JPH07151197A - Chain tensioner - Google Patents

Abstract

PURPOSE:To improve the service life of a chain tensioner, and prevent the sway and vibration of the chain. CONSTITUTION:The guide witdh W1 of a chain tensioner 22 is reduced at a center part (i) and gradually increased toward end parts (ii), (iii). This constitution restricts the vibration and sway of a whole chain 6 at the part of the guide width W1, reduces the vibration and sway of the whole chain 6 to prevent generation of the noise. The rubbing between the chain 6 and a guide part 24 is made close to the rubbing in the condition without any vibration or sway of the chain 6 to improve the service life of the chain tensioner 22 by making the part of the guide width W1 in an extremely short range. The height of the guide part 24 is increased at the guide width W1 part and gradually reduced toward the end parts (ii), (iii). This constitution reduces the contact area between the chain 6 and the guide part 24, and reduces the rubbing between the guide part 24 and the chain 6, improving the service life of the chain tensioner 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chain tensioner improved so as to prolong the service life of the chain tensioner and prevent chain sway and vibration.

[0002]

2. Description of the Related Art First, the use of a chain tensioner will be described by taking an engine timing chain as an example. In FIG. 8 and FIG. 9, a timing chain 6 is applied to the crank timing sprocket 2, the cam timing sprocket 3, the idler sprocket 4 and the idler sprocket 5 which are fixed to the crankshaft 1, and the rotation of the crankshaft 1 is the timing chain. It is adapted to be transmitted to the cam timing sprockets 9, 10, 11 and 12 via 7 and 8. One end of the chain tensioner 13 is rotatably supported by a cylinder head 15 via a bolt 14, and an adjuster 17 fixed to the cylinder block 16 presses the guide surface of the chain tensioner 13 against the timing chain 6. As a result, the timing chain 6 is constantly tensioned to maintain accurate cam timing.

A conventional chain tensioner will be described with reference to FIG. In the figure, the guide surface of the chain tensioner 13
18 is a gentle curve on the convex side, and this guide surface 18 fixes the elastic body 20 to the chain tensioner main body 19 as shown in FIG. 7 which is a longitudinal section of FIG. Body 20
The guide surface 18 has a guide width W substantially equal to the width of the chain 6.
And a guide portion 21 of height H is formed on both edges of the guide surface 18.
Are provided in a protruding state. The guide width W is the same width over the entire length L of the guide surface 18 shown in FIG. 6, and the height H of the guide portion 21 is the same over the entire length of the guide surface 18.

Further, Japanese Patent Laid-Open No. 63-6262 discloses a chain tensioner in which a guide portion is formed at the center of the guide surface, and Japanese Patent Laid-Open No. 2-296046 discloses a guide for a chain tensioner. It is disclosed that a guide portion is formed over substantially the entire length of the surface. The guide portions disclosed in these publications have the same guide width W and height H over the entire area, and are substantially the same as those shown in FIGS. 6 and 7.

[0005]

In the timing chain 6 shown as an example in FIG. 8, the chain tensioner 13 is provided to the timing chain 6 by the adjuster 17.
Since the guide surface is pressed and the tension is constantly applied, the vibration of the timing chain 6 is prevented and the cam timing is maintained during normal vehicle traveling. In some cases, the adjuster 17 may not be able to fully follow up after various accelerations and decelerations, and it may not be possible to constantly apply proper tension to the timing chain. Therefore, the timing chain vibrates or swings.

In this way, when the adjuster 17 cannot follow up completely and the timing chain vibrates or swings, the guide width W and the height of the guide surface are different from those of the guide portion of the conventional chain tenyona. If it is the same over almost the entire length, the vibration of the timing chain is forcibly restrained over the entire guide surface.

As a result, wear of the guide portion increases,
The service life of the chain tensioner may be shortened, and the timing chain may vibrate or oscillate, causing noise.

The present invention provides a chain tensioner which prolongs the service life of the chain tensioner and prevents the chain from swinging or vibrating.

[0009]

[Means for Solving the Problems] The first means for solving the above problems according to the present invention is to form a chain tensioner by pressing a chain suspended on a sprocket with a chain tensioner to eliminate looseness of the chain. In the chain tensioner that guides the chain by the guide part to eliminate the swing and vibration of the chain, the guide width of the guide part of the chain tensioner is gradually widened toward the end part at the center part,

As a second means, the above-mentioned chain tensioner is characterized in that the height of the guide portion of the chain tensioner is made higher at the central portion and gradually lowered toward the end portions.

[0011]

Since the present invention is constructed as described above, it has the following effects. That is, since the guide width of the guide portion of the chain tensioner is narrowed at the center and gradually widened toward the ends, it is possible to restrain the vibration and swing of the entire chain between the sprockets at the narrow guide width portion at the center. Therefore, it is possible to reduce the vibration and swing of the entire chain between the sprockets, and the guide width is narrowed in the central part and gradually widened toward the ends, so this narrow part of the central part is minimized. It is possible to make the range very short, which makes it possible to make the rubbing between the chain and the guide portion in the narrow guide portion in this central portion close to the rubbing in the state where there is no vibration or swing of the chain.

In this way, by vibrating and swinging the chain as a whole at the central portion where the guide width is narrow, the free length of the chain that is substantially unconstrained is smaller than that at the central portion where the guide width is narrow. It becomes short before the sprocket, and it becomes possible to reduce vibration and swing of the chain during this period. Since the guide width is gradually widened from the narrow guide width in the central part, guide the chain by reducing the rubbing between the guide part and the chain while allowing some vibration of the chain during this period. Will be possible.

Since the guide width is gradually widened toward the end, and the height of the guide portion is increased in the central portion having the narrow guide width and lowered in the end portion, the chain and the guide portion are separated from each other. The contact area between them is reduced, and the friction between the guide portion and the chain is reduced, so that the wear of the guide portion can be reduced.

[0014]

EXAMPLE An example of the present invention will be described below. FIG. 1 is a view showing the front of the chain tensioner 22, and guide portions 24 are provided on both edges of the guide surface 23. In the guide surface 23, the guide width W1 at the central portion (a) is smaller than the guide widths W2 and W3 at the end portions (b) and (c). In the case of the present embodiment, the inner side surface of the guide portion 24 is a convex curved surface, and the guide width W is gradually widened toward the ends (b) and (c). Further, as another embodiment, the inner side surface of the guide portion 24 is not formed into a convex curved surface but has a trapezoidal shape, and the central portion (a) to the end portion (b) of the guide surface 23,
The guide width W may be gradually widened toward (c).

Further, in FIG. 2 showing the side surface of FIG. 1, the guide surface 23 is a convex gentle curved surface along the bending deformation of the chain 6, and the height of the guide portion 24 is the central portion (a). It is the highest and is gradually lower toward the ends (b) and (c). This will be described in more detail. As shown in FIGS. 3 to 5, the chain tensioner 22
The elastic body 20 is fixed to the chain tensioner main body 19.

In FIG. 3, which is a vertical cross section taken along the line A--A (end B) in FIG. 2, the guide width W2 is somewhat wider than the width of the chain 6. On the other hand, in FIG. 4, which is a longitudinal section taken along the line BB (central portion B) in FIG. 2, the guide width W1 is substantially equal to the width of the chain 6. The height H1 of the guide portion 24 is higher than H2. Further, in FIG. 5 which is a vertical cross section taken along the line C--C (end C) in FIG. 2, there is no guide portion 24 in this portion, and the chain 6 is guided only by the guide surface 23.

The operation of this embodiment having the above-mentioned structure will be described below. Guide part 24 of chain tensioner 22
Since the guide width W1 of the central portion of the above is narrowed and gradually widened toward the ends (b) and (c), the vibration of the entire chain 6 having a long span between the cam timing sprocket 3 and the crank timing sprocket 2 in FIG. And the swing can be restrained in the narrow portion of the guide width W1 in the central portion, the vibration and swing of the entire chain 6 between the sprockets can be reduced, and the guide width W can be reduced. The central part (a) is narrowed and the end part (b) is
Since the width is gradually widened toward (c), the narrow part of the central part (a) can be made extremely short, and thus the chain 6 at the narrow part of the guide width W1 in the central part (a) can be reduced. The rubbing between the guide portion 24 and the guide portion 24 can be brought close to the rubbing in a state where there is no vibration or swing of the chain 6. For example, as shown in FIG. 1, the inside of the guide portion 24 is formed into an arc shape having a large radius of curvature to form a guide width W1.
The contact between 24 and the chain 6 becomes a point contact, and it becomes possible to approximate the rubbing in the state where there is no vibration or swing of the chain 6.

In this manner, by restraining the vibration and swing of the entire chain 6 in the portion where the guide width W1 of the central portion (a) is narrow, the free length of the chain 6 which is not restrained is substantially the central portion ( It becomes shorter between the narrow portion of the guide width W1 in (a) and the sprocket, and the vibration and swing (amplitude) of the chain 6 during this period can be reduced. And the guide width W1 of this central part (a)
Since the guide width is gradually widened from the narrow part of the chain to the ends (b) and (c), the rubbing of the guide part 24 and the chain 6 can be reduced while allowing the vibration and swing of the chain 6 to some extent during this period. Then, the chain 6 can be guided by the guide surface 23.

Then, the guide width W is set to the end portions (b) and (c).
As the height of the guide portion 24 is gradually widened toward the end, the narrow portion of the guide width W1 in the central portion (a) is increased and is lowered toward the end portions (b) and (c). The contact area between the guide portion 24 and the guide portion 24 is reduced, and the friction between the guide portion 24 and the chain 6 is reduced, so that the wear of the guide portion 24 can be reduced. Further, by providing the guide portion 24 so as to extend toward the end portions (b) and (c), it serves to reinforce the central portion (a). By reducing the rubbing between the guide portion 24 and the chain 6, it is possible to reduce the loss of mechanical energy due to the friction between them.

[0020]

As described above in detail, according to the present invention, the guide width of the guide portion of the chain tensioner is narrowed at the central portion and gradually widened toward the end portions. Therefore, the vibration and swing of the entire chain between the sprockets are at the central portion. It can be restrained by the narrow guide width part of the part, reduce the vibration and swing of the entire chain between the sprockets, prevent the noise generated due to the vibration of the chain, etc. Since the central part is narrowed and gradually widened toward the ends,
The narrow part of the central part is set to an extremely short area so that the rubbing between the chain and the guide part in the part with the narrow guide width in the central part approaches the rubbing in the state where there is no vibration or swing of the chain, and wear of the chain tensioner Can be reduced and the service life can be extended.

In this way, by restraining the vibration and swing of the entire chain at the central portion where the guide width is narrow, the free length of the chain that is substantially unconstrained is from the portion where the central guide width is narrow. It becomes short before the sprocket, and the vibration and swing of the chain during this time can be reduced, and the generation of noise due to the vibration of the chain can be reduced. Since the guide width is gradually widened from the narrow guide width in the central part, guide the chain by reducing the rubbing between the guide part and the chain while allowing some vibration of the chain during this period. As a result, the wear of the chain tensioner can be reduced and the service life can be extended.

Since the guide width is gradually widened toward the end, and the height of the guide portion is increased in the central portion having the narrow guide width and lowered toward the end portion, the chain and the guide portion are separated from each other. The contact area between them is reduced, and the rubbing between the guide portion and the chain is reduced, so that the wear of the guide portion can be reduced and the service life of the chain tensioner can be extended.

In this way, the vibration and swing of the chain are reduced, wear is further reduced, and the service life of the chain tensioner is extended, whereby the function of the chain tensioner is maintained and the engine valve timing is maintained. In addition, it is possible to reduce the generation of noise. Further, since it is only necessary to change the guide portion of the chain tensioner, it is easy to apply it to existing ones.

[Brief description of drawings]

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

FIG. 2 is a plan view of FIG.

FIG. 3 is a vertical cross-sectional view taken along the line AA of FIG.

FIG. 4 is a vertical sectional view taken along line BB in FIG.

5 is a vertical sectional view taken along the line CC of FIG.

FIG. 6 is a plan view of a conventional example.

7 is a vertical sectional view taken along the line DD of FIG.

FIG. 8 is an explanatory view showing a usage mode of the chain tensioner.

9 is a vertical cross-sectional view taken along the line EE of FIG.

[Explanation of sign]

 6 Chain 22 Chain tensioner 23 Guide surface 24 Guide section

Claims (2)

[Claims] 1. A chain tensioner in which a chain stretched over a sprocket is pushed by a chain tensioner to eliminate looseness of the chain and a guide portion formed on the chain tensioner guides the chain to eliminate swinging and vibration of the chain. In the chain tensioner, the guide width of the guide portion of the chain tensioner is narrowed at the central portion and gradually widened toward the end portions. 2. A chain tensioner according to claim 1, wherein the height of the guide portion of the chain tensioner is made higher at the central portion and gradually lowered toward the end portion.