JPH0949554A - Chain tensioner for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize engagement of the teeth of a rack gear with that of a ratchet gear by disposing a plunger on the traveling surface of a timing chain, and providing the teeth of the ratchet gear on the chain cover side. SOLUTION: A plunger 30 is disposed on the traveling surface of a timing chain 11, and the teeth 39 of a ratchet gear is provided on the chain cover side. The direction of the supporting shaft 40 of the ratchet teeth 39 is made parallel to the traveling direction of the timing chain 11. As a result, an angle of approx. 90 degrees is formed between the timing chain 11 and a ratchet mechanism 38 as indicated by an arrowhead C-D. As a result of the timing chain 11 traveling, a pad 31 changes, and even if its movement is transmitted to the ratchet mechanism 38, the engagement of the rack teeth 37 with the ratchet teeth 39 will not be unstable because when a change of the pad 31 is transmitted to the ratchet mechanism 38, its movement is kept in the tooth width direction of the rack teeth 37 and the ratchet teeth 39, not in the teeth engagement direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine chain tensioner device used in an automobile or the like.

[0002]

2. Description of the Related Art An engine used in an automobile or the like is provided with a timing chain for driving a camshaft on one side of the engine body, and the outside thereof is covered with a chain cover. However, this timing chain is always forced to rotate at high speed. , It will fluctuate if a predetermined tension is not applied during driving. Therefore, a chain tensioner will be installed to provide tension. As a general mechanism of this chain tensioner, a hole is provided in the body of the chain tensioner body, a plunger is inserted into this hole, a pad is attached to the tip of the plunger to face the engine chain, and the hydraulic pressure applied to the hole It is known that a pad is pressed against a timing chain.

In such a case where the pad is hydraulically pressed against the timing chain, it is inconvenient for the pressing force to be lost immediately when the hydraulic pressure decreases. Therefore, some mechanism is provided to reduce the hydraulic pressure. But do not let the pad come off the timing chain immediately. The invention disclosed in Japanese Unexamined Patent Publication No. 6-94089 is also an improvement of the invention, and in the related art, since the rack teeth are locked to the tip end surface of the piston, sometimes excessive tension is applied to the timing chain. It is a solution to a certain problem.

FIG. 3 shows the engine with the chain cover removed, and FIG. 4 shows a cross section taken along the line YY. In these drawings, 1 is a crankshaft, and 2 is a crank timing sprocket mounted on the crankshaft 1. An idler shaft 3 is provided above the crankshaft 1 and supports an idler sprocket 4. A first-stage timing chain 5 is bridged between the crank timing sprocket 2 and the idler sprocket 4.

The idler sprocket 4 is integrally provided with a second idler sprocket 6 having a smaller number of teeth. The second idler sprocket 6 and the two camshafts 7 and 8 located thereabove. A second-stage timing chain 11 is bridged between the timing sprockets 9 and 10 mounted on the. Reference numeral 12 is a crankcase, 13 is a cylinder block, 14 is a cylinder head, and 15 is a cylinder head cover.

A chain cover 16 having an upper end in contact with the cylinder head cover 15 is provided outside the cylinder block 13 and the cylinder head 14, and all of the first-stage timing chain 5 and the second-stage timing chain 1 are provided.
It covers the bottom of 1. Reference numeral 17 in FIG. 3 is a chain guide for guiding the traveling of the first-stage timing chain 5, and reference numeral 18
Is a chain tensioner for tensioning the timing chain 5, and 19 is a chain tensioner 18 for the timing chain 5.
It is a tensioner adjuster that adjusts the force of pressing to the side.

A tensioner adjuster 20 is provided inside the cylinder head 14 to give a proper tension to the timing chain 11 of the second stage. A chain guide 21 is provided inside the cylinder head cover 15 so as to guide the timing chain 11 between the two timing sprockets 9 and 10. In FIG. 4, reference numeral 22 is a crank pulley, 23 is an idler pulley, 24 is an oil pump drive sprocket, and 25 is an oil pump drive chain.

FIG. 5 is an enlarged front view of the details of the tensioner adjuster 20 shown in FIG.
Is a plan view thereof. To explain this structure, 26 is a body, which is attached to the cylinder head 14 by a bolt 28 (see FIG. 3) inserted through a hole 27 provided at one end. A hole 29 is provided in the body 26 toward the timing chain 11 side.
A plunger 30 is inserted in the. Plunger 30
A pad 31 is attached to the tip of the, and its front surface is in contact with the timing chain 11.

A spring 32 is provided inside the plunger 30.
Is interposed. Further, a check ball 34 is in contact with a plate 33 which is screwed to the plunger 30 and serves as a bottom plate. The check ball 34 receives the hydraulic pressure of the lubricating oil applied from the oil passage 36 provided in the cap screw 35.
Due to the hydraulic pressure and the elastic force of the spring 32, the plunger 30 is urged in the direction protruding from the hole 27 (the direction in which the pad 31 contacts the timing chain 11).

Rack teeth 37 are provided on a part of the outer periphery of the plunger 30, and ratchet teeth 39 of a ratchet mechanism 38 are engaged with the rack teeth 37. The ratchet teeth 39 of the ratchet mechanism 38 allow movement of the plunger 30 in a direction projecting from the hole 29 by a spring (not shown) or the like, and prevent movement in the opposite direction. 40 is a support shaft of the ratchet teeth 39, and 41 is an adjusting screw.

When the engine having such a structure operates, the pad 31 of the tensioner adjuster 20 is brought into pressure contact with the second-stage timing chain 11 to give an appropriate tension. The movement of the plunger 30 that sends the pad 31 to the timing chain 11 side of the second stage is freely performed, but when the hydraulic pressure applied to the plunger 30 via the check ball 34 decreases due to the stop of the engine or the like, the ratchet mechanism 38. By this action, the contact force of the pad 31 with the timing chain 11 is kept constant.

[0012]

SUMMARY OF THE INVENTION Even in the above configuration,
Although it is possible to sufficiently obtain the function that the pad 31 does not separate from the timing chain 11 when the engine stops and the hydraulic pressure decreases, as is apparent from FIG. 5, the support shaft 40 of the ratchet teeth 39 causes the timing chain 11 to move. Since it is provided in a direction intersecting with the traveling direction (direction of arrow A) of the plunger 3, when the pad 31 is swung in the direction of arrow AB by the traveling of the timing chain 11, the swing of the pad 31 is caused.
There is a risk that the rack teeth 37 and the ratchet teeth 39 are transmitted to the engaging portion via 0, and the engagement becomes unstable. If the engagement becomes unstable in this way, it may cause the ratchet teeth 39 to be chipped, so in the prior art, a sufficiently large strength has been dealt with.

The present invention has been made in view of this point, and it is an object of the present invention to solve the above problems by changing the direction of the ratchet mechanism. Incidentally, the structure of Japanese Patent Application Laid-Open No. 6-94089 mentioned above as a prior art is different in structure, and therefore the problem of the present invention cannot be solved.

[0014]

As a means for solving the above-mentioned problems, the present invention provides a timing chain mechanism for driving a camshaft on one side surface of an engine body, and covers the outside with a chain cover. A chain tensioner device that gives tension to the chain is provided with a hole in the body, a plunger is inserted into the hole, a pad is attached to the tip of the plunger to face the timing chain of the engine, and the pad is pressed by the hydraulic pressure applied to the hole. A ratchet that presses against the timing chain and that restricts the return of the plunger by engaging the ratchet tooth engraved on the outer periphery of the plunger between the plunger and the body with the ratchet tooth that rotates around the spindle. In the engine tensioner device formed by interposing the mechanism,
A plunger is disposed on the traveling surface of the timing chain, and ratchet teeth are provided on the chain cover side.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below, omitting the description of the same parts as those of the prior art described above with reference to FIGS. In the present embodiment, the support shaft 40 of the ratchet teeth 39 is oriented parallel to the traveling direction of the timing chain 11. Spindle 40
By setting this direction, the timing chain 11
The ratchet mechanism 38 and the ratchet mechanism 38, as shown by arrows CD,
It will have an angle of about 90 degrees.

In the above embodiment, the ratchet teeth 3
The position 9 has an angle of about 90 degrees with respect to the traveling direction of the timing chain 11, but this angle is not limited to 90 degrees. Since the present invention is characterized in that the plunger is disposed on the traveling surface of the timing chain and the ratchet teeth are provided on the chain cover side, the spindle 40 of the ratchet teeth 39 causes the timing chain 11 to travel in the traveling direction. You just have to face the direction you avoid.

As described above, when the position of the ratchet teeth 39 is changed as compared with the conventional one, the pad 31 fluctuates due to the traveling of the timing chain 11, and even if the movement is transmitted to the ratchet mechanism 38, the rack teeth are moved. 37 and ratchet teeth 3
The engagement of 9 does not become unstable. This is pad 3
This is because, when the variation of 1 is transmitted to the ratchet mechanism 38, the movement thereof is in the tooth width direction of the rack teeth 37 and the ratchet teeth 39, and not in the tooth engaging direction unlike the conventional one described above.

[0018]

As described above, the present invention is the engine tensioner device in which the plunger is disposed on the traveling surface of the timing chain and the ratchet teeth are provided on the chain cover side, so that the timing chain travels. As a result, the movement of the pad does not affect the function and wear of the ratchet mechanism. Since it can be realized by changing the positions of the ratchet teeth and the rack teeth engaging with the ratchet teeth, the present invention can be immediately applied to the existing engine only by exchanging related parts.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a front view showing the relationship between an engine timing chain and a chain tensioner.

FIG. 4 is a sectional view taken along the line YY of FIG.

5 is a partial cross-sectional view showing enlarged details of a chain tensioner portion in FIG.

FIG. 6 is a plan view of that of FIG. 5;

[Explanation of symbols]

 6 Second idler sprocket 7 Cam shaft 8 Cam shaft 9 Timing sprocket 10 Timing sprocket 11 Second stage timing chain 16 Chain cover 20 Tension adjuster 26 Body 29 Hole 30 Plunger 31 Pad 37 Rack tooth 38 Ratchet mechanism 39 Ratchet tooth 40 Support shaft

Claims (1)

[Claims] 1. A chain tensioner device for providing a timing chain mechanism for driving a camshaft on one side surface of an engine body, the outside of which is covered with a chain cover to provide tension to the timing chain. The plunger is fitted in and the pad is attached to the tip of the plunger to face the timing chain of the engine, and the pad is pressed against the timing chain by the hydraulic pressure applied to the hole, and the outer circumference of the plunger is provided between the plunger and the body. A chain tensioner device for an engine formed by interposing a ratchet mechanism that regulates a return of a plunger by engaging a ratchet tooth that rotates around a support shaft with a rack tooth that is engraved on the timing chain. Install a plunger on the running surface of the A chain tensioner device for an engine, which is provided with a set tooth.