JP2002098203A - Chain tensioner device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chain tensioner capable of preventing a slack side chain from vibrating sideways. SOLUTION: A chain 5 is set over between a sprocket 2 mounted on a crankshaft 1 and another sprocket 4 mounted on a cam shaft 3, and a pressing force of a chain tensioner 30 is given to the swing side end of a swingable chain guide 10 installed confronting at the slack side chain 5a of the chain 5 so that the slack side chain 5a is tightened. The chain guide 10 is arranged swingable round one of the crankshaft 1 and cam shaft 3 so that the contacting position of the chain guide 10 with the slack side chain 5a is kept constant, and the slack side chain 5a is prevented from sideways vibrating by swinging of the chain guide 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chain tensioner device for maintaining a constant tension of a camshaft driving chain of an internal combustion engine.

[0002]

2. Description of the Related Art As shown in FIG. 4, in a chain transmission for driving a camshaft in which a chain 44 extends between a sprocket 41 attached to a crankshaft 40 and a sprocket 43 attached to a camshaft 42, Chain 44
A chain guide 45 is provided opposite to the slack side chain 44a, and one end of the chain guide 45 is swingably supported about a shaft 46 supported by the engine block, and a chain tensioner is attached to the swing side end of the chain guide 45. The slack side chain 44a is tensioned by being pressed by a pressing member 48 of 47.

Here, a hydraulic or mechanical type chain tensioner 47 is used. In the hydraulic chain tensioner 47, a plunger 48 as a pressing member is pressed by a spring to provide outward protrusion, and is provided to the plunger 48 from the slack side chain 44 a via the chain guide 45. The pushing force is buffered by a hydraulic damper and the slack side chain 4
The change in tension 4a is absorbed.

In the above-described chain tensioner device, since the valve is opened and closed by the rotation of the cam attached to the cam shaft 42 and the elasticity of the valve spring, the rotational load of the cam shaft 42 changes. For this reason, the camshaft 42
, The tension of the slack side chain 44a changes, and the change in the tension causes the chain guide 45 to swing at a high frequency.

Since the chain guide 45 is supported by the engine block, vibration from the engine is also transmitted.

[0006]

By the way, in the chain tensioner device shown in FIG.
5 is swingably supported about a shaft 46 supported by the engine block. Therefore, if the shaft 46 is inclined with respect to the crankshaft 40 or the camshaft 42, when the chain guide 45 swings, A shift in the width direction of the chain guide 45 occurs at the contact portion between the chain guide 45 and the slack side chain 44a.

In the chain tensioner device shown in FIG. 4, a chain 44a between the chain guide 45 and the sprocket 43 and between the chain guide 45 and the sprocket 41 are guided without sliding on the chain guide 45. In the non-existent region, fluttering occurs during engine operation.

Therefore, when the chain guide 45 swings at a high speed due to the high frequency vibration of the chain 44, the slack side chain 44a vibrates laterally, and the lateral vibration affects the engagement between the slack side chain 44a and the sprockets 41, 43. Giving NVH characteristics, sprockets 41 and 43 and chains 4
It will worsen the wear state of parts such as No. 4.

Further, in the chain tensioner device shown in FIG.
In order to keep the contact of the chain guide 4a, the chain guide 45 is bent in the longitudinal direction and the slack side chain 44a is guided by the convex curved surface, so that the contact length between the chain guide 45 and the slack side chain 44a is short, On the contrary, the surface pressure of the portion becomes large, and the contact portion is easily worn.

An object of the present invention is to provide a chain tensioner device capable of reducing the lateral vibration of a chain.

[0011]

In order to solve the above-mentioned problems, according to the present invention, a chain is passed between a sprocket mounted on a crankshaft and a sprocket mounted on a camshaft, and a slack side chain of the chain is provided. A chain guide opposed to the chain guide is swingably supported, and a pressing force of a chain tensioner is applied to a swing-side end of the chain guide to tension the slack-side chain. A configuration is adopted in which the guide is swingably supported about one of the crankshaft and the camshaft.

[0012] With the above configuration, the chain guide swings about one of the crankshaft and the camshaft, so that the contact position between the chain guide and the slack side chain can be kept substantially constant at all times. For this reason, even if the chain guide vibrates at a high frequency, the slack side chain does not laterally vibrate, the NVH characteristics are improved, and wear of parts such as the chain guide and sprocket can be suppressed.

Here, in order to smoothly engage the slack side chain with the sprocket on the cam shaft side, it is preferable that the chain guide is supported so as to be swingable about the cam shaft. In supporting the chain guide in that case, a method can be adopted in which an arm is provided at the end of the chain guide on the traveling end side of the slack side chain, and the end of this arm is supported by a cam shaft.

In a chain guide swingably supported about a cam shaft, a slack side chain is connected to an end of the chain guide surface formed on the chain guide on the swing center side by a pitch circle of a cam shaft side sprocket. By providing a guideway consisting of a substantially linear flat surface for guiding on a line,
Even if the chain guide swings, the guide path is always maintained so that the slack side chain is guided on the pitch circle tangent of the cam shaft side sprocket, so that the cam shaft side sprocket and the slack side chain are always smooth. And the NVH characteristics can be further improved.

In the chain tensioner device according to the present invention, when a chain guide composed of a metal lever and a synthetic resin shoe provided on the surface of the lever facing the chain is used, the slack side chain And the chain can be moved smoothly.

The chain tensioner for pressing the chain guide may be a mechanical chain tensioner.
It may be a hydraulic chain tensioner. When the hydraulic chain tensioner is employed, the pushing force applied to the plunger as the pressing member is buffered by the hydraulic damper, so that it is possible to realize a chain tensioner device with less noise.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a sprocket 2 attached to a crankshaft 1 and a camshaft 3
A chain 5 is extended between the sprockets 4 attached to the chain 5, and a chain guide 10 is provided opposite to the slack side chain 5a of the chain 5.

The chain guide 10 comprises a lever 11 made of a light alloy such as an aluminum alloy, and a shoe 12. An arm 13 is provided at an end of the lever 11 on the crankshaft side. Are rotatably supported by the camshaft 3.

Shoe support surface 14 provided on lever 11
Is a convex curved surface 14a at the swinging end.
A flat surface 14b is provided on the tip side in the chain running direction of a.

The shoe 12 is made of a synthetic resin having good abrasion resistance and slipperiness such as a polyamide resin.
1 has a length and a width that cover the entire shoe support surface 14. The shoe 12 is detachably attached to the lever 11.

In order to make the shoe 12 detachable, here, a plurality of engaging pieces 15 are provided on both sides of the shoe 12, while a notch 16 into which the engaging piece 15 is fitted is provided on both sides of the lever 11. Is formed, and the projection 17 provided on the notch 16 is engaged with the engagement hole 18 formed on the engagement piece 15.

A hook piece 19 is provided at one end of the shoe 12 for engaging with one end face of the lever 11.
A protrusion 21 provided at one end of the lever 11 is engaged with an engagement hole 20 formed at the end 9.

Chain guide surface 2 formed on shoe 12
2 includes a first guideway 22a formed of a convex curved surface and a first guideway 22a thereof.
At the end of the guide path 22a, there is provided a second guide path 22b formed of a continuous, substantially linear flat surface.
b guides the slack side chain 5a on the tangent to the pitch circle of the camshaft side sprocket 4. Also, on both sides of the chain guide surface 22, ridges 23 for guiding both side surfaces of the slack side chain 5 a are provided.

A hydraulic chain tensioner 30 is provided at the swinging end of the chain guide 10. The chain tensioner 30 has a plurality of mounting pieces 31, each of which is fixed to the engine block by tightening a bolt 32.

The chain tensioner 30 has a slidable plunger 33 provided with an outwardly projecting property by pressing a spring (not shown).
Plunger contact part 1 provided on lever 11 by 3
1a to depress the chain guide 10 to loosen the chain 5
a, and the vibration applied to the chain guide 10 from the slack side chain 5a is buffered by a hydraulic damper (not shown) to keep the tension of the slack side chain 5a constant.

When the engine is driven and the rotation of the crankshaft 1 is transmitted to the camshaft 3 via the sprockets 2 and 4 and the chain 5, the cam provided on the camshaft 3 opens and closes the valve. 3, the load on the slack side chain 5a of the chain 5 changes due to the change in the load. The chain guide 10 swings due to the change in the tension of the slack side chain 5a.

At this time, the chain guide 10 is
, The contact position between the chain guide 10 and the slack side chain 5a is always kept constant.

For this reason, even if the chain guide 10 vibrates at a high frequency due to the high-speed rotation of the engine, the slack side chain 5a only vibrates in the moving direction but does not vibrate in the lateral direction, thereby improving the NVH characteristics. , Sprockets 2, 4 and chains 5 can be suppressed from being worn.

Further, by providing a linear second guide path 22b for guiding the slack side chain 5a on the pitch circle tangent of the camshaft side sprocket 4 on the chain guide surface 22 of the shoe 12 forming the chain guide 10, Even if the chain guide 10 swings, the slack side chain 5a can always be guided on the pitch circle tangent of the cam shaft side sprocket 4.

Therefore, the camshaft-side sprocket 4 and the slack-side chain 5a can always smoothly mesh with each other.
VH characteristics can be further improved.

In the embodiment, the chain guide 10 is swingably supported about the camshaft 3. However, the chain guide 10 may be supported swingably about the crankshaft 1. In this case, the chain guide surface 22 of the chain guide 10 is provided at the end on the crankshaft side with the slack side chain 5.
a is provided with a first guide path formed of a linear flat surface for guiding a in the tangential direction of the pitch circle of the crankshaft-side sprocket 2. To be provided.

[0032]

As described above, according to the present invention, the chain guide, to which the pressing force of the chain tensioner is applied, is swingably supported about one of the crankshaft and the camshaft. The contact position of the side chain can always be kept constant, and the slack side chain can be prevented from laterally vibrating due to the swing of the chain guide.

For this reason, it is possible to improve the NVH characteristics, suppress the wear of the parts of the chain and the sprocket, and improve the durability.

Further, by providing the chain guide with a substantially linear guide path for guiding the slack side chain on the pitch circular tangent of the sprocket, the slack side chain and the sprocket can be smoothly meshed with each other, and the NVH characteristics can be improved. Can be further improved.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a chain tensioner device according to the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a front view showing a lever and a shoe of the chain guide shown in FIG. 1;

FIG. 4 is a front view showing a conventional chain guide device.

[Explanation of symbols]

 Reference Signs List 1 crankshaft 2 sprocket 3 camshaft 4 sprocket 5 chain 5a slack side chain 10 chain guide 11 lever 12 shoe 13 arm 22 chain guide surface 22b second guide path 30 chain tensioner

Claims (5)

[Claims] 1. A chain spans between a sprocket attached to a crankshaft and a sprocket attached to a camshaft, and a chain guide opposed to a slack side chain of the chain is swingably supported. In a chain tensioner device in which a pushing force of a chain tensioner is applied to a swinging end of a guide to tension a slack side chain, the chain guide is supported swingably about one of a crankshaft and a camshaft. A chain tensioner device characterized in that: 2. An arm is provided at an end of the chain guide on the running end side of the slack side chain, and a tip end of the arm is supported by a cam shaft so that the chain guide can swing about the cam shaft. The chain tensioner device according to claim 1. 3. A guide comprising a substantially linear flat surface for guiding a slack side chain on a tangent to a pitch circle of a cam shaft side sprocket at an end of the chain guide surface formed on the chain guide on a swing center side. The chain tensioner device according to claim 2, wherein a path is provided. 4. The chain tensioner device according to claim 1, wherein the chain guide comprises a metal lever and a synthetic resin shoe provided on a surface of the lever facing the chain. . 5. The chain tensioner device according to claim 1, wherein said chain tensioner comprises a hydraulic chain tensioner.