KR20030049426A - Sprocket for timing chain - Google Patents

Abstract

PURPOSE: A sprocket for a timing chain is provided to decrease vibration and noise by absorbing impact with engaging the timing chain with the gear teeth flexibly, and to improve the durability by preventing wear with lubricating the gear teeth. CONSTITUTION: A sprocket(1) is divided into two bodies(4,5), and two bodies are combined by a bolt(3). An oil hole(7) is formed radially in a bonding surface(6), and the center of the oil hole is connected to an oil supply passage(8). An annular oil space(11) is formed from the outside of the bolt to a recess of a gear tooth part(9), and ends of gear tooth parts are contacted to each other by bent portions(9a). An elastic ring damper(12) is inserted to the end of the annular space, and made of a steel spring, stainless steel or high carbon steel. The elastic ring damper is protruded upward more than the recess, and oil is supplied to the annular space through the oil supply passage. Impact is absorbed, and vibration and noise are reduced by displacing the damper with contacting the roller or the bush of the chain to the elastic ring damper in engaging the sprocket with the chain. Wear is prevented, and endurance is improved by lubricating efficiently with supplying oil to gear teeth and the contact portion of the chain.

Description

Sprockets for Timing Chains

The present invention relates to a sprocket for a timing chain for use in power transmission to a camshaft.

The valve mechanism is a mechanism that opens and closes the intake valve and the exhaust valve of each cylinder in the order of ignition order and is operated by the camshaft.

The camshaft of a four-cycle engine is designed to rotate at 1/2 of the crankshaft rotation speed, and the opening / closing timing of each valve is matched with the valve timing with respect to the rotation of the crankshaft.

Camshaft drives are generally installed at the front of the crankcase, and are classified into timing gear type, timing chain type and timing belt type. However, the timing gear type is almost at present due to the noise increase due to gear wear during use. Timing belt type that is not used, has low noise, light weight, no lubrication, no need for regular tension adjustment, and can design the position of camshaft freely with good power transmission efficiency. Mainly used.

In order to use the timing chain, a sprocket designed to transmit the power by processing the teeth defined on the circumference of the forced wheel is inserted between the links of the chain. When the teeth of the timing chain and the sprocket are engaged, the impact force acts and causes noise and Since vibration is generated and abrasion is accelerated, the sprocket 20 is divided into two body 21 and 22 by the tooth width direction as shown in FIG. 3, and then joined and fastened by bolts 23. , Oil hole 24 is formed in the joint portion so that the oil supplied through the oil supply passage 26 of the sprocket shaft 25 (meaning the crankshaft and camshaft) is also supplied to the teeth 27 so as to lubricate the chain and teeth. The impact when the mold part 27 is engaged is alleviated and the wear is prevented.

On the other hand, the chain and the sprocket is a solid friction between the metals, it is difficult to prevent the perfect wear only by lubrication by oil supply, so that the heat treatment of the teeth 27 is generally performed to improve the wear resistance of the sprocket, According to the precision and roughness and the operation of the chain, that is, the behavior of the chain tensioner, abnormal wear (scuffing, fitting wear) of the chain and sprocket occurs frequently.

This is because the system optimization (tuning) work in the development of the chain system is insufficient or the initial tuning is well performed, but it is often caused by the product variation of the chain system components afterwards. In particular, the teeth of the chain sprocket are often a problem, but the shape of the tooth 28, which is in contact with the roller (or bush) of the chain, also greatly affects the teeth.

In particular, the existing sprockets contact the chain with a fixed tooth (roller chain; rolling contact, bush chain: sliding contact), so when the upper and lower limits within the product specifications are applied, the contact stress and There is a possibility that the impact force acts locally on the teeth 27 and damages the teeth, so that the shape and roughness of the teeth 28 need to be managed precisely. Developing a sprocket to have is a very difficult and time-consuming and costly problem.

Accordingly, the present invention has been proposed in view of the above point, and its object is to provide flexibility when the timing chain and teeth are engaged to absorb shocks, thereby reducing vibration and noise, and improving durability by preventing wear. An object of the present invention is to provide a sprocket for a timing chain having an improved lubricity to a mold part.

In order to achieve the above object, the present invention is a sprocket for a timing chain which is divided into two bodies in the tooth width direction and fastened and joined by bolts, the annular space exposed to the atmosphere around the teeth on the outer joining surface of the bolts. It is formed, and the outer ring of the annular space is characterized in that the elastic ring damper is engaged so that its outer peripheral surface slightly protrudes above the base.

1 is a front sectional view showing a sprocket for a timing chain according to the present invention.

2 is a side view of a sprocket for a timing chain according to the present invention.

3 is a prior art

※ Explanation of codes for main parts of drawing

1: Sprocket 2: Sprocket Shaft

3: bolt 4,5 split body

6: joining surface 7: oil hole

8: oil supply passage 9: teeth

9a: bend 10: basement part

11: annular space 12: elastic ring damper

13: bolt

Hereinafter, the configuration of the present invention will be described with reference to the accompanying drawings.

1 is a sectional front view of a sprocket for timing chains according to the present invention, and FIG. 2 is a side view of a sprocket for timing chains according to the present invention.

Reference numeral 1 in the figure denotes the sprocket (for the timing chain) of the present invention, and is fixedly mounted to one end of the sprocket shaft 2 (cam shaft and crank shaft) by a bolt 13 or a key.

The sprocket 1 for timing chain is composed of two bodies 4 and 5 divided in the tooth width direction, and the two divided bodies 4 and 5 are joined to each other and joined together, and then joined by bolts 3. Doing.

On the joint surface 6 of the split bodies 4 and 5 of the sprocket 1, an oil hole 7 is formed radially from the center toward the outer side, and the center part of the oil hole 7, namely, to one place. The central point of convergence is in communication with the oil supply passage 8 formed along the center of the sprocket shaft 2.

The oil hole 7 is formed up to the vicinity of the bolt 3, and the divided body 4, 5 is connected to the contact surface 6 (bonded surface) which is in close contact with the main power surface of the bolt 3, An annular oil space 11 is formed from the outside to the base 10 of the tooth 9, i.e. exposed to the atmosphere, and the two ends of the teeth 9 and 9 are bent inwardly in a L-shape. The bent portions 9a and 9a are in close contact with each other.

In the outermost side of the annular space 11, an elastic ring damper 12 made of metal, for example, spring steel, stainless steel, or high carbon steel, is fitted. It protrudes slightly higher than 10) and is supported by the bent portions 9a and 9a at the ends thereof.

According to the present invention having the above configuration, the elastic ring damper 12 protrudes slightly higher than the base 10 when an impact occurs while the roller or bush of the chain is engaged with the teeth 9 when rotating in engagement with the timing chain. ) Is absorbed by the displacement of the elastic ring damper 12 generated by the annular space 11 while being in contact with the c), and the oil supplied through the oil supply passage 8 of the shaft 2. After flowing along the oil hole 7, the annular space 11 is reached through the gap between the contact surface 6 (the joining surface), which is the fastening surface of the bolt 3, to fill the annular space 11, thereby providing elasticity. The ring damper 12 is buffered by hydraulic pressure and oil is supplied to the teeth 9 and the chain through gaps between the elastic ring dampers 12 to maintain smooth lubrication function to prevent wear. Will be done.

According to the present invention as described above to form an annular space open to the outside on the outer side of the sprocket which is formed by joining the two divided bodies, mounting the elastic ring damper so that the annular space exposed to the upper portion than the bottom of the annular space By supplying the oil supplied through the oil supply passage of the sprocket mounting shaft to the annular space, the roller or bush of the chain comes into contact with the elastic ring damper when the sprocket is engaged with the chain, causing the elastic ring damper to cause displacement. Therefore, the impact force is absorbed to reduce noise and vibration, and the oil is supplied to the annular space that enables the displacement of the elastic ring damper to smoothly maintain the displacement of the elastic ring damper, and the supplied oil passes through the gaps and the teeth. It is supplied to the contacts of the chain to improve lubricity, preventing wear and improving durability. have.

Claims (5)

In a sprocket for a timing chain, which is divided into two bodies in the tooth width direction and fastened and joined by bolts, an annular space exposed to the atmosphere around the teeth is formed on the outer joining surface of the bolt, and is formed outside the annular space. A sprocket for a timing chain, wherein an elastic ring damper is engaged such that its outer circumferential surface protrudes slightly above the base. The method of claim 1, The sprocket for the timing chain, characterized in that the oil is supplied through the oil supply passage formed in the center of the sprocket shaft. The method of claim 2, A sprocket for a timing chain, characterized in that an oil hole having a central side communicating with the oil supply passage and an outer end side thereof formed adjacent to the annular space side are radially formed on the joint surface of the divided body. The method of claim 1, The elastic ring damper is a sprocket for a timing chain, characterized in that the support is trapped by the bent portion of the teeth end. The method of claim 4, wherein The elastic ring damper is a sprocket for a timing chain, characterized in that formed of any one material selected from the group of spring steel, stainless steel and high carbon steel.