JPH0211830A - Cam chain tensioner for four cycle engine - Google Patents

Abstract

PURPOSE:To improve the durability of a back surface part by forming an oil hole extended in the longitudinal direction of the back surface part in the vicinity of a joint surface between a tensioner back surface part joined with a cam chain and a reinforcing plate for the back surface part and cooling the inside of the back surface part by allowing oil to flow in the oil hole. CONSTITUTION:An oil hole 39 is formed in the vicinity of a joint surface 38 with a reinforcing plate 36, on the back surface part 35 of a tensioner 31, and said oil hole 39 is extended along in the longitudinal direction of the back surface part 35, and the upper edge is opened at the upper edge part of the back surface part 35. Further, the lower edge of the oil hole 39 is allowed to communicate to a shaft supporting oil hole 40 drilled in a shaft supporting part 37. Therefore, when the engine lubricating oil is sent under pressure from the oil hole 40, said lubricating oil rises in the oil hole 39 and cools the inside of the back surface part 35, and further flows down to a slide contact surface 42 from a small hole 41 and further to a push guide 44 from a back side small hole 43. Since the lubricating oil flows in the oil hole 39, the inside of the tensioner back surface part 35 is cooled, and the rubber deterioration and breakage on the tensioner back surface part 35 due to heat can be prevented, and the durability of the tensioner back surface part 35 can be improved.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention provides a cam chain tensioner that applies appropriate tension to the cam chain of a 4-day engine, and a cam chain tensioner that can suitably cool the back surface of the tensioner. Regarding cam chain tensioners for cycle engines.

(Prior Art) In a four-cycle engine, a valve operating cam that controls the opening and closing of an intake valve and an exhaust valve is driven by a cam chain in synchronization with the rotation of a crankshaft. Many overhead cam type four-cycle engines have a cam chain that passes through a cam chain that passes through a cylinder block and a cylinder head in the upper and lower directions.

If the tension on this cam chain is loosened, the timing will be disrupted, so place a cam chain tensioner on one side of the cam chain to tighten it. An adjuster device is used to maintain the appropriate tension at all times.

As shown in FIG. 6, the cam chain tensioner 1 makes sliding contact with the cam chain 2, so it is necessary to lubricate the sliding contact part (hereinafter referred to as the tensioner back part 3). The tensioner back part 3 is generally made of hard rubber. conventionally,
The lubricating oil that has slipped through the valve mechanism such as the cam and rocker arm is guided to the tensioner rear part 3 by natural fall, and the oil pool is located below the cam drive sprocket attached to the crank shirt 1 in the transmission case. [
J. By lubricating the cam chain 2, the tensioner back surface 3 is lubricated.

Further, since the cam chain tensioner 1 comes into sliding contact with the cam chain chain 2, durability is also required of the tensioner back part 3. This durability is generally achieved by coating the tensioner back portion 3 with a synthetic resin or the like.

However, as the engine speeds have increased in recent years, the tensioner back part 3 becomes hot due to the heat of the cam chain 2 or the heat generated by the engine itself, and hardens and crumbles, reducing its durability. There is that.

For this reason, it is conceivable to cover the tensioner back surface 3 with a thicker layer of synthetic resin, but this would increase the cost.

On the other hand, the tensioner back section 3 is reinforced by a reinforcing plate 4, and a bushing guide 6 made of hard rubber is fixed to the reinforcing plate 4 at the contact portion of the adjuster device 5.

In this bushing guide 6, the contact portion of the adjuster device 5 may become depressed due to the pressing force from the adjuster device 5 and the tension from the cam chain 2. Furthermore, the bushing guide 6 may harden due to the above-mentioned frictional heat, and the above-mentioned depression may become significant, causing the adjuster device 5 to protrude more than necessary.

(Problems to be Solved by the Invention) As described above, a decrease in the durability of the cam chain tensioner 1, particularly the tensioner back portion 3, poses a significant hindrance to increasing the rotation speed of the engine.

This invention was made in consideration of the above facts,
It is an object of the present invention to provide a cam chain tensioner for a 4-cycle engine, which can improve its durability by suitably cooling the back part of the tensioner.

[Structure of the invention]

(Another Means to Solve the Problems) This invention provides a cam chain that is wound between a cam drive sprocket attached to the crankshaft of a 4-stroke engine and a cam chain attached to the camshaft, and constantly presses the cam chain. In a cam chain tensioner for a four-stroke engine that applies appropriate tension to the cam chain, there is a tensioner back surface that slides on the cam chain, and a reinforcing plate that is joined to the tensioner back surface and reinforces this back surface near the joint surface. To,
The tensioner is characterized in that an oil hole is formed extending in the longitudinal direction of the back surface of the tensioner.

(Function) Therefore, according to the cam chain tensioner for a four-cycle engine according to the present invention, the rear surface of the dyen tensioner can be cooled from the inside by flowing oil through the oil hole, so that the rear surface of the tensioner can slide into contact with the cam chain. Even if frictional heat is generated by the tensioner, or even if the engine itself generates a significant amount of heat, thermal damage can be prevented and the durability of the back surface of the tensioner can be improved.

(Example) Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 4, the cylinder section of a four-stroke engine is constructed by stacking a cylinder block 11, a cylinder head 12, and a head cover 13, and below the cylinder block 11 is connected a mission case 32, which will be described later, containing a crank chamber. be done.

The main parts of the engine include a cylinder 14, a cylinder 15, a crank 16, a connecting rod 17, an intake valve 18, one exhaust valve, a cam 20, and the like.

A camshaft 21 and a rocker arm shaft 22 are arranged in the cylinder head 12, and a crankshaft 23 is arranged in the transmission case 32. The intake valve 18 and the exhaust valve 19 are controlled to open and close via a lever arm 24 according to the rotation of a cam 20.

The camshaft 21 and crankshaft t171-23 have a cam driven sprocket 25 as shown in FIG.
and cam drive sprockets 1 to 26 are respectively attached. The cam chain 2 is inserted between the cam drive sprocket 23 and the cam driven sprocket 25.
7 is wound around, and the rotational force from the crank shirts 1 to 23 is transmitted to the camshaft 21.

Here, the ratio of the number of teeth between the cam drive sprockets 1 to 26 and the cam drive sprocket 25 is as follows:
The setting is such that the cam shirts 1 to 21 rotate once for every two rotations of No. 3. Further, the cam drive sprocket 26, the cam driven sprocket 25, and the cam chain 27 are arranged in cam chain chambers 28 and 29 formed vertically through one side of the cylinder block 11 and the cylinder head 12.

The tension of the cam chain 27 is ensured by a cam chain guide 3o and a cam chain tensioner 31. The cam chain guide 30 is connected to the cylinder head 1
2 and the transmission case 32. Further, the cam chain tensioner 31 is slidably supported by the transmission case 32. This cam chain tensioner 31 is attached to a bushing rod 34 of an adjuster device 33.
The cam chain 27 is always pressed by the cam chain 27, and even if the cam chain 27 is extended, the cam chain is held under appropriate tension.

As shown in an enlarged view in FIG. 1(A), the cam chain tensioner 31 includes a tensioner back portion 35 that slides on the cam chain 27, and a reinforcing plate 36 that reinforces the tensioner back portion 35. be done. Tensioner back part 35
is generally made of hard rubber. A shaft support 37 is provided at the lower part of the tensioner rear part 35 in the drawing in a direction perpendicular to the plane of the paper in FIG. . This shaft support 37 is supported by the transmission case 32 as shown in FIG. 1(B), and the cam chain tensioner 31 is slidably provided.

As shown in FIG. 1(C), an oil hole 39 is formed in the tensioner back surface 35 near the joint surface 38 with the reinforcing plate 36. This oil hole 39 extends along the longitudinal direction of the tensioner back part 35 as shown in FIGS. 1(Δ) and (B),
Its upper end opens at the upper end of the tensioner back section 35 .

Further, the lower end of the oil hole 39 communicates with a shaft support oil hole 40 bored in the shaft support 37 .

A plurality of small holes 41 communicating with the oil hole 39 are formed at appropriate positions in the longitudinal direction of the oil hole 39 . This small hole 41 is
Sliding surface 4 of tensioner back section 35 with cam chain 27
The holes are perforated in a direction substantially perpendicular to or diagonally with respect to 2.

Further, as shown in FIGS. 1A and 1C, the reinforcing plate 36 is formed with a small hole 43 on the back side that communicates with the oil hole 39.

This backside small hole 43 is formed above a bushing guide 44 against which the bushing rod 34 of the adjuster device 33 presses.

Therefore, as shown by the arrow in FIG. 1(B), the shaft support oil hole 4
When engine lubricating oil or the like is fed under pressure from 0, this lubricating oil passes through the oil hole 39 to internally cool the tensioner back part 35, and also flows from the small hole 41 to the sliding surface 42 and then from the back side small hole 43. The lubricating oil is made to flow down to the bush guides 44 respectively.

In this way, since the lubricating oil flows in the oil hole 39, the tensioner back section 35 is internally cooled, preventing rubber deterioration and damage of the tensioner back section 35 due to heat, and improving the durability of the tensioner back section 35. I can do it.

Further, since the lubricating oil is actively supplied to the sliding surface 42 through the small holes 41, the lubrication and cooling of the sliding surface 42 are significantly improved, and the durability of the tensioner back surface 35 is further improved. Furthermore, since the lubricity of the circular contact surface 42 is improved in this way, there is no need to coat the sliding contact surface 42 with a synthetic resin or the like, and costs can be reduced.

Furthermore, since the lubricating oil is actively supplied to the bush guide 44 from the small hole 43 on the back side, the bush guide 44 is well lubricated and cooled. Therefore, the dents caused by the contact of the adjuster device 33 with the push rod 34 can be reduced, and the durability of the bush guide can also be improved.

In the above embodiment, the shaft support oil hole 40 is a blind hole within the shaft support 37 as shown in FIG. 1(B), but this shaft support oil hole 45 is shown in FIG. Alternatively, a through hole may be formed, and one end of the shaft support oil hole 45 may be closed by the transmission case 32.

Further, as shown in FIGS. 2(A) and 2(B), when the widthwise central portion of the reinforcing plate 36 is bulged toward the back side to form a protrusion 46 to improve rigidity, this bulge 46 An oil hole 47 that functions similarly to the oil hole 36 may be provided inside the oil hole 36 .

Furthermore, J in FIG. 2(C): Sea urchin, two reinforcing plates 48.
4.9 may be joined together, a bulge 50 may be formed at the center in the width direction, and the oil hole 51 may be formed surrounded by the bulge 50 to function as the oil hole 39.

Further, in the above embodiment, the shaft support oil hole 40 for supplying lubricating oil to the oil hole 39 is formed in the shaft support 47. Alternatively, lubricating oil or the like may be fed under pressure from this oil supply hole to the oil hole 39.

〔Effect of the invention〕

As described above, according to the cam chain tensioner for a four-cycle engine according to the present invention, the vicinity of the joint surface between the back surface of the tensioner that is joined to the cam chain and the reinforcing plate that is joined to the back surface of the tensioner and reinforces this back surface. In addition, since an oil hole is formed that extends in the longitudinal direction of the back surface of the tensioner, by flowing oil through the oil hole, the back surface of the tensioner can be cooled from inside, increasing the durability of the back surface of the tensioner. It can be improved.

[Brief explanation of the drawing]

FIGS. 1A and 1B are side views showing a cam chain tensioner for a four-stroke engine according to the present invention, respectively;
Partially cutaway front view, Figure 1 (C) is the IC- of Figure 1 (A)
2(A), (B), and (C) are sectional views corresponding to FIG. 1(C) showing other embodiments of the present invention, and FIG. 3 is a sectional view taken along the IC line. FIG. 4 is a longitudinal cross-sectional view showing a 4I Nicle engine to which the cam chain tensioner of FIG. 1 is applied, and FIG. FIG. 6 is a vertical cross-sectional view taken along the cam chain chamber of the four-cycle engine shown in the figure, and FIG. 6 is a perspective view showing a conventional cam chain tensioner. 21...Camshaft, 23...Clamp shift set, 25...Cam driven sprocket, 26...Cam drive sprocket, 27...Cam chain, 3
DESCRIPTION OF SYMBOLS 1... Cam chain tensioner, 35... Tensioner back part, 36... Reinforcement plate, 38... Joint surface, 39
... Oil hole, 40 ... Shaft support oil hole, 42 ... Joint surface.

Claims (1)

[Claims] A 4-cycle engine that is wrapped between the cam drive sprocket attached to the crankshaft of a 4-stroke engine and the cam driven sprocket attached to the camshaft, and constantly presses the cam chain to maintain appropriate tension on the cam chain. In the cam chain tensioner described above, a tensioner back surface that slides on the cam chain and a reinforcing plate that is joined to the tensioner back surface and reinforces this back surface extend in the longitudinal direction of the tensioner back surface near the joint surface. A cam chain tensioner for a four-stroke engine, which is characterized by having an oil hole formed therein.