respect to the cam rotation speed at the attachment point and the maximum compression point, respectively, of the compression coil spring according to the present invention.

FIG. 10 is a graph showing the amount of increase in the stress on the plus side and the minus side with respect to the cam rotation speed at the attachment point and the maximum compression point of the compression coil spring based on Conventional Technique 1, respectively.

FIG. 11 is a graph showing the amount of increase in stress on the plus side and the minus side with respect to the cam rotation speed at the attachment point and the maximum compression point, respectively, of the compression coil spring based on Prior Art 3.

FIG. 12 is a graph showing the amount of increase in stress on the plus side and the minus side with respect to the cam rotation speed at the attachment point and the maximum compression point, respectively, of the compression coil spring based on Conventional Technique 4.

[Explanation of symbols]

 Reference Signs List 1 cylinder head 2 valve seat 3 valve 3a valve stem 4 valve guide 5 cotter 6 valve retainer 7 compression coil spring 8 shoe 9 cam

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[Procedure amendment]

[Submission date] April 2, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

In Japanese Patent Application Laid-Open No. 54-91656 (prior art 3), two equally-pitch portions including a densely wound portion and a coarsely wound portion are provided, and the densely wound portion is first formed near the maximum compression point. A configuration is shown in which the spring constant changes closely at the same portion. According to this, the entire coil spring functions as an effective winding over substantially the entire range of the attachment point and the maximum compression point, and since the mass is large and the spring constant is small, there are many regions where the natural frequency is low , and the resonance prevention effect is reduced. Relatively small.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, a main object of the present invention is to reduce the increase in the positive side stress due to resonance at the maximum compression point. It is another object of the present invention to provide a compression coil spring in which a dynamic average stress is reduced without increasing a dynamic maximum amplitude, thereby preventing permanent deformation and breakage of the spring and enabling reduction in size and weight.

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

FIG. 6

[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] Fig. 7

[Correction method] Change

[Correction contents]

FIG. 7

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenjiro Kawanabe 3131 Miyatamura, Kamiina-gun, Nagano Prefecture Japan-originated Articles (72) Inventor Mitsutoshi Kanasu 3131 Miyatamura, Kamiina-gun, Nagano Prefecture Japan-originated Article

Claims (9)

[Claims] 1. A compression coil spring that repeatedly deforms between an attachment point in a state where a predetermined precompression load is applied and a maximum compression point, wherein the attachment point and the maximum compression point are changed from the attachment point. The deflection-load spring characteristic up to a transition point set in a section of 30% or less of the deflection amount between the above and the transition point is linear, and in the section of the deflection amount up to the maximum compression point exceeding the transition point, the deflection-load spring characteristic Has a downwardly convex non-linear characteristic. 2. A compression coil spring that repeatedly deforms between a mounting point in a state where a predetermined precompression load is applied and a maximum compression point, wherein the mounting point and the maximum compression point are changed from the mounting point. , The natural frequency of the spring up to the transition point set in a section of 30% or less of the deflection amount between the springs is kept constant, and in the section of the deflection amount up to the maximum compression point exceeding the transition point, as the deflection increases, A compression coil spring, wherein the natural frequency of the spring is rapidly increased. 3. The compression coil spring has unequal-pitch closely-wound portions and equally-pitch coarse-wound portions, and at the attachment point, the wires of the spring do not adhere to each other, and the transition point 3. The compression coil spring according to claim 1, wherein the element wire is gradually brought into close contact with the unequally densely wound portion from a minimum pitch portion. 4. 4. The compression coil spring has a non-uniform pitch as a whole, and at the attachment point, the strands of the spring do not adhere to each other. The compression coil spring according to claim 1, wherein the compression coil spring is configured to be gradually contacted. 5. The compression coil spring has a close-wound portion of equal pitch and a coarsely-wound portion of unequal pitch, and at the attachment point, the wires of the spring do not adhere to each other. From, after the element wire comes into close contact with the close-pitch tightly wound portion, until the maximum compression point is reached, the element wire gradually comes into close contact with the minimum pitch portion of the unequal pitch coarsely-wound portion. The compression coil spring according to claim 1 or 2, wherein: 6. The compression coil spring according to claim 3, wherein the densely wound portion and the coarsely wound portion are vertically symmetrically distributed. 7. The compression coil spring according to claim 1, wherein the compression coil spring is configured as a valve spring of an internal combustion engine. 8. The compression coil spring is configured as a valve spring of an internal combustion engine, and the tightly wound portion is provided on a cylinder head side.
The compression coil spring according to any one of claims 1 to 5, wherein the coarsely wound portions are arranged to correspond to the valve stems, respectively. 9. A compression coil spring for a valve spring of an internal combustion engine that repeatedly deforms between an attachment point in a state where a predetermined precompression load is applied and a maximum compression point, The deflection-load spring characteristic up to the transition point set in a section of 30% or less of the deflection amount between the attachment point and the maximum compression point is linear, and the section of the deflection amount up to the maximum compression point exceeding the transition point The deflection-load spring characteristic has a downwardly convex non-linear characteristic, and the dynamic stress amplitude of the compression coil spring in the vicinity of the attachment point is relatively large. 3. The compression coil spring according to claim 1, wherein the rotation of the compression coil spring around the axis is promoted to cause rotation of a valve coupled thereto.