KR19990035140A - Structure of the pulley connected to the timing belt - Google Patents

Abstract

The present invention relates to a pulley connected to a timing belt used for driving a valve of a vehicle engine, and in particular, to improve the structure of the pulley to minimize the thermal stress and noise generated at the contact between the pulley and the timing belt and at the same time The present invention relates to a structure of a pulley connected to a timing belt focused on suppressing vibration and improving reliability of valve timing, and a pulley connected to a timing belt 30 used to drive an engine intake / exhaust valve. 20, characterized in that at least one compressed air discharge groove 20B is formed circumferentially on the teeth 20A of the pulley 20.

Description

Structure of the pulley connected to the timing belt

The present invention relates to a pulley connected to a timing belt used for driving a valve of a vehicle engine, and in particular, to improve the structure of the pulley to minimize the thermal stress and noise generated at the contact between the pulley and the timing belt and at the same time It relates to a structure of a pulley connected to a timing belt focused on suppressing vibration to improve the reliability of valve timing.

In general, in gasoline engines, intake and exhaust valves are provided on the cylinder head side, and these intake and exhaust valves are driven by a camshaft. In addition, a gear drive, a timing chain drive, or a timing belt drive is used to operate the cam shaft in conjunction with the crank shaft.

First, the driving of the camshaft by the gear is the most reliable power transmission method compared to other driving methods, and the deformation of the crankshaft and the camshaft hardly occurs even when the engine rotates at a high speed. Moreover, even when the inside of the engine becomes hot, the cam shaft is highly reliable in driving. However, since the drive of the camshaft by the gear increases the distance between the crankshaft and the camshaft, the engine with a large number of camshafts, for example, single over head camshaft (SOHC), double over head camshaft (DOHC), V-shaped eight cylinder, Horizontally opposed six-cylinders have disadvantages such as excessively complicated gear trains, increased engine weight, and increased gear noise.

The second timing chain drive is intended to solve the disadvantages of the gear drive method, and is lighter and less expensive to rebuild than the drive of the cam shaft by the gear. On the other hand, when the engine rotates at a high speed, the vibration of the timing chain increases, or even when the length of the timing chain itself increases due to the increase in the distance between the crankshaft and the camshaft. There is a disadvantage in that it interferes with rotation.

The third timing belt drive is a rubber belt made of synthetic rubber such as chloroprene with glass fiber or steel wire as a wick, and teeth are formed on the inside of the belt. It has the advantages of heat and durability over timing chains, and also has advantages in terms of vibration, noise, weight and price. That is, it is used for the engine of light weight, high output, and high quietness.

That is, the conventional timing belt drive is the camshaft gear pulley 20, 21, 22, 23, crankshaft gear pulley 24, oil pump pulley 25, damper pulley 26 and idle as shown in FIG. The timing belt 30 is connected to the pulley 27.

Therefore, when the crank shaft 10 rotates, the cam shafts 40, 41, 42, 43 rotate through the timing belt 30 to drive the valve device.

However, in the case of the timing belt drive, the timing belt 30 and the cam shaft gear pulleys 20, 21, 22, and 23 of the cam belt gear pulleys at the high speed are interposed between adjacent teeth of the timing belt 30. Instantaneous air compression occurs continuously, and this compression force causes vibration of the timing belt 30. Therefore, not only vibration and noise occur in the timing belt 30, but also thermal stress occurs at the contact portion between the timing belt 30 and the pulleys 20, 21, 22, and 23, resulting in a decrease in the life of the timing belt 30.

Therefore, the bad phenomenon appearing in the timing belt 30 adversely affects the valve opening and closing time, causes knocking, and causes the engine output to be reduced.

The present invention has been made in view of the above circumstances, and improves the structure of the pulley to minimize the thermal stress and noise generated in the contact portion between the pulley and the timing belt, and at the same time suppress the vibration of the timing belt to ensure the reliability of the valve timing. The object is to provide a structure of a pulley connected to a timing belt focused on improving the speed.

Specific means of the present invention for achieving the above object is, in each pulley connected to the timing belt used to drive the intake and exhaust valves of the engine, each compression circumferentially on the upper surface of the tooth of the pulley At least one air discharge groove is formed.

1 is an installation state of a pulley connected to a timing belt of a conventional engine.

2 is a block diagram of a pulley according to an embodiment of the present invention.

3 is a block diagram of a pulley according to another embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

20: Pulley 20A: Chibu

20B: compressed air release groove 30: timing belt

31: Chibu

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the pulley 20 connected to the timing belt used to drive the intake and exhaust valves of the engine as shown in Figs. 2 and 3, respectively, circumferentially on the upper surface of the teeth 20A of the pulley 20, respectively. At least one compressed air discharge groove 20B is formed.

At this time, the cross-sectional area of the compressed air discharge groove 20B is set in proportion to the contact area between the teeth 31 of the timing belt 30 and the camshaft gear pulley 20 that is being bitten off.

That is, when the contact area with the timing belt 30 which contacts the pulley 20 is large, the clearance gap between the adjacent teeth 20A of the pulley 20 becomes large, and the pulley 20 and the timing belt 30 are large. The large amount of air that is sucked in between the instantaneously and rapidly through the compressed air discharge groove (20B) of the pulley 20 is increased cross-sectional area.

In addition, the compressed air discharge groove 20B may be formed at a predetermined slope θ on the circumference of the pulley 20 as shown in FIG.

The operation of the pulley of the present embodiment configured as described above will be described.

First, when the engine rotates at a high speed, the timing belt 30 rotates the pulley 20 by the rotational force of the crank shaft. At this time, as shown in FIG. 2, the timing belt 30 and the pulley 20 are driven by the centrifugal force. Air is sucked between the teeth and is quickly discharged again through the compressed air discharge groove 20B of the pulley 20.

As such, the compressed air is removed between the pulley 20 and the teeth 20A and 31 that are bited during the high speed rotation of the timing belt 30, thereby eliminating the vibration applied to the timing belt 30, thereby eliminating the timing belt ( The vibration of 30) can be reduced, so that accurate valve timing can be expected and noise can be reduced.

In addition, the side slip phenomenon of the timing belt 30 is reduced, and the frictional heat escapes through the compressed air discharge groove 20B, thereby preventing overheating of the timing belt 30.

As described above, according to the present invention, by forming a compressed air discharge groove in the pulley, vibration and noise of the timing belt generated during winding rotation with the timing belt can be reduced, so that accurate valve timing can be expected.

There is also an additional advantage of prolonging the life of the timing belt by preventing overheating caused by frictional contact between the timing belt and the pulley.

Claims (2)

In the pulley 20 connected to the timing belt 30 used to drive the engine intake / exhaust valves, each compressed air discharge groove circumferentially on the teeth 20A of the pulley 20 ( 20B) The pulley structure connected to the timing belt characterized by the above-mentioned. 2. The structure of the pulley according to claim 1, wherein the compressed air discharge groove (20B) is formed to have a predetermined inclination (θ) with respect to the circumference of the timing belt (30).