JPH076367B2 - Engine timing belt tension adjustment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for adjusting tension of a timing belt in an engine.

(Prior Art) Generally, a drive structure of an engine valve train has a crankshaft and a camshaft to which a crank pulley and a cam pulley are attached, and a timing belt is attached to these pulleys so that the camshaft is rotated by the rotational force of the crankshaft. Is configured to be rotationally driven.

Conventionally, when mounting a timing belt on such a pulley, first, the crank pulley and the cam pulley are respectively aligned with predetermined crank angle positions, and in this state, the timing belt is prevented from being greatly loosened. Then, the timing belt is pressed by the belt tensioner to adjust its tension, and the belt tensioner is fixed at this pressing position. The belt tensioner normally adjusts the tension of the timing belt on the way from the crank pulley on the side opposite to the tension side of the timing belt to the cam pulley. That is, the belt tensioner and both the pulleys are arranged in the order of rotation of the engine in the order of the crank pulley, the belt tensioner and the cam pulley. Further, when the timing belt is attached to each pulley, a certain amount of tension is applied by the force of the operator so that the timing belt is not loosened so that the timing belt is pressed by the belt tensioner. The relative rotational displacement that occurs between the pulleys when adjusting the tension is very small, which is not a problem.

However, in the case of an engine having two or more camshafts and their cam pulleys, such as a V-type engine, the rotational drive load of the entire cam pulley is very large, so pressing the timing belt with a belt tensioner will reduce the tension. It cannot be made uniform over the entire length. Therefore, there is a problem in that the tension adjustment work is troublesome because it requires a troublesome work of turning the timing belt itself several times while pressing the timing belt with the belt tensioner.

Therefore, in order to solve such a problem, by providing a cam pulley rotatably with respect to each cam shaft and eliminating the rotational drive load of the cam pulley when pressing the timing belt with the belt tensioner, the timing belt of the belt tensioner is replaced. It has been proposed that the tension of the timing belt can be made uniform over the entire length only by pressing (see JP-A-57-83617).

However, this proposal requires another troublesome work of fixing each cam pulley to the cam shaft after fixing the belt tensioner, and thus there is a dislike that the workability cannot be sufficiently improved. Further, since the structure of the connecting portion between the cam pulley and the cam shaft becomes complicated, there is a problem in terms of productivity.

(Object of the Invention) In view of the above points, an object of the present invention is to improve the tension adjusting method of a timing belt in an engine having a plurality of cam pulleys as described above, and to prevent the tension of the timing belt from increasing without complicating the structure. Is easily and surely made uniform over the entire length.

(Structure of the Invention) In order to achieve the above object, the structure of the present invention is such that a crank pulley, a belt tensioner, and
In the engine timing belt tension adjusting method in which a plurality of cam pulleys are arranged and these pulleys are interlocked with each other by a timing belt, the crank pulley and each cam pulley are respectively adjusted to predetermined crank angle positions, and the engine rotation of the belt tensioner is performed in this state. The cam pulley on the side closer to the direction is fixedly held and the timing belt is attached to each pulley so as not to cause a large slack, and then the belt tensioner is pressed against the timing belt and a predetermined torque is applied to the crank pulley in the engine rotation direction. After the slack of the timing belt is absorbed by the belt tensioner, the belt tensioner is fixed at the position where the timing belt is pressed, and then the fixed holding of the cam pulley is released.

As a result, by applying a predetermined torque in the engine rotation direction to the crank pulley while the cam pulley on the side closer to the engine rotation direction of the belt tensioner is fixedly held, all the slack of the timing belt is collected on the belt tensioner side, and the belt tensioner The tension of the timing belt is thereby made uniform over the entire length. Even in the case of the present invention, when the timing belt is attached to each pulley, a certain amount of tension is applied by the force of the operator so that the timing belt does not cause a large slack as in the conventional case. Therefore, when a predetermined torque is applied to the crank pulley and the slack of the timing belt is absorbed by the belt tensioner, the relative rotational displacement generated between the pulleys is extremely small, which does not cause a problem.

(Effect of the invention) Therefore, according to the present invention, the timing can be adjusted by a simple operation of applying a predetermined torque in the engine rotation direction to the crank pulley while the cam pulley on the side closer to the engine rotation direction of the belt tensioner is fixed and held. The slack of the belt can be collected on the belt tensioner side so that the tension of the timing belt can be surely made uniform over the entire length, so the timing belt tension adjustment work is simplified,
The workability can be greatly improved. Moreover,
In adjusting the tension, it is sufficient to simply provide a mechanism for fixing and holding one cam pulley, and the structure is simple. Therefore, good productivity is secured and it is very advantageous in practice.

(Example) Hereinafter, the Example of this invention is described based on drawing.

1 to 3 show a 6-cylinder V-type engine A according to an embodiment of the present invention. The V-type engine A has first and second banks 1 and 2 arranged in a V shape on the left and right. An oil pan 4 is attached to the lower surface of the cylinder block 3 of each of the banks 1 and 2. A crankcase (not shown) composed of the oil pan and the lower part of the four cylinder block 3
A crankshaft 5 extending in the front-rear direction is provided inside, and a crank pulley 6 is attached to a front end portion of the crankshaft 5 so as to rotate integrally with the crankshaft 5.

In the cylinder block 3, three odd-numbered cylinders 7, ... Are formed in the first bank 1 and three even-numbered cylinders 7, ... Are formed in the second bank 2 in the front-rear direction. A piston (not shown) is slidably fitted therein. Further, the cylinder heads 8 and 8 of the first and second banks 1 and 2 which are airtightly joined to the upper surface of the cylinder block 3 are provided with intake ports 9 and exhausts which communicate with the cylinders 7 in correspondence with the cylinders 7. port
10, an intake port 9 is opened and closed by an intake valve 11, and an exhaust port 10 is opened and closed by an exhaust valve 12.

A camshaft 13 extending in the same direction as the crankshaft 5 (front-rear direction) is arranged on the cylinder heads 8 of the banks 1 and 2, respectively.
Cam pulleys 14a and 14b are attached to the front end of 13 so as to rotate integrally with the cam shaft 13. A timing belt 15 is wound around the cam pulleys 14a and 14b and the crank pulley 6, and
The rotational force of the timing belt 15 from the crank pulley 6.
Each camshaft 13 is rotated synchronously with the crankshaft 5 by transmitting the camshaft 13 to both cam pulleys 14a and 14b via the shaft. Each of the camshafts 13 has a pair of rocker shafts 16, 1 extending parallel to the camshafts 13.
6 are linked to the intake valve 11 and the exhaust valve 12 via intake and exhaust rocker arms 17a and 17b which are swingably supported by each of the intake valve 11 and the intake valve 11 by the rotation of the camshaft 13.
And a valve mechanism 18 that controls the opening and closing of the exhaust valve 12.

Further, 19 is a belt tensioner for adjusting the tension of the timing belt 15 when the timing belt 15 is mounted on the crank pulley 6 and the cam pulleys 14a, 14b, and the belt tensioner 19 is provided in front of the cylinder block 3. An arm 21 swingably attached to a wall surface via a bearing shaft 20, and a free end of the arm 21 is rotatably provided and abuts against a timing belt 15 in a state of being pressed inwardly of the wheel. Pulley 22 and arm 21 at one end
To the locking portion 30 provided on the free end portion of the cylinder block 3, and the other end to the locking portion 31 provided on the front wall surface of the cylinder block 3,
A set spring 23 for biasing the arm 21 in a swinging direction by the pulley 22 in a direction of pressing the timing belt 15 is provided. Here, the belt tensioner 19 adjusts the tension of the timing belt 15 on the way from the crank pulley 6 on the opposite side of the timing belt 15 to the cam pulley 14a on the first bank 1 side. That is, the belt tensioner 19 and the above pulleys 6, 14a,
14b is a crank pulley 6 in the rotation direction R of the engine A,
Belt tensioner 19, cam pulley 14 on the first bank 1 side
That is, the cam pulley 14b on the second bank 2 side is arranged in this order.

In addition, as shown in FIG. 3, the front wall surface of the cylinder head 8 on the first bank 1 side is provided with an insertion hole 25 that can be fitted into the service hole 24 of the cam pulley 14a. The hole 25 is provided when the cam pulley 14a is set when the timing belt 15 is attached.
Matches one service hall 24 of
A service pin 26 can be inserted through 24.
Reference numeral 27 is an idle pulley corresponding to the belt tensioner 19 and guiding the pulling side of the timing belt 15 toward the inner side of the wheel.

Next, the timing belt tension adjusting method for an engine according to the present invention is applied to the timing belt 15 in the V-type engine A.
The case of attaching the to the crank pulley 6 and the two cam pulleys 14a and 14b will be described.

First, the crank pulley 6 and the two cam pulleys 14a and 14b are aligned with a predetermined crank angle position (a position which becomes a compression top dead center in the first cylinder 7) by a set mark drawn on each side surface. At this time, the first bank 1 near the engine rotation direction R of the belt tensioner 19
On the side, the insertion hole 25 on the front wall surface of the cylinder head 8 coincides with one service hole 24 of the cam pulley 14a.

Then, in this state, the service pin 26 is connected to the first
The cam pulley 14a is inserted into the insertion hole 25 through the service hole 24 of the cam pulley 14a on the bank 1 side to hold the cam pulley 14a non-rotatably, and the predetermined portions of the timing belt 15 are respectively fixed to the crank pulley 6 and the cam pulleys 14a, 14b. Engage these pulleys 6,1
The timing belt 15 is attached to 4a and 14b. At this time, the timing belt 15 does not generate a large slack between the two left and right cam pulleys 14a, 14b, between the cam pulley 14b and the idle pulley 27, and between the idle pulley 27 and the crank pulley 6. A certain amount of tension is applied to the belt 15. Also, the belt tensioner 19
The timing belt 15 is swung in the direction opposite to the direction in which the timing belt 15 is abutted and pressed (the direction of arrow C in FIG. 1) so as not to interfere with the mounting of the timing belt 15.

Next, the engaging portion of the arm 21 of the belt tensioner 19
One end of the set spring 23 is hooked on the 30 and the other end of the set spring 23 is hooked on the locking portion 31 of the cylinder block 3, and the belt tensioner 19 is driven by the biasing force of the set spring 23 to cause the timing belt 15 to move. After pressing the inside of the wheel, a predetermined torque is applied to the crank pulley 6 in the engine rotation direction R by using a turning metal fitting or the like.

At this time, since the cam pulley 14a on the first bank 1 side is fixed and held non-rotatably as described above, the timing belt
All parts of the pulling side 15 from the cam pulley 14a to the crank pulley 6 are pulled by applying torque. Therefore, all the slack of the timing belt 15 is collected between the crank pulley 6 having the belt tensioner 19 and the cam pulley 14a, and the belt tensioner 19 presses the timing belt 15 so as to absorb the slack. Has a uniform tension without sagging over its entire length. However, when the timing belt 15 is worn, a certain amount of tension is applied by the force of the operator so that the timing belt 15 is not loosened significantly. Crank pulley 6 to absorb slack
Also, the cam pulley 14b rotates only slightly, and the displacement of the mounting angular positions of these does not pose a problem.

Then, the free end of the arm 21 of the belt tensioner 19 is bolted to the front wall surface of the cylinder block 3,
The belt tensioner 19 is fixed while pressing the timing belt 15. Next, the set spring 23 is removed from the belt tensioner 19 and the locking portions 30 and 31 of the cylinder block 3, and the service pin 26 is pulled out from the insertion hole 25 of the cylinder head 8 on the first bank 1 side to fix and hold the cam pulley 14a. To cancel. With the above, the tension adjustment work of the timing belt 15 is completed. When the engine A is operated after the tension adjustment work is completed, the belt tensioner 19 functions as an idle pulley that guides the timing belt 15 by pulling the timing belt 15 toward the inside of the wheel without the set spring 23. become.

As described above, in the engine timing belt tension adjusting method of the present invention, the engine pulley is rotated by the crank pulley 6 while the cam pulley 14a on the first bank 1 side of the belt tensioner 19 near the engine rotation direction R is fixedly held so as not to rotate. By a simple operation of applying a predetermined torque in the direction R, all the slack of the timing belt 15 can be collected on the belt tensioner 19 side, and the tension of the timing belt 15 can be surely made uniform over the entire length. The service pin 2 is also used to hold and release the cam pulley 14a.
6 can be carried out only by inserting or pulling out from the service hole 24 of the cam pulley 14a into the insertion hole 25 on the front wall surface of the cylinder head 8, so that the tension adjustment work of the timing belt 15 becomes very simple and the workability thereof is improved. It can be greatly improved.

Moreover, in adjusting the tension, an insertion hole 25 for inserting the service pin 26 to fix and hold the cam pulley 14a is provided on the front wall surface of the cylinder head 8 on the first bank 1 side in the conventional V-type engine. Since it does not complicate the structure, good productivity and the like can be secured, which is very advantageous in practice.

In the above embodiment, the present invention is applied to the two cam pulleys 14a,
The case where the invention is applied to the 6-cylinder V-type engine A equipped with 14b has been described, but the number of cam pulleys is not limited to two, and it is needless to say that the same can be applied to an engine equipped with more cam pulleys.

[Brief description of drawings]

The drawing shows an embodiment of the present invention, and FIG.
FIG. 2 is a front view of the type engine, FIG. 2 is a cross-sectional view of a cylinder head portion on the first bank side of the engine, and FIG. 3 is a partially cutaway arrow view seen from the direction B in FIG. A ... V type engine, R ... rotation direction, 6 ... crank pulley, 14a, 14b ... cam pulley, 15 ... timing belt, 19 ... belt tensioner, 24 ... service hole, 25 ... insertion hole, 26 …… Service pin.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Nobuhiro Fujii 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Toyo Kogyo Co., Ltd. (56) Reference JP-A-57-83617 (JP, A)

Claims (1)

[Claims] 1. A timing belt tension adjusting method for an engine, wherein a crank pulley, a belt tensioner, and a plurality of cam pulleys are sequentially arranged in an engine rotating direction, and these pulleys are linked by a timing belt. Align the cam pulleys to their respective predetermined crank angle positions, hold the cam pulley on the side closer to the engine rotation direction of the belt tensioner in this state, and attach the timing belt to each pulley so as not to cause a large slack. Is pressed against the timing belt and a predetermined torque is applied to the crank pulley in the engine rotation direction,
A timing belt tension adjusting method for an engine, comprising: fixing the belt tensioner at a position where the timing belt is pressed after absorbing the slack of the timing belt by the belt tensioner, and then releasing the fixed holding of the cam pulley.